Project Summary

The purpose of this project is to develop an active arm brace, which is controlled by the user’s surface electromyography (EMG) signals. This can be used for physical therapy and to assist the user with routine activities. In order to process the EMG signals and eliminate noise, a bandpass filter is used to allow frequencies between 50Hz to 500Hz while blocking unwanted noise. These frequencies are observed in EMG signals produced by the muscles in the arm. The filtered signals then enter the rectification stage, and are finally fed into the microcontroller to generate a control signal for the servo motor. The servo motor controls the brace attached to the arm through a set of Bowden cables, which are connected to a mechanical joint on the user’s elbow. The Bowden cable provides torque to either lift or lower the user’s arm with an additional weight up to 10 lbs. The user will also have the option to manually control the arm through a joystick device. In addition, an OLED display interface will display temperature, battery life and warning messages to alert the user of any system problems. On the joystick device, a button stops the servo motor from running to prevent and avoid hazardous outcomes.The majority of the device’s weight, including the servo motor and circuitry which is located inside a backpack which will be carried by the user. Ultimately, the user should feel as if they are in control of their arm without too much effort while providing smooth movements depending on the direction that is desired.