Stuart Stevenson wrote: > On Sun, Oct 10, 2010 at 1:05 PM, Jon Elson <[email protected]> wrote: > > >> >> Wow, that is really weird! >> >> > the motor has an encoder so we built a splitter cable and routed the encoder > feedback to EMC2 and the drive. > No, the splitting of the signal is not weird, the fact that EMC is getting unaltered encoder data, and it has those weird lags at the accel inflection points. I was SURE it was some kind of computer-caused delay in the servo data. > I see the disturbance in two places when I have the accel as low as 2. The > accel is set to 50 in the example. > > 50 inch/sec^2? On a big machine? That seems like it is too high, and no surprise the drive can't follow. There is electrical time constant in these motors, as opposed to mechanical time constant (real inertia). It takes time for the drive to ramp up current in the motor. If there is a tunable parameter in the drive for damping on the torque (current) loop, you may need to reduce that damping, or maybe even in the velocity loop. The drive just appears to be sluggish in response to any sudden changes in command.
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