I have a DIY gantry machine and I have a stack of resolver position sensors (contactless rotary encoder 4096 steps per rev).

After an incedent where my machine somehow lost it's position, machining a load of parts with a 1.5mm x,y error, I wondered how easy it is to add absolute encoders to it. It's running a UC100 with Mach 3, steppers and ballscrews.

I guess another option is to add a home check, every so often in the program or at least at the start of the program.

What do people do to combat this kind of error?