CN114460904B - Digital twin system for gantry robot - Google Patents
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Abstract
The invention relates to the technical field of digital twin, in particular to a digital twin system for a gantry robot, which consists of a real gantry robot in a physical world, a virtual gantry robot in a digital world and cloud servers connected with each other; 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 calculating 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 carry out data transmission through communication between the cloud server and the Ethercat; according to the invention, the 1:1 virtual gantry robot model is subjected to kinematic simulation in a virtual scene, so that three-dimensional visual on-line monitoring and visual feedback remote closed-loop control of a real gantry robot are realized, and the virtual and actual running position errors of the gantry robot are 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 for a gantry robot.
Background
The digital twin technology comprises one of engines for realizing subversion type transition in various large fields such as 5G capital construction, extra-high voltage, inter-city high-speed railways, urban rail transit, large data centers, new energy automobile charging piles, artificial intelligence, industrial Internet and the like.
Aiming at a digital twin system of a robot, china patent No. 202110055322.6 discloses a method for driving virtual model simulation by adopting historical data based on a digital twin technology.
For example, chinese patent No. CN202010517266.9 discloses a digital twin spraying simulation system and method for a coating line, and relates to the field of spraying simulation. According to the data representation result of the simulated coating line, the real coating line operation result can be mapped, so that predictive deduction of possible problems and design optimization of the whole production line are facilitated, the method used realizes virtual-to-physical synchronous correspondence, and virtual and actual bidirectional control is not realized.
The digital twin system of the underground substation inspection robot based on the UE4 is developed by Li Xin et al in the paper, the inspection environment roaming and the central control function can be completed, and the management of the database is completed through a system interface. Li Fu et al build the virtual simulation experiment teaching platform of intelligent robot high-risk operation under the complex environment, move high-risk complex scene and robot high-end equipment into virtual laboratory with the help of virtual simulation technique, have accomplished teaching and experimental requirement. Wang Hao et al, based on digital twin technology, designed the automatic feeding and discharging system to be electromechanical, shortening the development period of new products and reducing the development cost. Because of the variety of robots, the digital twin technology is slowly moved to a specific and customized road, and research and application of the digital twin technology at home and abroad show blowout development, and meanwhile, a plurality of new research results are emerging. However, the digital twin technology is designed, developed and applied in an automatic production line in an exploration stage, the research results are few, the systematicness is lacking, and the digital twin technology is rarely researched on a gantry robot system. Most of the prior art of digital twin systems only realize the remote real-time monitoring function of virtual scenes, but can not control robots and analyze problems by using the digital twin systems.
The scientificity and the practicality of the digital twin system for the robot to research are combined with the robot to finish the research of scheduling planning by comprehensively considering the self structural requirement of the robot, and an intelligent operation platform of the robot is constructed. The gantry robot has obvious application value in the aspects of replacing manpower, improving production efficiency, stabilizing product quality and the like as an automatic robot system solution with low cost and simple system structure. In recent years, digital twin technology is widely applied to intelligent factories and intelligent workshops. The large-span gantry robot is an indispensable part in an intelligent factory, can serve a plurality of machines, and can finish common industrial production fields such as dispensing, plastic dropping, spraying, stacking, sorting, packaging, welding, metal processing, carrying, loading and unloading, assembling, printing and the like. The digital twin system of the gantry robot can be constructed to realize a remote control function, meanwhile, risks can be avoided, safety monitoring and early warning can be timely carried out, and dangers are avoided.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides the digital twin system for the gantry robot, and the digital twin system for the gantry robot is constructed to realize a remote control function, avoid risks, and timely monitor and early warn safety to avoid the risks.
In order to solve the technical problems, the invention adopts the technical method that:
the digital twin system for the gantry robot comprises a real gantry robot in the physical world, a virtual gantry robot in the digital world and a cloud server for interconnecting the real gantry robot and the virtual gantry robot in the physical world;
the real gantry robot in the physical world is formed by interaction of a gantry robot main body mechanism, a driving module, a vision measuring module and a control module respectively;
the virtual gantry robot in the digital world is formed by interaction of a three-dimensional online monitoring module, a control decision module, a motion analysis and path planning module and a pose calculation module;
the cloud server is respectively connected with the physical world and the digital world through the Ethercat communication module and the Internet module;
the gantry robot main body mechanism comprises a truss, a crank arm or a straight arm, a fine tuning mechanism and an end effector;
the driving module comprises a servo driver and a servo motor;
the visual measurement module comprises a visual controller, an industrial camera, a laser range finder, a marker and visual positioning software, wherein the visual positioning software consists of high-precision calibration and visual 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, the kinematic analysis of a mechanical structure, navigation areas, grid division and three-dimensional path planning;
the pose calculation module comprises a database, data acquisition and storage, data integration and precision evaluation;
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 data bidirectional interaction.
The technical method of the invention is further improved as follows: the virtual gantry robot in the digital world is constructed based on the 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 the internal equipment are consistent, the consistency corresponding relation is realized through off-line vision calibration, and the method comprises the following steps:
s11, a corner of a real gantry robot and the edge of a workbench of each internal device are provided with a calibration plate for visual positioning, the calibration plate is ensured to obtain clear imaging within the imaging range of a camera, and the image of the calibration plate at the moment is recorded as I 0 ；
S12, defining that the real gantry robot moves to the lowest end in the Z direction, and when the XY direction moves to one corner of the gantry robot, the position of the corresponding calibration plate center when the imaging under the camera coordinate system is positioned at the image center is the zero point of the gantry robot, and the corresponding intersection point in the XYZ direction is the origin O of the world coordinate system;
s13, driving the gantry robot to move to a visual calibration plate of a j-th internal equipment workbench along the XYZ axis by taking an origin O as a starting point, and ensuring imaging I of the calibration plate in a camera j And I 0 The same applies. At this time, the coordinates of the device j in the world coordinate system are noted as (X j ,Y j ,Z j ) The method comprises the steps of carrying out a first treatment on the surface of the Wherein X is j X direction travel X direction screw range; y is Y j =y-direction travel x Y-direction screw span; z is Z j Range of the Z direction stroke multiplied by the Z direction screw rod.
The technical method of the invention is further improved in that the monitoring process in the three-dimensional online monitoring module comprises the following steps:
s21, loading a three-dimensional model, a virtual camera and a virtual experiment scene of the virtual gantry robot by a user through an operation button of a control decision module, and starting an online monitoring task;
s22, the motion data of the actual gantry robot are transmitted to the virtual gantry robot in real time through a network, and the virtual gantry robot drives the virtual gantry robot to realize the motion consistent with the real gantry robot through motion analysis and motion simulation, so that the purpose of remote online monitoring is achieved.
S23, storing the data of the actual gantry robot movement in a database, and enabling a user to check and play back historical data according to time;
s24, the virtual gantry robot can conduct technological process previewing through motion analysis and motion simulation according to user instructions so as to determine whether the existing technological process is reasonable.
The technical method of the invention is further improved in that the virtual gantry robot in the digital world controls the physical world gantry robot to move, and the operation steps are as follows:
s31, a user designates specific operation tasks, flows and targets by controlling operation buttons of the decision module;
s32, planning a reasonable running path for the real gantry robot through gantry robot kinematics analysis, navigation area grid division and three-dimensional path planning, sending path key point data to a control module of the real gantry robot in real time, enabling the real gantry robot in the physical world to follow the virtual path by tracking the running track of the digital world gantry robot in real time, shaping position information received by the physical world gantry robot by designing an input shaper, and therefore reducing vibration of the tail end of a cantilever beam, and enabling the real gantry robot in the physical world to track the real position of the digital world gantry robot more accurately;
S33, when the end effector of the physical world gantry robot moves to the vicinity of the target position, the vision measurement module starts to work, the vision measurement method is to obtain the deviation in the z direction by using the laser range finder, the deviation in the xy direction is obtained by using the 2D vision measurement method of the digital camera, the data of the marker is captured in real time, the deviation of the current position from the target position is calculated by the vision measurement module, the deviation value is sent to the motion controller and the pose processing module of the physical world gantry robot for positioning accuracy assessment, and the accurate regulation and control of the position are realized by the motion control deviation compensation algorithm.
The technical method of the invention is further improved in that the real gantry robot in the physical world tracks the running track of the gantry robot in the digital world in real time, and the following of the virtual path comprises the following steps:
s321, using the cloud server as a bridge for data exchange between the digital world and the physical world through deployment of the cloud server;
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 digital world position information received by the server in real time, or sends the path position information to the physical world gantry robot controller through the EtherCAT bus in real time, and the physical world gantry robot tracks the digital world gantry robot in real time through an external position setting method;
S324, the position information received by the physical world gantry robot is shaped by designing an input shaper, so that vibration of the tail end of the cantilever beam is reduced, and the real-time position of the digital world gantry robot is tracked more accurately.
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, through a high-precision camera calibration algorithm, the exposure degree and the ambiguity of a camera are adaptively adjusted, an optimal calibration image is obtained, high-precision camera calibration is realized, and a camera internal reference with higher precision is obtained;
s332, obtaining the xy-direction deviation through a two-dimensional vision measurement technology, obtaining the z-direction deviation through a laser range finder, repeatedly reaching an initial position for a plurality of times by the gantry robot, calculating a rotational translation matrix of a camera and a marker at the moment of reaching and a rotational translation matrix at the moment of the initial position, obtaining 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 realized.
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 an end effector, a truss, a crank arm and a fine adjustment mechanism of the virtual model, and performing forward and reverse kinematic calculation on the robot so as to perform motion control on the robot and complete translation and rotation track simulation;
s42, in a virtual simulation platform built by the Unity3D, reading boundary points of each workbench in the virtual environment as a set, constructing a new point set through area obstacle avoidance analysis, merging the point sets of each workbench, and completing node construction of the three-dimensional navigation grid;
s43, completing single-target three-dimensional path planning on a three-dimensional navigation grid by combining with a Navmesh search strategy, providing a navigation path for a robot, and then completing multi-target path planning under an industrial process by combining with pipeline scheduling to provide position data for a digital twin system.
The technical method of the invention is further improved in that the kinematic analysis comprises the construction of a kinematic equation of a crank arm, a fine adjustment mechanism and a travelling mechanism in Cartesian space, and comprises the following steps:
s411, the movement of the end effector and the end effector of the truss in cartesian space may be decomposed into: translational motion along a certain straight line and rotational motion around a fixed shaft, the end effector and the truss can be simulated by adopting straight line tracks, and the end effector and the truss can be divided into translational track simulation and rotational track simulation;
Let the coordinates of the track start point be P ES (x E(0) ,y E(0) ,z E(0) ) The coordinate of the end position is P EE (x E(1) ,y E(1) ,z E(1) ) From the end point P EE To the starting point P ES Is of track length L E :
L E ＝|P EE (x E(1) ,y E(1) ,z E(1) )-P ES (x E(0) ,y E(0) ,z E(0) )| (1)
Wherein subscript E is the end effector, assuming point P in the current state E(i) (x E(i) ,y E(i) ,z E(i) ) To the starting point P ES Is s E(i) ，s E(i+1) For the track length of the next state at time interval deltat, let s be E(i) The corresponding linear velocity is v E(i) Acceleration a E And assume s E(i+1) At a linear velocity v E(i+1) ：
s E(i+1) ＝s E(i) +v E(i+1) ·ΔT (2)
The linear motion trajectory equation is:
if v E(i) 2 /2a E ≤L E -s E(i) The interpolation point is in the acceleration constant speed section, and the interpolation equation is:
if v E(i) 2 /2a E ＞L E -s E(i) The interpolation point is in the deceleration section, and the end effector is alpha E Until the segment interpolation is completed:
v E(i+1) ＝v E(i) -a E ΔT (5)
assume that the end effector angle at a certain time is θ E(i) ，θ E(i+1) For the angle at the next instant in time with a time interval of Δt, assume θ E(i) The corresponding linear velocity is omega E(i) Angular acceleration of alpha E And set the next interpolation point theta E(i+1) At a speed of omega E(i+1) ：
θ E(i+1) ＝θ E(i) +ω E(i+1) ·ΔT (6)
When omega E(i) 2 /2α E ≤θ E -θ E(i) When the interpolation point is in the acceleration constant speed section:
when omega E(i) 2 /2α E ＞θ E -θ E(i) When the interpolation point is in the deceleration section:
ω E(i+1) ＝ω E(i) -α E ΔT (8)
the truss moves in the Cartesian space only including translational movement along a certain straight line; similarly, assume that the truss is from endpoint P TE (x T(1) ,y T(1) ,z T(1) ) To the starting point P TS (x T(0) ,y T(0) ,z T(0) ) Track length L of (2) T The method comprises the following steps:
L T ＝|P TE (x T(1) ,y T(1) ,z T(1) )-P TS (x T(0) ,y T(0) ,z T(0) )| (9)
subscript T is truss; linear motion trajectory equation of truss
If v T(i) 2 /2a T ≤L T -s T(i) The interpolation point of the truss is in an acceleration constant speed section; the interpolation equation is:
if v T(i) 2 /2a T ＞L T -s T(i) Interpolation points of the truss are in a deceleration section:
v T(i+1) ＝v T(i) -a T ΔT (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 l A The vertical diagonal is set to h A ，l A And h A At an angle of theta A When the mechanical crank arm stretches upwards to a certain position, the vertical diagonal line is set to be h A(i+1) The difference in height between the two is set to delta h A The angle of the mechanical arm after being retracted is changed into theta A(i+1) The difference angle between the two is delta theta A The relationship is as follows:
from the geometrical relationships, the vertical diagonal and side length relationships are as follows:
by calculating the relation, delta theta can be known A And Δh A The relationship of (2) is as follows:
the kinematic relationship of the available crank arm is as follows:
the principle of the translation track simulation of the end effector is consistent, and the height parameters of the crank arm joint are interpolated:
h A(i+1) ＝h A(i) +v A(i+1) ·ΔT (17)
assuming endpoint P JE (x J(1) ,y J(0) ,z J(1) ) To the starting point P JS (x J(0) ,y J(0) ,z J(0) ) The track height of (2) is H:
H＝|P JE (x J(1) ,y J(0) ,z J(1) )-P JS (x J(0) ,y J(0) ,z J(0) )| (18)
wherein, the subscript J is a crank joint and the middle point P J(i) (x J(i) ,y J(0) ,z J(i) ) To the starting point P JS Track length h J(i) The linear motion trajectory equation is:
s413, a gantry robot fine adjustment mechanism belongs to a parallel mechanism structure, and the side length of a crank arm connecting rod of the mechanism is assumed to be l F The height of the horizontal connecting rod of the fixed platform relative to the horizontal connecting rod of the movable platform is set to be h F(i) ，l F And h F(i) At an angle of theta F(i) The distance between the position of the movable platform fixing device along the horizontal connecting rod direction and the front end of the connecting rod under the self coordinate system is set to be m F(i) When the fine adjustment mechanism expands and contracts a certain position in the Z-axis direction, the length is set to be m Fz(i+1) The difference length between the two is set as delta m Fz At this time, the height is set to h Fz(i+1) The difference in height between the two is set to delta h Fz At this time, the angle is set to θ Fz(i+1) The difference angle between the two is delta theta Fz The relationship is as follows:
wherein, the subscript F represents the fine adjustment mechanism, and the delta theta can be known by calculating the relation Fz And Δm Fz The relationship of (2) is as follows:
by calculating the relation, delta theta can be known Fz And Δh Fz The relationship of (2) is as follows:
the kinematic relationship of the fine adjustment mechanism is as follows:
wherein i is {1,2,3 … }, θ Fz(i) For fine-tuning the angle of rotation of the shaft of the linkage joint of the mechanism, κ Fz 、Is delta theta Fz And Δm Fz The corresponding relation coefficient of each joint, kappa Fz ′、/>Is delta theta Fz And Δh Fz The relationship 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, facing a working scene, which is the requirement of door panel processing, the gantry robot needs to grab the door panel and place the door panel at a designated position, and the workbench needs to finish operations such as cutting, punching, assembling and the like of the door panel; reading boundary points of each workbench in the virtual environment as a set Vw, constructing a new point set Ve through area obstacle avoidance analysis, merging the point sets of each workbench, and completing node construction of the three-dimensional navigation grid;
S422, dividing the space of a movement area of the end effector of the gantry robot, wherein the maximum and minimum heights h of the end effector are defined by the upper and lower limits of the extension and retraction of the mechanical crank arm E(max) And h E(min) Height range h of end effector E(i) The method can be set as follows:
h E(min) ≤h E(i) ≤h E(max) (24)
the internal space omega of the large-span gantry robot can be divided into two parts by the upper limit height and the lower limit height of the end effector:
wherein Ω 1 Omega for the region where the end effector can move dramatically 2 Is an area which can not make leap movement;
s423, the model is simplified to ensure that the end effector does not collide with the obstacle during movement and rotation, Ω 1 Adding key point sets for constructing grids to planes with different heights in the region;
s424, assuming that all points on the same plane form a set;
V＝{Vw,Ve}＝{V 1 ,V 2 ,…V n },{V 1 ,…V i }∈Vw,{V i+1 ,…V n }∈Ve (26)
three points V in space that are not collinear i (x i ,y i ,z i )，V j (x j ,y j ,z j )，V k (x k ,y k ,z k ) The plane equation is composed of:
by the analysis, the collected point set and the point set added under mathematical analysis for avoiding collision are summarized, a plane equation set is established simultaneously, a multi-plane set in space is formed, three non-collinear points form a plane triangle convex hull, and a space polygon set formed by the planes of each convex hull form a convex polygon navigation grid.
The technical method of the invention is further improved in that in step S43, a single-target three-dimensional path planning process is completed on a three-dimensional navigation grid, and the method comprises the following steps:
s431, after a grid is constructed, a Navmesh path-finding algorithm drives a virtual model to move by calculating the minimum path cost, and in a three-dimensional virtual environment, a scene is represented by a convex polygon set to be a structure similar to a graph, and a plurality of nodes can be formed among the convex polygons;
s432, forming an open area between nodes of the graph, wherein any point in the area can be reached through a straight line and are connected with each other, the edge of the node represents the area which can directly reach the connection of two polygons, the areas are connected in two directions, and various graph searching algorithms can be used for searching a communication path on the basis of the graph structure;
s433, on an industrial production line, various material handling tasks are solved by adopting assembly line scheduling, and the actual factory production line tasks are completed by combining a Navmesh path-finding algorithm and a three-dimensional grid.
Compared with the prior art, the digital twin system for the gantry robot has the beneficial effects that:
1. a digital twin system for gantry robots is provided, through which target positions are set directly, and real robots can directly run to designated positions according to a path planning algorithm without human intervention.
2. The digital twin system for the gantry robot can remotely monitor the running state of the real gantry robot in real time, realize closed-loop high-precision positioning control, and has more lifelike scene and more immersion feeling for a user.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical methods in the prior art, the drawings required for the embodiments or the description of the prior art will be briefly described, and it is apparent that the drawings in the following description are only some embodiments of the present invention and that other drawings may be obtained according to the drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram 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 the 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 gantry robot fine tuning mechanism model of the present invention;
FIG. 6 is a schematic diagram of the horizontal kinematic positional relationship of the fine adjustment mechanism of the present invention;
FIG. 7 is a schematic diagram of the geometry of the kinematic position of the horizontal plane of the fine adjustment mechanism of the present invention as it moves in the x-direction;
FIG. 8 is a schematic diagram of the geometry of the kinematic position of the horizontal plane of the fine adjustment mechanism of the present invention as it moves in the y-direction;
FIG. 9 is a schematic diagram of the horizontal kinematic rotational relationship geometry of the fine adjustment mechanism of the present invention;
FIG. 10 is a schematic diagram of the rotational relationship geometry of the horizontal kinematic branching structure of the fine tuning mechanism of the present invention;
FIG. 11 is a schematic diagram of a three-dimensional mesh construction detour obstacle avoidance analysis of the present invention;
FIG. 12 is a schematic diagram of a three-dimensional mesh construction leap obstacle avoidance analysis of the present invention;
FIG. 13 is a schematic diagram stage one of the three-dimensional grid key point set construction of the present invention;
FIG. 14 is a schematic diagram stage two of the three-dimensional grid key point set construction of the present invention;
FIG. 15 is a schematic diagram stage three of the three-dimensional grid key point set construction of the present invention;
fig. 16 is a schematic diagram of a NavMesh algorithm search strategy principle of the present invention, step one;
fig. 17 is a schematic diagram of a NavMesh algorithm search strategy principle of the present invention, step two;
fig. 18 is a schematic diagram of a NavMesh algorithm search strategy principle of the present invention, step three;
fig. 19 is a schematic diagram of a NavMesh algorithm search strategy principle of the present invention, 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 multi-station process production ordering Gantt chart incorporating pipeline scheduling in accordance with the present invention;
FIG. 22 is a schematic diagram of a user-oriented interactive interface of the present invention.
Detailed Description
The invention is further illustrated by 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 gantry robot digital twin system 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 micro-adjustment mechanism and the crank arm structure so as to perform motion control on the robot. After the grid construction is carried out on the three-dimensional convex polygon, the three-dimensional path planning algorithm design based on different tasks is completed according to the processing requirements of the gantry robot. And manually setting target positions of the gantry robot, calculating a reasonable path from the initial position to the target positions by the gantry robot through a path planning algorithm, and if a plurality of target positions need to be reached, setting priorities of the targets, and generating a reasonable path according to task allocation instructions. And then, according to the generated path, the gantry robot in the physical world realizes the following of the virtual path through a following control algorithm and operates to a designated target position.
S02, a control module and a driving module: the virtual simulation platform sends path position information to motion control software in real time, and the servo motor and the servo driver realize real-time tracking of the running track of the digital world gantry robot by the physical world gantry robot through ADS communication and an external position setting method; the exposure degree and the ambiguity of the camera are adaptively adjusted through a high-precision camera calibration algorithm, an optimal calibration image is obtained, high-precision camera calibration is realized, and a camera internal reference with higher precision is obtained; the initial position of the gantry robot is manually set, a rotation translation matrix of a camera and a marker in the initial position is calculated, calculated values are recorded in a database, and interface display of data can be realized on a man-machine interaction interface; the gantry robot repeatedly arrives at the initial position for a plurality of times, a rotation translation matrix of the camera and the marker at the arrival time and a rotation translation matrix at the initial position time are calculated, the current position deviation is obtained, a position deviation interface is displayed and sent to the fine adjustment mechanism to compensate the deviation, and high-precision positioning is achieved.
S03, a gantry robot and a vision measurement 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 the vicinity of a target position, a vision measurement 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 the accurate regulation and control of the position are realized through a motion control deviation compensation algorithm.
S04, pose calculation and three-dimensional online monitoring module: and acquiring and storing pose data obtained after deviation compensation, carrying out data integration and precision evaluation on the data, and transmitting the data to a database. The historical data formed in the database can drive the gantry robot model to perform synchronous motion simulation,
and displaying real-time data on the simulation interface to realize remote monitoring.
S05, cloud server: and the interconnection of the physical world and the digital world is realized through Ethercat communication and the Internet.
As shown in fig. 2, the embodiment of the invention provides an interactive method for directly reading and writing data by a simulation platform and a multiple-benefit control system without a data transmission system, which comprises the following steps:
s21, adding a route to the gantry robot controller, downloading a program to the controller, and then running the controller;
s22, selecting a NET Framework v4.0.30319 version, adding an ADS library file, wherein the path is C\TwinCAT\Adsapi\NET;
s23, writing a c# program in the Unity3D simulation platform to read and write data, wherein reading and writing are mainly performed by using two functions of ReadAny and WriteAny.
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 the end effector 4 is responsible for the tasks of door plate grabbing, loading and unloading and the like. The cross beam 5 and the support column 6 are used as a supporting 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, so that the functions of fixing and supporting the robot are realized.
As shown in fig. 4, the U-shaped crank arm mechanism 2 is in charge of connecting the structure of the crank arm by the side cover 8, drives the crank arm upper arm 9 to rotate, and the servo motor 10 is arranged at the middle joint of the crank arm upper arm 9 and the crank arm lower arm 11, and the left end and the right end are respectively. The bearing 12 is responsible for fixing the end of the lower arm 11 of the crank arm, and 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 bases 15 of the fine adjustment mechanism to move, an upper bearing support plate 16 is fixed under each bearing screw base, connecting rods 17-18 are connected and fixed by a lower bearing support plate 19, and a movable platform connecting piece 20 is connected with the structures of the three lower bearing support plates and an end effector connecting base 21.
As shown in fig. 6, when the fine adjustment mechanism moves along the horizontal plane, the coordinate transformation needs to be completed between the self coordinate system and the spatial coordinate system of each joint position relationship.
As shown in fig. 7 and 8, point P is when the end effector moves in the X-axis and Y-axis directions of the world coordinate system Fa (x Fa ,y Fa ,z Fa )、P Fb (x Fb ,y Fb ,z Fb ) And P Fc (x Fc ,y Fc ,z Fc ) The corresponding vector mapping relation matrix of the self coordinate system of the movable platform connector is as follows:
wherein k is 1 And k 2 The geometric relationship is as follows: k (k) 1 ＝-1/2，Similarly, the point R can be found from the formula (23) Fa (x′ Fa ,y′ Fa ,z′ Fa )、R Fb (x′ Fb ,y′ Fb ,z′ Fb ) And R is Fc (x′ Fc ,y′ Fc ,z′ Fc ) The corresponding proper mapping relation matrix of the coordinate system of the connecting rod is as follows:
wherein k is 3 ＝κ Fz = -0.6, which is the Z-axis position conversion relation coefficient. Similarly, point Q Fa (x″ Fa ,y″ Fa ,z″ Fa )、Q Fb (x″ Fb ,y″ Fb ,z″ Fb ) And Q Fc (x″ Fc ,y″ Fc ,z″ Fc ) The corresponding proper mapping relation matrix of the 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 transformation needs to be completed between the self coordinate system and the space coordinate system of the rotation relationship of each link and the link group.
As shown in fig. 10, when the end effector O' (x) O′ ,y O′ ,z O′ ) Point R when moving in the X-axis and Y-axis directions of the world coordinate system Fa 、R Fb And R is Fc Corresponding rotation vector of self coordinate system of connecting rodAnd->The mapping relation 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. Similarly, point S Fa 、S Fb And S is Fc Corresponding to the rotation vector of the inner link groupAnd->The mapping relation matrix is as follows: />
Similarly, point S Ta 、S Tb And S is Tc Corresponding four-bar linkage self-coordinate system rotation vectorAnd->The mapping relation 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 obstructions are described 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 the path plan for a grid containing obstacles. The obstacle avoidance strategy adopted during detour is suitable for the obstacles in the area where the leap movement cannot be performed.
As shown in fig. 12, if the obstacle height is below the upper limit of the end effector. A new set of planar points is constructed around the obstacle and the robot performs a path search on the reconstructed mesh. The obstacle avoidance strategy is to span an obstacle. The method can effectively reduce the path cost and improve the path searching and moving efficiency.
As shown in fig. 13, 14, 15, is the process of moving the end effector from plane α to plane β. To avoid collision, is Ω 1 Planes of different heights of the region add a set of key points for constructing the grid. For terrains of different heights, the end effectors need to take their own structure into account when moving. The inner cylinder 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 cylinder and the outer cylinder is an expanded safety distance. Assume that the radius of the outer cylinder is r C ' the radius of the inner cylinder is r C The relationship between the two can be preliminarily set as follows:
r C ′＝μ·r C ,μ∈(1.2～1.3) (34)
where μ is a coefficient of relationship. It is assumed that a simplified model O of the end effector needs to be moved from plane α to point H on plane β. When straight line l in plane alpha 1 Tangential to the outer radius circle of the cylinder, the end effector can move in the z-axis. 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 expansion point D, E, F on any straight line passing through the point H, the point G form a node set (ve= { D, E, F, G, H }). A convex polygon shaped navigation grid is then formed. The end effector can calculate the shortest path to the plane using the NavMesh algorithm.
As shown in fig. 16, 17, 18, 19, the NavMesh algorithm is selected as four steps of the navigation search strategy on the basis of a three-dimensional grid. The NavMesh algorithm is based on the principle of the a-x algorithm. Based on the constructed plane set adjacency information, polygon sets passing from the start point to the end point are 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＝{V 1 ,V 2 ,V 3 ,…} (35)
First, in the initial triangle SV 1 V 2 Finding the adjacent edge SV in the list 1 And SV(s) 2 ；
Second step, V 3 Inside the funnel, the funnel edge SV is updated 3 The funnel will become narrower; v (V) 4 Outside the funnel, the funnel does not need to be updated;
third step, V 5 Inside the funnel, the funnel edge SV is updated 5 ；V 6 Outside the funnel, the funnel does not need to be updated;
fourth, repeating the above 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 table No. 1 is in the non-idle state, the table No. 2 is used as the target position. If both work stations are working, the robot needs to wait for its finishing. Likewise, numbers 3 and 4 are one group and numbers 5 and 6 are another group.
As shown in fig. 21, the multi-station path planning and scheduling under the industrial process is completed by using the production ordering gater graph.
On an industrial production line, various material handling tasks are solved by utilizing assembly line scheduling, and the following assumptions are made for the purpose:
a. assuming that there are n jobs on a pipeline, each job requires m tasks to be performed, respectively
T 1i ,T 2i ,…,T mi I is more than or equal to 1 and n is more than or equal to n. And this task T ji Only at the device P j Executing the above steps, wherein j is more than or equal to 1 and less than or equal to m;
b. for any job i, at task T ji Before completion T (j-1)i Cannot be performed;
c. the working time of each workbench is the same and is T w ；
d. The same equipment cannot process more than one task at any time;
e. the workpiece positions are arranged according to a certain priority;
f. each machine performs a particular job that must be completed before the product moves to the next location in the production line;
on a digital twin platform, the position of the table can be read directly. The order in which the positions of all the tables are based on the Gantt chart is listed in FIG. 9. In the pipeline of the Gantt chart, a certain time interval is set, and the robot is set to return to the initial position to fetch the gate. Otherwise, selecting the position of the workbench as a target point according to the sequence of the Gantt chart. Three stages are needed for production allocation, 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. The stage 2 is the middle stage of wood door processing, and the circulation times can be set according to requirements. Stage 3 is the end stage and no further processed door panels are provided. The multi-objective path planning problem of the gantry robot can be solved by combining the assembly line scheduling model with the three-dimensional path planning method.
As shown in FIG. 22, the embodiment of the invention constructs an interactive and controllable digital twin system interface, which comprises a function option area, a gantry robot whole simulation monitoring screen, a crank arm and fine adjustment mechanism simulation monitoring screen and a state monitoring and control area. The function option area is used for user login, picture setting and other function settings; the whole motion condition state of the gantry robot and the motion of the crank arm fine adjustment mechanism are presented through simulation monitoring pictures; the state monitoring and controlling area is used for displaying the connection state of the data acquisition channel, virtual and actual motion coordinates in Cartesian space after unifying a coordinate system, limit states of the end manipulator and the fine adjustment mechanism and debugging information generated in the running process.
The above examples are only illustrative of the preferred embodiments of the present invention and are not intended to limit the scope of the present invention, and various modifications and improvements made by those skilled in the art to the technical method of the present invention should fall within the scope of protection defined by the claims of the present invention without departing from the spirit of the design of the present invention.
Claims (10)
1. The digital twin system for the 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 connected with the real gantry robot in the physical world and the virtual gantry robot in the digital world;
The real gantry robot in the physical world is formed by interaction of a gantry robot main body mechanism, a driving module, a vision measuring module and a control module respectively;
the virtual gantry robot in the digital world is formed by interaction of a three-dimensional online monitoring module, a control decision module, a motion analysis and path planning module and a pose calculation module;
the cloud server is respectively connected with the physical world and the digital world through the Ethercat communication module and the Internet module;
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 visual measurement module comprises a visual controller, an industrial camera, a laser range finder, a marker and visual positioning software, wherein the visual positioning software consists of high-precision calibration and visual 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, a 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, a kinematic analysis of a mechanical structure, a navigation area, grid division and three-dimensional path planning;
the pose calculation module comprises a database, data acquisition and storage, data integration and precision evaluation;
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 data bidirectional interaction.
2. The gantry robot-oriented digital twin system according to claim 1, wherein the digital world virtual gantry robot is constructed based on the physical world real gantry robot in a 1:1 ratio, and the origin of coordinates, physical dimensions, and three-dimensional space layout of the internal devices are consistent, and the correspondence of the consistency is realized through off-line visual calibration, comprising the steps of:
s11, a corner of a real gantry robot and the edge of a workbench of each internal device are provided with a calibration plate for visual positioning, the calibration plate is ensured to obtain clear imaging within the imaging range of a camera, and the image of the calibration plate at the moment is recorded as I 0 ；
S12, defining that the real gantry robot moves to the lowest end in the Z direction, and when the XY direction moves to one corner of the gantry robot, the position of the corresponding calibration plate center when the imaging under the camera coordinate system is positioned at the image center is the zero point of the gantry robot, and the corresponding intersection point in the XYZ direction is the origin O of the world coordinate system;
S13, driving the gantry robot to move to a visual calibration plate of a j-th internal equipment workbench along the XYZ axis by taking an origin O as a starting point, and ensuring imaging I of the calibration plate in a camera j And I 0 At this time, the coordinates of the device j in the world coordinate system are recorded as (X j ,Y j ,Z j ) The method comprises the steps of carrying out a first treatment on the surface of the Wherein X is j X direction travel X direction screw range; y is Y j =y-direction travel x Y-direction screw span; z is Z j Range of the Z direction stroke multiplied by the Z direction screw rod.
3. The gantry robot oriented digital twinning system of claim 1, wherein the monitoring process in the three-dimensional on-line monitoring module is as follows:
s21, loading a three-dimensional model, a virtual camera and a virtual experiment scene of the virtual gantry robot by a user through an operation button of a control decision module, and starting an online monitoring task;
s22, transmitting motion data of the actual gantry robot to the virtual gantry robot in real time through a network, and driving a three-dimensional model of the virtual gantry robot by the virtual gantry robot through motion analysis and motion simulation to realize motion consistent with the actual gantry robot, so that the purpose of remote online monitoring is achieved;
s23, storing the data of the actual gantry robot movement in a database, and enabling a user to check and play back historical data according to time;
S24, the virtual gantry robot can conduct technological process previewing through motion analysis and motion simulation according to user instructions so as to determine whether the existing technological process is reasonable.
4. The gantry robot oriented digital twin system of claim 1, wherein the digital world virtual gantry robot controls the physical world gantry robot to move, comprising the following steps:
s31, a user designates specific operation tasks, flows and targets by controlling operation buttons of the decision module;
s32, planning a reasonable running path for the real gantry robot through gantry robot kinematics analysis, navigation area grid division and three-dimensional path planning, sending path key point data to a control module of the real gantry robot in real time, enabling the real gantry robot in the physical world to follow the virtual path by tracking the running track of the digital world gantry robot in real time, shaping position information received by the physical world gantry robot by designing an input shaper, and therefore reducing vibration of the tail end of a cantilever beam, and enabling the real gantry robot in the physical world to track the real position of the digital world gantry robot more accurately;
S33, when the end effector of the physical world gantry robot moves to the vicinity of the target position, the vision measurement module starts to work, the vision measurement method is to obtain the deviation in the z direction by using the laser range finder, the deviation in the xy direction is obtained by using the 2D vision measurement method of the digital camera, the data of the marker is captured in real time, the deviation of the current position from the target position is calculated by the vision measurement module, the deviation value is sent to the motion controller and the pose processing module of the physical world gantry robot for positioning accuracy assessment, and the accurate regulation and control of the position are realized by the motion control deviation compensation algorithm.
5. The gantry robot-oriented digital twin system of claim 4, wherein real gantry robots of the physical world track the motion trajectories of the digital world gantry robots in real time, and wherein following the virtual path comprises the steps of:
s321, using the cloud server as a bridge for data exchange between the digital world and the physical world through deployment of the cloud server;
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 digital world position information received by the server in real time, or sends the path position information to the physical world gantry robot controller through the EtherCAT bus in real time, and the physical world gantry robot tracks the digital world gantry robot in real time through an external position setting method;
s324, the position information received by the physical world gantry robot is shaped by designing an input shaper, so that vibration of the tail end of the cantilever beam is reduced, and the real-time position of the digital world gantry robot is tracked more accurately.
6. The gantry robot oriented digital twinning system of claim 4, wherein the vision measurement module calculates a deviation of the current position from the target position, comprising the steps of:
s331, through a high-precision camera calibration algorithm, the exposure degree and the ambiguity of a camera are adaptively adjusted, an optimal calibration image is obtained, high-precision camera calibration is realized, and a camera internal reference with higher precision is obtained;
s332, obtaining the xy-direction deviation through a two-dimensional vision measurement technology, obtaining the z-direction deviation through a laser range finder, repeatedly reaching an initial position for a plurality of times by the gantry robot, calculating a rotational translation matrix of a camera and a marker at the moment of reaching and a rotational translation matrix at the moment of the initial position, obtaining 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 realized.
7. The gantry robot-oriented digital twin system of claim 1, wherein the algorithm of the motion analysis and path planning module comprises the steps of:
s41, performing kinematic analysis on an end effector, a truss, a crank arm and a fine adjustment mechanism of the virtual model, and performing forward and reverse kinematic calculation on the robot so as to perform motion control on the robot and complete translation and rotation track simulation;
s42, in a virtual simulation platform built by the Unity3D, reading boundary points of each workbench in the virtual environment as a set, constructing a new point set through area obstacle avoidance analysis, merging the point sets of each workbench, and completing node construction of the three-dimensional navigation grid;
s43, completing single-target three-dimensional path planning on a three-dimensional navigation grid by combining with a Navmesh search strategy, providing a navigation path for a robot, and then completing multi-target path planning under an industrial process by combining with pipeline scheduling to provide position data for a digital twin system.
8. The gantry robot oriented digital twinning system of claim 7, wherein the kinematic analysis of the kinematic analysis and path planning module includes the construction of kinematic equations for the crank, fine tuning mechanism and running mechanism in cartesian space, comprising the steps of:
S411, the movement of the end effector and the end effector of the truss in cartesian space may be decomposed into: translational motion along a certain straight line and rotational motion around a fixed shaft, the end effector and the truss can be simulated by adopting straight line tracks, and the end effector and the truss can be divided into translational track simulation and rotational track simulation;
let the coordinates of the track start point be P ES (x E(0) ,y E(0) ,z E(0) ) The coordinate of the end position is P EE (x E(1) ,y E(1) ,z E(1) ) From the end point P EE To the starting point P ES Is of track length L E :
L E ＝|P EE (x E(1) ,y E(1) ,z E(1) )-P ES (x E(0) ,y E(0) ,z E(0) )| (1)
Wherein subscript E is the end effector, assuming point P in the current state E(i) (x E(i) ,y E(i) ,z E(i) ) To the starting point P ES Is s E(i) ，s E(i+1) For the track length of the next state at time interval deltat, let s be E(i) The corresponding linear velocity is v E(i) Acceleration a E And assume s E(i+1) At a linear velocity v E(i+1) ：
s E(i+1) ＝s E(i) +v E(i+1) ·ΔT (2)
The linear motion trajectory equation is:
if v E(i) 2 /2a E ≤L E -s E(i) The interpolation point is in the acceleration constant speed section, and the interpolation equation is:
if v E(i) 2 /2a E ＞L E -s E(i) The interpolation point is in the deceleration section, and the end effector is alpha E Acceleration deceleration of (c)Until the interpolation of the section is completed:
v E(i+1) ＝v E(i) -a E ΔT (5)
assume that the end effector angle at a certain time is θ E(i) ，θ E(i+1) For the angle at the next instant in time with a time interval of Δt, assume θ E(i) The corresponding linear velocity is omega E(i) Angular acceleration of alpha E And set the next interpolation point theta E(i+1) At a speed of omega E(i+1) ：
θ E(i+1) ＝θ E(i) +ω E(i+1) ·ΔT (6)
When omega E(i) 2 /2α E ≤θ E -θ E(i) When the interpolation point is in the acceleration constant speed section:
When omega E(i) 2 /2α E ＞θ E -θ E(i) When the interpolation point is in the deceleration section:
ω E(i+1) ＝ω E(i) -α E ΔT (8)
the truss moves in the Cartesian space only including translational movement along a certain straight line; similarly, assume that the truss is from endpoint P TE (x T(1) ,y T(1) ,z T(1) ) To the starting point P TS (x T(0) ,y T(0) ,z T(0) ) Track length L of (2) T The method comprises the following steps:
L T ＝|P TE (x T(1) ,y T(1) ,z T(1) )-P TS (x T(0) ,y T(0) ,z T(0) )| (9)
subscript T is truss; linear motion trajectory equation of truss
If v T(i) 2 /2a T ≤L T -s T(i) The interpolation point of the truss is in an acceleration constant speed section; the interpolation equation is:
if v T(i) 2 /2a T ＞L T -s T(i) Interpolation points of the truss are in a deceleration section:
v T(i+1) ＝v T(i) -a T ΔT (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 l A The vertical diagonal is set to h A ，l A And h A At an angle of theta A When the mechanical crank arm stretches upwards to a certain position, the vertical diagonal line is set to be h A(i+1) The difference in height between the two is set to delta h A The angle of the mechanical arm after being retracted is changed into theta A(i+1) The difference angle between the two is delta theta A The relationship is as follows:
from the geometrical relationships, the vertical diagonal and side length relationships are as follows:
by calculating the relation, delta theta can be known A And Δh A The relationship of (2) is as follows:
the kinematic relationship of the available crank arm is as follows:
the principle of the translation track simulation of the end effector is consistent, and the height parameters of the crank arm joint are interpolated:
h A(i+1) ＝h A(i) +v A(i+1) ·ΔT (17)
assuming endpoint P JE (x J(1) ,y J(0) ,z J(1) ) To the starting point P JS (x J(0) ,y J(0) ,z J(0) ) The track height of (2) is H:
H＝|P JE (x J(1) ,y J(0) ,z J(1) )-P JS (x J(0) ,y J(0) ,z J(0) )| (18)
wherein, the subscript J is a crank joint and the middle point P J(i) (x J(i) ,y J(0) ,z J(i) ) To the starting point P JS Track length h J(i) The linear motion trajectory equation is:
s413, a gantry robot fine adjustment mechanism belongs to a parallel mechanism structure, and the side length of a crank arm connecting rod of the mechanism is assumed to be l F The height of the horizontal connecting rod of the fixed platform relative to the horizontal connecting rod of the movable platform is set to be h F(i) ，l F And h F(i) At an angle of theta F(i) The distance between the position of the movable platform fixing device along the horizontal connecting rod direction and the front end of the connecting rod under the self coordinate system is set to be m F(i) When the fine adjustment mechanism expands and contracts a certain position in the Z-axis direction, the length is set to be m Fz(i+1) The difference length between the two is set as delta m Fz At this time, the height is set to h Fz(i+1) The difference in height between the two is set to delta h Fz At this time, the angle is set to θ Fz(i+1) The difference angle between the two is delta theta Fz The relationship is as follows:
wherein, the subscript F represents the fine adjustment mechanism, and the delta theta can be known by calculating the relation Fz And Δm Fz The relationship of (2) is as follows:
by calculating the relation, delta theta can be known Fz And Δh Fz The relationship of (2) is as follows:
the kinematic relationship of the fine adjustment mechanism is as follows:
wherein i is {1,2,3 … }, θ Fz(i) For fine-tuning the angle of rotation of the shaft of the linkage joint of the mechanism, κ Fz 、Is delta theta Fz And Δm Fz The corresponding relation coefficient of each joint, kappa Fz ′、/>Is delta theta Fz And Δh Fz The relationship coefficient of each corresponding joint.
9. The gantry robot oriented digital twin system of claim 7, wherein the node construction of the three-dimensional navigation grid in step S42 comprises the steps of:
S421, facing a working scene, which is the requirement of door panel processing, the gantry robot needs to grab the door panel and place the door panel at a designated position, and the workbench needs to complete cutting, punching and assembling operations of the door panel; reading boundary points of each workbench in the virtual environment as a set Vw, constructing a new point set Ve through area obstacle avoidance analysis, merging the point sets of each workbench, and completing node construction of the three-dimensional navigation grid;
s422, dividing the space of a movement area of the end effector of the gantry robot, wherein the maximum and minimum heights h of the end effector are defined by the upper and lower limits of the extension and retraction of the mechanical crank arm E(max) And h E(min) Height range h of end effector E(i) The method can be set as follows:
h E(min) ≤h E(i) ≤h E(max) (24)
the internal space omega of the large-span gantry robot can be divided into two parts by the upper limit height and the lower limit height of the end effector:
wherein Ω 1 Omega for the region where the end effector can move dramatically 2 Is an area which can not make leap movement;
s423, the model is simplified to ensure that the end effector does not collide with the obstacle during movement and rotation, Ω 1 Adding key point sets for constructing grids to planes with different heights in the region;
s424, assuming that all points on the same plane form a set;
V＝{Vw,Ve}＝{V 1 ,V 2 ,…V n },{V 1 ,...V i }∈Vw,{V i+1 ,...V n }∈Ve (26)
Three points V in space that are not collinear i (x i ,y i ,z i )，V j (x j ,y j ,z j )，V k (x k ,y k ,z k ) Constituted flatThe surface equation is:
by the analysis, the collected point set and the point set added under mathematical analysis for avoiding collision are summarized, a plane equation set is established simultaneously, a multi-plane set in space is formed, three non-collinear points form a plane triangle convex hull, and a space polygon set formed by the planes of each convex hull form a convex polygon navigation grid.
10. The gantry robot-oriented digital twin system according to claim 7, wherein 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, a Navmesh path-finding algorithm drives a virtual model to move by calculating the minimum path cost, and in a three-dimensional virtual environment, a scene is represented by a convex polygon set to be a structure similar to a graph, and a plurality of nodes can be formed among the convex polygons;
s432, forming an open area between nodes of the graph, wherein any point in the area can be reached through a straight line and are connected with each other, the edge of the node represents the area which can directly reach the connection of two polygons, the areas are connected in two directions, and various graph searching algorithms can be used for searching a communication path on the basis of the graph structure;
S433, on an industrial production line, various material handling tasks are solved by adopting assembly line scheduling, and the actual factory production line tasks are completed by combining a Navmesh path-finding algorithm and a three-dimensional grid.
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| CN116214542B (en) * | 2023-03-23 | 2023-11-10 | 广东省特种设备检测研究院东莞检测院 | Digital twin system of spherical tank inner wall climbing robot |
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