Force Control of a Flexible Finger with Distributed Sensors and Piezoelectric Actuators

This paper is concerned with the theoretical and experimental study of the force control of a miniature robotic finger that grasps an object at portions other than the fingertip. The artificial finger is a uniform flexible cantilever equipped with a distributed set of compact grasping force sensors. Control action is applied by a piezoceramic bimorph strip place at the base of the finger. The mathematical model of the assembled electromechanical system is developed. The distributed sensors are described by a set of concentrated mass-spring systems. The formulated equations of motion are applied to the study of control problem where the finger is commanded to grasp its object with a time-constant force 0.03 N regardless of the contact position of the finger with the object. Both the PID and H ₀ , regulators are tested and their control behaviours are compared with each other.