A Day For Hardware

There were a few hardware items on Robie that I decided to tackle yesterday. One of the more annoying things that I've had to deal with since day 1 is the fact that my old used-and-abused Robie didn't have any rubber tread left on his wheels. This makes traction a tricky proposition. I was able to conduct some tests on the carpet ok, but he still slips a bit.

I happened to have some robot wheels kicking around from another project. These are the typical mounted-on-yellow-plastic set that you see in 90% of the robot platforms for sale in Ebay. They looked like they might fit the bill without modifications, but upon closer inspection both the diameter and width were too big.


That didn't deter me much though. I carefully cut down each of the side to make the track thinner. Then I cut out a section to shrink down the diameter. A bit of contact cement secured them to the original Robie wheels. Now they look like they came from the factory! There's a small seam if you look closely, but other than that it's pretty clean.

Next I went on to try and mount my HC-SR04 distance sensor. The best sport I could come up with is the front panel where the speaker mounts. As it turns out, there is enough room in there for both the distance sensor and the speaker (which I intend to utilize).

The only trick to cutting the plastic to to use a small cutoff wheel on the Dremel and go slow! My measurements were bang on, so the sensor is essentially press-fit in place. I put some electrical tape on it as well (not shown) just for insurance.

Finally I tackled the camera mounting. This part was a bit tricky. Because the ribbon cable for the Raspi cam is fairly short, I needed to ensure that the ribbon socket was pointing down. The circuit board barely fits between the eye mounts and the bottom lip of the head. So I was careful about where I drilled my hole. The Raspi cam lense enclosure itself is square. So after I drilled a pilot hole I had to file down the hole to make it square as well. After I got the fit right I secured it using some 2-part epoxy. I was careful to only use a couple of small dabs on the sides. Therefore if I ever need to replace the cam, all I need to do is cut the epoxy with and exacto blade.


He kinda looks like he has a mustache now, doesn't he?