Calligraphic motion by humanoid robot arm using air cylinder actuators as endoskeletons

For the purpose of implementation of human smooth and fast movement to a pneumatic robot, the authors used a humanoid robot arm with pneumatic agonist-antagonist actuators as endoskeletons which has control mechanism in the stiffness of each joint, and the controllability was experimentally discussed. Using Kitamori´s method to experimentally decide the control gains and using I-PD controller, three joints of the humanoid robot arm were experimentally controlled. The results showed that the controllability to step-wise input was less than one degree in error to follow the target angles, and the time constant was less than one second. The simultaneous input of command to five joints was brought about the overshoot of about ten percent increase in error. The robot arm generated the calligraphic motion when a humanoid robot hand was attached to it. These results suggested that the I-PD controller and control gains obtained in this study were proper for the humanoid robot arm with pneumatic agonist-antagonist actuators to move smoothly, quickly and accurately.