Design&Control Performance Study Of Ankle Joint Rehabilitation Training Device Driven By PMA

Ankle joint rehabilitation training is a therapy that achieves ankle joint movement function recovery via motion training exercise. Ankle joint is the most complicated joint of lower limb of human body, also is one of the most important joints. Patient of nerve injury and limbs disabled unable to move autonomously for a long time, will easily cause ankle joint adhesion and muscle atrophy. Thus, rational and scientific rehabilitation training of ankle joint is very necessary. Isokinetic Continuous Passive Motion (CPM) and isokinetic Active Resistance Motion (ARM) is the most widely used and recognized as the most effective method among various training methods. Isokinetic rehabilitation training motion can only fulfill in professional isokinetic rehabilitation training device. Traditional ankle joint isokinetic rehabilitation training devices are driven by motor or air cylinder, which is easy to be carried out and have good control performance, but lack of safety and compliance. In contrast, Pneumatic Muscle Actuator (PMA) is a new kind of actuator which not only is compliant and safe to use, but also have the similar length-to-force characteristic with biological muscle. Thus, an ankle joint rehabilitation training device driven by PMA as well as isokinetic CPM&ARM controller were designed in this paper. And simulated experiments were conducted to study the control performance of the device.Firstly, according to the requirements of ankle joint rehabilitation training, overall scheme of the ankle joint rehabilitation training device was proposed, as well as pneumatic system and mechanical system were designed.Secondly, embedded system was used as control system of the rehabilitation training device. Embedded hardware and software system were designed, including selection of main control module and sensor, setup of software development environment, developments of measure-control circuit and application software code.Thirdly, experimental research on control performance of isokinetic CPM of the rehabilitation training device was conducted by using weight blocks to simulate foot’s mass. Feedforward-PID feedback control algorithm was applied to study the control performance. Then input leading and position compensation were added to the control algorithm in order to achieve better control performance.Finally, according to the requirements of ankle joint isokinetic ARM rehabilitation training, isokinetic ARM controller was designed, as well as simulated and human participated isokinetic ARM experiments were conducted.Experimental results demonstrate that the rehabilitation training device designed in this paper can fulfill the requirements of ankle joint isokinetic CPM and isokinetic ARM, can provides the guidance for the design and study of lower limb rehabilitation training robot.