A passivity-based adaptive sliding mode position-force control for robot manipulators

Based on a novel orthogonalized sliding mode error co-ordinate system, a passivity-based adaptive sliding mode control that yields the global exponential convergence of position and force tracking errors is proposed. The holonomic constraint is efficiently manipulated to derive two orthogonal transformations at the velocity level. These transformations are used to propose a convenient representation of error modelling such that simple proofs of passivity and stability are established. Sliding modes arise on the tangential and normal subspaces at the contact point. The parametric uncertainty is compensated via an adaptive control loop and the sliding modes allow one to conclude the exponential convergence. Computer simulation data show a robust performance.