Joint Impedance Pneumatic Control for Multilink Systems

Abstract

In this paper, we propose a general controller for complex tasks such as coordination or manipulation for grasping systems or dynamic gaits for legged robots. Moreover, this controller is adapted to pneumatic actuated structures. The aim is then to ensure a dynamic tracking of position and force for systems which may interact with the environment or cooperate with each other. For that, we propose a nonlinear controller based on a computed torque method taking into account the actuator and the mechanical models. The originality lays in the consideration of impedance behaviour at each joint during free and constrained tasks. It leads to continuous control laws between contact and non-contact phases. The asymptotic stability is ensured using Popov criteria. The application proposed is the control of one pneumatic leg of a biped robot. We present a dynamic model of the leg and chosen trajectories. Simulation results of this new controller are presented, leading to a good behaviour of the leg during a whole walking cycle at relatively high velocities.