Team Lisa Wiki
Welcome to the Wiki pages for Team Lisa!
This was a project for Principles and Practices of Assistive Technology (PPAT) in Fall 2016 at MIT. We made a motorized wheelchair controller mount for our client, Lisa. She lives at the Boston Home, a center for people with progressive neurological diseases, and has Multiple Sclerosis. With her old controller mount, she would often bump into sinks and tables because the controller was difficult to push out of the way and jutted out, preventing her from getting as close as she wanted. She wanted a method to move the mount out of the way easily so that she could access sinks and tables. Our solution was to create a motorized controller mount, which uses a DC Gear Motor and a microcontroller (Arduino UNO) so that Lisa can move the mount with the push of a button. One button press moves the mount away from her, and another press moves it back in front of her. You can find all the relevant documentation for this project on the Wiki page, including code and design files. We hope that this Wiki will allow anyone to learn more about how this device works and to create their own such device.
You can watch a video about our device here: https://vimeo.com/195648615
Authors: Suma Anand, Abhinav Gandhi, Nora Kelsall, Mark Vrablic
What is our device?
We created a motorized mount for Lisa's power wheelchair controller. Lisa pushes a button once to move the arm out of the way, and pushes it again to move it back in front of her. The button sends a signal to an Arduino UNO, which turns on a geared DC motor. The motor then rotates the arm to the desired position.
Some additional electronic components power the Arduino and give it information about the mount's position. The Arduino communicates with the motor through the following process:
Button press --> Arduino UNO --> Motor driver --> Motor
The Arduino is powered by Lisa's wheelchair battery:
Wheelchair battery (24 V) --> Buck converter (24V --> 12 V) --> Voltage regulator (12V --> 5V) --> Arduino UNO
The Arduino gets information about the mount's position from a limit switch. When the button is first pressed, the motor rotates clockwise and the mount is pushed out of the way until the limit switch fixed under the mount is closed. When the button is pressed again, the motor rotates in the counter-clockwise direction for 2.15 seconds, which brings the joystick mount back to the original position.
Why this device?
Lisa has progressive Multiple Sclerosis, which has severely affected her trunk to a point where she has no control over it. She has good motor control of her right arm but is slowly losing control of her left. Lisa is a power wheelchair user. Her wheelchair has a controller mounted onto the arm of her wheelchair, which juts outward, preventing her from accessing surfaces like a sink or a computer table. The current mechanism of the mount is such that it rotates outward and back when a lateral force is applied on it. However, the mount is held in place with a spring loaded locking mechanism and Lisa cannot exert the amount of lateral force required to push it out of the way. Our automated controller mount designed for her wheelchair helps her do this without a problem.