Gravity compensation control of compliant joint systems with multiple drives

This paper presents a sufficient condition to establish the existence of unique equilibrium points for three types of gravity compensation controller when applied to over-actuated systems. As compared to the existing work, this paper extends the current theory by introducing feedback gain matrices that are not constrained to being diagonal and positive definite. The inherently COmpliant huMANoid (COMAN) served as a platform for the validation of the designed gravity compensation controller that employed reference link positions. The displayed experimental results provide evidence of successful link tracking of sinusoidal references on a humanoid system composed of series elastic actuators.