So, I built a 4' cat wheel to get my cats some (much needed) exercise.I have a Wio Link (ESP8266 running Arduino code) running a distance tracking and reporting sketch that gets the distance covered and reports it to a MQTT server for logging and reporting.The Following is the general build description (for those who really want to know):Supplies:I started out with the basic supplies, a 4x8 sheet of plywood, I think I used either 3/8 or 1/4 plywood. 1x2 for the floor supports, and 2x4 for the base that supports the entire thing. I grabbed a wagon wheel (hard rubber 'tire' and metal hub) for the barrings. Finally I purchased 4x8 sheet of 1/4th thick underlayment to make into the floor itself. I picked up scraps of carpet from a flooring shop dumpster for a comfortable walking surface. Later on I grabbed a long length of speaker cloth.First, the wheel:I cut the plywood in half and used a jigsaw to cut the circle. In order to get the circle right I attached a screw in the center, then ran a wire to the jigsaw, that worked ok but the saw blade flexed a lot so the circle wasn't clean, I should have used a router for that instead. I then cut a 1.something strip off the outer edge of the circle (the actual size of the 1x2). This is used for the strip that ringed the outside of the floor. I cut the 1x2s into 1ft long sections for the floor supports, I attached them to the back and used the strip I cut off the second circle as the outer edge of the floor. The smaller circle I glued to the back giving it extra support (used too-thin plywood).I cut the underlayment into strips and glued and stapled it to the floor supports, it wasn't easy to curve but it was easier than wood (this is a pressed board, very similar to cardboard). I tried using it for the outside as well but it started falling apart, then when it came to the last bit being uncovered I just didn't like the look of it. I removed all of the outside and used the speaker cloth instead, it reduced weight and looks much better than the underlayment.After a quick painting I glued the carpet on using Foam Fix 74 spray adhesive.For the axle and bearings, I used a metal wagon wheel that had a hard rubber 'tire', and a long 3/4 bolt (made sure it was long enough to go through the hub, 2x4, and have extra space for washers and the bolt). Using a grinder I cut the wheel part of the hub off just leaving the center section, in doing so I also cut the welds that were used to keep the two halves of metal together. I drilled the two halves for smaller bolts that go through them and secure them together with the plywood between them, this gives it plenty of strength and allows the wheel to turn nicely. After a touch of paint and oiling the bearings everything rolled nicely.Next, the Base:I used some math to get my angles and distances right, I wanted the base to be 'inside' the shadow of the wheel so the wheel width is the width of the entire thing. This worked a little too well as I got some marking on the wall when the wheel slid too close when the cats were using it, that wouldn't have happened if the base stuck out a bit more, but I'll live with it.After figuring out the angles, and cutting to length, I used a table saw to cut a ton of strips out of the ends (followed with some chiseling and sanding) allowing me to join them together as an overlap. I also used the same technique to attach the base to the supports, I added an angle piece to keep up the strength, though I'm not sure it's actually needed considering the low weights involved.After assembly and initial testing with the cats, I found out that the wheel was flexing enough to rub on the supports slowing the cats down and making lots of noise, so I added a small wheel to the bottom part of the base that rides against the bottom of the wheel giving it enough support to not flex (again, used too-thin plywood for the back).I added carpet to the bottom of the base so it doesn't scratch my nice wood floors, also reduced sliding a bit.Finally, the tracking:After the cats started using it a bit, I decided I wanted to find out how much and when they used it, thus the tracking.I had a Wio Link sitting around and decided to use that. The onboard software didn't do what I wanted so I flashed it with an Arduino package (thanks Platform.IO and Atom!) which works beautifully!For tracking I ran through several possibilities before settling on using an IR Tracking bar from a robot kit I had lying around, it features 5 IR sensors and is often used for line following, if it can be used for that it can be used for position tracking.Unfortunately, the IR sensors are analog output, and the Wio Link only has 1 analog pin, so I had to grab an I2C ADC expander that had 4 analog inputs. I could have then used all 5 sensors (1 analog on the Wio Link, 4 on the ADC) but decided that 4 bit precision was sufficient to the task. I was glad of this later on when I tried to fit it in the box, the full size sensor bar just didn't leave enough room for anything else, trimming it allowed the Wio Link to fit in there as well (project box was just a touch too small).After the coding and testing I assembled it all and added the Grey Code to the back of the wheel.The Aftermath:My cats use it, mostly around 4am. They don't go too far but it is used.This project took more than a year to complete, and I've lost track of many of my receipts so I don't know the total cost of this wheel, but I am proud of it and enjoyed the planning and problem solving that went into designing it, and the fun of working on it as well.Future plans:I have some cleanup to do on the software, I want to update it to have configurable MQTT settings (the WIFI configuration library I am using allows additional configurable settings, but you have to do all the work of using them and saving them). And change the webserver to serve up some stats and maybe allowing some configuration.I would also like to setup RFID so I can track the distance per cat (I have 2). Though I'm suspecting only one is really using it, my other cat remains fairly fat.Otherwise I'm happy with how it has turned out and enjoyed the process of making it.Let me know if you have any questions! via /r/DIY https://ift.tt/2rKOPPx
