Design Of Motion Control System For Six Axis Cooperative Robot

"Made in China 2025" proposes to take high-end equipment,short board equipment and intelligent equipment as the breakthrough point,pay close attention to tackling key core technologies,strengthen the accumulation of knowledge and experience,continuously improve the ability of independent development and system integration,and realize the intellectualization of key areas of manufacturing industry.As the representative of intelligent equipment,robot related technology is the focus of future development.Traditional robots are generally used in the scene of repeated labor,lack of active collision detection function and low security.With the enrichment of application scenarios,the market demand for robots that can realize man-machine cooperative production is increasing,and cooperative robots with perfect safety functions become the breakthrough direction of future development.The performance of the control system determines the efficiency of the cooperative robot,and the effectiveness of the collision detection algorithm determines the safety of the cooperative robot.In this paper,a control system is designed for a 6-DOF cooperative robot.Beckhoff industrial computer is selected as the master station,and the communication between the controller and the robot is realized through EtherCAT bus.In the aspect of collision detection between robot and environmental obstacles,a two-level detection algorithm is proposed to judge the collision between planned trajectory and environmental obstacles,which effectively improves the collision detection efficiency of robot.In this paper,the overall structure of the control system of cooperative robot is designed.Beckhoff c6920-0060 industrial computer is selected as the controller,and cormorgan RGM module is selected as the joint axis of the robot;The communication between the robot and the serial controller is realized by EtherCAT bus.In the aspect of robot motion algorithm,the kinematics method is used to establish the relationship model between the robot axis rotation parameters and the end pose,and the D-H method is used to establish the linkage coordinate system of the cooperative robot;the forward kinematics and inverse kinematics problems of the robot model are solved and verified.Combined with the five segment velocity S-curve algorithm and strict synchronous planning strategy,the synchronous control planning of the velocity of each joint axis is realized,which makes the motion process of the robot stable and avoids the problem of velocity overshoot.In this paper,a capsule collision detection model is established based on the shape characteristics of the connecting rod of the cooperative robot.The idea of geometric model method is used to realize the collision detection among the connecting rods of the robot,which solves the problem of collision detection among the connecting rods of the cooperative robot.In this paper,a two-level detection algorithm is proposed to detect the collision between robot and environmental obstacles.In the first judgment process,the adaptive dynamic collision detection method is used to quickly screen out the trajectory range that may collide with the obstacle sphere model.In the second judgment process,the separation axis method is used to accurately determine the collision between the trajectory points in the range and the obstacle oriented bounding box(OBB).Compared with adaptive dynamic collision detection method and geometric model method in Matlab environment,it is verified that the two-level detection algorithm can ensure the real-time performance and the detection result is more accurate,which solves the problem of collision detection between cooperative robot and environmental obstacles.In this paper,the PLC FIFO(first input first output)function of Twin CAT NC PTP(numerical control point to point)is used to control each axis of the cooperative robot,so that the six joint axes move in strict accordance with the planned collision free trajectory under the premise of position coupling,and the multi axis synchronous motion of the cooperative robot is realized.The simulation experiments of robot kinematics algorithm,collision detection algorithm and five speed S-curve algorithm are carried out based on Matlab platform,and the "screen face following" experiment is carried out on the built six axis robot control platform.The experimental results verify the accuracy of the kinematics related algorithms in this paper,which shows that the control system has stable performance,good synchronization,and can complete the control task reliably.In this paper,through the design of the control system of the cooperative robot,the research of the robot motion algorithm and the design of the synchronous motion control method of the robot joints are completed,and a two-level detection algorithm is proposed to realize the collision detection between the cooperative robot and the environmental obstacles.The experimental results show that the two-level collision detection algorithm is faster than the geometric model method and more accurate than the adaptive dynamic collision detection algorithm,which is more suitable for robot control system;the system can correctly realize the functions of kinematics solution,trajectory planning,collision detection and multi axis synchronous motion,and has good engineering practicability.