Collision Handling for Humanoids using Proprioceptive Sensing
Jonathan Vorndamme, Moritz Schappler and Sami Haddadin
Institute of Automatic Control at Leibniz, Universit¨at Hannover
High-performance collision handling, is a fundamental robot capability for safe and sensitive operation/interaction in unknown environments, which is divided into the five phases detection, isolation, estimation, classification and reaction. For complex robots, such as humanoids, collision handling is obviously significantly more complex than for classical static manipulators. In particular, the robot stability during the collision reaction phase has to be carefully designed and relies on high fidelity contact information that is generated during the first three phases. In this work, a unified real-time algorithm capable of determining unknown contact forces and contact locations for humanoid robots is presented. It is based on proprioceptive sensing only, i.e. joint position, velocity and torque, as well as force/torque sensing along the structure. The proposed scheme uses nonlinear model-based momentum observers that are able to recover the unknown contact forces and the respective locations. The dynamic loads acting on internal force/torque sensors are also corrected based on a novel nonlinear compensator. The presented methods are evaluated under various conditions in a simulation of the Atlas robot. In summary, we propose a full solution to the problem of collision detection, collision isolation and collision estimation for the general class of humanoid robots.