CN114460904A - Digital twin system facing gantry robot - Google Patents
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Abstract
The invention relates to the technical field of digital twins, in particular to a digital twinning system facing a gantry robot, which consists of a real gantry robot in the physical world, a virtual gantry robot in the digital world and a cloud server interconnecting the real gantry robot and the virtual gantry robot in the digital world; the real gantry robot in the physical world consists of a gantry robot, a driving module, a vision measuring module and a control module, and the virtual gantry robot in the digital world consists of a motion analysis and path planning module, a control decision module, a pose calculation module and a three-dimensional online monitoring module; the virtual gantry robot in the digital world and the real gantry robot in the physical world are communicated with the Ethercat through a cloud server to perform data transmission; the method carries out kinematic simulation on the 1:1 virtual gantry robot model in a virtual scene, realizes three-dimensional visual online monitoring and visual feedback remote closed-loop control of a real gantry robot, and enables the error between the virtual and actual operation positions of the gantry robot to be within plus or minus 0.2 mm.
Description
Technical Field
The invention relates to the technical field of digital twinning, in particular to a digital twinning system facing a gantry robot.
Background
The digital twin technology is one of engines for realizing subversive transformation in various fields of 5G capital construction, extra-high voltage, intercity high-speed railway and urban rail transit, large data center, new energy automobile charging pile, artificial intelligence, industrial internet and the like.
Aiming at a digital twin system of a robot, China invention patent No. CN202110055322.6, discloses a method for driving a virtual model simulation by adopting historical data based on a digital twin technology, which comprises data storage and data calling, wherein a time-sequence database is adopted to store the historical data collected by a production line, but the real-time data of the twin system is not processed.
For another example, chinese patent No. CN202010517266.9 discloses a digital twin spray simulation system and method for a coating line, which relates to the field of spray simulation. According to the data expression result of the simulated coating line, the real coating line operation result can be mapped really, so that the predicative inference on the possible problems and the design optimization of the whole production line are facilitated, the used method realizes the synchronous correspondence of the virtual to the physical, and the virtual and actual two-way control is not realized.
The inventor of Lixin et al in the article develops a UE 4-based digital twin system of a robot for inspecting a downhole substation, can complete the functions of environment roaming inspection and central control, and completes the management of a database through a system interface. Li Fu et al have built intelligent robot high-risk operation virtual simulation experiment teaching platform under the complex environment, have carried high-risk complex scene and the high-end equipment of robot into virtual laboratory with the help of virtual simulation technique, have accomplished teaching and experimental requirement. Wanhao et al, based on the digital twin technology, carry out electromechanical integration design on an automatic loading and unloading system, shorten the development period of new products and reduce the development cost. Due to the fact that the types of robots are various, the digital twin technology is gradually specified, a customized road is developed by well-jet type in research and application of the digital twin technology at home and abroad, and meanwhile, a plurality of new research results are brought forward. However, the design, development and specific application of the digital twin technology in an automatic production line are still in an exploration stage, the research results are few, the systematicness is lacked, and the research on the gantry robot system by the digital twin technology is rare. At present, most of the prior art of the digital twin system only realizes the remote real-time monitoring function of a virtual scene, but cannot control the robot and analyze the problem by using the digital twin system.
For the robot with a complex structure, the digital twin system integrates the scientificity and the practicality of robot research, and the robot intelligent operation platform is constructed by comprehensively considering the self structure requirements of the robot to complete the research of dispatching and planning. The gantry robot is used as an automatic robot system solution with low cost and simple system structure, can replace manpower, improves the production efficiency, stabilizes the product quality and has obvious application value. In recent years, the digital twin technology is widely applied to intelligent factories and intelligent workshops. The large-span gantry robot is an essential part in an intelligent factory, can serve a plurality of machines, and can finish the common industrial production fields of glue dispensing, plastic dripping, spraying, stacking, sorting, packaging, welding, metal processing, carrying, loading and unloading, assembling, printing and the like. The digital twin system for constructing the gantry robot can realize the remote control function, avoid risks, perform safety monitoring and early warning in time and avoid dangers.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a digital twin system facing a gantry robot, which can realize a remote control function, avoid risks, perform safety monitoring and early warning in time and avoid dangers.
In order to solve the technical problems, the technical method adopted by the invention is as follows:
a digital twin system facing a gantry robot comprises a real gantry robot in a physical world, a virtual gantry robot in a digital world and a cloud server interconnecting the real gantry robot and the virtual gantry robot in the digital world;
the real gantry robot in the physical world is formed by respectively interacting a gantry robot main body mechanism, a driving module, a vision measuring module and a control module;
the virtual gantry robot in the digital world is formed by a three-dimensional online monitoring module, a control decision module, a motion analysis and path planning module and a pose calculation module in an interactive mode;
the cloud server is respectively interconnected with the Ethercat communication module and the Internet module to realize a physical world and a digital world;
the gantry robot main body mechanism comprises a truss, a crank arm or a straight arm, a fine adjustment mechanism and an end effector;
the driving module comprises a servo driver and a servo motor;
the vision measurement module comprises a vision controller, an industrial camera, a laser range finder, a marker and vision positioning software, wherein the vision positioning software comprises high-precision calibration and vision positioning;
the control module comprises a motion controller and motion control software, wherein the motion control software comprises NC control, an I/O interface and a PLC;
the three-dimensional online monitoring module comprises a gantry robot virtual model, gantry robot motion simulation, historical data playback and real-time data display;
the control decision module comprises a task allocation instruction, priority setting, target position setting and motion path transmission;
the motion analysis and path planning module comprises a virtual gantry robot, kinematic analysis of a mechanical structure, navigation area and grid division and three-dimensional path planning;
the pose calculation module comprises a database, a data acquisition and storage module, a data integration module and a precision evaluation module;
the internet module comprises a communication protocol, data bidirectional interaction and a server;
the Ethercat communication module comprises a communication interface, a local port and a data bidirectional interaction component.
The technical method of the invention is further improved in that: the virtual gantry robot in the digital world is constructed based on a real gantry robot in the physical world according to the proportion of 1:1, the coordinate origin, the physical size and the three-dimensional space layout of internal equipment of the real gantry robot in the physical world have consistency, and the consistency corresponding relation is realized by offline visual calibration, and the method comprises the following steps:
s11, installing a calibration plate for visual positioning at one corner of the real gantry robot and at the edge of the workbench of each internal device, ensuring that the calibration plate can obtain clear imaging in the imaging range of the camera, and recording the timeThe calibration plate image is I0；
S12, defining the Z direction of the real gantry robot to move to the lowest end, when the XY direction moves to one corner of the gantry robot, the position of the imaging of the center of the corresponding calibration plate under the camera coordinate system when the imaging is positioned at the center of the image is the zero point of the gantry robot, and the intersection point of the corresponding XYZ directions is the origin O of the world coordinate system;
s13, driving the gantry robot to move to the visual calibration plate of the jth internal equipment workbench along the XYZ axis with the origin O as the starting point, and ensuring the imaging I of the calibration plate in the camerajAnd I0The same is true. In this case, the coordinate of the device j in the world coordinate system is represented as (X)j,Yj,Zj) (ii) a Wherein, XjThe stroke in X direction is multiplied by the stroke of the screw rod in X direction; y isjThe distance in the Y direction is multiplied by the measuring range of the screw rod in the Y direction; zjThe stroke in the Z direction is multiplied by the measuring range of the screw rod in the Z direction.
The technical method of the invention is further improved in that the steps of the monitoring process in the three-dimensional online monitoring module are as follows:
s21, loading a three-dimensional model, a virtual camera and a virtual experimental scene of the virtual gantry robot by a user through controlling an operation button of the decision module, and starting an online monitoring task;
s22, transmitting the motion data of the actual gantry robot to the virtual gantry robot in real time through a network, and driving the three-dimensional model of the virtual gantry robot to realize the motion consistent with that of the real gantry robot through motion analysis and motion simulation by the virtual gantry robot, thereby achieving the purpose of remote online monitoring.
S23, storing the motion data of the actual gantry robot in a database, and allowing a user to view and playback historical data according to time;
and S24, the virtual gantry robot can perform process flow preview through motion analysis and motion simulation according to the user instruction so as to determine whether the existing process flow is reasonable.
The technical method is further improved in that the virtual gantry robot in the digital world controls the gantry robot in the physical world to move, and the operation steps are as follows:
s31, the user appoints specific operation task, flow and target by controlling the operation button of the decision module;
s32, planning a reasonable running path for the real gantry robot by the virtual gantry robot through the kinematic analysis of the gantry robot, the grid division of a navigation area and the three-dimensional path planning, sending path key point data to a control module of the real gantry robot in real time, realizing the following of the virtual path by the real gantry robot in the physical world through tracking the running track of the digital world gantry robot in real time, and shaping the position information received by the physical world gantry robot through designing an input shaper so as to reduce the vibration at the tail end of the cantilever beam and enable the real-time position of the digital world gantry robot to be tracked more accurately;
and S33, when the end effector of the physical world gantry robot moves to the position near the target position, the vision measurement module starts to work, the vision measurement method is that the laser range finder is used for obtaining the deviation in the z direction, the digital camera 2D vision measurement method is used for obtaining the deviation in the xy direction, the data of the marker is captured in real time, the vision measurement module calculates the deviation of the current position from the target position, the deviation value is sent to the motion controller and the pose processing module of the physical world gantry robot for positioning accuracy evaluation, and accurate regulation and control of the position are realized through a motion control deviation compensation calculation method.
The technical method is further improved in that the real gantry robot in the physical world tracks the running track of the digital world gantry robot in real time, and the following of the virtual path comprises the following steps:
s321, deploying the cloud server to serve as a bridge for data exchange between the digital world and the physical world;
s322, acquiring the real-time position of the digital world gantry robot, setting the IP and port number of the server on the virtual simulation platform, and then sending path position information to the server in real time;
s323, the physical world gantry robot sets the IP and port number of the server through TwinCAT software, then receives the position information of the digital world received by the server in real time, or sends the path position information to the physical world gantry robot controller through an EtherCAT bus in real time by a virtual simulation platform, and realizes the real-time tracking of the digital world gantry robot running track by the physical world gantry robot through a method given by an external position;
and S324, shaping the position information received by the physical world gantry robot by designing an input shaper so as to reduce the vibration of the tail end of the cantilever beam and enable the cantilever beam to more accurately track the real-time position of the digital world gantry robot.
The technical method is further improved in that the vision measurement module calculates the deviation of the current position from the target position, and the method comprises the following steps:
s331, adaptively adjusting the exposure and the ambiguity of the camera through a high-precision camera calibration algorithm to obtain an optimal calibration image, so as to realize high-precision camera calibration and obtain camera internal parameters with higher precision;
s332, obtaining deviation in the xy direction through a two-dimensional vision measurement technology, obtaining deviation in the z direction through a laser range finder, repeatedly enabling the gantry robot to reach the initial position for multiple times, calculating a rotation and translation matrix of the camera and the marker at the moment of arrival and a rotation and translation matrix at the moment of the initial position to obtain the current position deviation, displaying a position deviation interface, and sending the position deviation interface to a fine adjustment mechanism to compensate the deviation, so that high-precision positioning is achieved.
The technical method of the invention is further improved in that the algorithm of the motion analysis and path planning module comprises the following steps:
s41, performing kinematic analysis on the end effector, the truss, the crank arm and the fine adjustment mechanism of the virtual model, and performing forward and reverse kinematic calculation on the robot so as to control the motion of the robot and finish translation and rotation track simulation;
s42, in the virtual simulation platform built by Unity3D, reading boundary points of each workbench in a virtual environment as a set, constructing a new point set through regional obstacle avoidance analysis, combining the point sets of the workbenches, and completing node construction of a three-dimensional navigation grid;
s43, completing single-target three-dimensional path planning on the three-dimensional navigation grid by combining with a NavMesh search strategy, providing a navigation path for the robot, then completing multi-target path planning under an industrial process by combining with assembly line scheduling, and providing position data for the digital twin system.
The technical method is further improved in that the kinematics analysis comprises the kinematics equation construction of the crank arm, the fine adjustment mechanism and the walking mechanism in the Cartesian space, and comprises the following steps:
s411, the motion of the end effector and the end effector of the truss in cartesian space can be decomposed into: the end effector and the truss can adopt linear track simulation, and can be divided into translation track simulation and rotation track simulation;
let the coordinate of the starting point of the track be PES(xE(0),yE(0),zE(0)) The coordinate of the end point position is PEE(xE(1),yE(1),zE(1)) From the end point PEETo the starting point PESHas a track length of LE:
LE＝|PEE(xE(1),yE(1),zE(1))-PES(xE(0),yE(0),zE(0))| (1)
Where subscript E is the end effector, assuming point P in the current stateE(i)(xE(i),yE(i),zE(i)) To the starting point PESHas a track length of sE(i)，sE(i+1)For the track length of the next state in time interval Δ T, assume sE(i)Corresponding linear velocity vE(i)Acceleration of aEAnd assume sE(i+1)Linear velocity vE(i+1)：
sE(i+1)＝sE(i)+vE(i+1)·ΔT (2)
The linear motion trajectory equation is:
if v isE(i) 2/2aE≤LE-sE(i)The interpolation point is in the acceleration uniform velocity section, and the interpolation equation is as follows:
if v isE(i) 2/2aE＞LE-sE(i)With interpolation point in the deceleration section and end-effector at αEUntil the interpolation of the segment is completed:
vE(i+1)＝vE(i)-aEΔT (5)
suppose the angle of the end effector at a certain time is thetaE(i)，θE(i+1)For the angle at the next instant in time interval Δ T, let θ beE(i)Corresponding linear velocity of ωE(i)Angular acceleration of alphaEAnd setting the next interpolation point thetaE(i+1)At a velocity of ωE(i+1)：
θE(i+1)＝θE(i)+ωE(i+1)·ΔT (6)
When ω isE(i) 2/2αE≤θE-θE(i)And then, the interpolation point is in the acceleration uniform velocity segment:
when ω isE(i) 2/2αE＞θE-θE(i)In time, the interpolation point is in the deceleration section:
ωE(i+1)＝ωE(i)-αEΔT (8)
the motion of the truss in the Cartesian space only comprises translational motion along a certain straight line; similarly, assume that the truss is from the terminus PTE(xT(1),yT(1),zT(1)) To the starting point PTS(xT(0),yT(0),zT(0)) Length L of trackTComprises the following steps:
LT＝|PTE(xT(1),yT(1),zT(1))-PTS(xT(0),yT(0),zT(0))| (9)
subscript T is a truss; linear motion trajectory equation of truss
If v isT(i) 2/2aT≤LT-sT(i)If the interpolation point of the truss is in the acceleration uniform speed section; the interpolation equation is:
if v isT(i) 2/2aT＞LT-sT(i)And the interpolation point of the truss is in the deceleration section:
vT(i+1)＝vT(i)-aTΔT (12)
s412, the telescopic structure of the mechanical crank arm of the gantry robot can be simplified into a diamond shape, and the side length of the telescopic structure is lAThe vertical diagonal is set as hA，lAAnd hAAt an angle of thetaAWhen the mechanical crank arm extends upwards to a certain position, the vertical diagonal line is set as hA(i+1)The difference between the two is set to be Δ hAThe angle of the arm after retraction becomes thetaA(i+1)The difference angle between them is set as delta thetaAThe relationship is as follows:
the vertical diagonal and the side length are related as follows according to the geometrical relationship:
by calculating the relationship, Delta theta can be knownAAnd Δ hAThe relationship of (a) to (b) is as follows:
the kinematic relationship of the available crank arms is as follows:
and (3) interpolating the height parameters of the crank arm joints according to the same translation track simulation principle of the end effector:
hA(i+1)＝hA(i)+vA(i+1)·ΔT (17)
assumed end point PJE(xJ(1),yJ(0),zJ(1)) To the starting point PJS(xJ(0),yJ(0),zJ(0)) Has a track height of H:
H＝|PJE(xJ(1),yJ(0),zJ(1))-PJS(xJ(0),yJ(0),zJ(0))| (18)
wherein, the subscript J is a crank joint and an intermediate point PJ(i)(xJ(i),yJ(0),zJ(i)) To the starting point PJSHas a track length of hJ(i)Then, the linear motion trajectory equation is:
s413, the fine adjustment mechanism of the gantry robot belongs to a parallel mechanism structure, and the side length of a crank arm connecting rod of the mechanism is assumed to be lFThe height of the horizontal connecting rod of the fixed platform relative to the horizontal connecting rod of the movable platform is set as hF(i)，lFAnd hF(i)At an angle of thetaF(i)Move the flatThe length of the position of the table fixing device along the direction of the horizontal connecting rod under the self coordinate system from the front end of the connecting rod is set as mF(i)When the fine adjustment mechanism is extended or contracted to a certain position in the Z-axis direction, the length is mFz(i+1)The difference length between the two is set as Δ mFzAt this time, the height is set to hFz(i+1)The difference between the two is set to be Δ hFzAt this time, the angle is set to thetaFz(i+1)The two differ by an angle delta thetaFzThe relationship is as follows:
wherein, the lower corner mark F represents a fine adjustment mechanism, and the delta theta can be known through calculation of the relationFzAnd Δ mFzThe relationship of (a) to (b) is as follows:
by calculating the relationship, Delta theta can be knownFzAnd Δ hFzThe relationship of (a) to (b) is as follows:
the kinematic relationship of the fine adjustment mechanism is as follows:
where i ∈ {1,2,3 … }, θFz(i)For fine-tuning the angle of rotation of the axis of the link joint of the mechanism, kFz、
Is Δ θFzAnd Δ mFzCoefficient of relationship, κ, between each jointFz′、
Is Δ θFzAnd Δ hFzThe relation coefficient of each corresponding joint.
The technical method of the invention is further improved in that the node construction of the three-dimensional navigation grid in the step S42 comprises the following steps:
s421, regarding a working scene as a requirement for door plate processing, wherein the door plate needs to be grabbed and placed at an appointed position by a gantry robot, and the door plate needs to be cut, punched, assembled and the like by a workbench; reading boundary points of each workbench in a virtual environment as a set Vw, constructing a new point set Ve through regional obstacle avoidance analysis, and combining the point sets of the workbenches to complete node construction of a three-dimensional navigation grid;
s422, the motion area space of the end effector of the gantry robot is divided, and the upper limit and the lower limit of the extension and contraction of the mechanical crank arm define the maximum height h and the minimum height h of the end effectorE(max)And hE(min)Height range h of end effectorE(i)Can be set as follows:
hE(min)≤hE(i)≤hE(max) (24)
the internal space omega of the large-span gantry robot can be divided into two parts through the upper and lower limit heights of the end effector:
wherein omega1Is the region where the end effector can move in a leap, Ω2A region where the flying movement is impossible;
s423, in order to ensure that the end effector does not collide with the obstacle during the movement and rotation, it is necessary to simplify the model, and Ω is used to avoid collision1Adding key point sets for constructing grids on planes with different heights in the region;
s424, assuming that all points on the same plane form a set;
V＝{Vw,Ve}＝{V1,V2,...Vn},{V1,...Vi}∈Vw,{Vi+1,...Vn}∈Ve (26)
three points V not collinear in spacei(xi,yi,zi)，Vj(xj,yj,zj)，Vk(xk,yk,zk) The plane equation formed is:
through the analysis, collected point sets and point sets added under mathematical analysis for avoiding collision are collected, a plane equation set is established in a simultaneous mode to form a multi-plane set in a space, three non-collinear points form a plane triangular convex hull, and a space polygon set formed by planes of all the convex hulls forms a convex polygon navigation grid.
The technical method of the invention is further improved in that in step S43, the single-target three-dimensional path planning process is completed on the three-dimensional navigation grid, and the method comprises the following steps:
s431, after a grid is constructed, the Navmesh routing algorithm drives a virtual model to move by calculating the minimum path cost, in a three-dimensional virtual environment, a scene is represented as a structure similar to a graph by a convex polygon set, and a plurality of nodes can be formed among convex polygons;
s432, an open area can be formed between nodes of the graph, any point in the area can reach and be connected with each other through a straight line, the edge of the node represents the area which can directly reach two polygons, the areas are connected in a bidirectional mode, and on the basis of the graph structure, various graph search algorithms can be used for searching communication paths;
and S433, on the industrial production line, various material carrying tasks are solved by adopting assembly line scheduling, and the actual factory production line task is completed by combining a NavMesh routing algorithm and a three-dimensional grid.
Compared with the prior art, the digital twin system for the gantry robot has the following beneficial effects:
1. a digital twin system facing a gantry robot directly sets a target position through the system, and a real robot can directly run to a specified position according to a path planning algorithm without human intervention.
2. A digital twin system facing to a gantry robot can remotely monitor the running state of a real gantry robot in real time, realize closed-loop high-precision positioning control, and is more vivid in scene and more immersive for users.
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In order to more clearly illustrate the embodiments of the present invention or the technical methods in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without any inventive work.
FIG. 1 is a schematic diagram of a frame of a gantry robot oriented digital twinning system of the present invention;
FIG. 2 is a flow chart of the digital twin data transmission of the present invention;
FIG. 3 is a schematic view of an overall model of the gantry robot of the present invention;
FIG. 4 is a schematic view of a mechanical crank arm model of the gantry robot of the present invention;
FIG. 5 is a schematic diagram of a fine adjustment mechanism model of the gantry robot according to the present invention;
FIG. 6 is a schematic diagram of the kinematic positional relationship geometry of the horizontal plane of the fine adjustment mechanism of the present invention;
FIG. 7 is a schematic diagram of the geometric structure of the fine adjustment mechanism of the present invention in which the kinematic position of the horizontal plane moves along the x direction;
FIG. 8 is a schematic diagram of the kinematic horizontal plane position of the fine adjustment mechanism of the present invention moving in the y direction;
FIG. 9 is a schematic diagram of the kinematic rotation relationship geometry for the horizontal plane of the fine adjustment mechanism of the present invention;
FIG. 10 is a schematic diagram of the rotational relationship geometry of the horizontal kinematic branch structure of the fine adjustment mechanism of the present invention;
FIG. 11 is a schematic diagram of a three-dimensional grid construction detour obstacle avoidance analysis of the present invention;
FIG. 12 is a schematic diagram of a three-dimensional mesh-constructed obstacle-avoidance analysis of the present invention;
FIG. 13 is a first stage of a schematic construction of a three-dimensional mesh keypoint set according to the present invention;
FIG. 14 is a schematic diagram of the construction of a three-dimensional mesh keypoint set at stage two in accordance with the present invention;
FIG. 15 is a schematic diagram of the construction of a three-dimensional mesh keypoint set at stage three in accordance with the present invention;
FIG. 16 is a schematic diagram of a first step of the NavMesh algorithm search strategy of the present invention;
FIG. 17 is a schematic diagram of the principle of the NavMesh algorithm search strategy of the present invention at step two;
FIG. 18 is a schematic diagram of the principle of the NavMesh algorithm search strategy of the present invention at step three;
FIG. 19 is a schematic diagram of the principle of the NavMesh algorithm search strategy of the present invention at step four;
FIG. 20 is a directed graph of a multi-station path planning pipeline processing sequence of the present invention;
FIG. 21 is a Gantt chart of multi-station processing production sequencing combined with pipeline scheduling of the present invention;
FIG. 22 is a schematic view of the user-oriented interactive interface of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the following examples:
the digital twin system of the gantry robot mainly comprises three parts, namely scene reconstruction, algorithm simulation, data reading and writing and interaction.
As shown in fig. 1, the digital twin system for the gantry robot comprises the following steps:
s01, a control decision, motion analysis and path planning module: and performing kinematic analysis on the mechanical structure of the equivalent proportion virtual gantry robot model, and performing inverse kinematic calculation on the fine adjustment mechanism and the crank arm structure so as to perform motion control on the robot. After the three-dimensional convex polygon is subjected to grid construction, the three-dimensional path planning algorithm design based on different tasks is completed according to the processing requirements of the gantry robot. The method comprises the steps of manually setting target positions of the gantry robot, calculating a reasonable path from an initial position to a target position of the gantry robot through a path planning algorithm, carrying out priority setting on a plurality of targets if the gantry robot needs to reach a plurality of target positions, and generating a reasonable path according to a task allocation instruction. And then, according to the generated path, the gantry robot in the physical world follows the virtual path through a following control algorithm and runs to a specified target position.
S02, control module and driving module: the virtual simulation platform sends path position information to the motion control software in real time, and the servo motor and the servo driver realize that the physical world gantry robot tracks the running track of the digital world gantry robot in real time through ADS communication and a method for giving external positions; the exposure and the ambiguity of the camera are adjusted in a self-adaptive manner through a high-precision camera calibration algorithm, the optimal calibration image is obtained, the high-precision camera calibration is realized, and the camera internal parameters with higher precision are obtained; the initial position of the gantry robot is manually set, a rotation and translation matrix of a camera and a marker in the initial position is calculated, the calculated value is recorded in a database, and interface display of data can be realized on a human-computer interaction interface; the gantry robot repeatedly arrives at the initial position for many times, the rotational translation matrix of the camera and the marker at the arrival time and the rotational translation matrix at the initial position time are calculated to obtain the current position deviation, and the position deviation interface is displayed and sent to the fine adjustment mechanism to compensate the deviation, so that high-precision positioning is realized.
S03, gantry robot and vision measuring module: the main body mechanism of the large-span crank arm gantry robot is divided into a truss, a crank arm, a cross beam and an end effector, when the end effector of the physical world gantry robot moves to a position near a target position, a vision measuring module starts to work, an industrial camera and a laser range finder above the end effector capture data of a marker in real time, the deviation of the current position from the target position is calculated through vision positioning software, the deviation value is sent to a motion controller of the physical world gantry robot, and accurate regulation and control of the position are achieved through a motion control deviation compensation algorithm.
S04, a pose calculation and three-dimensional online monitoring module: and acquiring and storing pose data obtained after deviation compensation, integrating the data and evaluating the precision, and transmitting the data to a database. Historical data formed in the database can drive the gantry robot model to perform synchronous motion simulation,
and displaying real-time data on a simulation interface to realize remote monitoring.
S05, cloud server: the physical world and the digital world are interconnected through Ethercat communication and the Internet.
As shown in fig. 2, the embodiment of the present invention provides an interactive method for directly reading and writing data from and into an emulation platform and a blessing control system without a data transmission system, including the following steps:
s21, adding a route to the gantry robot controller, downloading a program to the gantry robot controller, and then operating the controller;
s22, selecting a virtual simulation platform, adding an ADS library file with a path of \ TwinCAT \ AdsApi \ NET with version 4.0.30319;
s23, writing a c # program on a Unity3D simulation platform to realize data reading and writing, and mainly using two functions of ReadAny and WriteAny to read and write.
As shown in fig. 3, the main structure of the large-span crank arm gantry robot comprises a walking beam 1, a U-shaped crank arm mechanism 2 is connected below the beam, a fine adjustment mechanism 3 is arranged between the U-shaped crank arm mechanism 2 and an end effector 4, and an end manipulator 4 is responsible for tasks such as door panel grabbing, loading and unloading. The cross beam 5 and the support column 6 are used as a support mechanism of the large-span gantry robot, and the connecting beam 7 is connected between the head and the tail of the cross beam 5 and has the functions of fixing and supporting the robot.
As shown in fig. 4, the U-shaped crank arm mechanism 2 is in charge of the structure of connecting the crank arm by the side cover 8, the upper crank arm 9 is driven to rotate, the servo motor 10 is placed at the middle joint of the upper crank arm 9 and the lower crank arm 11, and the left end and the right end are respectively provided with one servo motor. The bearing 12 is responsible for fixing the end of the crank arm lower arm 11, the lowest end is connected with the lower bracket 13, and is responsible for fixing the sucker.
As shown in fig. 5, three SGM7a motors 14 are disposed above the fine adjustment mechanism 3, and are respectively responsible for driving three bearing screw seats 15 of the fine adjustment mechanism to move, an upper bearing support plate 16 is fixed below each bearing screw seat, and connecting rods 17-18 are connected, the connecting rods are fixed by a lower bearing support plate 19 below the bearing screw seats, and a movable platform connecting member 20 is connected with the three lower bearing support plates and the end effector connecting seat 21.
As shown in fig. 6, when the fine adjustment mechanism moves along the horizontal plane, the coordinate system of the fine adjustment mechanism and the spatial coordinate system of the position relationship of each joint need to complete coordinate conversion.
As shown in FIGS. 7 and 8, point P occurs when the end effector is moved in the X-axis and Y-axis directions of the world coordinate systemFa(xFa,yFa,zFa)、PFb(xFb,yFb,zFb) And PFc(xFc,yFc,zFc) The corresponding self coordinate system vector mapping relation matrix of the movable platform connecting piece is as follows:
wherein k is1And k2The relation coefficient is converted for the horizontal plane position, and the geometrical relation shows that: k is a radical of1＝-1/2， 
Similarly, the point R can be found from the formula (23)Fa(x′Fa,y′Fa,z′Fa)、RFb(x′Fb,y′Fb,z′Fb) And RFc(x′Fc,y′Fc,z′Fc) The corresponding proper mapping relation matrix of the self coordinate system of the connecting rod is as follows:
wherein k is3＝κFzAnd the Z-axis position conversion relation coefficient is-0.6. Likewise, point QFa(x″Fa,y″Fa,z″Fa)、 QFb(x″Fb,y″Fb,z″Fb) And QFc(x″Fc,y″Fc,z″Fc) The corresponding proper mapping relation matrix of the self coordinate system of the connecting rod is as follows:
as shown in fig. 9, when the fine adjustment mechanism moves along the horizontal plane, the coordinate system of the rotation relationship between each link and the linkage and the spatial coordinate system need to complete coordinate conversion.
When the end effector O' (x) is as shown in FIG. 10O′,yO′,zO′) When moving to the X-axis and Y-axis directions of the world coordinate system, the point RFa、RFbAnd RFcCorresponding rotation vector of self coordinate system of connecting rod
And
the mapping relationship matrix is as follows:
wherein k is the amplification factor of the horizontal plane rotation conversion relation and is determined by the size of the fine adjustment mechanism. Likewise, point SFa、SFbAnd SFcCorresponding inner connecting rod set rotation vector
And
the mapping relationship matrix is as follows:
likewise, point STa、STbAnd STcCorresponding four-bar linkage self coordinate system rotation vector
And
the mapping relationship matrix is as follows:
as shown in fig. 11, it is assumed that an obstacle exists between the start point S and the end point G. Static rectangular obstacles are depicted from different views. If the height of the obstacle is above the upper limit of the end effector, the obstacle is marked to prohibit the robot from searching for a grid containing obstacles in the path plan. The obstacle avoidance strategy adopted during the detour is suitable for the obstacles which cannot fly over the moving area.
As shown in fig. 12, if the height of the obstacle is below the upper limit of the end effector. A new set of plane points is constructed around the obstacle and the robot performs a path search on the reconstructed mesh. The obstacle avoidance strategy is to cross an obstacle. The method can effectively reduce the path cost and improve the path searching and moving efficiency.
As shown in fig. 13, 14 and 15, the process of moving the end effector from the plane α to the plane β is shown. To avoid collision, is Ω1The planes of different heights of the region add a set of keypoints for constructing the mesh. For different heights of terrain, the end effectors need to be moved to take into account their structure. The inner cylindrical diameter of the hollow cylinder O serves as the diagonal length of the end effector. In order to avoid collision, the radius difference of the inner and outer cylinders is an expanded safety distance. Assuming a radius of the outer cylinder rC', the radius of the inner cylinder is rCThe relationship between the two can be preliminarily set as:
rC′＝μ·rC,μ∈(1.2～1.3) (34)
where μ is the coefficient of relationship. Assume that a simplified model O of the end effector needs to be leveledThe plane alpha moves to a point H on the plane beta. Line l in plane alpha1The end effector is movable in the z-axis when tangent to the outer radius circle of the cylinder. Starting from point A, B, C on the plane, (Vw ═ { a, B, C }) the center of the navigation agent cylinder O, the target point H on the plane, and the extension point D, E, F, point G on any straight line passing through point H form a node set (Ve ═ { D, E, F, G, H }). A convex polygon navigation mesh is then formed. The end effector may compute the shortest path to the plane using the NavMesh algorithm.
As shown in fig. 16, 17, 18 and 19, the NavMesh algorithm is selected as four steps of the navigation search strategy on the basis of the three-dimensional grid. The NavMesh algorithm is based on the principle of the a-algorithm. According to the constructed plane set adjacency information, a polygon set passing from the start point to the end point is searched. Wherein S is a starting point, G is an end point, and the rest are intermediate nodes. The set is denoted by V.
V＝{V1,V2,V3,…} (35)
First, at initial triangle SV1V2Finding neighbor edge SV in list1And SV2；
Second step, V3In the inner side of the funnel, the SV at the funnel side is updated3The funnel will become narrower; v4At the outer side of the funnel, the funnel does not need to be updated;
third step, V5In the inner side of the funnel, the SV at the funnel side is updated5；V6Outside the funnel, the funnel does not need to be updated;
and fourthly, repeating the steps to construct the shortest path.
As shown in fig. 20, the door needs to be processed in the order of the arrows in the drawing. The function of the table 1 is the same as that of the table 2. When the stage No. 1 is in a non-idle state, the stage No. 2 serves as a target position. If both stations are working, the robot needs to wait for its processing to be completed. Similarly, numbers 3 and 4 are one group, and numbers 5 and 6 are the other group.
As shown in fig. 21, the multistation path planning and scheduling in the industrial process is completed by using a production sequencing gantt chart.
On an industrial production line, various material handling tasks are solved by utilizing assembly line scheduling, and therefore the following assumptions are made:
a. suppose there are n jobs on a pipeline, each requiring m tasks to be performed, one for each job
T1i,T2i,…,TmiI is more than or equal to 1 and less than or equal to n. And this task TjiOnly at the device PjExecuting, j is more than or equal to 1 and less than or equal to m;
b. for any job i, at task TjiBefore completion, T(j-1)iCannot be executed;
c. the working time of each working table is the same and is Tw；
d. The same device cannot process more than one task at any time;
e. arranging the positions of the workpieces according to a certain priority;
f. each machine performs a specific job and must be completed before the product moves to the next location in the production line;
on the digital twin platform, the position of the stage can be read directly. The sequence of the gantt chart based positioning of all the stages is listed in fig. 9. In the production line of the Gantt chart, a robot is set to return to an initial position for taking a door at a specified time interval. Otherwise, selecting the position of the workbench as the target point according to the sequence of the Gantt chart. The production allocation needs three stages, stage 1 is the initial state of the wooden door processing task, and the robot is in an idle state for most of the time. And the stage 2 is an intermediate stage of wood door processing, and the cycle number can be set according to requirements. Stage 3 is the end stage, where no finished door panels are provided. The assembly line scheduling model is combined with a three-dimensional path planning method, so that the problem of multi-target path planning of the gantry robot can be solved.
As shown in fig. 22, the embodiment of the present invention constructs an interactive and controllable digital twin system interface, which includes a function option area, an overall simulation monitoring screen of the gantry robot, a simulation monitoring screen of the crank arm and the fine tuning mechanism, and a status monitoring and controlling area. The function option area is used for setting functions such as user login, picture setting and the like; the whole motion state of the gantry robot and the motion of the crank arm fine adjustment mechanism are displayed through a simulation monitoring picture; the state monitoring and control area is used for displaying the connection state of the data acquisition channel, virtual and actual motion coordinates in a Cartesian space after a coordinate system is unified, the limiting states of the end operator and the fine adjustment mechanism and debugging information generated in the operation process.
The above-mentioned embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical method of the present invention by those skilled in the art should fall within the protection scope defined by the appended claims of the apparatus of the present invention without departing from the spirit of the present invention.
Claims (10)
1. A digital twin system facing a gantry robot is characterized in that: the system comprises a real gantry robot in the physical world, a virtual gantry robot in the digital world and a cloud server interconnecting the real gantry robot and the virtual gantry robot in the digital world;
the real gantry robot in the physical world is formed by respectively interacting a gantry robot main body mechanism, a driving module, a vision measuring module and a control module;
the virtual gantry robot in the digital world is formed by a three-dimensional online monitoring module, a control decision module, a motion analysis and path planning module and a pose calculation module in an interactive mode;
the cloud server is respectively interconnected with the Ethercat communication module and the Internet module to realize a physical world and a digital world;
the main body mechanism of the gantry robot comprises a truss, a crank arm or a straight arm, a fine adjustment mechanism and an end effector;
the driving module comprises a servo driver and a servo motor;
the vision measurement module comprises a vision controller, an industrial camera, a laser range finder, a marker and vision positioning software, wherein the vision positioning software comprises high-precision calibration and vision positioning;
the control module comprises a motion controller and motion control software, wherein the motion control software comprises NC control, an I/O interface and a PLC;
the three-dimensional online monitoring module comprises a gantry robot virtual model, gantry robot motion simulation, historical data playback and real-time data display;
the control decision module comprises a task allocation instruction, priority setting, target position setting and motion path transmission;
the motion analysis and path planning module comprises a virtual gantry robot, kinematic analysis of a mechanical structure, navigation area and grid division and three-dimensional path planning;
the pose calculation module comprises a database, a data acquisition and storage module, a data integration module and a precision evaluation module;
the internet module comprises a communication protocol, data bidirectional interaction and a server;
the Ethercat communication module comprises a communication interface, a local port and a data bidirectional interaction component.
2. The digital twin system facing to the gantry robot as claimed in claim 1, wherein the digital world virtual gantry robot is constructed based on the physical world real gantry robot according to a ratio of 1:1, the coordinate origin, the physical dimensions and the three-dimensional space layout of the internal devices have consistency, and the consistency correspondence is realized by off-line visual calibration, comprising the following steps:
s11, installing a calibration plate for visual positioning at one corner of the real gantry robot and at the edge of the workbench of each internal device, ensuring that the calibration plate can obtain clear imaging in the imaging range of the camera, and recording the image of the calibration plate at the moment as I0；
S12, defining the Z direction of the real gantry robot to move to the lowest end, when the XY direction moves to one corner of the gantry robot, the position of the imaging of the center of the corresponding calibration plate under the camera coordinate system when the imaging is positioned at the center of the image is the zero point of the gantry robot, and the intersection point of the corresponding XYZ directions is the origin O of the world coordinate system;
s13, driving with origin O as starting pointThe movable gantry robot moves to the visual calibration plate of the jth internal equipment workbench along XYZ axes and ensures the imaging I of the calibration plate in the camerajAnd I0Similarly, in this case, the coordinate of the device j in the world coordinate system is (X)j,Yj,Zj) (ii) a Wherein, XjThe travel in the X direction is multiplied by the range of the screw rod in the X direction; y isjThe distance in the Y direction is multiplied by the measuring range of the screw rod in the Y direction; zjThe stroke in the Z direction is multiplied by the measuring range of the screw rod in the Z direction.
3. A gantry robot-oriented digital twin system as claimed in claim 1, wherein the steps of monitoring the process in the three-dimensional online monitoring module are as follows:
s21, loading a three-dimensional model, a virtual camera and a virtual experimental scene of the virtual gantry robot by a user through controlling an operation button of the decision module, and starting an online monitoring task;
s22, transmitting the motion data of the actual gantry robot to the virtual gantry robot in real time through a network, and driving the three-dimensional model of the virtual gantry robot to realize the motion consistent with that of the real gantry robot through motion analysis and motion simulation by the virtual gantry robot so as to achieve the purpose of remote online monitoring;
s23, storing the motion data of the actual gantry robot in a database, and allowing a user to view and playback historical data according to time;
and S24, the virtual gantry robot can perform process flow preview through motion analysis and motion simulation according to the user instruction so as to determine whether the existing process flow is reasonable.
4. A digital twin system facing a gantry robot as claimed in claim 1, wherein the virtual gantry robot in the digital world controls the gantry robot in the physical world, and the operation steps are as follows:
s31, the user appoints specific operation task, flow and target by controlling the operation button of the decision module;
s32, the virtual gantry robot plans a reasonable running path for the real gantry robot through the kinematic analysis of the gantry robot, the grid division of a navigation area and the three-dimensional path planning, and sends path key point data to a control module of the real gantry robot in real time, the real gantry robot in the physical world follows the running track of the digital world gantry robot in real time to realize the following of the virtual path, and an input shaper is designed to shape the position information received by the physical world gantry robot so as to reduce the vibration of the tail end of the cantilever beam and enable the real gantry robot to more accurately track the real-time position of the digital world gantry robot;
and S33, when the end effector of the physical world gantry robot moves to the position near the target position, the vision measurement module starts to work, the vision measurement method is that the laser range finder is used for obtaining the deviation in the z direction, the digital camera 2D vision measurement method is used for obtaining the deviation in the xy direction, the data of the marker is captured in real time, the vision measurement module calculates the deviation of the current position from the target position, the deviation value is sent to the motion controller and the pose processing module of the physical world gantry robot for positioning accuracy evaluation, and accurate regulation and control of the position are realized through a motion control deviation compensation algorithm.
5. A gantry robot-oriented digital twin system as claimed in claim 4, wherein the real gantry robot of the physical world tracks the moving track of the digital world gantry robot in real time, and the following of the virtual path comprises the following steps:
s321, deploying the cloud server to serve as a bridge for data exchange between the digital world and the physical world;
s322, acquiring the real-time position of the digital world gantry robot, setting the IP and port number of a server on a virtual simulation platform, and then sending path position information to the server in real time;
s323, the physical world gantry robot sets the IP and port number of the server through TwinCAT software, then receives the position information of the digital world received by the server in real time, or sends the path position information to the physical world gantry robot controller through an EtherCAT bus in real time by a virtual simulation platform, and realizes the real-time tracking of the digital world gantry robot by the physical world gantry robot through a method given by an external position;
and S324, shaping the position information received by the physical world gantry robot by designing an input shaper so as to reduce the vibration of the tail end of the cantilever beam and enable the cantilever beam to more accurately track the real-time position of the digital world gantry robot.
6. A gantry robot-oriented digital twin system as claimed in claim 4, wherein the vision measuring module calculates the deviation of the current position from the target position, comprising the steps of:
s331, self-adaptively adjusting exposure and ambiguity of the camera through a high-precision camera calibration algorithm to obtain an optimal calibration image, so as to realize high-precision camera calibration and obtain camera internal parameters with higher precision;
s332, obtaining deviation in the xy direction through a two-dimensional vision measurement technology, obtaining deviation in the z direction through a laser range finder, repeatedly enabling the gantry robot to reach the initial position for multiple times, calculating a rotation and translation matrix of the camera and the marker at the moment of arrival and a rotation and translation matrix at the moment of the initial position to obtain the current position deviation, displaying a position deviation interface, and sending the position deviation interface to a fine adjustment mechanism to compensate the deviation, so that high-precision positioning is achieved.
7. The digital twin system for gantry robot of claim 1, wherein the algorithm of the motion analysis and path planning module comprises the following steps:
s41, performing kinematic analysis on the end effector, the truss, the crank arm and the fine adjustment mechanism of the virtual model, and performing forward and reverse kinematic calculation on the robot so as to control the motion of the robot and finish translation and rotation track simulation;
s42, in the virtual simulation platform constructed by Unity3D, reading boundary points of each workbench in a virtual environment as a set, constructing a new point set through regional obstacle avoidance analysis, and combining the point sets of the workbenches to complete node construction of the three-dimensional navigation grid;
s43, completing single-target three-dimensional path planning on the three-dimensional navigation grid by combining with a NavMesh search strategy, providing a navigation path for the robot, then completing multi-target path planning under an industrial process by combining with assembly line scheduling, and providing position data for the digital twin system.
8. The gantry robot-oriented digital twin system of claim 7, wherein the kinematic analysis of the kinematic analysis and path planning module includes the kinematic equation construction of the crank arm, the fine tuning mechanism and the traveling mechanism in Cartesian space, and comprises the following steps:
s411, the motion of the end effector and the end effector of the truss in cartesian space can be decomposed into: the end effector and the truss can adopt linear track simulation, and can be divided into translation track simulation and rotation track simulation;
let the coordinate of the starting point of the track be PES(xE(0),yE(0),zE(0)) The coordinate of the end point position is PEE(xE(1),yE(1),zE(1)) From the end point PEETo the starting point PESHas a track length of LE:
LE＝|PEE(xE(1),yE(1),zE(1))-PES(xE(0),yE(0),zE(0))| (1)
Where subscript E is the end effector, assuming point P in the current stateE(i)(xE(i),yE(i),zE(i)) To the starting point PESHas a track length of sE(i)，sE(i+1)For the track length of the next state in time interval Δ T, assume sE(i)Corresponding linear velocity vE(i)Acceleration of aEAnd assume sE(i+1)Linear velocity vE(i+1)：
sE(i+1)＝sE(i)+vE(i+1)·ΔT (2)
The linear motion trajectory equation is:
if v isE(i) 2/2aE≤LE-sE(i)The interpolation point is in the acceleration uniform velocity section, and the interpolation equation is as follows:
if v isE(i) 2/2aE＞LE-sE(i)With interpolation point in the deceleration section and end-effector at αEUntil the interpolation of the cost segment is completed:
vE(i+1)＝vE(i)-aEΔT (5)
suppose the angle of the end effector at a certain time is thetaE(i)，θE(i+1)For the angle at the next instant in time interval Δ T, let θ beE(i)Corresponding linear velocity of ωE(i)Angular acceleration of alphaEAnd setting the next interpolation point thetaE(i+1)At a velocity of ωE(i+1)：
θE(i+1)＝θE(i)+ωE(i+1)·ΔT (6)
When ω isE(i) 2/2αE≤θE-θE(i)And then, the interpolation point is in the acceleration uniform velocity segment:
when ω isE(i) 2/2αE＞θE-θE(i)In time, the interpolation point is in the deceleration section:
ωE(i+1)＝ωE(i)-αEΔT (8)
the motion of the truss in the Cartesian space only comprises translational motion along a certain straight line; similarly, assume that the truss is from the end point PTE(xT(1),yT(1),zT(1)) To the starting point PTS(xT(0),yT(0),zT(0)) Length L of trackTComprises the following steps:
LT＝|PTE(xT(1),yT(1),zT(1))-PTS(xT(0),yT(0),zT(0))| (9)
subscript T is a truss; linear motion trajectory equation of truss
If v isT(i) 2/2aT≤LT-sT(i)If the interpolation point of the truss is in the acceleration uniform speed section; the interpolation equation is:
if v isT(i) 2/2aT＞LT-sT(i)And the interpolation point of the truss is in the deceleration section:
vT(i+1)＝vT(i)-aTΔT (12)
s412, the telescopic structure of the mechanical crank arm of the gantry robot can be simplified into a diamond shape, and the side length of the telescopic structure is lAVertical diagonal line is set as hA，lAAnd hAAt an angle of thetaAWhen the mechanical crank arm extends upwards to a certain position, the vertical diagonal line is set as hA(i+1)The difference between the two is set to be Δ hAThe angle of the arm after retraction becomes thetaA(i+1)The difference angle between them is set as delta thetaAThe relationship is as follows:
the vertical diagonal and the side length are related as follows according to the geometrical relationship:
by calculating the relationship, Delta theta can be knownAAnd Δ hAThe relationship of (a) to (b) is as follows:
the kinematic relationship of the available crank arms is as follows:
and (3) interpolating the height parameters of the crank arm joints according to the same translation track simulation principle of the end effector:
hA(i+1)＝hA(i)+vA(i+1)·ΔT (17)
assumed end point PJE(xJ(1),yJ(0),zJ(1)) To the starting point PJS(xJ(0),yJ(0),zJ(0)) Has a track height of H:
H＝|PJE(xJ(1),yJ(0),zJ(1))-PJS(xJ(0),yJ(0),zJ(0))| (18)
wherein, the subscript J is a crank joint and an intermediate point PJ(i)(xJ(i),yJ(0),zJ(i)) To the starting point PJSHas a track length of hJ(i)Then, the linear motion trajectory equation is:
s413, the fine adjustment mechanism of the gantry robot belongs to a parallel mechanism structure, and the side length of a crank arm connecting rod of the mechanism is assumed to be lFThe height of the horizontal connecting rod of the fixed platform relative to the horizontal connecting rod of the movable platform is set as hF(i)，lFAnd hF(i)At an angle of thetaF(i)The length of the position of the movable platform fixing device along the direction of the horizontal connecting rod under the self coordinate system and the front end of the connecting rod is set as mF(i)When the fine adjustment mechanism is extended or contracted to a certain position in the Z-axis direction, the length is mFz(i+1)The difference length between the two is set as Δ mFzAt this time, the height is set to hFz(i+1)The difference between the two is set to be Δ hFzAt this time, the angle is set to thetaFz(i+1)The two differ by an angle delta thetaFzThe relationship is as follows:
wherein, the lower corner mark F represents a fine adjustment mechanism, and the delta theta can be known through calculation of the relationFzAnd Δ mFzThe relationship of (a) to (b) is as follows:
by calculating the relationship, Delta theta can be knownFzAnd Δ hFzThe relationship of (a) to (b) is as follows:
the kinematic relationship of the fine adjustment mechanism is as follows:
wherein i ∈ {1 ∈ [ ],2,3…}，θFz(i)For fine-tuning the angle of rotation of the axis of the link joint of the mechanism, kFz、
Is Δ θFzAnd Δ mFzCoefficient of relationship, κ, between each jointFz′、
Is Δ θFzAnd Δ hFzThe relation coefficient of each corresponding joint.
9. A gantry robot-oriented digital twin system as claimed in claim 7, wherein the node construction of the three-dimensional navigation grid in step S42 includes the following steps:
s421, regarding a working scene as a requirement for door plate processing, wherein the door plate needs to be grabbed and placed at an appointed position by a gantry robot, and the door plate needs to be cut, punched, assembled and the like by a workbench; reading boundary points of each workbench in the virtual environment as a set Vw, constructing a new point set Ve through regional obstacle avoidance analysis, combining the point sets of the workbenches, and completing node construction of the three-dimensional navigation grid;
s422, the motion area space of the end effector of the gantry robot is divided, and the upper limit and the lower limit of the extension and contraction of the mechanical crank arm define the maximum height h and the minimum height h of the end effectorE(max)And hE(min)Height range h of end effectorE(i)Can be set as follows:
hE(min)≤hE(i)≤hE(max) (24)
the internal space omega of the large-span gantry robot can be divided into two parts through the upper and lower limit heights of the end effector:
wherein omega1For the end-effector to be movable in a flying mannerRegion of (d), omega2A region where the flying movement is impossible;
s423, in order to ensure that the end effector does not collide with the obstacle during the movement and rotation, the model needs to be simplified to Ω1Adding key point sets for constructing grids on planes with different heights in the region;
s424, assuming that all points on the same plane form a set;
V＝{Vw,Ve}＝{V1,V2,...Vn},{V1,...Vi}∈Vw,{Vi+1,...Vn}∈Ve (26)
three points V not collinear in spacei(xi,yi,zi)，Vj(xj,yj,zj)，Vk(xk,yk,zk) The plane equation formed is:
through the analysis, collected point sets and point sets added under mathematical analysis for avoiding collision are collected, a plane equation set is established in a simultaneous mode to form a multi-plane set in a space, three non-collinear points form a plane triangular convex hull, and a space polygon set formed by planes of each convex hull forms a convex polygon navigation grid.
10. A gantry robot-oriented digital twin system as claimed in claim 7, wherein in step S43, the single-target three-dimensional path planning process is performed on the three-dimensional navigation grid, and the method comprises the following steps:
s431, after a grid is constructed, the Navmesh routing algorithm drives a virtual model to move by calculating the minimum path cost, in a three-dimensional virtual environment, a scene is represented as a structure similar to a graph by a convex polygon set, and a plurality of nodes can be formed among convex polygons;
s432, an open area can be formed between nodes of the graph, any point in the area can reach and be connected with each other through a straight line, the edge of the node represents the area which can directly reach two polygons, the areas are connected in a bidirectional mode, and on the basis of the graph structure, various graph searching algorithms can be used for searching communication paths;
and S433, on the industrial production line, various material carrying tasks are solved by adopting assembly line scheduling, and the actual factory production line task is completed by combining a NavMesh routing algorithm and a three-dimensional grid.
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