A Design of Lower Limb Rehabilitation Robot and its Control for Passive Training

Artificial intelligence-based rehabilitation robots can be applied for peoples with lower limb motor dysfunction usually caused by accident, war, sports, spinal cord injury, paralysis, and vascular diseases to enhance the motion ability of their lower limbs. A design of lower limb rehabilitation robot as well as its trajectory tracking which is suitable for passive training of patient with paralyzed or weak limbs have been presented in this paper. The contents were well organized and presented. Also, the experimental procedural setup of the lower limb rehabilitation robot is well described and conducted. Initially, AC servo motor was chosen as the actuator for controlling the robot due to good stability, fast response, low noise, wide speed range, low cost, high efficiency, and low maintenance. The corresponding simulation analysis of the actuator shows that it is good and can meet the design requirements. Secondly, the motion control of the robot was investigated using the kinematics model of the hip and knee transmission subsystem, the human hip and knee trajectory curves, the motion control data generation process, the planning target track, and the required servo motor drive pulse control instruction. Finally, the control experiments were conducted such that the pulse signal of the servo shaft rotational angle is received by the servo drive for pitch control in position control mode. By default, a complete rotation of 0.072 degrees corresponds to 500 pulses of the motor rotation time control. The experimental results show that by using PID controller, the actual trajectory is closer to the desired trajectory closely follows the actual trajectory and hence, demonstrated a promising patient's recovery.