This week Gordie, Lina, and I completed our proposed P Comp project of hacking an old PC mouse to design a mouse footpad for the floor.
We met on Canal Street and went shopping for material to use for the footpad. After visiting some amazing plastics stores We went to a fabric store where we found a faux fur mikey mouse print fabric that was perfect for the project. We knew once we saw it that we had to go for this material. It inspired us to build the pad in the shape of a mouse’s head, with the face divided into quadrants holding the sensors controlling the left/right and up/down movement of the mouse, and the right and left ears serving as the right and left click buttons.
The other key was Lina’s decision to use relays to operate the click buttons on the mouse. We had discussed using transistors, but Lina was familiar with relays and they were a lot easier to wire up on the board.
The relays were the right call, as you can see here as we use them to simulate the right/left click action of the mouse.
The next challenge was to simulate the x- and y-axes movement of the cursor on the screen. We initially thought to pull the encoder wheels off the mouse and attach them directly to the axle of the motors, but that didn’t work all that well, as you can see here:
The problem was that the encoders really had to sit in their housing in order to properly activate the movement function of the two axes, but the size of the motors prevented us from allowing them to placed where they normally would be if we left them attached directly to the motor axles as seen in the video.
Eventually, we solved the problem with the motors by taking the parts from another mouse, putting its encoder wheels in the housing provided by the mouse, and then cutting the encoder wheels from the first mouse down and using them as gears to intersect with the now properly housed encoder wheels. Here's a video of us showing Mustafa how the motors work.
The left and right clicks were working, even after we transferred the sensors to the “mouse pad”. We also soddered all the wires to a perf board so that we could ensure all the components could stay in place on the mouse pad.
Here's a video of our prototype working all together. It was 2:30am and we were a little out of it but it was successful
The last challenge was to build the housing for the guts of the mouse to hold the motors. We built a makeshift “Stonehenge” that was not an aesthetic triumph, but it did work!
It was a grueling but fun really fun project but in the end it worked for our PCOMP class. Here's the demo of the final project. Many thanks to everyone who helped us with this mousepad. Special thanks goes to Lina’s husband Andres, Anaid, who provided us with so much help with parts and suggestions (particularly, schooling us on soddering the perf board), Todd, who was constantly around with great suggestions, Oscar, who help us solve the problem of powering the project, Rory, John Dimatos, and of course, Scott, our teacher, who gave generously of his time with extended office hours on Monday!
Since we had so much trouble getting the mousepad to work right before the presentation, Gordie took the liberty of building a new housing for it out of wood, which can be seen here:
Here's how he did it. "I drilled the top support with two sizes of drill bits (7/8" for the body of the motors; 5/8" for the head) to provide a tighter casing for the two motors, and secured them in their holes with rubber corks. I replaced the encoder wheel "gears", which were sliding up the shaft, with the gears that came with the kit, so they fit the shafts of each motor snugly. I secured the base of the mouse to one block of wood, and then cut up a dowel to form columns to support the top block which houses the motors. While the bottom of the columns are secured with wood screws to the base of the new housing, the top is for now unsecured, which allows us to lift it off to show the inner workings of the project. Thank you SO much for your hardwork Gordie!
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