Nonlinear Regulation of End-Effector Motion for a Flexible Robot Arm

摘要

In this paper we consider the problem of controlling via state-feedback the end-effector motion of a one-link flexible robot arm described by a nonlinear dynamic model. Due to the non-minimum phase nature of the system zero-dynamics, use of pure inversion-based techniques is unfeasible. In order to obtain stable tracking of desired tip trajectories, a nonlinear regulation approach is followed. Alternate general design procedures that exploit system invertibility are presented, leading to regulators of different complexity and realtime demand. Issues about the generation of output reference trajectories and the off-line computation of the associated steady-state trajectories are discussed, using the one-link flexible arm as a case study. Simulation results obtained for a spline trajectory and for a point-to-point motion show the achievable tracking accuracy and the wide applicability of the presented control technique.