A Hybrid Position/Force Controller for Joint Robots

In this paper, we present a hybrid position/force controller for operating joint robots. The hybrid controller has two goals -- motion tracking and force regulating. As long as these two goals are not mutually exclusive, they can be decoupled in some way. In this work, we make use of the smooth and invertible mapping from joint space to task space to decouple the two control goals and design controllers separately. The traditional motion controller in task space is used for motion control, while the force controller is designed through manipulating the desired trajectory to regulate the force indirectly. Two case studies -- contour tracking/polishing surfaces and grabbing boxes with two robotic arms -- are presented to show the efficacy of the hybrid controller, and simulations with physics engines are carried out to validate the efficacy of the proposed method.