A Task-Based Post-Impact Safety Protocol Based on Energy Tanks

As situations with robots working in human environments are becoming increasingly important, the aspect of safety is crucial. As a consequence, the design of human friendly robots has been intensively researched in the past years, producing both mechanical and control design advancements. In this work, a safety-aware control architecture is proposed in a scenario in which a predefined task has to be executed. At the core of its implementation, a novel dynamic energy injection protocol is introduced for energy tanks. Contrarily to their most common employment in the past, energy tanks are used to provide relevant information on energy flows used by the safety protocol, rather than to guarantee passivity of the controlled robot, which does not imply safety. The algorithm is able to detect collisions and divergence from nominal task execution by identifying unwanted energy flows, encoded in the energy tanks. A reaction strategy based on low impedance control is implemented in case of collision detection. Experiments on a 7-DoF manipulator successfully validate the proposed strategy.