Arduino Wheelchair Project: Motorized Controller Mount

Motorized Controller Mount

This was an Arduino wheelchair project we developed for Principles and Practices of Assistive Technology (PPAT) in Fall 2016 at MIT. We made an Arduino-based 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.Motorized Controller Mount

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 this Arduino wheelchair project, that is 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 watch a video of our device in action below.

We understand that this is not just a problem faced by Lisa alone. A large number of powered wheelchair users face this and similar problems all over the world. We created this Arduino wheelchair tutorial with open source designs for anyone who wants to replicate the project. You can find all the relevant documentation for this project on the Wiki page, including code and design files. In this tutorial, we will try to show you the steps for creating the same.

According to Lisa, “it works just like I’d imagined.”

Parts Required for this Arduino Wheelchair Project

We ensured that the parts used for our Arduino wheelchair prototype were common and easily available. Here is a comprehensive list of all the parts with their specifications.

  1. 1” Aluminum 6061 Extruded Bar stock
  2. Scrap piece of steel sheet metal 1.1 – 1.2mm thick
  3. Cytron 12V 17RPM 194.4oz-in Spur Gearmotor
  4. Motor mount bracket
  5. Screws and nuts – multiple sizes
  6. set screw: 8-32 size and thread
  7. Heavy duty limit switch
  8. Arduino UNO(we used this as we had one lying around. You can use a smaller board such as Arduino Nano if you like)
  9. L293D motor driver IC
  10. LM2596 buck converter IC
  11. LM7805 voltage regulator IC

Manufacturing the Mechanical Parts

There are two mechanical parts that need to be manufactured for this Arduino wheelchair project. One out of steel sheet metal and another from the extruded aluminum bar. The CAD files for the two parts are available for download.

The process for machining the aluminum part: The aluminum part was machined from 1” Aluminum 6061 Extruded Bar stock. First, the stock was milled to create a 1”x1”x1” cube. A ½” end mill was used to cut a centered .52” wide groove, .375” deep to fit around the bar of the joystick mount. A .325” deep, hole ½” in diameter was then drilled through the center of the groove to fit around the nut that holds the bar in place. Subsequently, a hole was drilled to fit around the motor shaft, which is 6mm in diameter. To connect this part to the motor, a set screw hole was drilled and tapped to accommodate a set screw of size and thread 8-32.

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