Computing a Manipulator Regressor Without Acceleration Feedback

Abstract

SUMMARY A manipulator regressor is an n x l matrix function in the dynamic expression τ = Y r or τ = W r , which linearizes the robotic dynamics with respect to a properly defined inertia parameter vector ζ r є R 1 . Many modern adaptive controllers require on-line computation of a regressor to estimate the unknown inertia parameters and ensure robustness of the closed-loop system. While the computation of Y is studied by Atkeson, An and Hollerbach 1 and Khosla and Kanade, 2 the computation of W for a general n –link robot has not been reported in the literature. This paper presents an algorithm to compute W for a general n –link robotic manipulator. The variables used to construct the regressor matrix are directly available from the outward iteration of a Newton-Euler algorithm; some additional arithmetic operations and first-order, low-pass filtering are needed. The identification of unknown inertia parameters is also discussed.