Why does the data travel in a Positive and Negative pattern?
During each Full Step position, a correctly made Step Motor will repeat itself due to the way it is mechanically made. Using Graph 1 as an example, measuring from the 50th microstepping position to the 100th microstepping position will equate to 0.9°. This step motor will always be 0.9° apart at every 50th microstep, no matter what the accuracy is.
Therefore, the step motor overshoots when the error is a positive step error. Conversely, the step motor undershoots when the error is a negative step error. During one Full Step travel (0.9°), those 50 microsteps will overshoot and undershoot, and eventually bring the motor back to the same error location as the previous Full Step position.
Why are there spikes in the graph? Does this pattern mean something?
2-Phase Step Motors have 4 mechanical steps (A, B, C, D). Similar to the explanation above, when the motor comes to the A position, it is always 0.9° away from the last time it was at the A position. This is where the spikes occur due to the motor's natural detent torque, pulling it and forcing it to reach exactly 0.9°.
5-Phase Step Motors have 10 mechanical steps. The repeatability will occur at every 7.2° (One Full Step × No. of Mechanical Phases).
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