Soft robotics with variable stiffness actuators: Tough robots for soft human robot interaction

Robots that are not only robust, dynamic, and gentle in the human robot interaction, but are also able to perform precise and repeatable movements, need accurate dynamics modeling and a high-performance closed-loop control. As a technological basis we propose robots with intrinsically compliant joints, a stiff link structure, and a soft shell. The flexible joints are driven by Variable Stiffness Actuators (VSA) with a mechanical spring coupling between the motor and the actuator output and the ability to change the mechanical stiffness of the spring coupling. Several model based and model free control approaches have been developed for this technology, e.g. Cartesian stiffness control, optimal control, reactions, reflexes, and cyclic motion control.