Mechanical characteristics analysis on PAM with elongation and torsion

Design and analysis on the new type of Pneumatic Artificial Muscle (PAM) with elongation and torsion is presented. The PAM we developed can not only elongate but also twist about its axis when supplied the air pressure. We establish the theoretical models of axial elongation using strain-energy function; analyze the twist performance applying the Moore integral; discuss the influences of wire diameter, active coils and helix angle of spring on the elongation and torsion angle. The Experimental data verified the theoretical model which provides a theoretical basis to make the flexible rotary joint and robot hand using this type PMA.