CN109584200B - Visual positioning system and positioning method in power exchange station - Google Patents

Visual positioning system and positioning method in power exchange station Download PDF

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Publication number
CN109584200B
CN109584200B CN201811038852.4A CN201811038852A CN109584200B CN 109584200 B CN109584200 B CN 109584200B CN 201811038852 A CN201811038852 A CN 201811038852A CN 109584200 B CN109584200 B CN 109584200B
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image
offset
point
circle
current
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CN109584200A (en
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张炜
吴广涛
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NIO Holding Co Ltd
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NIO Anhui Holding Co Ltd
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    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T7/00—Image analysis
    • G06T7/0002—Inspection of images, e.g. flaw detection
    • G06T7/0004—Industrial image inspection
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T7/00—Image analysis
    • G06T7/70—Determining position or orientation of objects or cameras
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/60—Other road transportation technologies with climate change mitigation effect
    • Y02T10/70—Energy storage systems for electromobility, e.g. batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/60—Other road transportation technologies with climate change mitigation effect
    • Y02T10/7072—Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors

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  • Engineering & Computer Science (AREA)
  • Computer Vision & Pattern Recognition (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Quality & Reliability (AREA)
  • Image Analysis (AREA)
  • Current-Collector Devices For Electrically Propelled Vehicles (AREA)

Abstract

The invention belongs to the technical field of electric automobile battery replacement, and in particular relates to a vision-based positioning system and a positioning method in a battery replacement station, wherein a chassis of an electric automobile is provided with two markers which respectively correspond to a first positioning point and a second positioning point; the power-changing trolley moves according to the current offset of the first matching point and the first locating point so as to align the first matching point with the first locating point, and rotates according to the current offset of the second matching point and the second locating point by taking the first matching point as a circle center so as to align the second matching point with the second locating point. The invention can realize the accurate positioning of the power conversion trolley and the electric automobile and improve the power conversion rate.

Description

Visual positioning system and positioning method in power exchange station
Technical Field
The invention belongs to the technical field of power conversion, and particularly provides a vision-based positioning system and a positioning method in a power conversion station.
Background
With the popularization of electric automobiles, how to effectively provide rapid and effective energy supply for automobiles with insufficient energy is always an urgent problem in the industry. In many energy supplementing modes, the replacement of the power battery is a highly feasible scheme, and is generally completed in a power exchange station. How to realize the accurate positioning between the electric automobile and the power exchange trolley is one of key technologies of the power exchange station.
At present, the positioning accuracy of the PSD (Position Sensitive Detector) ranging method, the laser positioning method and other methods is low, and accurate positioning cannot be provided for a control closed loop in the power change process.
Accordingly, there is a need in the art for a high precision positioning method in a power exchange station to address the above-described problems.
Disclosure of Invention
In order to solve the above problems in the prior art, that is, in order to solve the problem of lower positioning accuracy between a battery changing trolley and an electric vehicle in a battery changing station in the prior art, the invention provides a vision-based positioning system in the battery changing station, wherein a chassis of the electric vehicle comprises at least two markers, the at least two markers comprise a first marker and a second marker, wherein the first marker corresponds to a first positioning point, and the second marker corresponds to a second positioning point; the battery replacement trolley is provided with a first matching point matched with the first locating point and a second matching point matched with the second locating point, and the locating system comprises: the image acquisition device is used for acquiring images of a chassis of the electric automobile to obtain a current position image; an image processor communicatively coupled to the image collector and configured to process the current position image to obtain a current offset between a current relative position and an ideal relative position, the current offset being divided into a first offset and a second offset, wherein the first offset is a current offset between the first matching point and a first location point, and the second offset is a current offset between the second matching point and a second location point; the adjustment module is in communication connection with the image processor, the adjustment module controls the power changing trolley to move according to the first offset so as to enable the first matching point to be aligned with the first locating point, and the adjustment module controls the power changing trolley to rotate around the first matching point serving as a circle center according to the second offset so as to enable the second matching point to be aligned with the second locating point.
In a preferred technical scheme of the positioning system, the image collector comprises a first image collector and a second image collector; the first image collector and the second image collector are arranged on the battery changing trolley, wherein the first image collector is used for collecting images of the first marker to obtain a first current position image, and the second image collector is used for collecting images of the second marker to obtain a second current position image; the image processor is configured to process the first current position image to obtain the first offset and to process the second current position image to obtain the second offset.
In an preferable technical scheme of the positioning system, the adjustment module comprises a first adjustment unit and a second adjustment unit, wherein the first adjustment unit controls the power changing trolley to move according to the first offset so as to align the first matching point with the first positioning point, and the second adjustment unit controls the power changing trolley to rotate according to the second offset by taking the first matching point as a circle center so as to align the second matching point with the second positioning point.
In the preferable technical scheme of the positioning system, a power battery is arranged on a chassis of the electric automobile, the marker is a pore plate on the power battery, and the positioning point is the center of a circular hole of the pore plate; the first offset is a first offset angle, the second offset is a second offset angle, wherein the first offset angle is a current offset angle between the first matching point and the first positioning point, and the second offset angle is a current offset angle between the second matching point and the second positioning point; the first adjusting unit controls the power changing trolley to move in a stepping mode according to the first offset angle so as to align the first matching point with the first matching point; the second adjusting unit controls the power changing trolley to rotate in a stepping mode by taking the first matching point as a circle center according to the second offset angle so as to align the second matching point with the second locating point.
In a preferred embodiment of the above positioning system, the image processing module is configured to calculate the current offset angle according to the following method: finding an image formed by the round hole of the pore plate in the current position image, and acquiring the circle center of the image formed by the round hole of the pore plate in the current position image; matching an image formed by the round hole of the pore plate in the current position image with an image formed by the round hole of the pore plate in the ideal position image; and if the matching result meets the precision requirement, aligning, and if the matching result does not meet the precision requirement, taking the difference between coordinates of the circle center of the circle in the current position image and the circle center of the circle in the ideal position image as a position difference (delta x, delta y), and taking arctan (delta y/delta x) as the current offset angle.
In a preferred embodiment of the positioning system, the image processing module is configured to perform the steps of finding an image of the circular hole of the orifice plate in the current position image and acquiring a center of the image of the circular hole of the orifice plate in the current position image according to the following method: searching a closed curve in the current position image; judging whether the closed curve is a circle meeting the precision requirement or not, wherein the precision requirement is to fit the closed curve into a circle and a circle center according to the definition of the circle, and calculate the distances between all points on the closed curve and the fitted circle center, and if the standard deviation sigma of the distances is less than or equal to kR, considering the closed curve as the circle meeting the precision requirement, wherein R is the radius of the fitted circle; if the closed curve meeting the precision requirement is one, taking the closed curve as an image of a round hole of the pore plate in the current position image; if the obtained closed curve meeting the precision requirement is 0, changing the precision requirement, and judging whether the closed curve is round meeting the new precision requirement; if the number of the obtained closed curves meeting the precision requirement is at least two, taking one closed curve with the minimum standard deviation sigma in the at least two closed curves as an image formed by a circular hole of the pore plate in the current position image; and taking the center of the selected closed curve as the center of an image formed by the round hole in the current position image.
In a preferred technical scheme of the positioning system, the marker comprises a template image and a comparison part corresponding to the template image, wherein the template image comprises a plurality of square lattices with the same size, the positioning point is the vertex of any lattice in the template image, the comparison part comprises a round part or a round hole, and in the direction perpendicular to the chassis of the electric automobile, the orthographic projection of the comparison part on the chassis of the electric automobile is positioned in the template image corresponding to the orthographic projection; the first offset vector is a first offset vector, the second offset is a second offset vector, wherein the first offset vector is a current offset vector between the first matching point and the first positioning point, and the second offset vector is a current offset vector between the second matching point and the second positioning point; the first adjusting unit controls the power changing trolley to move according to the first offset vector so as to align the first matching point with the first matching point; and the second adjusting unit controls the power-changing trolley to rotate by taking the first matching point as a circle center according to the second offset vector so as to align the second matching point with the second positioning point.
In a preferred embodiment of the above positioning system, the image processing module is configured to calculate the current offset vector according to the following method: acquiring the side length of the grid in the current position image as a first side length, acquiring the side length of the grid in the ideal position image as a second side length, and taking the ratio of the second side length to the first side length as a correction coefficient; processing the current position image to obtain a circle center of a circle in the current position image as a basic coordinate, and multiplying the basic coordinate by the correction coefficient to obtain a correction coordinate; and taking the difference between the correction coordinate and a standard coordinate as the current offset vector, wherein the standard coordinate is the coordinate of the circle center of the circle in the ideal position image.
In a preferred embodiment of the positioning system, the image processor is configured to perform the step of processing the current position image to obtain the center of the circle in the current position image according to the following method: performing blurring processing on the current position image to obtain a blurred current position image; intercepting a current template image on the blurred current position image, wherein the current template image comprises the circle and is square with a specific length as a side length; acquiring the boundary of the circle in the current template image; and acquiring the circle center of the circle in the current template image by adopting a Hough circle finding method.
In a preferred technical scheme of the positioning system, the adjusting module is arranged on the power changing trolley.
In a preferred technical scheme of the positioning system, the battery changing trolley is an automatic guided transport vehicle or a rail guided vehicle.
In order to solve the technical problem, the invention also provides a visual-based positioning method in the power exchange station, wherein the chassis of the electric automobile comprises at least two markers, the at least two markers comprise a first marker and a second marker, the first marker corresponds to a first positioning point, and the second marker corresponds to a second positioning point; the battery changing trolley is provided with a first matching point matched with the first locating point and a second matching point matched with the second locating point, and the locating method comprises the following steps: the image acquisition device acquires an image of a chassis of the electric automobile to obtain a current position image; the image processor processes the current position image to obtain a current offset between a current relative position and an ideal relative position, wherein the current offset is divided into a first offset and a second offset, the first offset is the current offset between the first matching point and a first positioning point, and the second offset is the current offset between the second matching point and a second positioning point; an adjustment module controls the power changing trolley to move according to the first offset so as to align the first matching point with the first positioning point; and the adjustment module controls the power changing trolley to rotate by taking the first matching point as a circle center according to the second offset so as to align the second matching point with the second positioning point.
In a preferred technical scheme of the positioning method, the image collector comprises a first image collector and a second image collector, the first image collector and the second image collector are installed on the battery-changing trolley, wherein the first image collector is used for collecting images of the first marker to obtain a first current position image, and the second image collector is used for collecting images of the second marker to obtain a second current position image; the image processor is configured to process the first current position image to obtain the first offset and to process the second current position image to obtain the second offset.
In the preferred technical scheme of the positioning method, the adjustment module comprises a first adjustment unit and a second adjustment unit, wherein the first adjustment unit controls the power changing trolley to move according to the first offset so as to align the first matching point with the first positioning point, and the second adjustment unit controls the power changing trolley to rotate around the first matching point as a circle center according to the second offset so as to align the second matching point with the second positioning point.
In the preferred technical scheme of the positioning method, a power battery is arranged on a chassis of the electric automobile, the marker is a pore plate on the power battery, and the positioning point is the circle center of a round hole of the pore plate; the first offset is a first offset angle, the second offset is a second offset angle, wherein the first offset angle is a current offset angle between the first matching point and the first positioning point, and the second offset angle is a current offset angle between the second matching point and the second positioning point; the first adjusting unit controls the power changing trolley to move in a stepping mode according to the first offset angle so as to align the first matching point with the first matching point; the second adjusting unit controls the power changing trolley to rotate in a stepping mode by taking the first matching point as a circle center according to the second offset angle so as to align the second matching point with the second locating point.
In the above preferred technical solution of the positioning method, the method for calculating the current offset angle includes the following steps: finding an image formed by the round hole of the pore plate in the current position image, and acquiring the circle center of the image formed by the round hole of the pore plate in the current position image; matching an image formed by the round hole of the pore plate in the current position image with an image formed by the round hole of the pore plate in the ideal position image; and if the matching result meets the precision requirement, aligning, and if the matching result does not meet the precision requirement, taking the difference between coordinates of the circle center of the circle in the current position image and the circle center of the circle in the ideal position image as a position difference (delta x, delta y), and taking arctan (delta y/delta x) as the current offset angle.
In the above preferred technical solution of the positioning method, the step of "finding an image formed by the circular hole of the orifice plate in the current position image and obtaining the circle center of the image formed by the circular hole of the orifice plate in the current position image" includes: searching a closed curve in the current position image; judging whether the closed curve is a circle meeting the precision requirement or not, wherein the precision requirement is to fit the closed curve into a circle and a circle center according to the definition of the circle, and calculate the distances between all points on the closed curve and the fitted circle center, and if the standard deviation sigma of the distances is less than or equal to kR, considering the closed curve as the circle meeting the precision requirement, wherein R is the radius of the fitted circle; if the closed curve meeting the precision requirement is one, taking the closed curve as an image of a round hole of the pore plate in the current position image; if the obtained closed curve meeting the precision requirement is 0, changing the precision requirement, and judging whether the closed curve is round meeting the new precision requirement; if the number of the obtained closed curves meeting the precision requirement is at least two, taking one closed curve with the minimum standard deviation sigma in the at least two closed curves as an image formed by a circular hole of the pore plate in the current position image; and taking the center of the selected closed curve as the center of an image formed by the round hole in the current position image.
In the preferred technical scheme of the positioning method, the marker comprises a template image and a comparison part corresponding to the template image, wherein the template image comprises a plurality of square lattices with the same size, the positioning point is the vertex of any lattice in the template image, the comparison part comprises a round part or a round hole, and in the direction perpendicular to the chassis of the electric automobile, the orthographic projection of the comparison part on the chassis of the electric automobile is positioned in the template image corresponding to the orthographic projection; the first offset is a first offset vector, the second offset is a second offset vector, wherein the first offset vector is a current offset vector between the first matching point and the first positioning point, and the second offset vector is a current offset vector between the second matching point and the second positioning point; the first adjusting unit controls the power changing trolley to move according to the first offset vector so as to align the first matching point with the first matching point; and the second adjusting unit controls the power-changing trolley to rotate by taking the first matching point as a circle center according to the second offset vector so as to align the second matching point with the second positioning point.
In the above preferred technical solution of the positioning method, the method for calculating the current offset vector includes the following steps: acquiring the side length of the grid in the current position image as a first side length, acquiring the side length of the grid in the ideal position image as a second side length, and taking the ratio of the second side length to the first side length as a correction coefficient; processing the current position image to obtain a circle center of a circle in the current position image as a basic coordinate, and multiplying the basic coordinate by the correction coefficient to obtain a correction coordinate; and taking the difference between the correction coordinate and a standard coordinate as the current offset vector, wherein the standard coordinate is the coordinate of the circle center of the circle in the ideal position image.
In the above preferred technical solution of the positioning method, the step of processing the current position image to obtain the center of the circle in the current position image includes: performing blurring processing on the current position image to obtain a blurred current position image; intercepting a current template image on the blurred current position image, wherein the current template image comprises the circle and is square with a specific length as a side length; acquiring the boundary of the circle in the current template image; and acquiring the circle center of the circle in the current template image by adopting a Hough circle finding method.
In the preferred technical scheme of the positioning method, the adjusting module is arranged on the power changing trolley.
In the preferred technical scheme of the positioning method, the battery changing trolley is an automatic guided transport vehicle or a rail guided vehicle.
In order to solve the technical problems, the invention also provides a power exchange station, which comprises the vision-based positioning system in any power exchange station.
As can be appreciated by those skilled in the art, in the technical scheme of the present invention, the current offset is obtained by processing the acquired current position image, and compared with the PSD (Position Sensitive Detector) ranging method, the laser positioning method and other methods, the accuracy of the visual positioning method is higher; the adjustment module controls the power changing trolley to move so as to align the first matching point with the first positioning point, and controls the power changing trolley to rotate by taking the first matching point as a circle center so as to align the second matching point with the second positioning point, so that the control on the movement of the power changing trolley is simpler, the control precision of the power changing trolley is improved, and the accurate positioning of the power changing trolley and the electric vehicle is further improved; the accurate positioning can be realized by only using two positioning points, so that the data processing capacity is smaller, and the positioning efficiency between the power conversion trolley and the electric automobile is improved.
The visual-based positioning system in a power exchange station is characterized in that a chassis of an electric automobile comprises at least two markers, wherein the at least two markers comprise a first marker and a second marker, the first marker corresponds to a first positioning point, and the second marker corresponds to a second positioning point; the battery replacement trolley is provided with a first matching point matched with the first locating point and a second matching point matched with the second locating point, and the locating system comprises: the image acquisition device is used for acquiring images of a chassis of the electric automobile to obtain a current position image; an image processor communicatively coupled to the image collector and configured to process the current position image to obtain a current offset between a current relative position and an ideal relative position, the current offset being divided into a first offset and a second offset, wherein the first offset is a current offset between the first matching point and a first location point, and the second offset is a current offset between the second matching point and a second location point; the adjustment module is in communication connection with the image processor, the adjustment module controls the power changing trolley to move according to the first offset so as to enable the first matching point to be aligned with the first locating point, and the adjustment module controls the power changing trolley to rotate around the first matching point serving as a circle center according to the second offset so as to enable the second matching point to be aligned with the second locating point.
The positioning system according to claim 2, wherein the image collector comprises a first image collector and a second image collector; the first image collector and the second image collector are arranged on the battery changing trolley, wherein the first image collector is used for collecting images of the first marker to obtain a first current position image, and the second image collector is used for collecting images of the second marker to obtain a second current position image; the image processor is configured to process the first current position image to obtain the first offset and to process the second current position image to obtain the second offset.
The positioning system according to claim 3 and claim 2, wherein the adjustment module includes a first adjustment unit and a second adjustment unit, the first adjustment unit controls the power changing trolley to move according to the first offset so as to align the first matching point with the first positioning point, and the second adjustment unit controls the power changing trolley to rotate according to the second offset with the first matching point as a center so as to align the second matching point with the second positioning point.
The positioning system according to the scheme 4 and the scheme 3 is characterized in that a power battery is installed on a chassis of the electric automobile, the marker is a pore plate on the power battery, and the positioning point is the circle center of a round hole of the pore plate; the first offset is a first offset angle, the second offset is a second offset angle, wherein the first offset angle is a current offset angle between the first matching point and the first positioning point, and the second offset angle is a current offset angle between the second matching point and the second positioning point; the first adjusting unit controls the power changing trolley to move in a stepping mode according to the first offset angle so as to align the first matching point with the first matching point; the second adjusting unit controls the power changing trolley to rotate in a stepping mode by taking the first matching point as a circle center according to the second offset angle so as to align the second matching point with the second locating point.
The positioning system according to claim 5, wherein the image processing module is configured to calculate the current offset angle as follows: finding an image formed by the round hole of the pore plate in the current position image, and acquiring the circle center of the image formed by the round hole of the pore plate in the current position image; matching an image formed by the round hole of the pore plate in the current position image with an image formed by the round hole of the pore plate in the ideal position image; and if the matching result meets the precision requirement, aligning, and if the matching result does not meet the precision requirement, taking the difference between coordinates of the circle center of the circle in the current position image and the circle center of the circle in the ideal position image as a position difference (delta x, delta y), and taking arctan (delta y/delta x) as the current offset angle.
The positioning system according to claim 6, wherein the image processing module is configured to perform the steps of finding the circle center of the image of the circular hole of the orifice plate in the current position image, and acquiring the circle center of the image of the circular hole of the orifice plate in the current position image, as follows: searching a closed curve in the current position image; judging whether the closed curve is a circle meeting the precision requirement or not, wherein the precision requirement is to fit the closed curve into a circle and a circle center according to the definition of the circle, and calculate the distances between all points on the closed curve and the fitted circle center, and if the standard deviation sigma of the distances is less than or equal to kR, considering the closed curve as the circle meeting the precision requirement, wherein R is the radius of the fitted circle; if the closed curve meeting the precision requirement is one, taking the closed curve as an image of a round hole of the pore plate in the current position image; if the obtained closed curve meeting the precision requirement is 0, changing the precision requirement, and judging whether the closed curve is round meeting the new precision requirement; if the number of the obtained closed curves meeting the precision requirement is at least two, taking one closed curve with the minimum standard deviation sigma in the at least two closed curves as an image formed by a circular hole of the pore plate in the current position image; and taking the center of the selected closed curve as the center of an image formed by the round hole in the current position image.
The positioning system according to claim 7, wherein the marker includes a template image and a contrast component corresponding to the template image, wherein the template image includes a plurality of square lattices of the same size, the positioning points are vertexes of any one lattice in the template image, the contrast component includes a circular portion or a circular hole, and in a direction perpendicular to the chassis of the electric automobile, an orthographic projection of the contrast component on the chassis of the electric automobile is located in the template image corresponding to the contrast component; the first offset vector is a first offset vector, the second offset is a second offset vector, wherein the first offset vector is a current offset vector between the first matching point and the first positioning point, and the second offset vector is a current offset vector between the second matching point and the second positioning point; the first adjusting unit controls the power changing trolley to move according to the first offset vector so as to align the first matching point with the first matching point; and the second adjusting unit controls the power-changing trolley to rotate by taking the first matching point as a circle center according to the second offset vector so as to align the second matching point with the second positioning point.
The positioning system of claim 8, 7, wherein the image processing module is configured to calculate the current offset vector as follows: acquiring the side length of the grid in the current position image as a first side length, acquiring the side length of the grid in the ideal position image as a second side length, and taking the ratio of the second side length to the first side length as a correction coefficient; processing the current position image to obtain a circle center of a circle in the current position image as a basic coordinate, and multiplying the basic coordinate by the correction coefficient to obtain a correction coordinate; and taking the difference between the correction coordinate and a standard coordinate as the current offset vector, wherein the standard coordinate is the coordinate of the circle center of the circle in the ideal position image.
The positioning system according to claim 9, wherein the image processor is configured to perform the step of "processing the current position image to acquire the center of a circle in the current position image" as follows: performing blurring processing on the current position image to obtain a blurred current position image; intercepting a current template image on the blurred current position image, wherein the current template image comprises the circle and is square with a specific length as a side length; acquiring the boundary of the circle in the current template image; and acquiring the circle center of the circle in the current template image by adopting a Hough circle finding method.
The positioning system according to any one of claims 10, 1-9, wherein the adjustment module is disposed on the battery changing cart.
The positioning system according to claim 11, wherein the battery changing carriage is an automated guided vehicle or a rail guided vehicle.
The scheme 12, a positioning method based on vision in a power exchange station, is characterized in that a chassis of an electric automobile comprises at least two markers, wherein the at least two markers comprise a first marker and a second marker, the first marker corresponds to a first positioning point, and the second marker corresponds to a second positioning point; the battery changing trolley is provided with a first matching point matched with the first locating point and a second matching point matched with the second locating point, and the locating method comprises the following steps: the image acquisition device acquires an image of a chassis of the electric automobile to obtain a current position image; the image processor processes the current position image to obtain a current offset between a current relative position and an ideal relative position, wherein the current offset is divided into a first offset and a second offset, the first offset is the current offset between the first matching point and a first positioning point, and the second offset is the current offset between the second matching point and a second positioning point; an adjustment module controls the power changing trolley to move according to the first offset so as to align the first matching point with the first positioning point; and the adjustment module controls the power changing trolley to rotate by taking the first matching point as a circle center according to the second offset so as to align the second matching point with the second positioning point.
The positioning method according to claim 13, wherein the image collector includes a first image collector and a second image collector, the first image collector and the second image collector are mounted on the battery-change cart, the first image collector is configured to perform image collection on the first marker to obtain a first current position image, and the second image collector is configured to perform image collection on the second marker to obtain a second current position image; the image processor is configured to process the first current position image to obtain the first offset and to process the second current position image to obtain the second offset.
The positioning method according to claim 14 and the positioning method according to claim 13, wherein the adjustment module includes a first adjustment unit and a second adjustment unit, the first adjustment unit controls the power changing trolley to move according to the first offset so as to align the first matching point with the first positioning point, and the second adjustment unit controls the power changing trolley to rotate according to the second offset with the first matching point as a center so as to align the second matching point with the second positioning point.
The positioning method according to the scheme 15 and the scheme 14 is characterized in that a power battery is installed on a chassis of the electric automobile, the marker is a hole plate on the power battery, and the positioning point is the center of a round hole of the hole plate; the first offset is a first offset angle, the second offset is a second offset angle, wherein the first offset angle is a current offset angle between the first matching point and the first positioning point, and the second offset angle is a current offset angle between the second matching point and the second positioning point; the first adjusting unit controls the power changing trolley to move in a stepping mode according to the first offset angle so as to align the first matching point with the first matching point; the second adjusting unit controls the power changing trolley to rotate in a stepping mode by taking the first matching point as a circle center according to the second offset angle so as to align the second matching point with the second locating point.
The positioning method according to claim 16, wherein the method for calculating the current offset angle includes the steps of: finding an image formed by the round hole of the pore plate in the current position image, and acquiring the circle center of the image formed by the round hole of the pore plate in the current position image; matching an image formed by the round hole of the pore plate in the current position image with an image formed by the round hole of the pore plate in the ideal position image; and if the matching result meets the precision requirement, aligning, and if the matching result does not meet the precision requirement, taking the difference between coordinates of the circle center of the circle in the current position image and the circle center of the circle in the ideal position image as a position difference (delta x, delta y), and taking arctan (delta y/delta x) as the current offset angle.
The positioning method according to claim 17, wherein the step of "finding an image of the circular hole of the orifice plate in the current position image and acquiring the center of the image of the circular hole of the orifice plate in the current position image" includes: searching a closed curve in the current position image; judging whether the closed curve is a circle meeting the precision requirement or not, wherein the precision requirement is to fit the closed curve into a circle and a circle center according to the definition of the circle, and calculate the distances between all points on the closed curve and the fitted circle center, and if the standard deviation sigma of the distances is less than or equal to kR, considering the closed curve as the circle meeting the precision requirement, wherein R is the radius of the fitted circle; if the closed curve meeting the precision requirement is one, taking the closed curve as an image of a round hole of the pore plate in the current position image; if the obtained closed curve meeting the precision requirement is 0, changing the precision requirement, and judging whether the closed curve is round meeting the new precision requirement; if the number of the obtained closed curves meeting the precision requirement is at least two, taking one closed curve with the minimum standard deviation sigma in the at least two closed curves as an image formed by a circular hole of the pore plate in the current position image; and taking the center of the selected closed curve as the center of an image formed by the round hole in the current position image.
The positioning method according to claim 18, wherein the marker includes a template image and a contrast member corresponding to the template image, wherein the template image includes a plurality of square lattices of the same size, the positioning point is a vertex of any one of the lattices in the template image, the contrast member includes a circular portion or a circular hole, and in a direction perpendicular to the chassis of the electric vehicle, an orthographic projection of the contrast member on the chassis of the electric vehicle is located in the template image corresponding thereto; the first offset is a first offset vector, the second offset is a second offset vector, wherein the first offset vector is a current offset vector between the first matching point and the first positioning point, and the second offset vector is a current offset vector between the second matching point and the second positioning point; the first adjusting unit controls the power changing trolley to move according to the first offset vector so as to align the first matching point with the first matching point; and the second adjusting unit controls the power-changing trolley to rotate by taking the first matching point as a circle center according to the second offset vector so as to align the second matching point with the second positioning point.
The positioning method according to claim 19, wherein the method for calculating the current offset vector includes the steps of: acquiring the side length of the grid in the current position image as a first side length, acquiring the side length of the grid in the ideal position image as a second side length, and taking the ratio of the second side length to the first side length as a correction coefficient; processing the current position image to obtain a circle center of a circle in the current position image as a basic coordinate, and multiplying the basic coordinate by the correction coefficient to obtain a correction coordinate; and taking the difference between the correction coordinate and a standard coordinate as the current offset vector, wherein the standard coordinate is the coordinate of the circle center of the circle in the ideal position image.
The positioning method according to claim 20, wherein the step of "processing the current position image to obtain the center of the circle in the current position image" includes: performing blurring processing on the current position image to obtain a blurred current position image; intercepting a current template image on the blurred current position image, wherein the current template image comprises the circle and is square with a specific length as a side length; acquiring the boundary of the circle in the current template image; and acquiring the circle center of the circle in the current template image by adopting a Hough circle finding method.
The positioning method according to any one of claims 21 to 12 to 20, wherein the adjustment module is provided on the battery changing cart.
The positioning method according to claim 22, wherein the battery changing trolley is an automated guided vehicle or a rail guided vehicle.
Scheme 23, a power plant comprising a vision-based positioning system in a power plant according to any one of the claims 1-11.
Drawings
Fig. 1 is a schematic structural diagram of a vision-based positioning system in a power exchange station according to an embodiment of the present invention.
Fig. 2 is a schematic partial side view of a power exchange station with a positioning system in an embodiment of the invention.
Fig. 3 is a positioning schematic diagram of a vision-based positioning system in a power exchange station in accordance with an embodiment of the present invention.
Fig. 4 is a flowchart of a visual positioning method in a power exchange station according to an embodiment of the present invention.
FIG. 5 is a schematic diagram of a label according to an embodiment of the present invention.
Fig. 6 is a flow chart of a visual positioning method in another power exchange station in an embodiment of the invention.
Fig. 7 is a flowchart of step S202 in the embodiment of the present invention.
Fig. 8 is a schematic diagram of a current position image in an embodiment of the present invention.
Fig. 9 is a flowchart of step S202 in the embodiment of the present invention.
Fig. 10 is a schematic structural diagram of a template image according to an embodiment of the present invention.
Fig. 11 is a flow chart of a visual positioning method in another power exchange station in an embodiment of the invention.
Fig. 12 is a flowchart of step S302 in the embodiment of the present invention.
Fig. 13 is a flowchart of step S202 in an embodiment of the present invention.
Detailed Description
Preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are merely for explaining the technical principles of the present invention, and are not intended to limit the scope of the present invention. Those skilled in the art can adapt it as desired to suit a particular application.
In order to ensure the endurance mileage of the electric automobile, the replacement of the power storage battery of the electric automobile in the power exchange station is a feasible method. For the power exchange station, how to realize accurate positioning between the electric automobile and the power exchange trolley is one of key technologies of the power exchange station. However, the visual positioning in the current market is coarse positioning, and the positioning accuracy is low.
In order to solve the problems, the invention provides a vision-based positioning system and a vision-based positioning method in a power exchange station, wherein the system is based on acquisition and processing of visual images so as to realize accurate positioning of a power exchange trolley/a power exchange platform and an electric automobile. The vision-based positioning system and the positioning method in the power exchange station provided by the invention are clearly and completely described below with reference to the accompanying drawings.
Fig. 1 is a schematic structural diagram of a vision-based positioning system in a power exchange station according to an embodiment of the present invention. Fig. 2 is a schematic partial side view of a power exchange station with a positioning system in an embodiment of the invention. Fig. 3 is a positioning schematic diagram of a vision-based positioning system in a power exchange station in accordance with an embodiment of the present invention. In order to facilitate the explanation of the positioning principle of the positioning system in this embodiment, fig. 2 shows a side view of the electric vehicle, and fig. 3 shows the battery changing trolley in an aligned position, so as to facilitate the display of the positions of the first positioning point and the second positioning point, although the electric vehicle is not shown in fig. 3. Referring to fig. 1 to 3, the power exchange station can provide a power exchange service for the electric automobile 6, in the power exchange process, the electric automobile 6 is usually driven into the power exchange station and stopped on the power exchange station 5, the power exchange platform 5 is used for providing a parking and power exchange place for the electric automobile 6, and the power exchange platform 5 is provided with a working hole, and the working hole is located below the positioned electric automobile 6, so that the power exchange trolley 6 can exchange power for the electric automobile 6 through the working hole.
The chassis of the electric vehicle 6 includes at least two markers, and for simplicity of description, the embodiment of the present invention is described with the chassis of the electric vehicle including two markers. For ease of illustration, these two markers are referred to as first marker a and second marker b, respectively. Wherein the first marker a corresponds to the first positioning point A, and the second marker B corresponds to the second positioning point B. A first matching point A matched with the first positioning point A is arranged on the battery changing trolley 1 And a second matching point B matching with the second locating point B 1 . It should be noted that the matching point in the present invention is only a determined position on the battery changing trolley, and is not necessarily an actual markAnd recording the point on the power changing trolley. In fig. 3, for clarity, the relative positional relationship of the marker, the positioning point and the matching point is that the marker is drawn at the corresponding position of the power conversion trolley, and for convenience, the current position and the ideal position of the power conversion trolley are drawn in the same drawing.
The positioning system provided in this embodiment includes an image collector 1, an image processor 2, and an adjustment module 3. Wherein,,
the image collector 1 is configured to perform image collection of a chassis of the electric vehicle 6 to obtain a current position image. The current position image comprises an image of the first anchor point a and/or the second anchor point B. The current position image is an image acquired under the condition that the specified position point and the matching point are in the current position relation. It should be noted that, because the number of image collectors is different and the collection angles set by the image collectors are different, the number of locating points included in the current position image is different.
The image processor 2 is in communication with the image collector 1 and the image processor 2 is configured to process the current position image to obtain a current offset between the current relative position and the ideal relative position. The current offset is divided into a first offset and a second offset, wherein the first offset is a first matching point A 1 The current offset with the first positioning point A, the second offset is the second matching point B 1 A current offset from the second anchor point B. The ideal position image is an image obtained by the image acquisition device for acquiring the image of the chassis of the electric automobile when the positioning is performed, and is related to the automobile type, namely, the images acquired by the image acquisition device are consistent when all the automobiles of the same automobile type are positioned, so that the ideal position image can be acquired in advance.
The adjustment module 3 is in communication with the image processor 2 and is configured to control the movement of the battery change cart 4 in accordance with the first offset to cause the first matching point a 1 Aligned with the first positioning point A, the adjusting module controls the power changing trolley 4 to take the first matching point as a circle center A according to the second offset 1 To make rotationSo that the second matching point B 1 Aligned with the second anchor point B.
Based on the positioning system, the embodiment also provides a visual positioning method in the power exchange station, and fig. 4 is a flowchart of the visual positioning method in the power exchange station in the embodiment of the invention. Referring to fig. 4, the positioning method includes the following steps:
step S101: the image collector is used for collecting images of the chassis of the electric automobile to obtain a current position image.
Step S102: the image processor processes the current position image to obtain a current offset between the current relative position and the ideal relative position, wherein the current offset is divided into a first offset and a second offset, the first offset is the current offset between the first matching point and the first positioning point, and the second offset is the current offset between the second matching point and the second positioning point.
Step S103: the adjustment module controls the battery changing trolley to move according to the first offset to align the first matching point with the first positioning point.
Step S104: and the adjustment module controls the power changing trolley to rotate by taking the first matching point as a circle center according to the second offset so as to align the second matching point with the second positioning point.
According to the visual positioning system and the visual positioning method in the power exchange station, the current offset is obtained by processing the acquired current position image, and compared with the PSD (Position Sensitive Detector) ranging method, the laser positioning method and other methods, the visual positioning method is high in accuracy; the adjustment module controls the power changing trolley to move so as to align the first matching point with the first positioning point, and controls the power changing trolley to rotate by taking the first matching point as a circle center so as to align the second matching point with the second positioning point, so that the control on the movement of the power changing trolley is simpler, the control precision of the power changing trolley is improved, and the accurate positioning of the power changing trolley and the electric vehicle is further improved; the accurate positioning can be realized by only using two positioning points, so that the data processing capacity is smaller, and the positioning efficiency between the power conversion trolley and the electric automobile is improved.
Referring further to fig. 1 and 2, in general, a power battery 601 is mounted on a chassis of the electric vehicle 5, and a marker is disposed on the power battery 601. By means of the design, on one hand, the electric automobile does not need to be refitted, on the other hand, as the power battery is usually provided by a company or a mechanism for providing power exchange service, the marker is fixed on the power battery, and uniform setting can be carried out, so that two positioning points of each electric automobile are located at fixed positions, and the positioning is carried out in the power exchange station conveniently. Preferably, the first positioning point a and the second positioning point B are aligned in the length direction of the electric vehicle 6, or the first positioning point a and the second positioning point B are aligned in the width direction of the electric vehicle 6. Because the section of the driving route of the battery changing trolley, which is close to the electric automobile, is generally parallel to the length direction or the width direction of the electric automobile, the positions of the first locating point and the second locating point are set, and the battery changing trolley can be aligned with the first locating point more easily.
With continued reference to fig. 1 and 2, the image collector 1 includes a first image collector and a second image collector, where the first image collector is configured to perform image collection on a first marker to obtain a first current position image, and the second image collector is configured to perform image collection on a second marker to obtain a second current position image, and the first image collector and the second image collector are mounted on the battery-change cart 4; the image processor 2 is configured to process the first current position image to obtain a first offset and to process the second current position image to obtain a second offset. The mode that each marker adopts different image collectors to collect and the position of each image collector is different can enable deformation of the marker in the collected current position image to be smaller, and therefore difficulty of image processing is reduced and accuracy of image processing is improved. Furthermore, the center of the lens in each image collector can be used as a matching point, so that the positioning accuracy is further improved.
With continued reference to fig. 1 and 3, the adjustment module 3 includes a first adjustment unit and a second adjustment unit, where the first adjustment unit controls the movement of the battery changing trolley 4 according to a first offset to make the first adjustment unitMatching point A 1 The second adjusting unit is aligned with the first positioning point A and controls the battery changing trolley to be matched with the first positioning point A according to the second offset 1 Rotated for the center of the circle to make the second matching point B 1 Aligned with the second anchor point B. The setting module comprises two adjusting units, which is beneficial to controlling the battery changing trolley.
With continued reference to fig. 1, the image collector 1 may preferably be a video camera or a still camera. The image acquisition of the marker can be achieved either by a camera that is continuously capable of continuously acquiring images or by a camera that can acquire only one image at a time.
With continued reference to fig. 1, the battery change cart 4 may preferably be an automated guided vehicle or a rail guided vehicle. Both can move according to the preset route, and it is to be noted that, because the power changing trolley needs to rotate, the automatic guiding transport vehicle needs to be provided with a related guiding route capable of guiding the power changing trolley to rotate; the track section which can rotate is designed for the track guided vehicle, and under the condition that the turntable is arranged below the track section which needs to rotate, the power conversion trolley can rotate on the track.
With continued reference to fig. 1, the adjustment module 3 may preferably be provided on the power changing trolley 4 to facilitate control of the power changing trolley.
FIG. 5 is a schematic diagram of a label according to an embodiment of the present invention. Referring to fig. 1, 3 and 5, in some positioning systems, the marker is the hole plate 602 of the power battery, and the positioning point is the center of a circular hole 6021 of the hole plate 602. In this embodiment, the orifice plate is used as the marker, and the orifice plate is an accessory on the power battery, and the orifice plate is used as the marker without modifying the power battery. In the present embodiment, the image processor 2 is configured to process the current position image to obtain a current offset angle as a current offset, wherein the first offset is a first offset angle, the second offset is a second offset angle, and the first offset angle is a first matching point a 1 A current offset angle between the first locating point A and the second locating point B 1 A current offset angle from the second anchor point B. First adjustment sheetThe cell controls the power changing trolley to move in a stepping mode according to the first offset angle so as to align the first matching point with the first matching point; the second adjusting unit controls the power changing trolley to rotate in a stepping mode by taking the first matching point as a circle center according to the second offset angle so as to align the second matching point with the second locating point. The positioning between the electric automobile and the level changing platform and between the level changing trolley and the electric automobile can be realized by adjusting in a stepping mode according to the offset angle. It should be noted that, the movement is performed in a step-by-step manner, and after each step, image acquisition and processing are required to determine whether alignment is performed, if alignment is performed, adjustment is stopped, and if alignment is not performed, further adjustment is performed until positioning is completed.
The embodiment also provides a visual positioning method in the power exchange station based on the positioning system with the marker as the pore plate, and fig. 6 is a flowchart of a visual positioning method in another power exchange station in the embodiment of the invention. Referring to fig. 6, the positioning method includes the following steps:
step S201: the image collector is used for collecting images of the chassis of the electric automobile to obtain a current position image.
Step S202: the image processor processes the current position image to obtain a current offset angle as a current offset, wherein the first offset is a first offset angle, and the second offset is a second offset angle, and the first offset angle is a first matching point A 1 A current offset angle between the first locating point A and the second locating point B 1 A current offset angle from the second anchor point B.
Step S203: the first adjusting unit controls the power changing trolley to move in a stepping mode according to the first offset angle so as to align the first matching point with the first matching point.
Step S204: the second adjusting unit controls the power changing trolley to rotate in a stepping mode by taking the first matching point as a circle center according to the second offset angle so as to align the second matching point with the second locating point.
Further, the image processor 2 is configured to execute step S202 to calculate the current offset angle as follows. Fig. 7 is a flowchart of step S202 in the embodiment of the present invention. Referring to fig. 7, the method for calculating the current offset angle includes the following steps:
step S2021: finding out an image formed by the round hole of the pore plate in the current position image, and acquiring the circle center of the image formed by the round hole of the pore plate in the current position image. Fig. 8 is a schematic diagram of a current position image in an embodiment of the present invention. Referring to FIG. 8, it should be noted that FIG. 7 shows a circle O in the ideal position image 1 For ease of illustration only, and in fact, circular O 1 And round O 2 Should be in different images.
Step S2022: and matching the image formed by the round hole of the orifice plate in the current position image with the image formed by the round hole of the orifice plate in the ideal position image. The ideal position image is an image acquired by the image acquisition device on the chassis of the electric automobile when the first matching point and the first positioning point and/or the second matching point and the second positioning point are in an aligned state. With continued reference to FIG. 8, the circle O in FIG. 8 is depicted by the dashed line 1 Is an image of the circular aperture of the aperture plate in the image of the ideal location.
Step S2023: and if the matching result meets the precision requirement, aligning, and if the matching result does not meet the precision requirement, taking the difference between coordinates of the circle center of the circle in the current position image and the circle center of the circle in the ideal position image as a position difference (delta x, delta y), and taking arctan (delta y/delta x) as a current offset angle. Specifically, please continue to refer to fig. 8, if the center O is set 1 The coordinates of (a) are (a) 1 ，b 1 ) Set the center of circle O 2 The coordinates of (a) are (a) 2 ，b 2 ) Then Δx=a 1 -a 2 ，Δy＝b 1 -b 2 Therefore, an accurate current offset direction can be calculated, and a stepping operation is performed according to the current offset direction, and at this time, the amplitude of the stepping can be increased so as to reduce the number of times of image acquisition and adjustment, thereby improving the positioning speed and reducing the load of image processing.
Further, the image processing module 2 is configured to execute step S2021 to calculate the current offset angle as follows. Fig. 9 is a flowchart of step S202 in the embodiment of the present invention. Referring to fig. 9, the step of "finding an image of a circular hole of the aperture plate in the current position image and acquiring a center of the image of the circular hole of the aperture plate in the current position image" includes:
step S20211: and searching a closed curve in the current position image. In the present invention, the method of searching the closed curve is that any point M on the target curve has two points with the minimum distance from the point M. It should be noted that, the point M represents only any point on the target curve, and when there is only one point on the target curve, the distance between the point M and the point M is the smallest.
Step S20212: judging whether the closed curve is a circle meeting the precision requirement, wherein the precision requirement is to fit the closed curve into the circle and the circle center according to the definition of the circle, and calculate the distances from all points on the closed curve to the fitted circle center, and if the standard deviation sigma of the distances is less than or equal to kR, the closed curve is considered to be the circle meeting the precision requirement, wherein R is the radius of the fitted circle. It should be noted that, according to different positioning accuracy requirements, k may be different values, where under the existing accuracy requirements, k is approximately equal to 0.05, that is, σ+.0.05r, that is, the circle is considered to be a circle meeting the accuracy requirements.
Step S20213: if the obtained closed curve meeting the precision requirement is one, taking the closed curve as an image of a round hole of the pore plate in the current position image; if the obtained closed curve meeting the precision requirement is 0, changing the precision requirement, and judging whether the closed curve is a circle meeting the new precision requirement; if the obtained closed curves meeting the precision requirement are at least two, taking one closed curve with the smallest standard deviation sigma in the at least two closed curves as an image of a round hole of the pore plate in the current position image. It should be noted that the new precision requirements are: the closed curve is circular under the precision requirement if the standard deviation sigma +.kR of at least w% of points on the closed curve is less than or equal to kR, wherein w can be adjusted according to specific conditions, for example, the closed curve is circular under the precision requirement if the standard deviation sigma +.ltoreq.kR of at least 75% of points on the closed curve is less than or equal to kR.
Step S20214: and taking the center of the selected closed curve as the center of an image formed by the round hole in the current position image.
In this embodiment, the adjustment accuracy requirement is that shadows or stains may occur during shooting, so that the circular hole of the orifice plate in the current position image cannot be completely circular, and an image formed by the circular hole of the orifice plate can be found even if shadows or stains occur after the adjustment accuracy, so that the method has strong adaptability.
Fig. 10 is a schematic structural diagram of a template image according to an embodiment of the present invention. Referring to fig. 1, 3 and 10, the marker includes a template image 603 and a comparison component corresponding to the template image, where the template image 603 includes a plurality of square lattices 6031 with the same size, and in some specific embodiments, the lattices 6031 are arranged along the row direction and the column direction, and the adjacent lattices have different colors, and of course, the arrangement manner of the lattices 6031 may also be different, which is not limited in the present invention. The positioning point is the vertex of any grid 6031 in the template image 603, the comparison part comprises a round part or a round hole, and in the direction perpendicular to the chassis of the electric automobile, the orthographic projection of the comparison part on the chassis of the electric automobile is positioned in the template image corresponding to the orthographic projection. Thus, the template image can be used as a reference, so that the calculation accuracy of the offset can be improved.
In this embodiment, the first offset is a first offset vector, and the second offset is a second offset vector, where the first offset vector is the first matching point a 1 A current offset vector between the first locating point a and the second matching point b 1 A current offset vector between the second positioning point b; the first adjusting unit controls the electric automobile and the power conversion platform to move relatively in a first direction according to the first offset vector so as to align the electric automobile and the power conversion platform in the first direction; the second adjusting unit controls the electric vehicle and the power changing trolley to move relatively in a second direction according to the second offset vector so as to align the power changing trolley with the electric vehicle. In the embodiment, the offset vector is directly calculated, so that the operation amount of image processing is reduced, and the electric vehicle and the level-changing platform or the power-changing trolley and the power can be completed at one time according to the offset vectorPositioning between the motor cars can be completed more quickly.
The present embodiment also provides a visual positioning method in a power exchange station based on a positioning system in which the marker includes a template image 603 and a contrast member, and fig. 11 is a flowchart of a visual positioning method in another power exchange station in an embodiment of the present invention. Referring to fig. 11, the positioning method includes the following steps:
Step S301: the image collector is used for collecting images of the chassis of the electric automobile to obtain a current position image.
Step S302: the image processor processes the current position image to obtain a current offset vector as a current offset, wherein the first offset vector is a first offset vector, the second offset vector is a second offset vector, and the first offset vector is a first matching point A 1 A current offset vector between the first locating point A and the second locating point B, wherein the second offset vector is a second matching point B 1 And the current offset vector between the second anchor point B.
Step S303: the first adjusting unit controls the power changing trolley to move according to the first offset vector so as to align the first matching point with the first matching point
Step S304: the second adjusting unit controls the power changing trolley to rotate by taking the first matching point as a circle center according to the second offset vector so as to align the second matching point with the second locating point.
Further, the image processor 2 is configured to perform step S302 to calculate the current offset angle as follows. Fig. 12 is a flowchart of step S302 in the embodiment of the present invention. Referring to fig. 12, the method for calculating the current offset angle includes the following steps:
step S3021: and acquiring the side length of the grid in the current position image as a first side length, acquiring the side length of the grid in the ideal position image as a second side length, and taking the ratio of the second side length to the first side length as a correction coefficient. The side length of the grid is the average side length of all grids in the image (current position image or ideal position image).
Step S3022: the current position image is processed to obtain the circle center of a circle in the current position image as a basic coordinate, and the basic coordinate is multiplied by a correction coefficient to be used as a correction coordinate. And correcting the basic coordinates through the correction coefficient, wherein the corrected basic coordinates are the coordinates of the basic coordinates in the ideal position image.
Step S3023: and taking the difference between the correction coordinate and the standard coordinate as the current offset vector, wherein the standard coordinate is the coordinate of the center of a circle in the ideal position image.
In this embodiment, by correcting the center coordinates of the circle in the current position image, the deformation of the image caused by the shooting position and the shooting angle of the image collector can be corrected, and the positioning accuracy is improved.
Further, fig. 13 is a flowchart of step S202 in the embodiment of the present invention. The step of processing the current position image to acquire the center of the circle in the current position image in step S202 includes:
step S2021: and blurring the current position image to obtain a blurred current position image. The blurring process may be performed by using a gaussian blurring method or other realizable blurring methods, where the blurring process is performed on the current position image to reduce noise in the image. Of course, if the acquired image is a black-and-white image, the blurring process can be directly performed, and if the acquired image is a color image, the gray-scale process can be performed first to reduce the post-processing difficulty.
Step S2022: and cutting out a current template image on the blurred current position image, wherein the current template image comprises a circle and is square with a specific length as a side length. In order to ensure the integrity of the circle after the screenshot, the specific side length should be larger than the diameter of the circle in the current position image, and further, in order to reduce the range of subsequent circle finding and the data processing amount, the specific side length should be smaller than 2 times of the diameter of the circle in the current position image as much as possible.
Step S2023: and acquiring a circular boundary in the current template image.
Step S2024: and acquiring the circle center of the circle in the current template image by adopting a Hough circle finding method.
The circle center of the circle in the current template image is obtained by intercepting the template and a Hough circle finding method, so that the subsequent circle finding range can be reduced, the data processing amount is reduced, and the integrity of the circle after screenshot is ensured; the method for finding the circle is simple, and the obtained coordinates of the center of the circle are accurate.
In order to solve the above technical problems, this embodiment provides a power exchange station, which includes the vision-based positioning system in the power exchange station in any one of the above embodiments, and has the beneficial effects of the vision-based positioning system in the power exchange station in any one of the above embodiments, which are not described herein.
Thus far, the technical solution of the present invention has been described in connection with the preferred embodiments shown in the drawings, but it is easily understood by those skilled in the art that the scope of protection of the present invention is not limited to these specific embodiments. Equivalent modifications and substitutions for related technical features may be made by those skilled in the art without departing from the principles of the present invention, and such modifications and substitutions will fall within the scope of the present invention.

Claims (21)

1. A vision-based positioning system in a power exchange station, which is characterized in that a chassis of an electric automobile comprises at least two markers, wherein the at least two markers comprise a first marker and a second marker, the first marker corresponds to a first positioning point, and the second marker corresponds to a second positioning point; the battery replacement trolley is provided with a first matching point matched with the first locating point and a second matching point matched with the second locating point, and the locating system comprises:
the image acquisition device is used for acquiring images of a chassis of the electric automobile to obtain a current position image;
an image processor communicatively coupled to the image collector and configured to process the current position image to obtain a current offset between a current relative position and an ideal relative position, the current offset being divided into a first offset and a second offset, wherein the first offset is a current offset between the first matching point and a first location point, and the second offset is a current offset between the second matching point and a second location point;
An adjustment module in communication with the image processor, the adjustment module controlling the movement of the battery changing trolley according to the first offset to align the first matching point with the first positioning point, the adjustment module controlling the rotation of the battery changing trolley according to the second offset to align the second matching point with the second positioning point with the first matching point as a center of a circle,
wherein the image processor is further configured to perform the steps of:
searching a closed curve in the current position image;
judging whether the closed curve is a circle meeting the precision requirement or not, wherein the precision requirement is to fit the closed curve into a circle and a circle center according to the definition of the circle, and calculate the distances between all points on the closed curve and the fitted circle center, and if the standard deviation sigma of the distances is less than or equal to kR, considering the closed curve as the circle meeting the precision requirement, wherein R is the radius of the fitted circle;
if the closed curve meeting the precision requirement is one, taking the closed curve as an image of a round hole of the pore plate in the current position image; if the obtained closed curve meeting the precision requirement is 0, changing the precision requirement, and judging whether the closed curve is round meeting the new precision requirement; if the number of the obtained closed curves meeting the precision requirement is at least two, taking one closed curve with the minimum standard deviation sigma in the at least two closed curves as an image formed by a circular hole of the pore plate in the current position image;
And taking the center of the selected closed curve as the center of an image formed by the round hole in the current position image.
2. The positioning system of claim 1, wherein the image acquisition device comprises a first image acquisition device and a second image acquisition device;
the first image collector and the second image collector are arranged on the battery changing trolley, wherein the first image collector is used for collecting images of the first marker to obtain a first current position image, and the second image collector is used for collecting images of the second marker to obtain a second current position image;
the image processor is configured to process the first current position image to obtain the first offset and to process the second current position image to obtain the second offset.
3. The positioning system of claim 2, wherein the adjustment module comprises a first adjustment unit and a second adjustment unit, wherein the first adjustment unit controls the power changing trolley to move to align the first matching point with the first positioning point according to the first offset, and the second adjustment unit controls the power changing trolley to rotate around the first matching point to align the second matching point with the second positioning point according to the second offset.
4. A positioning system as set forth in claim 3 wherein,
a power battery is arranged on a chassis of the electric automobile, the marker is a pore plate on the power battery, and the positioning point is the circle center of a round hole of the pore plate;
the first offset is a first offset angle, the second offset is a second offset angle, wherein the first offset angle is a current offset angle between the first matching point and the first positioning point, and the second offset angle is a current offset angle between the second matching point and the second positioning point;
the first adjusting unit controls the power changing trolley to move in a stepping mode according to the first offset angle so as to align the first matching point with the first matching point;
the second adjusting unit controls the power changing trolley to rotate in a stepping mode by taking the first matching point as a circle center according to the second offset angle so as to align the second matching point with the second locating point.
5. The positioning system of claim 4, wherein the image processor is configured to calculate the current offset angle as follows:
Finding an image formed by the round hole of the pore plate in the current position image, and acquiring the circle center of the image formed by the round hole of the pore plate in the current position image;
matching an image formed by the round hole of the pore plate in the current position image with an image formed by the round hole of the pore plate in the ideal position image;
and if the matching result meets the precision requirement, aligning, and if the matching result does not meet the precision requirement, taking the difference between coordinates of the circle center of the circle in the current position image and the circle center of the circle in the ideal position image as a position difference (delta x, delta y), and taking arctan (delta y/delta x) as the current offset angle.
6. A positioning system as set forth in claim 3 wherein,
the marker comprises a template image and a comparison part corresponding to the template image, wherein the template image comprises a plurality of square lattices with the same size, the positioning points are vertexes of any lattice in the template image, the comparison part comprises a round part or a round hole, and in the direction perpendicular to the chassis of the electric automobile, the orthographic projection of the comparison part on the chassis of the electric automobile is positioned in the template image corresponding to the orthographic projection;
The first offset is a first offset vector, the second offset is a second offset vector, wherein the first offset vector is a current offset vector between the first matching point and the first positioning point, and the second offset vector is a current offset vector between the second matching point and the second positioning point;
the first adjusting unit controls the power changing trolley to move according to the first offset vector so as to align the first matching point with the first matching point;
and the second adjusting unit controls the power-changing trolley to rotate by taking the first matching point as a circle center according to the second offset vector so as to align the second matching point with the second positioning point.
7. The positioning system of claim 6 wherein the image processor is configured to calculate the current offset vector as follows:
acquiring the side length of the grid in the current position image as a first side length, acquiring the side length of the grid in the ideal position image as a second side length, and taking the ratio of the second side length to the first side length as a correction coefficient;
processing the current position image to obtain a circle center of a circle in the current position image as a basic coordinate, and multiplying the basic coordinate by the correction coefficient to obtain a correction coordinate;
And taking the difference between the correction coordinate and a standard coordinate as the current offset vector, wherein the standard coordinate is the coordinate of the circle center of the circle in the ideal position image.
8. The positioning system of claim 7, wherein the image processor is configured to perform the step of processing the current position image to obtain the center of a circle in the current position image as follows:
performing blurring processing on the current position image to obtain a blurred current position image;
intercepting a current template image on the blurred current position image, wherein the current template image comprises the circle and is square with a specific length as a side length;
acquiring the boundary of the circle in the current template image;
and acquiring the circle center of the circle in the current template image by adopting a Hough circle finding method.
9. Positioning system according to any of the claims 1-8, characterized in that,
the adjusting module is arranged on the power changing trolley.
10. The positioning system of claim 9 wherein the positioning system comprises a plurality of positioning devices,
the electricity changing trolley is an automatic guiding transport vehicle or a rail guiding vehicle.
11. The visual-based positioning method in the power exchange station is characterized in that a chassis of the electric automobile comprises at least two markers, wherein the at least two markers comprise a first marker and a second marker, the first marker corresponds to a first positioning point, and the second marker corresponds to a second positioning point; the battery changing trolley is provided with a first matching point matched with the first locating point and a second matching point matched with the second locating point, and the locating method comprises the following steps:
the image acquisition device acquires an image of a chassis of the electric automobile to obtain a current position image;
the image processor processes the current position image to obtain a current offset between a current relative position and an ideal relative position, wherein the current offset is divided into a first offset and a second offset, the first offset is the current offset between the first matching point and a first positioning point, and the second offset is the current offset between the second matching point and a second positioning point;
an adjustment module controls the power changing trolley to move according to the first offset so as to align the first matching point with the first positioning point;
The adjustment module controls the power changing trolley to rotate by taking the first matching point as the center of a circle according to the second offset so as to align the second matching point with the second positioning point,
wherein, the positioning method further comprises:
searching a closed curve in the current position image;
judging whether the closed curve is a circle meeting the precision requirement or not, wherein the precision requirement is to fit the closed curve into a circle and a circle center according to the definition of the circle, and calculate the distances between all points on the closed curve and the fitted circle center, and if the standard deviation sigma of the distances is less than or equal to kR, considering the closed curve as the circle meeting the precision requirement, wherein R is the radius of the fitted circle;
if the closed curve meeting the precision requirement is one, taking the closed curve as an image of a round hole of the pore plate in the current position image; if the obtained closed curve meeting the precision requirement is 0, changing the precision requirement, and judging whether the closed curve is round meeting the new precision requirement; if the number of the obtained closed curves meeting the precision requirement is at least two, taking one closed curve with the minimum standard deviation sigma in the at least two closed curves as an image formed by a circular hole of the pore plate in the current position image;
And taking the center of the selected closed curve as the center of an image formed by the round hole in the current position image.
12. The positioning method according to claim 11, wherein,
the image collector comprises a first image collector and a second image collector, the first image collector and the second image collector are arranged on the battery-changing trolley, wherein the first image collector is used for collecting images of the first marker to obtain a first current position image, and the second image collector is used for collecting images of the second marker to obtain a second current position image;
the image processor is configured to process the first current position image to obtain the first offset and to process the second current position image to obtain the second offset.
13. The positioning method according to claim 12, wherein,
the adjustment module comprises a first adjustment unit and a second adjustment unit, wherein the first adjustment unit controls the power changing trolley to move according to the first offset so as to enable the first matching point to be aligned with the first positioning point, and the second adjustment unit controls the power changing trolley to rotate around the first matching point as a circle center according to the second offset so as to enable the second matching point to be aligned with the second positioning point.
14. The positioning method according to claim 13, wherein,
a power battery is arranged on a chassis of the electric automobile, the marker is a pore plate on the power battery, and the positioning point is the circle center of a round hole of the pore plate;
the first offset is a first offset angle, the second offset is a second offset angle, wherein the first offset angle is a current offset angle between the first matching point and the first positioning point, and the second offset angle is a current offset angle between the second matching point and the second positioning point;
the first adjusting unit controls the power changing trolley to move in a stepping mode according to the first offset angle so as to align the first matching point with the first matching point;
the second adjusting unit controls the power changing trolley to rotate in a stepping mode by taking the first matching point as a circle center according to the second offset angle so as to align the second matching point with the second locating point.
15. The positioning method according to claim 14, wherein the calculation method of the current offset angle includes the steps of:
finding an image formed by the round hole of the pore plate in the current position image, and acquiring the circle center of the image formed by the round hole of the pore plate in the current position image;
Matching an image formed by the round hole of the pore plate in the current position image with an image formed by the round hole of the pore plate in the ideal position image;
and if the matching result meets the precision requirement, aligning, and if the matching result does not meet the precision requirement, taking the difference between coordinates of the circle center of the circle in the current position image and the circle center of the circle in the ideal position image as a position difference (delta x, delta y), and taking arctan (delta y/delta x) as the current offset angle.
16. The positioning method according to claim 13, wherein,
the marker comprises a template image and a comparison part corresponding to the template image, wherein the template image comprises a plurality of square lattices with the same size, the positioning points are vertexes of any lattice in the template image, the comparison part comprises a round part or a round hole, and in the direction perpendicular to the chassis of the electric automobile, the orthographic projection of the comparison part on the chassis of the electric automobile is positioned in the template image corresponding to the orthographic projection;
the first offset is a first offset vector, the second offset is a second offset vector, wherein the first offset vector is a current offset vector between the first matching point and the first positioning point, and the second offset vector is a current offset vector between the second matching point and the second positioning point;
The first adjusting unit controls the power changing trolley to move according to the first offset vector so as to align the first matching point with the first matching point;
and the second adjusting unit controls the power-changing trolley to rotate by taking the first matching point as a circle center according to the second offset vector so as to align the second matching point with the second positioning point.
17. The positioning method according to claim 16, wherein the method for calculating the current offset vector comprises the steps of:
acquiring the side length of the grid in the current position image as a first side length, acquiring the side length of the grid in the ideal position image as a second side length, and taking the ratio of the second side length to the first side length as a correction coefficient;
processing the current position image to obtain a circle center of a circle in the current position image as a basic coordinate, and multiplying the basic coordinate by the correction coefficient to obtain a correction coordinate;
and taking the difference between the correction coordinate and a standard coordinate as the current offset vector, wherein the standard coordinate is the coordinate of the circle center of the circle in the ideal position image.
18. The positioning method according to claim 17, wherein the step of processing the current position image to obtain the center of a circle in the current position image includes:
Performing blurring processing on the current position image to obtain a blurred current position image;
intercepting a current template image on the blurred current position image, wherein the current template image comprises the circle and is square with a specific length as a side length;
acquiring the boundary of the circle in the current template image;
and acquiring the circle center of the circle in the current template image by adopting a Hough circle finding method.
19. Positioning method according to any of the claims 11-18, characterized in that,
the adjusting module is arranged on the power changing trolley.
20. The positioning method of claim 19, wherein,
the electricity changing trolley is an automatic guiding transport vehicle or a rail guiding vehicle.
21. A station comprising a vision-based positioning system in a station according to any one of claims 1-10.
CN201811038852.4A 2018-09-06 2018-09-06 Visual positioning system and positioning method in power exchange station Active CN109584200B (en)

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