On-orbit calibration of the SPDM force-moment sensor

Abstract

A six-axes force/moment sensor can be completely characterized by a 6/spl times/6 gain matrix whose elements can be estimated from a sequence of sensor outputs and applied forces. Unlike the conventional calibration procedure that uses an external hardware to produce the load forces, we present a calibration procedure that applies inertial forces as a result of movement of a manipulator payload in free space. The subsequent inertial forces and moments are calculated by using the Newton-Euler formulation assuming known inertial parameters (mass, center of mass, inertia tensor) of the payload. An extended Kalman filter is employed to perform the estimation of the sensor gain matrix based on the measurements of the manipulator velocity and the sensor outputs. The performance of the proposed estimator is evaluated by simulation.