I have a Double reverse 4:6 bar. It is a 4 motor high speed, i y cables opposite sided motors to distribute power evenly. The lift slight leans to the right when going up and I have 2 strong braces on top and bottom. I can’t do PID side comparison since the motors are y cabled to both sides. Any suggestions on how I make it striagher
Make sure the screws that hold the linkages together are all tightened the same, and make sure each side has the same tensions as far as rubber bands go. If anything, just add one rubber band to the side that leans, it should help.
Although just curious, what cross-bracing do you have on the parts of your lift? If it’s flatbar, I would highly recommend switching to standoffs or half c-channel, as they resist bending in multiple dimensions. And do make sure they connect in the middle where they meet.
It’s full c channels
I’ve also found that robots with only one tower on each side exhibit more lean that robots with either two towers or a floating tower. I myself use a floating because it has the best of both worlds; lighter than using two towers but still gets the stability of the second tower. Does your robot only have one tower per side?
As @Mystellianne said, it could be uneven friction on one side. I believe this is a likely cause. Test each side separately for friction.
Given that most of the time you’d be running all 4 motors at the same power, I’d suggest redoing the Y-cables so you can compensate in the software.
Another thing: You said the lift is Y-cabled, and I know that you probably want to keep it that way to not change the wiring. However, the problem is that the motors on opposing sides are the ones that need to be wired together. But what if you just Y-cabled each side separately, and just plugged the wire in backwards that goes directly to the motor that needs to be inverted? This way you could keep the Y Cables, and also use software to fix the leaning problem
I would say that build quality is one of your main issues here. Try leaving about an open 1/32 space on your lift axles, which should significantly decrease friction on both sides. If both sides seem loose already, try balancing out the friction or weight as much as possible on both sides so both sides of the lift have equal load on them. Most of the time, it shouldn’t be a motor power issues, but if it is, try detaching both motors and seeing if one runs slower than the other, and then try diagnosing if it is the wire, motor controller, motor itself, or maybe even the cortex.
Ive screwed everything in evenly, How would you suggest i "test"for friction
Detach the motors and try pulling the lift in the middle of a cross-member.
With the motors detached, you can even assess the total friction and ballance of your lift using a force-gauge (Newton-calibrated spring scale).