Modeling, identification, and control of a pneumatically actuated, force controllable robot

Focuses on modeling and control of a light-weight and inexpensive pneumatic robot that can be used for position tracking and for end-effector force control. Unlike many previous controllers, our approach more fully accounts for the nonlinear dynamic properties of pneumatic systems such as servovalve flow characteristics and the thermodynamic properties of air compressed in a cylinder. We show with theory and experiments that pneumatic actuators can rival the performance of more common electric actuators. Our pneumatic robot is controlled by extending existing manipulator control algorithms to handle the nonlinear flow and compressibility of air. The control approach uses the triangular form of the coupled rigid body and air flow dynamics to establish path tracking. In addition to the trajectory tracking control law, a hybrid position/force control algorithm is developed. The experimental results indicate that the tip forces on the robot can be controlled without the need for an expensive force/torque sensor usually required by electric motors driven systems.