Multi-model observer and state feedback position control of a flexible robotic actuator

This paper proposes a state feedback control of a lightweight electric actuator dedicated to manipulation tasks. Taking advantage of an optimized back-drivable mechatronic design, the use of proprioceptive measures at the motor level enables the estimation of the unmeasured terminal position of the mechanical motor-to-joint transmission and force disturbance. An accurate model of the actuated mechanical flexible transmission is introduced to determine unmeasurable states with a model-based observer. The observer and the controller are synthesized by tacking into account the non-linear dynamic behavior of the mechatronic system. Non-linearities are reformulated into a polytopic multi-model, and dynamic performances of the controlled system are fixed by root-clustering. This synthesis is performed through Linear Matrix Inequalities (LMIs) and is experimentally validated with a single degree-of-freedom manipulator.