Published November 26, 2023 © GPL3+

Myo-Assist Knee Brace

Elevate leg strength and joint mobility with Myo-assist, perfect for diverse applications from stroke recovery to sports injury rehab.

IntermediateFull instructions provided12 hours446

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Things used in this project

Hardware components

SparkFun MyoWare Muscle Sensor Development Kit

SparkFun Qwiic Pro Micro - USB-C (ATmega32U4)

DSSERVO DS3225MG

M3 threaded insert

608zz bearing

Software apps and online services

Arduino IDE

Hand tools and fabrication machines

3D Printer (generic)

Story

What is the Myo-Assist Knee Brace?

The Myo-Assist knee brace is an active orthosis that enables intensive training of weak legs to improve muscle strength and joints mobility. The Myo-Assist knee brace works similar to an e-bike by supporting the movements initiated by the user. These exercises strengthen muscles and joints and also can be used for improving range of motions.

It is a cost effective solution active orthosis to support the knees. The Myo-Assist knee brace can be useful for, but not limited to patients with or recovering from stroke, multiple sclerosis, spinal cord injury, and sports injury.

Note: a base amount of muscle function is still necessary to allow the device to function.

Design overview:

The knee brace is constructed with 3D printed PLA+ the top part sits on your thigh and the bottom part on your calve. Velcro straps is used for securing the brace to your leg. To sense the muscle activation, we use the MyoWare® 2.0 Muscle Sensor is an all-in-one electromyography (EMG) sensor from Advancer Technologies and SparkFun. Once muscle activation above a certain threshold is detected, the servo will assist the movement of the user.

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Build instructions:

1. Download and 3D print.stl files.

The.stl files are available to download from the "Attachments" section. For the gears I recommend increasing the wall thickness to 5 and infill to 70% or more, for other parts you can use your default settings. I use gyroid infill with 15% infill and Tree support for the calve and thigh brace part.

Once all the parts are printed, it is recommended to sand the parts especially the inner part of the braces to prevent discomfort when wearing the knee brace.

2. Assemble the parts.

Insert the 608zz bearings as shown in the picture, you can use a mallet if necessary.

Add threaded inserts for mounting the servo.

The bigger spur gear should be glued to the top (thigh) part of the brace as shown in the picture. The bottom (calve) part of the brace mounts from the inner side to the rod of the spur gear.

Mount the small spur gear to the servos and tighten it by using a screw.

Test to see if everything fits and the mechanical portion of the build can function well.

3. Wiring.

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Pro Micro D4 <> Left Servo Sig

Pro Micro D5 <> Right Servo Sig

Pro Micro D6 <> Button

Pro Micro A0 <> Muscle Sensor Sig

Pro Micro Vin <> 5V

Left Servo Vin <> 5V

Right Servo Vin <> 5V

Left Servo GND <> GND

Right Servo GND <> GND

Muscle Sensor GND <> GND

4. Programming.

The.ino code is available for download in the "Attachments" section.

5. Use it and start training.

Congratulations you have finished the build! Time to start training!

Code

myoassist_knee_brace.ino

#include <Servo.h>

Servo leftservo;  // create servo object to control a servo
Servo rightservo;

int emg = A0;  // analog pin used to connect the muscle sensor
int val;    // variable to read the value from the analog pin

void setup() {
  leftservo.attach(4);
  rightservo.attach(5);
  Serial.begin(9600);
}

void loop() {
  val = analogRead(emg);
  Serial.println(val);
  val = map(val, 0, 1023, 0, 180);     // scale it for use with the servo (value between 0 and 180)
  leftservo.write(val);                  // sets the servo position according to the scaled value
  rightservo.write(180-val);
  delay(15);                           // waits for the servo to get there
}

Credits

Samuel Alexander

4 projects • 18 followers

Comments

Awards

Honorable Mention Prize Traveling

Build2gether Inclusive Innovation Challenge

Myo-Assist Knee Brace