Abstract: Based on flexible pneumatic actuator (FPA), a type of flexible pneumatic torsion joint is proposed. The torsion joint is composed of two arcual FPAs. When inflating the two FPAs with compressed air, the torsion joint turns with an angle. The variety of the shell thickness of FPA is analyzed and the moment equilibrium equation of the FPA free end is established. Hence the static model of torsion joint is obtained. Experimental system is constructed to measure the air pressure and turning-angle relationship of the torsion joint. There is certain error between the experimental result and the simulated curve. The factors affecting the static model are also analyzed and the mathematic model of torsion joint is modified based on the experimental results. The modified model can better describe the inflating process and deflating process of the torsion joint.

Key words: Flexible pneumatic actuator, Flexible pneumatic torsion joint, Static model