Development of automatic Continuous Passive Motion therapeutic system

After knee replacement surgery, a patient immediately needs a therapeutic treatment. A therapist flexes and extends the leg around the knee to eliminate the joint stiffness. The research is to design and develop a system of automatic Continuous Passive Motion (CPM) device so that patients no longer have to control it. The system will stop and return to its starting condition whenever there is patient pain. It is a force that is released by the patient in an opposite direction and will be represented as holding the DC motor shaft. A DC motor, H-bridge, microcontroller, and ADC modules are needed to develop this system. DC motor rotates clockwise with about 4V–5V as its voltage. If the DC motor receives load, the voltage will decrease and will be detected by ADC. The motor will stop if the voltage reaches 3V or less. After around 1.5s, it will rotate again with an opposite direction. The system is very sensitive to the patient pain, and if it is applied to CPM, it can improve patient safety.