InsaneEpp
Sounds O.K to me. As the axis approaches the target the error becomes less, providing automatic deccelleration until the error is a minimum 1 pulse. Therefore the axis should not overshoot.
Esjaavik. +/- 1 encoder pulse has to be realistic or the machine will not have any accuracy. The PID loop gain is set to provide enough current to drive the machine axis to ZERO, but I agree we have to limit the MAX error. The key to this is the servo loop time constant or error sample rate. The time constant can be set (depending on the application and resolution) from say 1 to 300 milliseconds and the max error will be the distance travelled in this time so we can limit the error. (max error x loop gain= max velocity). This is a very basic example but I hope it explains why the velocity will not go through the roof.
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mike potter |