It seems straightforward but I gather that backlash compensation can do some nasty things to line planning – or to the jerk on the machine if you don’t control it. Take the case of a 360 degree circle in XY. There are points at the 4 quadrants where the direction in X or Y reverses. Backlash compensation would cause the nice, smooth planned circle to jump 0.5mm to the left, right, up or down. This looks to the line planner as a 90 degree turn – followed immediately by another 90 degree turn (but the machine shouldn’t be loaded – because it’s traveling through the slop region). The planner would like to slow down to a velocity that it can make the corner, then speed up momentarily through the correction line, then slow down again for the end of the correcting line. If it does this it will cause the tool to go though a dip in velocity at the quadrants, and will affect the smoothness of the cut. The alternative – not slowing down – is worse, as the tool will try to move “instantaneously”, and cause a stepper to drop steps, or jerk the table and rough-up the cut accordingly. I imagine the right answer is going to be somewhere in between those two extremes, and may require some special detection or handling aside from normal line planning. Anyway, I plan to have a go at it, but I do think it will be challenging.
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