Force control of kinematically constrained manipulators in the presence of contact point disturbances

摘要

It is envisioned that in the future long-arm manipulators such as the Space Shuttle RMS and the ETS-VII Remote Manipulator Arm will be required to perform various types of constrained motion tasks, such as work-surface inspection, assembly, and cleanup. In the presence of contact point disturbances, due to either unknown contour profiles or movement of the work surface relative to the robot, the robot must ensure a minimum amount of contact force error while at the same time maintaining the desired constraint. This paper discusses the disturbance rejection properties of several commonly-used explicit force control strategies and highlights the control issues particular to force control of kinematically constrained mechanisms. A general disturbance-based model for constrained manipulators which is based on previous work on the simulataneous position/force control of constrained robots is also presented. Simulation results of this model elucidate the problems and issues relevant to the force control task of kinematically constrained manipulators.