Abstract
The paper presents force feedback compensation for joint torque control on P-E (pneumatic-electric) hybrid driven robots, whose joints are torque controlled by pneumatic artificial muscles (PAM) combined with electric servomotors in parallel. Although the delay in the pressure control loop can be reduced by the servomotors, torque error still remains due to the modeling error of PAM, miss-adjustment of wire tension, and so forth. To overcome the problem, we fabricated small inline force sensors to plug into PAMs. The method is evaluated by balance control on exoskeleton robot XoR2. By using the force feedback, the torque error was reduced, and the balance performance has been improved.
