Pseudolinks and the self-tuning control of a nonrigid link mechanism

The pseudolink concept for representing the tip position of a nonrigid link is developed. The pseudolink is defined as the line segment connecting the proximal and distal ends of the links. Pseudolink length and angle are determined online using joint encoder information together with strain measurements taken along the link. External sensors are not required and trajectory planning can be carried out a priori under a rigid-link assumption. A self-tuning control based on pseudolinks is discussed. Laboratory experiments on a rotating nonrigid link show the proposed control leads to improved performance over a control that ignores compliance