Analysis and Development of a Semiactive Damper for Compliant Actuation Systems

The development of actuation systems with intrinsic compliance has recently gained increased attention due to the benefits that compliance brings with respect to interaction, safety, and energy efficiency. However, the incorporation of compliance into the actuation system results in systems with more complex dynamics that are not trivial to control due to the induced oscillations and the decreased mechanical bandwidth. To assist the control of robots powered by compliant actuators, this study proposes the use of physical damping in the structure of the compliant actuator. A motivation study is presented to demonstrate the improvements in compliant joint performance gained by introducing physical damping. The variable physical damping actuator (VPDA) aims to improve the control of compliant actuators with the provision of a desired physical damping level on demand. A single degree-of-freedom compliant joint is used to evaluate the ability of the VPDA in replicating different values of physical damping when the link of the compliant joint is perturbed. The performance of the unit is experimentally verified, showing that the VPDA system (mechanism and its control) is capable of generating desired viscous damping levels with good fidelity assisting to regulate the generated oscillations.