Variable stiffness actuators

The concept of variable stiffness actuators is of relevance to emerging robotics applications. In particular, the intrinsic compliance of the actuator can ensure safe human-robot and robot-environment interaction, even in unexpected collisions. From the analysis of two elementary design classes, lying at the basis of the majority of variable stiffness actuator designs, it is concluded that they are not energy efficient in changing the apparent output stiffness. This can be an issue in mobile applications, where the available energy is limited. Therefore, a new class of energy-efficient variable stiffness actuators is introduced. The conceptual design has been validated by means of simulations and experiments with a prototype realisation.