Variable Structure Tracking Control of Robot Manipulator in Task Space in the Presences of Structure and Unstructured Uncertainties in Dynamics and Kinematics

In most of the researches which has been conducted until now on the robot manipulator tracking control, it has been presumed which the kinematic of robot manipulator or Jacobian Matrix of robot from the joint space to the task space is quite known. However, none of the physical parameters in robot manipulator equations can be calculated by high accuracy. In addition, when the robot manipulator moves something, uncertainties occur in length, direction and point of contact of end-effector. Hence, uncertainties occur on the kinematic of robot manipulator either, and due to the different functions of the robot manipulator, its kinematic is changed as well. Therefore, ensuring stability of the closed-loop system in the presence of uncertainties in the dynamics and kinematics of robot manipulator is quite challenging. In this paper, for overcoming on these uncertainties, we present our simple robust control for tracking the position of robot manipulator in the presence of uncertainties in the dynamics kinematics and Jacobian Matrix of the robot manipulator. The proving of the stability shows the closed-loop system has Global asymptotic stability. Then, to overcome the practical problems of proposed control, amendments will be provided. The closed loop system with improved control has limited uniform stability. Since in many of the operations has been performed by the robot manipulator, transient error plays an important role. Due to this reason, the modified control structure is a changed in a way which could improve the transient error. Finally, for displaying the function of the final controller, a case study is implemented on a two-link elbow robot. Mathematical proof and simulation results confirm the good performance of the proposed control.