Step 5 - Wiring components

Wiring Arduino + Potentiometer (Option 1)

Using something like a potentiometer may be an easy way to get a usable device working really quickly. A Potentiometer is a Radio-dial-like knob that you can turn and which can simulate the type of signal we could get from a muscle. You turn it one way and the arm will pull up, you turn it the other way and the arm will go down again. This 'knob' could be mounted on the arm brace, or if the user has movement in their fingers like my daughter has then you could potentially mount it on their hand.

We tested out various different approaches using switches and other things but this circuit and approach worked the best. We found the following site that we used to help us: http://www.silvinopresa.com/how-to/arduino/control-a-servo-with-arduino-and-a-potentiometer/

Wiring Arduino + Flex sensor (Option 2)

Using a flex sensor is a simple way of getting started. As you flex the sensor, the arm brace will flex at the same time. You could, therefore, connect the flex sensor to a thumb or finger or wrist, and control the arm that way. Here is a video we used to help us: https://youtu.be/YF2GwKQcQ3s and here is a text resource that helped us too: https://www.electronicshub.org/interfacing-flex-sensor-with-arduino/

Wiring Arduino + Muscle Sensor (Option 3)

If you have a strong muscle signal to use then you could try the using a MyoWare muscle sensor to control the actuator. In our case, this only worked for me and not my daughter as her signals were just too weak.

However, if you want to test this out, here is a video we used to figure out how to do that: https://youtu.be/-JYi08WKe6c

Wiring for mobility and ease of use

The above wiring is not suitable for real world use other than for testing. So the next step is to test out if the circuit works (After finishing step 6) and if it does, to come back here and make some final adjustments.

Optional - Help build next version

The next version of the assistive arm that we are currently working on will not use the Arduino, potentiometer or the MyoWare muscle sensor but rather a series of electrodes that will provide a Raspberry Pi up to 8 separate raw signals from the limb. The onboard software will learn to recognize the unique signals being produced by the limb and use those to control the assistive device.

With this approach, we were able to consistently pick up my daughter's muscle signals! If you want to help us with this challenge please go to this page: Help Needed.