We had a computerized bender where I used to work, it was a 3 wheel job with the center wheel moving up and down. The center wheel moved with hydraulics, and had a gear rack that drove an encoder. We did have issues with accuracy. The machine tried to 'learn' when to shut off the hydraulic valve so that it ends up in the right spot. The cylinder had a flow control that had to be adjusted for different operations. The timing for the solenoid valve would be different every time you adjusted flow, so I think we would try to run it a cycle after making an adjustment to allow it to learn. Positioning error I think was around 10 to 20 thou, which made a big difference with what we were doing.
May not be an issue with what you are doing, but I thought it might be helpful
Good luck
Joe
If you try to make everything idiot proof, someone will just breed a better idiot!