A nonlinear high-gain observer for n-link robot manipulator which has measurement noise in a feedback control framework

This paper presents the design of an output feedback controller (OFBC) for an n-link robot manipulator. This is achieved by using non-linear high gain observer. As measurement noise poses a great difficulty while estimating the system states, as the gain of the observer increases the measurement noise significantly amplified, causing higher steady state error. A non-linear high gain observer is proposed to overcome this problem. Non-linear high gain observer has an advantage over other non-linear state estimating techniques. The estimation of states is achieved with great accuracy and in a very small time. A comparison of linear and non linear high gain observer is also included to show the effectiveness of the proposed scheme.

1. Introduction

Robots occupy an esteemed place in the modernization of many industrial sectors. In the last twenty years robots has been installed into a wide-range of industries, use of robots has evolved to the reality of computer-controlled electromechanical devices, from the science fiction movies stuff. In this situation, robot control methods which achieve more stable and robust performance are significantly important.