What a great design and a fun build. I'm starting to get this thing really dialed in. It took a decent amount of tweaking to get it work perfectly. It has to grab tight enough left-to-right and top-to-bottom so that when the perpendicular grippers move away, the cube doesn't get dragged along out of position. I actually have the screws attaching the gripper servo horns to the servo not tightened down all the way, allowing a little bit of play in the grippers. When I tighten them down, for some reason the grippers go ever so slightly askew, enough to sometimes catch the edge of the cube.
I've gotten excellent support form otvinta3d. I sent them my debug info and they replied with some parameters to use, I plugged them in and now it correctly recognizes the colors virtually every time. I've had maybe 2 "MISIDENT" errors out of like 50 runs.
A few times, the gripper would make the 90 degree turn, and then drag the cube with it when it retracted, so when it turned the gripper back to the neutral position it would undo the turn it just did, resulting in the cube not solving correctly. You just need to make minor adjustments until the cube is held in place securely by any 2 grippers alone while the other ones retract.
This has been an amazingly fun build. Everybody that sees this thing in action loves it.