Amazing. Your pusher drone is really cool too - reminds me of Burt Rutan’s Long-EZ. I used to work next to Scaled Composites in Mojave, California and his brother Dick Rutan would fly around in his.
I’ve also been excited to follow your progress on the closed loop motors - I’d been wondering the same thing. I’ve used expensive brushless motors with encoders in the past (maxongroup.com), both with hand-rolled PID loops and hardware controllers and was excited to see that there are now consumer level cost effective options that appear to just work.
For closing the loop on the X and Y axis I feel like it winds up more valuable to track absolute position rather than motor position (removing any worries about belt stretching, slipping, etc). There are really expensive linear encoders (at least, I assume they’re expensive because they’ve got no listed price) such as Serie 3 - Fagor Automation , but I’m not sure what the cheap equivalent looks like. From my prior life I’m wondering if it could be as simple as a sticker with an encoding pattern along the rail and a cheap optical sensor to count dots, but obviously there’s a lot of development to get from concept to implementation…