Study On The Power Assist Exoskeleton System For Upper Limb Driven By Pneumatic Artificial Muscles

Power assist exoskeleton system for upper limb driven by assist pneumatic artificial muscles, is a kind of device that can provide assisted power when people need to improve their power. This system can be applied to military operation、 disaster relief、rescue,and it also benefits the elderly and people with muscle weakness. Pneumatic artificial muscle is a new-style pneumatic actuator. Its characteristic of power/length is similar to biologic muscle. It outputs more power at the same weight or at the same volume, which improves the flexibility of exoskeleton. It is also cheap、safe and quick to response. More and more researchers pay attention to pneumatic artificial muscles used as actuator for exoskeleton. But the researches on pneumatic artificial muscles were focused on rehabilitation device. In this dissertation, pneumatic artificial muscles are first used in power assist exoskeleton system, and related research is carried out.First of all, based on the movement mechanism of upper limb, the mechanical structure design of the system is carried out. It is suitable for wearing. It mainly includes the design of shoulder and elbow. The joint of elbow has one degree of freedom, while the joint of shoulder has three. Its actuator is pneumatic artificial muscle, and steel wire is used to transfer the force.Secondly, kinetic and dynamic analysis of the mechanism is conducted in this paper. Besides, the simulation model is set up in ADAMS to calculate the torque needed in the process of lifting the weight. So the design of mechanical structure can be checked.Thirdly, based on the mechanical structure design, the control system is studied to realize the position control of joints and man-machine cooperation. Each pneumatic artificial muscle needs two high-speed solenoid vavles to contol inflation and deflation separately. Besides, mathematic model of power assist exoskeleton system for upper limb based on pneumatic artificial muscles is put forward. And then the characteristic of the system is studied, the model of the system is simulated with the software Matlab/Simulink. The result of the simulation verifies that the mathematic model is right.Finally, the overall experiment platform is set up to test the characteristic of the system.PID controller is used in position control of shoulder and elbow joints. Man-machine cooperation test is conducted. The experiment results show that the system has good performance in step function response, and it has the ability to adapt to the change of load. The joint of elbow can finish the movement of man-machine cooperation. The test proves that the system can provide assisted power when people need to improve their power.