Residual-based contacts estimation for humanoid robots

The residual method for detecting contacts is a promising approach to allow physical interaction tasks with humanoid robots. Nevertheless, the classical formulation, as developed for fixed-base robots, cannot be directly applied to floating-base systems. This paper presents a novel formulation of the residual based on the floating-base dynamics modeling of humanoids. This leads to the definition of the internal and external residual. The first estimates the joints effort due to the external perturbation acting on the robot. The latter is an estimation of the external forces acting on the floating-base of the robot. The potential of the method is shown proposing a simple internal residual-based reaction strategy, and a procedure for estimating the contact point that combines both the internal and external residuals.