CONTROL AND STABILITY OF A 3 DOF RRR ROBOT ARM

Abstract

The mechanical design of the robot arm was illustrated with a CAD drawing and the control goal was stated. A feedback control system for the arm configuration is presented and specifications were given for the design with the servo parameters. Next, the transfer functions of the feedback systems, the process and the controller were modelled. The closed-loop system was a fourth-order system and not a second-order system. So, the controller parameters were selected such that two poles are dominant and located appropriately to meet the design specifications/second-order results. The remaining poles of our fourth-order system were located such that their contribution to the overall response was negligible. The appropriate locations for the dominant poles of the closed loop system were determined using second-order system approximation formulae. The step response was plotted and the system was tested using the Nyquist criterion. The results showed that the system was stable and within the specifications.