CN106153331B - The measuring device and method of flexible doublejointed mechanical arm vibration based on machine vision - Google Patents
The measuring device and method of flexible doublejointed mechanical arm vibration based on machine vision Download PDFInfo
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- CN106153331B CN106153331B CN201610829885.5A CN201610829885A CN106153331B CN 106153331 B CN106153331 B CN 106153331B CN 201610829885 A CN201610829885 A CN 201610829885A CN 106153331 B CN106153331 B CN 106153331B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M13/00—Testing of machine parts
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
- G01H9/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means
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Abstract
The measuring device and method for the flexible doublejointed mechanical arm vibration based on machine vision that the invention discloses a kind of.The device includes doublejointed flexible mechanical arm, CCD camera, camera fixing device, absolute value encoder, multiple LED light tube and PC machine.Absolute value encoder is installed on rotary electric machine, and LED light tube is placed on two armed lever tail ends, and CCD camera is placed at middle joint, and the output port of CCD camera and encoder is connect with PC machine.Camera fixing device makes camera lens direction be in the angular bisector direction for the angle that two-arm bar is formed, and each frame image of CCD camera detection and the real time positioning data of encoder are sent to PC machine；Handled through PC machine, with this movement position it is static when facula position compared with, obtain the vibration displacement of light source, and then analyze mechanical arm vibration performance.The present invention can not contact, do not measure two-arm vibration of bar feature with not changing measured object vibration characteristics, facilitate and compare and study, can be widely used.
Description
Technical field:
The present invention relates to the measurement method of flexible doublejointed mechanical arm vibration, especially a kind of flexibilities based on machine vision
The measuring device and method of doublejointed mechanical arm vibration.
Background technique:
Multi-joint mechanical arm, also referred to as articulated robot be the most common industrial robot in current industrial circle form it
One.Suitable for the mechanical automation operation of many industrial circles, for example, the work such as automatic assembling, spray painting, carrying, welding.This
The modal damping of class flexible structure is small, once the effect by certain exciting force, significantly vibrates last very long.
This not only will affect the work of structure, so that structure is generated premature fatigue rupture, and influence the service life of structure, or cause
The damage of structure Instrumental.Therefore need to measure and inhibit the vibration of such flexible structure.
In the prior art, the vibration measurement of flexible joint mechanical arm mainly has using piezoelectric patches, acceierometer sensor, angle
Rate gyroscope sensor, photoelectrical position sensor (Position Sensitive Detector) and fiber-optic grating sensor
The methods of (Fiber Grating Sensor): because a variety of links such as signal amplification, filtering can cause signal when piezoelectric patches measures
Delay and delayed phase, measuring speed is slow, is limited in scope；Acceierometer sensor and angular rate gyroscope sensor are quick to noise
The problems such as feeling, there is sluggish and temperature drift influences its precision；The measurement range of photoelectrical position sensor is smaller, structure is complicated, operation
Difficulty is big, calculating process is cumbersome and expensive；The most important problem of fiber-optic grating sensor is the demodulation of transducing signal, due to
Fiber grating is more fragile, is very easy to destroy in a bad working environment, thus could use after needing to be packaged it,
Structure is complicated for packaging technology and safeguard measure.
Summary of the invention:
The object of the present invention is to provide a kind of structure is simple, performance is stablized, the flexibility based on machine vision being convenient for measuring
The measuring device and method of doublejointed mechanical arm vibration realize that non-contact, accurately one-shot measurement obtains machine at two simultaneously in real time
The vibration performance of tool arm.
The technical solution for realizing the aim of the invention is as follows, a kind of flexible doublejointed mechanical arm vibration based on machine vision
Measuring device and method, which includes doublejointed flexible mechanical arm, CCD camera, camera fixing device, absolute encoder
Device, multiple LED light tube and PC machine install absolute value encoder, and the output of encoder on diarticular armed lever rotary electric machine
End is connect with PC machine, and LED light tube is placed on two armed lever tail ends, and CCD camera is placed on the joint between two mechanical arm armed levers, and
CCD camera is configured with camera lens, and the output port of CCD camera is connect with PC machine.When camera fixing device guarantees camera lens direction
It carves at the angular bisector in the angle that two-arm bar is formed, CCD camera can measure the vibration of two armed lever tail end LED light tube simultaneously
Each frame image, and be sent to PC machine；The real time data of encoder reaches PC machine and carries out the movement of operation positioning mechanical arm
Position；PC machine handles image, obtained compared with facula position when static with this movement position vibration displacement at LED light tube and
Reflect the parameter of flexible doublejointed mechanical arm structural low-frequency vibration.
The measurement method of flexible doublejointed mechanical arm vibration based on machine vision, which is characterized in that steps are as follows:
Step 1: according to the LED light tube position in the image of each frame of CCD camera acquisition, entire image is divided into two
The corresponding subregion of armed lever tail end LED light tube, and determine the upper corresponding light source acquisition position in each region；
Step 2: according to the camera image data of incoming PC machine, the mass center position of each light source hot spot in image coordinate system is determined
It sets；
Step 3: data, positioning mechanical arm movement angle, the mass center position that step 2 is acquired are acquired according to absolute value encoder
Corresponding movement angle data record this moment is set in PC machine；
Step 4: according to quiet under the facula mass center position acquired under the conditions of different vibration measurings, with manipulator motion position at this time
Only facula mass center position is handled, and obtains the horizontal displacement Δ x and vertical displacement delta y of two corresponding LED light tube；
Step 5: according to the parameter of CCD camera, to two LED light tube from image coordinate system to world coordinate system vertical position
Move transformation factor Kx, horizontal transformation factor KyIt is demarcated；
Step 6: the water demarcated according to horizontal displacement Δ x, the vertical displacement delta y and step 5 of LED light tube each in image
Flat transformation factor Kx, vertical transitions factor Ky, obtain the real standard displacement x of each LED light tube, practical vertical displacement y；
Step 7: the position curve of each LED light tube is drawn out in the actual displacement obtained according to step 6, to each LED
The displacement of luminous tube carries out Fast Fourier Transform (FFT), obtains the first-order modal frequency and second order mode of flexible doublejointed mechanical arm vibration
State frequency.
The present invention compared with the prior art, has following remarkable advantage: (1) detection method based on machine vision is not only more
Intuitively, the low-frequency vibration information of flexible mechanical arm is more easily obtained, and whole device is grasped by the detection to LED light tube
Make that simple, easy to implement, measurement noise is small.(2) absolute value encoder positioning mechanical arm position is used, noiseproof feature is strong, number
According to high reliablity.(3) it is directed to the special construction of mechanical arm, nyctitropic CCD camera can be changed with movement in joint placement, it can
To be detected simultaneously by two LED light tube light sources of two mechanical arm armed lever tail ends, apparatus structure, save the cost are greatly simplified.(4)
In the case where not changing the vibration performance of measured object, light source is tracked by machine vision, detects the dynamic displacement of flexible structure,
Has many advantages, such as the vibration characteristics that non-contact, measurement range is wide, does not change measured object.
Detailed description of the invention:
Fig. 1 is that the present invention is based on the structural schematic diagrams of the measuring device of the flexible doublejointed mechanical arm of machine vision vibration；
Fig. 2 is camera fixing device simplified schematic diagram；
Fig. 3 is image analysis schematic diagram；
Specific embodiment:
The present invention is described in further detail with reference to the accompanying drawings and detailed description.
The present invention passes through the vibration of the mechanical arm tail end illuminating source of acquisition different motion position using the method for machine vision
The device and method of low frequency modal analysis is realized in dynamic displacement.
As shown in Figure 1, the measuring device that the flexible doublejointed mechanical arm based on machine vision vibrates includes doublejointed flexibility
Mechanical arm 1, CCD camera 2, camera fixing device 3, absolute value encoder 4, multiple LED light tube 5 and PC machine 6；The flexibility
Doublejointed mechanical arm 1 installs absolute value encoder 4, and the output end of encoder and PC machine 6 on diarticular armed lever rotary electric machine
Connection, LED light tube 5 are placed on 1 liang of armed lever tail end of doublejointed flexible mechanical arm, and CCD camera 2 is placed between two mechanical arm armed levers
Joint on, and CCD camera is configured with camera lens, and the output port of CCD camera 2 connect with PC machine 6.As shown in Fig. 2, the camera
Fixed device forms a diamond structure with doublejointed flexible mechanical arm two-arm bar, and diagonal line is using retractable material as CCD phase
Machine support, bracket can be on cornerwise bracket of diamond structure according to manipulator motion position change direction, CCD camera,
Guarantee that the CCD camera lens direction moment is in the angular bisector direction of the angle of two-arm bar formation.
The measurement method of flexible doublejointed mechanical arm vibration based on machine vision, steps are as follows:
Step 1: according to 5 position of LED light tube in the image of each frame of the acquisition of CCD camera 2, entire image is divided into
The corresponding subregion of two armed lever tail end LED light tube 5, and determine the upper corresponding light source acquisition position in each region；
Step 2: according to the camera image data of incoming PC machine 6, the mass center of each light source hot spot in image coordinate system is determined
Position；
Step 3: data, positioning mechanical arm movement angle, the mass center that step 2 is acquired are acquired according to absolute value encoder 4
The corresponding movement angle data record this moment in position is in PC machine 6；
As shown in figure 3, absolute value encoder 4 records rotational angle in motor when motor rotation drives mechanical arm work, obtain
Rotational angle to armed lever 1 is α, and the rotational angle of armed lever 2 is that (direction is initial level direction and rotation counterclockwise to 180 ° of-β
Turn), the slewing area of α, β are 0 ° of < α >, 90 °, 0 ° 90 ° of < β >, and two armed levers when for (α, β) are in image coordinate system
Projected position are as follows:
Y in formula1 (α, β), Y2 (α, β)Respectively armed lever 1 and y-axis coordinate position of the armed lever 2 in (α, β) location drawing picture coordinate system
It sets, l1,l2For the LED light tube 5 of 1 liang of armed lever tail end of doublejointed flexible mechanical arm is arranged in the distance of 2 camera lens of CCD camera.
X-axis direction non-displacement when static, so when obtaining static without friction and mechanical arm and being in the position (α, β), armed lever 1,
Light source coordinate in 2 image coordinate system of CCD camera on armed lever 2 are as follows:
Step 4: according to the facula mass center position acquired under the conditions of different vibration measurings, with 1 machine of doublejointed flexible mechanical arm at this time
Static facula mass center position under tool arm movement position is handled, and the horizontal displacement Δ x of two corresponding LED light tube 5 is obtained
With vertical displacement delta y, specific step is as follows:
According to step 1, step 2 detecting step and Fig. 3, under the position (α, β), this frame image of CCD camera record
Through operation obtain armed lever 1 on image coordinate system, on armed lever 2 light source centroid position:
(X1,Y1)′(α,β)=(x1,y1), (X2,Y2)′(α,β)=(x2,y2) (3)
And then obtain the displacement in two armed lever glazing sources in image coordinate system:
Δ x in formula1,Δy1, Δ x2,Δy2Horizontal displacement and vertical displacement in respectively two armed lever image coordinate systems.
Step 5: vertical from image coordinate system to world coordinate system to two LED light tube 5 according to the parameter of CCD camera 2
Shift transformation factor Kx, horizontal transformation factor KyIt is demarcated, the specific steps are as follows:
Establish coordinate system: by taking the armed lever of the top of flexible doublejointed mechanical arm 1 as an example, with armed lever tail end LED light tube 5
Placement location OWFor origin, the direction that camera 2 is directed toward when armed lever is static is Z axis, establishes world coordinate system OW-WWXWYWZW；With CCD
The optical center O of camera 2CFor origin.The angle bisection for the angle that camera lens direction, i.e. 1 two-arm bar of doublejointed flexible mechanical arm are formed
Line direction is that Z axis establishes image coordinate system OC-WCXCYCZC；
Image coordinate system OC-WCXCYCZCIn horizontal displacement, vertical displacement to world coordinate system OW-WWXWYWZWTransformation
Relationship are as follows:
X=KxΔ x, y=KyΔy (6)
Wherein Δ x, Δ y are the horizontal displacement and vertical displacement in image coordinate system, and x, y are actual in world coordinate system
Horizontal displacement and vertical displacement, Kx KyBecome for the horizontal displacement transformation factor of image coordinate system to world coordinate system and vertical displacement
Change the factor.
Step 6: according to horizontal displacement Δ x, the vertical displacement delta y and step 5 of LED light tube 5 each in image calibration
Horizontal transformation factor Kx, vertical transitions factor Ky, the real standard displacement x of each LED light tube, practical vertical displacement y are obtained,
Specific step is as follows:
Composite type (4), formula (5) and formula (7) obtain:
The real standard displacement and practical vertical displacement of light source on armed lever 1 are as follows:
x1=KxΔx1=x1 (8)
The real standard displacement and practical vertical displacement of light source on armed lever 2 are as follows:
x2=KxΔx2=x2 (10)
Step 7: the actual displacement obtained according to step 6 draws out the position curve of each LED light tube 5, to each
The displacement of LED light tube 5 carries out Fast Fourier Transform (FFT), obtain flexible 1 vibration of doublejointed mechanical arm first-order modal frequency and
Second-order modal frequency.Specific step is as follows:
Repeatedly measurement different location is (α1, β1)、(α2, β2) ... the armed lever tail end light source displacements for waiting location points, to its into
Row Fast Fourier Transform (FFT) obtains the first-order modal frequency and second-order modal frequency of flexible doublejointed 1 liang of armed lever of mechanical arm.
In conclusion machine vision vibration measurement device constructed by method proposed by the present invention, can be directed to doublejointed
Mechanical arm special construction, is positioned using absolute value encoder, is realized and is vibrated at a CCD camera measurement two.This method has
Non-contact, not change measured object vibration characteristics, many advantages, such as device is simple, accuracy is high.
Claims (1)
1. a kind of measuring device of the flexible doublejointed mechanical arm vibration based on machine vision, including doublejointed flexible mechanical arm
(1), it is characterised in that: the device further includes CCD camera (2), camera fixing device (3), absolute value encoder (4), multiple LED
LED light tube (5) are arranged in luminous tube (5) and PC machine (6), the flexibility doublejointed mechanical arm (1), two armed lever tail ends, joint
It places camera fixing device (3), CCD camera (2) is fixed on camera fixing device (3) and configured with camera lens, two joint setting
Absolute value encoder (4), CCD camera (2) are connect with the output port of absolute value encoder (4) with PC machine (6)；
The camera fixing device (3) forms a diamond structure with doublejointed flexible mechanical arm (1) two-arm bar, and diagonal line uses
Retractable material can be in as CCD camera (2) bracket, bracket according to manipulator motion position change direction, CCD camera (2)
On cornerwise bracket of diamond structure, the angle that guarantee CCD camera (2) the lens direction moment is in the angle of two-arm bar formation is flat
Separated time direction.
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| CN107398926B (en) * | 2017-07-18 | 2023-09-26 | 华南理工大学 | Flexible arm vibration measurement device and method based on terminal visual detection |
| CN107639635B (en) * | 2017-09-30 | 2020-02-07 | 杨聚庆 | Method and system for calibrating pose error of mechanical arm |
| CN107588940A (en) * | 2017-10-15 | 2018-01-16 | 安徽理工大学 | Flexible mechanical arm damping test device and its application method based on machine vision |
| CN108731788B (en) * | 2018-05-22 | 2020-06-09 | 河海大学常州校区 | Visual detection device and method for low-frequency vibration of aerial work arm |
| CN109253874B (en) * | 2018-10-19 | 2020-03-31 | 日照职业技术学院 | Robot arm flexibility ratio detection device |
| CN109727267B (en) * | 2018-12-29 | 2020-02-11 | 中国计量科学研究院 | Standard virtual sine linear vibration measurement method |
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| CN101387546B (en) * | 2008-10-29 | 2010-09-08 | 华南理工大学 | Space sailboard bend and torsion low frequency mode detecting method and apparatus based on vision |
| US8505384B2 (en) * | 2011-02-08 | 2013-08-13 | United Technologies Corporation | Rig for measuring bladed component mistuning |
| CN102322938A (en) * | 2011-08-22 | 2012-01-18 | 华南理工大学 | Visual measuring device for vibration of piezoelectric flexible board structure and control method |
| CN103267567B (en) * | 2013-06-05 | 2015-09-30 | 南京理工大学 | Based on measurement mechanism and the method for the flexible cantilever beam vibration of machine vision |
| CN103895023B (en) * | 2014-04-04 | 2015-08-19 | 中国民航大学 | A kind of tracking measurement method of the mechanical arm tail end tracing measurement system based on coding azimuth device |
| CN104048744B (en) * | 2014-07-08 | 2017-03-08 | 安徽常春藤光电智能科技有限公司 | A kind of contactless real-time online vibration measurement method based on image |
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