Whole-body control of a mobile manipulator using feedback linearization based on dual quaternions

Abstract

This paper presents a whole-body pose control of a mobile manipulator using a cascade scheme with two control loops. In the outer loop there is a nonlinear controller based on dual-quaternion feedback linearization—whose reference is a unit dual quaternion representing the desired end effector's pose—that acts as a dynamic trajectory generator and generates input signals for both nonholonomic mobile base and manipulator arm, the inner loop uses the input signals generated by the outer-loop as reference for an input-output linearizing controller that explicitly takes into account the nonholonomic constraints of the mobile base. Experimental results on a real platform are performed in order to compare the proposed scheme to a traditional whole-body kinematic controller using the pseudoinverse of the Jacobian matrix. The results show that the abrupt initial movement that is a characteristic of the classic approach, when the initial error is too large, is mitigated by the use of the nonlinear control.