A Modified Control Approach to Increase Singularity Avoidance in 7-DOF Redundant Arms

This paper is concerned with singularity avoidance in the process of position and force control of 7-DOF redundant robot arm using a signal combined with the control signal. In this paper singularity avoidance is considered as the secondary task and an outer-inner loop controller called the augmented hybrid impedance control scheme is used. The inner loop consists of a Cartesian-level potential difference controller, a redundancy resolution scheme at the acceleration level, and a joint-space inverse dynamics controller. Simulation results for a 7-DOF robot arm are given to illustrate the performance of proposed technique. The proposed algorithm affects control signal for a redundant robot so as to increase its singularity avoidance and the results showed a significant increment in robot runtime. A strategy for adapting parameters for different kind of robots was developed and specially implemented for a PA10 7-DOF redundant robot. The proposed scheme is applied to the Mitsubishi PA10 7-DOF robot arm and the results showed the motion profile of the robot became smoother and their runtime increased.

Keywords:

Singularity avoidance , Position and force control , Redundancy resolution , Mitsubishi PA10