Active stiffness control of a manipulator in cartesian coordinates

TLDR

The paper presents a method for actively controlling the apparent stiffness of a manipulator end effector. The method lets programmers set arbitrary translational and rotational stiffnesses in hand coordinates and uses a rapid servo algorithm that transforms the problem into joint space at run time. The approach enables simultaneous position and force control, allows stiffness to be adjusted programmatically for different tasks, and is demonstrated with application examples.

Abstract

A method of actively controlling the apparent stiffness of a manipulator end effecter is presented. The approach allows the programmer to specify the three transnational and three rotational stiffness of a frame located arbitrarily in hand coordinates. Control of the nominal position of the hand then permits simultaneous position and force control. Stiffness may be changed under program control to match varying task requirements. A rapid servo algorithm is made possible by transformation of the problem into joint space at run time. Applications examples are given.