Robust Control Design for the Accurate Trajectory Tracking of Multi Degree of Freedom Robot Manipulator

In this research, new robust control has been designed for the position control of five DOF robot manipulators. It is a tedious job to derive the exact mathematical model of a multi DOF robot manipulator. Therefore integral sliding mode control (ISMC) has been used for the trajectory tracking control. ISMC is robust against parametric uncertainties, and external disturbance meanwhile the implementation of the ISMC does not require the mathematical model of the system. To compensate system uncertainties, dynamics, and external disturbance high magnitude of switching gain has been required. This high gain cause chattering in control input which is not feasible for the real system. In this research, the requirement is to reduce the tracking error as much as possible therefore a nonlinear extended state observer (ESO) has been integrated with ISMC to improve the tracking error and reduce the chattering from the control input. ESO estimates the system state and the perturbation. This estimated perturbation consists of system uncertainties, model and unmodeled dynamics, and external disturbance. The proposed scheme has been implemented on MATLAB/ Simulink and the result has been compared with existing ISMC. It has been observed that the tracking error of each joint of the proposed scheme is smaller than the existing one.

I. Introduction

The dismantling of the Nuclear power plants (NPPs) after the shutdown is a problem for the authorities. Currently, there are 450 operational NPPs in the world. In South Korea, the Kori 1 has been phased out in 2017 and the other three will be in the next few years. NPP has a dynamic environment. It is feasible to use a robot for the dismantling of a highly radioactive area such as Reactor vessel internal (RVI) of NPPs. Robots are used for the cutting, dismantling, and cleaning of RVI.