I haven’t had a chance to test the software modifications in Spot X yet, because both of the robots are in pieces, but testing on the bench seems to show that the higher motor speeds are in fact better for the controller. I took the chance to add in acceleration and deceleration towards target speeds, so now the motors have gradual spin-up. Using the microsecond timer rather than the millisecond timer in the PIC program gives a lot more fine control of the acceleration curve so I will be interested to see what that looks like when the robot is together.
I decided to strip down old Spot X’s bumpers and refurbish them. The foam was in fairly poor shape after 13 years or so, so I tore off the wooden bumpers and unsoldered all the components. I was left with about 1-2mm of solidified super glue stuck onto the PCB. Using a chisel I managed to get most of it off, and what remains should not interfere with the process of rebuilding the bumpers. Once the PCBs were cleaned, I replaced all the components. For the rear bumpers I repositioned the current limiting resistors and installed new 5mm LEDs. Everything else remained the same.
I managed to repurpose a sensor breakout board for use with the old bumpers. The switch pinouts were all wrong but with a bit of drilling, some wire and a zero ohm link wired in the right place I think I have got the wiring correct. I’ll plug everything in and test once the PCBs have dried.
For the actual bumpers, I did the same as I did for the bumpers for new Spot X – that is, cut out some strips of acrylic and spray paint them. With the paint and the foam and the components, any damage caused by the original glue will barely show. Let’s hope I don’t super glue my thumb again. Once the bumpers are reconstructed I’ll rebuild the robot and continue testing.
The bearings on new SpotX were starting to fall out, so I mixed up some araldite and glued them in place. I managed to do that without getting the glue in places where it wasn’t wanted, but the 5 minute epoxy cures so fast that you don’t have time to do the job carefully, I ended up having to mix another batch. I may need to glue the inner bearings in place too, because I have noticed one that likes to pop out. Perhaps a little plastic glued behind it will retain it.
My only regret is that it looks like I will need to use the old SLA batteries for the robots after all, although with the thermal problems apparently in abatement for now, maybe that’s less of an issue. It’s worth testing anyway.