Study on a variable stiffness actuation with differential drives

Abstract

Variable stiffness actuation (VSA) has been paid more attention to as a novel actuating class for robotics to change the apparent output stiffness. However, most designs internally present a set of elastic elements. This paper proposes a novel VSA based on a brief planetary with dual motor inputs, and presents some variable stiffness analyses based on power flow, torque, force and motor performance. It is shown that, when the VSA is driven by differential drives, the stiffness is determined by the external load (load force, load velocity and force impact) and the internal inputs (motor voltage, torque performance and electrical characteristics). In particular, the VSA can be manipulated by controlling motor performance without common elastic elements and complex mechanism.