Jon Elson wrote: > [snip] >> Dont know if EMCs PID loop has been modified to allow an external (not >> DPosition/DT) velocity input. If the PID component had a velocity input, you >> could use HostMot2s encoder velocity output as a better velocity feedback >> term >> than the (crunchy) DPosition/DT >> > This is pid2, but it still doesn't solve the quantization noise in the > encoder-derived velocity. > Actually, it does. The Mesa encoder counter has a timestamp of when the last encoder edge was seen, so the velocity is based on accurate (to some fraction of a microsecond) time sampling, not the servo loop rate (with its associated jitter). The same method is also used in the software encoder module, though the jitter will be much worse since the base thread is also subject to interrupt latency issues.
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