New experimental results on vibration damping of a hydraulically actuated flexible robot

The paper presents an effective approach to vibration damping of hydraulically driven flexible robots using virtual passive elements. As it is impossible to obtain an accurate analytic model for multilink flexible robots with hydraulic actuators due to the closed kinematic loops this approach was developed. Here the hydraulic actuator is designed to have passive mechanical properties by suitable (velocity) control. These passive mechanical properties are selected to represent a spring-damper-element which is a passive energy dissipative device that always withdraws energy from a system and therefore never will destabilize it. Hence the controller is basically model independent. Only the selection of the spring stiffness and the damping constant remains an issue