Enabling passivity for Cartesian workspace restrictions

An emerging trend in the field of human-robot collaboration is the disassembly of end-of-life products. Safety is a crucial requirement of the disassembly process since worn-out or damaged products could break, possibly resulting in
dangerous behavior of the robot. To protect the user from such behavior, this work addresses this challenge through the implementation of an energy-aware Cartesian impedance controller, combined with virtual workspace restrictions. Hereby, the passivity of the robotic system is ensured. The paper proposed two approaches to ensure the passivity of the system when subjected to workspace restrictions due to unplanned interactions and contact loss. The first approach employs an augmented energy tank with restricted energy flow. The second approach monitors the overall energy flow, regulating and separating non-passive behavior, caused by workspace restrictions. The approaches are evaluated and compared with each other, by using a KUKA LBR iiwa robot. The results highlight the potential of virtual workspace restrictions in human-robot collaborative disassembly tasks.