Fuzzy supervisory assisted impedance control to reduce collision impact

Under any abnormal loading on the manipulator end-effector, instability in motion and secondary damages are to be expected. We study a novel approach for active control of the robot manipulator trajectory within and after the impulsive loading caused by collision. Here we have adopted the position-based impedance controller as a force control strategy, inspiring human reaction against the sudden and impulsive loadings. The approach is to issue a new position command along the impact direction and routing smoothed trajectory just after the impact loading. Due to variant properties of impact and to translate human reactions amid impact interval, fuzzy logic-based supervisory system is utilized to modify impedance parameters. Fuzzy rule-based and inference system are defined and resulted control surfaces are illustrated. Finally the response of the system is compared with the case without the proposed controller in the overall scheme. The result shows significant increase in stability and decrease in torque dissipation and therefore, a reasonable reduction in collision impact.