I recently participated in an amazing hackathon-like 3 day event called TOM in which makers and people with disabilities (aka need knowers) have 72 hours to plan, design and build solutions for a specific daily challenge the need knower has.
Our need knower is a 26 years old woman that due to her severe Cerebral Palsy, has very limited movement. She is able to move her left foot and some of her right hand fingers. She lives at home and on a daily basis comes to Maarag, a center for specialized employment for the disabled.
Our team set out to create an assistive technology to enable her to be involved in scanning documents for archiving.
We wanted her to be able to press a foot switch that would open the scanner lid and then press it again to close the scanner lid and automatically operate the scanning. At this center they usually work in pairs so her partner would put the pages in each time.
Step 1: Equipment
Arduino 1.6.6 IDE
Servo - Hitec HS-805BB with a Four Point Mega Horn attached
Computer with scanner application
Wires, breadboard, screws, wood glue, etc…
Step 2: Plan
Consulting with a mechanics engineer we decided to base the solution on the way a seesaw works. Meaning we’d extend to scanner lid and attach a weight to it to create a lever so that the center of balance (the fulcrum) would be right behind the scanner hinge. Then a servo engine would easily be able to tip the lid open and close.
Step 3: Extending the Scanner Lid
- Cut a sheet of plexiglass to fit the scanner lid and extend it by 8 cm at the back
- Attach it to the original scanner lid. As a temporary solution we used simple office clips to attach it. There are much nicer fasteners you can use.
- We then added a metal cylinder at the end of plexiglass. You can calculate the exact weigh you need or you can just trial and error with different scrap metal to find the right one. It should be heavy enough to tip the lid open when you touch the plexiglass lid around 2 cm in from the back and light enough to tip the lid close when you touch the plexiglass lid around 6 cm in (counting from the end of the scanner in the direction of the front of the scanner).
Step 4: Electronics
We used an Arduino Uno to get an input from the foot switch, trigger the servo motor and when the lid is closed, activate the scanner application.
Using a Uno and not a Leonardo meant we weren’t able to activate a mouse click or a enter event on the computer with the scanner application.
After a great deal of frustration and hacking, we managed to get it working but uploading sketches to the controller is still not straight forward and you always need to upload both, first the EasyScan code below and then the Bride code.
For more information on the hacking needed:
Step 5: 3D Printing the Rod Component
The final component we needed was the rod that actually pushed the lid back and forth.
We 3D printed a component that fits on the servo engine’s ‘four point mega horn’ attachment with a rod connected to one point.
The original Solidworks file and STL below.
Step 6: Housing the Scanner
In our solution the scanner needed to be placed 6 cm higher than the table so we build a simple case with MDF spray painted white. Inside the case we left room for the electronics to fit in.
In addition, you need to build an MDF structure to hold the engine and keep it from moving around.
Step 7: Putting It All Together.
- The motor with the rod component sits on the left side of the scanner, adjacent to the case. The exact y position of the motor can be calculated or as we did, you can just move it back and forth a few millimeters each time, activate the engine and tweak it so that the rod reaches the right point at the back to make the lid open and then the right place somewhere in the middle of the lid to make it close.
- Attach the engine housing including the engine without the rod component to the side of the scanner case.
- Place the rest of the electronics within the case and secure them in place with screws or hot glue.
- Put in the scanner with the extended lid and weight.
- Screw back the rod component on to the servo.
- Activate the scanner application on the computer
- Attach the foot switch.
And you’re good to go.
Step 8: Summary
As I mentioned at the beginning this project was completed within less than 72 continuous hours meaning we barely slept and we weren’t that friendly by the end of it but when our need knower came in on the last day we were very satisfied.
The foot switch was attached to her wheelchair and she was easily able to press it to open the lid, close the lid and see the scanner working.