Immersion & Invariance Adaptive Force-Motion Control for Robot Manipulator Contact Task *

Abstract

This paper proposes an immersion and invariance (I&I) adaptive hybrid force-motion controller (IHFMC) for a two-degree-of-freedom (DoF) robot manipulator in contact with a rigid planar surface with unknown orientation. Based on the constrained dynamics, we present the classical hybrid force-motion control (HFMC) that decouples motion and force subspaces. In order to account for uncertainty in the orientation of the surface, we develop an I&I adaptive approach. The initial closed-loop system is inspired by the non-adaptive HFMC depending on estimated parameters. This closed-loop is immersed into a target dynamics that evolves on an invariant manifold designed to be attractive. The proposed controller ensures global exponential convergence of the position and force tracking errors as well as the parameter estimation error under a persistency of excitation (PE) condition. Simulations on a 2-DoF arm validate the proposed method, and a comparison to the non-adaptive HFMC is given.