Time is rushing by!

Well, the competition that seemed so far in the distant future is now less than a month away, and it feels like there is still so much to do! But unfortunately I (and the rest of the team) don’t have a huge amount of time to devote to it. Although my “day job” is related to some of the challenges (I lecture in Computer Science at Manchester Metropolitan University, and my research interests are in autonomous software), I don’t get a chance to work on Glitterator in this time, and it takes up a significant part of my week. And then this week too we had both world book day (child’s costume to make for school), and most importantly, my youngest’s birthday (and associated party on Saturday). In fact I won tickets to the Saturday session of the raspberry pi birthday bash, but could go because of my daughter’s party. (I thought I’d entered for Sunday tickets – but really it’s a good thing that they weren’t, because that would have been another day’s less work on Glitterator – and we got quite a bit done on Sunday.)

This week also saw the release of the zero w, and Pimoroni released some really cool kits to go with it. As soon as I saw them, I placed an order for a mood light kit, for my daughter’s birthday present. And thanks to the efficiency of the Pimoroni crew, it was delivered on her birthday. Of course then I realised my mistake… two more sets of headers to solder! (One for the zero w, one for the unicorn hat.) I managed to have this ready for her when she got home from school on Friday, but then we ran into a problem – we couldn’t get the unicorn hat code to work on the zero w! Thankfully we are the sort of household that has spare old-model zeroes lying around, so I could swap one of these in. (We don’t really need wireless on a mood light anyway.) She had a great time putting it together, and is very happy with the finished product!

Also released alongside the zero w was the new scroll pHAT HD, and I’ve snapped one of these up to add glitter to Glitterator. I’ve made a little sandwich out of the zero w, a mote pHAT and the scroll pHAT HD (this involved soldering another two sets of headers of course 🙄), and had it running in my office yesterday to blind all comers. 😉   Ultimately, I’m aiming to have this sitting on top of Glitterator, replacing at least some of the mote sticks with flexible APA102 strips, and the pi3 “brains” of Glitterator sending high-level commands to the zero, which will run the low level code to drive the lights.

Also this weekend, we managed to get a maze built, and started to do some testing with this. And here we ran into problems. Glitterator has a real tendency to veer off to the right. This is because of its compact design, which means the motors are mounted at an offset to each other, and so to get the drive shafts in the same position on each side, the right hand motor is geared (with a 1:1 ratio) to shift the drive. The problem is, Lego gears are far from perfect, and we get quite a bit of “skipping”, resulting in the right track turning more slowly, and so the veering to the right. I’d noticed it a bit in the straight line speed test runs, but thought it was something to do with my coding rather than the hardware. So this is a problem we need to work on. But we also had a bigger problem that I haven’t had a chance to debug yet… after several tests, working quite happily with our ToF sensors, Glitterator started rebooting when these were attached. At first I thought it might be overheating, but hard driving using the remote without the sensors attached made it even hotter and yet not reboot. And then I ran out of time… so that’s a problem I will have to solve next weekend!

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One final issue that cropped up is how difficult it is to do fine-grained control with the remote. Essentially, the top speed is so fast that it’s very difficult to manipulate at low speeds with the little joysticks on the PS3 controller. I think I have a solution to this: I’ll make use of a couple of the buttons on the controllers to increase/decrease the max speed. (So for example if you decrease, flicking to full forward will only drive at 90% of the max speed.) Again, I ran out of time so didn’t get a chance to implement this, but I will probably have a chance to handle this mod one evening this week.

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