The decoupling of a harmonic-drive-spring system for position and torque control on two different axes

The motivation of this paper is to implement a control algorithm to control the angular position of one axis and the torque on another axis in a harmonic drive system. Obviously, two independently operated actuators on any two axes form an essential part of the setup. One of the motors is coupled through a spring-damper element to the corresponding shaft. The paper summarizes the most important properties of harmonic drives. It gives the torque equations of the harmonic-drive-spring system and also presents a minimal state-space realization for controller synthesis. The decoupling of the multivariable system by state feedback with symbolic calculations is achieved.