Pneumatically actuated exoskeleton for gait rehabilitation

This paper describe the mechanical and control system design of a 10 DOF (Degrees Of Freedom) lower limbs exoskeleton for gait rehabilitation of patients with gait dysfunction. The system has 4 double-acting rod pneumatic actuators (two for each leg), that controls the hip and knee joints. Motion of each cylinder’s piston is controlled by two pressure proportional valves, connected to both cylinder chambers. The pneumatic actuators are controlled by proportional-pressure valves. The control strategy has been specifically designed in order to ensure a proper position control guiding patient’s legs along a fixed reference gait pattern. For this purposes Fuzzy controller with additional force compensator was developed. A numerical solution of the inverse kinematics problem based on video image analysis has been used. The controller was successively implemented and tested on embedded real-time PC104 system. Laboratory experiments without patient are carried out and the results are reported and discussed