Dynamics Analysis And Control Research Of Controllable Mechanism Welding Manipulator Considering Clearance

Controllable mechanism integrates the advantages of closed-loop mechanism and open-chain mechanism.It has high running speed,strong bearing capacity,simple control and certain flexibility.It is well suited to the development needs of modern machinery industry.The application of"multi-degree-of-freedom controllable mechanism" in the field of robotic mechanisms has advantages over the current series robots in terms of vibration magnitude,residual vibration time,working speed and working efficiency.However,in the course of use,this kind of robot sometimes has a large abnormal vibration,which seriously affects its normal work.Therefore,there is an urgent need to conduct a comprehensive and in-depth study on the dynamic performance of this kind of multi-degree-of-freedom controllable mechanism robot,and find out the reasons for this abnormal vibration.The clearance of the motion pair is a key factor affecting the smooth,efficient and accurate operation of the mechanical system.Therefore,it has certain theoretical significance and practical engineering value to deeply study the influence of clearance of motion pairs on the dynamic performance of controllable mechanism robot.In this paper,a controllable mechanism welding robot is taken as the research object.The kinematics and dynamics of the robot without considering and without clearance are systematically analyzed,and a certain control method is adopted to compensate the end displacement error caused by clearance.The main work of this paper is as follows:The configuration of the controllable mechanism welding robot is analyzed,and its kinematics model is established by using D-H rule.On this basis,the continuous contact clearance pair model is adopted,and the kinematics of the robot considering clearance under this model is analyzed.Compared with the ideal welding robot,the end position error of the robot considering clearance is obtained.Using the three-state clearance model,the model of rotating pair considering clearance is established,and the dynamics model of the controllable mechanism welding robot without and without clearance is established.Dynamics simulation and comparative analysis are carried out for robots without considering and without considering clearance.The dynamic response of the robot considering clearance under different clearance size,different driving speed and different motion pair material is analyzed,which provides a theoretical reference for the selection of assembly accuracy,motion pair material and working speed range of the robot.The joint control system of robot with gap nonlinearity is established,and the parameters of the control system are identified by using particle swarm optimization(PSO).The control system of the robot is simulated and analyzed.The results show that a certain control method can effectively reduce the end displacement error of the controllable mechanism welding robot considering the clearance and improve the operation accuracy of the robot.