Simultaneous Motion Tracking and Joint Stiffness Control of Bidirectional Antagonistic Variable-Stiffness Actuators

Since safe human-robot interaction is naturally linked to compliance in these robots, this requirement presents a challenge for the positioning accuracy. The class of variable-stiffness robots features intrinsically soft contact behavior where physical stiffness can even be altered during operation. Here we present control scheme bidirectional, antagonistic actuators that achieve high-precision link-side trajectory tracking while simultaneously ensuring contact. Furthermore, approach enables regulate pretension antagonism. theoretical claims are confirmed by formal analyses passivity and proof uniform asymptotic stability desired trajectories. Experiments on forearm joint DLR robot David verify proposed approach.