Fractional-Order Impedance Control For A Wheel-Legged Robot

To make robots walk smoothly and stably, it is necessary to solve ground impacts during dynamic walking. Compliance motion control can help to reduce the impacts and improve the robot's adaptability to complex terrain. Impedance control is a useful framework to provide robot's leg compliance. The conventional impedance control employs second-order mass-damping-spring system as a force disturbance controller. In this paper, position-based impedance control is applied to legged locomotion of the wheel-legged robot and a novel impedance controller with fractional order form is put forward to increase the system degrees of freedom for adjustment. The simulation tests of electric cylinder actuator and leg systems are carried out to demonstrate the effectiveness of the proposed algorithm.