Force Controlled Interaction Tasks and Intuitive Teaching of a Pneumatic Manipulator

A method is presented for the force controlled interaction tasks and intuitive teaching of a pneumatic actuator without using a load cell for force feedback. A sliding mode force controller is designed to provide high bandwidth actuator force tracking using a four-way proportional valve. A unified velocity (free space) and contact force (constrained environment) controller is designed. A novel sigmoid velocity trajectory is planned for velocity command in free space. The contact force is proportional to the velocity immediately before the contact, which lies in the final flat zone of the sigmoid velocity trajectory. Based on this methodology, an efficient and intuitive robot programming method is proposed by directly guiding the robot in the most natural way for force-controlled interaction tasks such as polishing and painting of small lot sizes with a very high number of part variants. The preliminary experimental results are promising.