Robust control of flexible joint robots

A new robust control scheme for general flexible joint robots with possible bounded parametric or structural uncertainty is derived using the pseudo-sliding surface concept. The switching control law derived from a set of approaching laws forces the robotic system tracking error vector to reach and remain on the shrinking superbox defined by a set of pseudo-sliding surfaces. The tracking errors can be proved to be globally and asymptotically convergent. The advantages of this approach are: (1) it is easy to define pseudo-sliding surfaces for the flexible joint robotic systems and to derive the robust control laws; (2) the control actions are chatter-free; (3) the control laws are based on the positions and velocities of the motor and joint angles only, therefore, no acceleration and jerk measurements or estimations are needed; and (4) the uncertainties in robotic system models do not need to satisfy any matching condition. Simulations, performed on a two-link planar manipulator, demonstrated the feasibility of this new scheme