Synchronization Precision Motion Control Of Multi-axis Robotic System With Actuator Constraints

With the increasing demand for greater productivity and low cost,robotics technology has been developed rapidly in modern manufacturing.Robotics technology is used in various fields and it is easy to work on various real platforms.With the rapid development of robotics technology,people have higher goals for the control precision of robot systems.Therefore,high-precision robot control technology plays a crucial role in robot control.In the process of robot control,the coordination of the robot system has always been a hot topic.How to solve the coordination of robot in the work process is an important research direction for electromechanical equipment,manufacturing processes,and transportation industry equipment.In this paper,starting from the coordination of the robot system,the concept of synchronous movement of each axis of the robot is proposed.Based on this,the precise motion control of the multi-axis robot will be studied.For the multi-axis robot system synchronous position precise motion control problem,most robot speed information is unmeasurable,only accurate position information can be provided.This paper proposes four methods for position control to facilitate engineering implementation.This paper firstly proposes the concept of synchronous position control,and then proposes a solution to the various problems of the synchronous position of the robot system,that is,a control algorithm.Firstly,a kind of approximate potential energy nonlinear function is introduced,whose function can be described as “small error amplification,large error saturation”.Based on the proposed output feedback PD with gravity compensation(PD+)synchronous position control algorithm,an improved output feedback nonlinear PD with gravity compensation(NPD+)synchronous position control algorithm is proposed;For the fact that the driver is easily saturated during the control process and the speed information of each axis of the multi-axis robot is difficult to obtain,an actuator constraints output feedback nonlinear saturated PD with gravity compensation(ONPD+)synchronous position control method with a defined upper bound is proposed.The proposed ONPD+ synchronization control has a clearly defined upper bound,and driver saturation can be effectively avoided by pre-selecting parameters of the controller to satisfy the determined conditions;Finally based on the effects of saturation and the influence of model parameters,a model-based actuator constraints state feedback PID synchronous position control method with a defined upper bound and an actuator constraints output feedback PID synchronous position control method are proposed to implement synchronous control of a multi-axis robot system.For the four proposed control algorithms,we theoretically prove the global asymptotic stability of closed multi-axis robotic systems based on Lyapunov stability theorem and La Salle invariance principle.While ensuring the rapid convergence of the position error,the synchronous position error quickly converges to zero.Using Matlab numerical simulation results verify that the proposed algorithm well guarantees the accuracy of synchronous control,and achieves the multi-axis robot system control under the premise of input constraint high precision synchronous position control.