Research On Joint Velocity Continuity For Motion Planning Of Redundant Manipulators

In recent years,robot technology has been widely used in modern industrial production,and has brought actual production benefits,which has attracted more and more attention.Among them,the motion planning and control of the robotic arm is an important part of robot technology.In the actual operation planning of the redundant manipulator,whether the joint speed and acceleration remain stable and continuous is one of the important indicators that affect its operation performance.However,due to the disturbance of the workspace environment,the characteristics of the motion planning scheme and the execution requirements of the actual given task,it is inevitable that the joint speed or acceleration of the robot arm will jump or deviate from the expected planning value.To a large extent,this results in unstable operation of the robot arm,which reduces the safety and reliability of the robot arm application.This master's thesis summarizes the reasons and occasions of occurrence of the velocity jump and analyzes the effects of joint velocity/acceleration jump or deviation from expected planning values In different stages of the task execution process.In order to remedy the defects,different speed/acceleration continuous/deviation correction motion planning algorithms are designed according to the complexity of the task.In order to verify the effectiveness of the proposed algorithm,the motion planning schemes have been simulated on MATLAB.The research content of this paper can be divided as follows:(1)This thesis designs a redundant manipulator motion planning scheme of redundant manipulator with specified initial joint velocity based on Pseudo-inverse algorithm because of the joint velocity jump phenomenon that the manipulator generates during task shifting.And in order to reduce the position error of the end-effector after adopting this scheme,a error compensation method is combined with the planning scheme to ensure the accuracy of tracking trajectory.The motion planning scheme can make the robot arm continuously approach the desired velocity for performing the task from the specified initial velocity,thereby eliminate the velocity jump of the robot arm during the task shifting.Moreover,a higher precision can be obtained for the end-effector tracking trajectory.(2)The redundant manipulator may experience deviation of joint velocity during the task execution.In order to remedy the defect,a motion planning scheme for deviation correction of joint velocity of manipulator is designed in this paper.The simulation results show that the motion planning scheme can correct the deviation of joint velocity during performing the task,and thus,a higher precision can be obtained for the end-effector tracking trajectory.(3)This thesis apply the designed joint velocity correction motion planning scheme to the rail manipulator to solve the problem that the end-effector deviates from the expected trajectory when the end-effector moves with the base movement because the joint velocity deviates from the expected value.This scheme can make the joint speed automatically converge to the expected value from the deviation value,and can correct the position error generated by the end effector in time,so as to ensure that the rail manipulator performs the task smoothly and safely.(4)Due to reasons such as the choice of motion planning scheme or the task requirements,industrial manipulator may experience sudden jump of initial joint acceleration or velocity when performing transport tasks,which will affect the service life of the manipulator motors and may lead to the damage of the transport items.In order to remedy the defect,a motion planning scheme of manipulator with continuous acceleration and velocity at the initial moment is designed in this thesis.The simulation results show that the motion planning scheme can eliminate the acceleration and velocity jump at the beginning of the task,and thus,a higher precision can be obtained for the end-effector tracking trajectory.