Flexible‐link robot arm control by a feedback linearization/singular perturbation approach

A nonlinear tracking controller for the link‐tip positions and velocities of a multi‐link flexible robot arm is designed that gives guaranteed performance. The controller has three parts: a model‐based trajectory generator, an inner loop based on input‐output feedback linearization, and an outer loop that stabilizes the internal dynamics (e.g., the flexible modes) using a singular perturbation design. We show how to stabilize the internal dynamics by selecting a physically meaningful modified performance output for tracking; this output is the slow portion of the link‐tip motions. That is, the tracking requirement is relaxed so that the internal dynamics are stabilizable through a boundary layer correction that attenuates the flexible mode vibrations.