Identification of Unknown Payload and Environmental Parameters for Robot Compliant Motion

When compliant motion control is applied with the computed-torque methed, an accurate dynamic model of the manipulator and environment is required. This paper presents a method for estimating the inertial parameters of a rigid body load and the unknown parameters of the constraint environment. The inertial parameters include the mass, center of gravity, and moment of inertia. The unknown parameters of the constraint environment consist in environmental stiffness and the geometric parameters of the constraint surface. The dynamic equation is written in the Newton-Euler formulation with the assumption that joint velocity and acceleration and contact force and torque are known through measurements. Since the identification equation is nonlinear in terms of the unknown parameters of the environment, the extended Kalman filter is used to produce an optimal estimation.