A novel actuation technology for safe physical human-robot interactions

The design of intrinsically safe systems is an important issue in the development of physical human-robot interactions, in particular in the medical field. In this paper, we explore a new approach, motivated by a medical robotic application framework. The system is statically balanced, in any configuration. Its actuation results from a controllable modification of the balancing. This notably limits the interaction forces between the robot and its environment, but yet authorizes important features like accurate positioning or tracking while in contact, which are key characteristics for the application. In this paper, the robotic device principle is introduced, together with its original actuation, which is developed and experimentally assessed for a one DOF system. Capabilities such as trajectory tracking in the free space, reaction to unexpected collision and tracking of a moving environment are reported. The generalization to more DOF, as required to complete medical tasks, is also discussed.