Decentralized force/position control for reconfigurable modular robot based on the nonlinear joint torque observer

A double closed-loop decentralized force controller based on the nonlinear joint torque observer was designed to solve the problem that the end-effector of the reconfigurable modular robot had wrist force sensor but joints had not in the constrained space. The modeling uncertainties and coupling interconnection terms between the joint subsystems were approximated by using adaptive fuzzy system. The double closed-loop regulation of the control input for the reconfigurable modular robot subsystems was constituted by means of contact force error and the error between the joint torque and the observer. Compared with the single closed-loop control, the proposed method improves the convergence speed and tracking accuracy of the end contact force. Finally, the simulation results according to different configurations of the reconfigurable modular robot show the effectiveness of the proposed method.