The upcoming Robogames kicked me in the butt enough to dust off my Onyx X plans.
You may recall, I was too busy with the robomagellan last year, and couldn't get Onyx in shape.
This time, I'm prioritizing the other way around -- magellan is standing aside, and I'll re-build Onyx based on learnings from before.
I have a bunch of interesting things I'd like to try, from "stabilized turret based on belts and brushless motors" to "on-board aim assist with Raspberry Pi," but in order to make it to this year, I've decided to hold myself to the simplest possible scheme.
Main problems to solve:
1. read-back of stats over XBee just doesn't work -- it is so slow turning around the on-air interface
2. the frame was really narrow and couldn't fit the target plates. This was great for maneuverability.
3. also, the frame took a bad fall, and is a bit twisted
4. the 5 GHz video would fade in and out, and all monitors I have at home cut out when sync isn't perfect
5. the head/turret would shake around more than I like when walking -- it was fairly top heavy
6. screws would come lose and be left on the floor all over when walking too fast
7. various bits (including the camera lens!) shattered from the airsoft pellets
1. I will build just a forward control this time, and if I have time left over, send read-back using another mechanism (second Xbee, WiFi, etc) Keep It Simple Stupid!
2. I can spare an extra inch in width/height to put the plates on the body.
3. I'll have to build a new frame to solve the space problem, so Tormach mill, here I come!
4. I'll throw money at this problem and buy a drone-approved video display that presumably doesn't lose composite sync from noise
5. Moving the plates off the turret will help. Also, while two guns looks awesome, I'll go for a single gun this time.
6. Threadlocker, every screw, every time. There is no such thing as "just testing and I'll do it better later" -- do it as if it's final every time.
7. Delrin is easily laser-cuttable, and can also be heat-strip-bent in a pinch. 1/32in delrin sheet is cheap and doesn't weigh too much. I'll build a shell of Delrin, and then add some 1/32 transparent polycarbonate around the bits that need visibility (camera, indicator LEDs)
Also, the previous body was smaller, and needed the turret heading servo to be mounted on top of the top plate, which meant the turret was high up, contributing to the jittery balance. This new body puts the servo in the same plane as the hip heading servos, inside the body. This leads to a lower center of gravity.
If I have time, I may build the infrastructure to support the turret with an external thrust bearing, but for now, the thrust washer on the heading servo will have to take the load. Because the servo is advanced from center of body, this means it may take some radial load, which is not great. Or I'll move center of gravity forward, and adjust the gait to compensate.
I'm thinking I'll post pictures here as things develop, to keep me honest and on-track. If anyone actually bothers reading and sees me deviating from the KISS principle, a swift kick would be much appreciated!