Gain Scheduled Control of Manipulators for Contact Tasks on Uncertain Flexible Objects

Abstract

This paper studies position/force hybrid control of a robot manipulator to interact with its uncertain flexible object. Because of its flexibility, the object dynamics will influence the robot's control system, and since it is a distributed parameter system, the object dynamics as seen from the robot's end-effector will change when the robot moves on its different locations. In this paper, the variation of the object dynamics as seen from the robot end-effector is formulated as an uncertain linear parameter-varying system (ULPV). Gain scheduled control is developed for controlling this kind of uncertain system. It is found, although the robot's position control loop is not influenced by the contact force, the robot's moving velocity influences the solution of the force control system's Riccati equation, which was used in constructing the system's force control input. Therefore, the position control loop should be designed with respect to the force control loop. Computer simulations show the effectiveness of our control approach.