D. J. Braun, M. Howard and S. Vijayakumar, Optimal Variable Stiffness Control: Formulation and Application to Explosive Movement Tasks, Autonomous Robots, vol. 33, no.3, pp. 237-253, 2012.

This paper presents an optimal control framework for robots with compliant actuation, focusing on how to coordinate motion and tailor time-varying torque and stiffness profiles to task objectives. The approach is demonstrated on an explosive ball-throwing task, where exploiting the intrinsic dynamics and energy storage of variable stiffness actuators improves performance. Both simulations and hardware experiments on a two-link robot confirm the method’s effectiveness.

Why it matters: Compliant actuators can store and release energy, offering performance benefits in dynamic tasks, but their control is complex. This work shows how optimal control can harness compliance to improve efficiency and task execution, laying the foundation for advanced applications of variable stiffness in robotics.