Development of a Rack-and-Pinion Mechanism with Arduino-Based PID Control System for a Continuous Passive Motion Device in Knee Rehabilitation

This paper outlines the design and prototyping methodology for a simple, cost-effective device intended for Continuous Passive Motion (CPM) therapy, specifically for knee rehabilitation. The device is designed to assist patients in recovery by providing controlled, repetitive motion to the knee joint without requiring active participation. Its core mechanism utilizes a rack-and-pinion system, which converts rotational motion into linear motion, ensuring smooth and consistent lower limb movement. A PID controller has been implemented using an Arduino Mega microcontroller to provide precise control over the motion. This setup allows for accurate adjustments to both position and speed, aligning with the therapeutic requirements for effective rehabilitation. Key success factors and failure points are also highlighted, providing valuable insights for future improvements and development.