Hybrid actuation of robotic manipulators: an integral mainfold control approach

The control of robotic manipulators powered by a hybrid actuation method is considered. The hybrid actuator consists of a pneumatically powered bladder actuator in conjunction with a traditional DC servomotor. A bladder actuator-DC motor pair is arranged coantagonistically with all identical pair to actuate manipulator joints. The proposed method of control for the hybrid actuator-powered robot utilizes all existing theory for the control of manipulators with flexible joint drives. A rigid control law in conjunction with a corrective control which compensates for pneumatic actuator compliance provides good trajectory tracking capability for low joint torsional stiffness, while retaining all the advantages of the proposed actuator configuration. It is seen that, for high joint torsional stiffness, a corrective control is virtually unnecessary, as the rigid control provides relatively good trajectory following capability. A 2-degree-of-freedom manipulator actuated with the hybrid actuator is simulated numerically to verify the performance of the proposed control law