Abstract:
Stroke is a serious medical condition that often involves the death of the recipient. Although fatality is not definite, many stroke survivors tend to suffer the inconvenience of losing the functions of their limbs. Studies have shown that task oriented recursive movements can help stroke affected individuals to recover mobility of their damaged limbs. Manual therapy used to make stroke patients recover movement is successful, but robot-assisted therapy excels in many fields including accuracy and repeatability. Many currently available rehabilitation robots share common disaffections of being overly complex, costly and voluminous. A compact and inexpensive upper limb rehabilitation device was therefore developed in this study to provide stroke therapy to the general public. For the developed rehabilitation device, DC motors were selected as the actuator of the system for their high power and torque capabilities. PID controller was implemented for control of motor position, while trapezoidal velocity profile was employed for motor speed control. Sensors such as accelerometers, encoders and strain gauges were utilized to provide detailed data of the rehabilitator and various onboard components. Safety was enforced with both boundary walls and limit switches, as well as software controlled emergency stop. Microcontrollers were used as the system controllers, with a main Master microcontroller handling system operations while two Slave microcontrollers were dedicated to the control of the DC motors. A GUI was developed for the PC to allow interfacing and control of the rehabilitator. The program permits tuning of various robot parameters, and offers different therapy modes as well as an interactive game. The upper limb rehabilitation device developed has followed the set specifications and achieved the desired performance. The rehabilitator is capable of producing successful trajectory runs with a maximum error of 5 mm at low speed (1.88 rad/s) and 6 mm at high speed (3.77 rad/s) under no load condition. Similar results were also obtained maximum deviation of 4 mm at low speed and 6 mm at high speed under arm loaded setup.