[Swede]

I've been experimenting with two motors, one brushed, one brushless DC, both of similar torque characteristics. The brushless is definitely quieter and smoother. But I was very surprised when I did a fairly "scientific" test using software by Logosol.

The servo amps are Logosol, and accept serial commands, outputting digital step/direction. A utility called DCN allows manipulation of the PID parameters, and further will graph position error during a sample move.

I set up the software for a 4000 tick, high speed, high accel. move. For both, I manually manipulated PID to minimize error, yet keep the servos from vibrating themselves to death.

The conclusion: The brushed motors perform significantly better than the brushless, at least in terms of position error. The graph of the brushed motor has the position error spiking upwards as the mass accelerates, then quickly correcting close to 0 for most of the move. As the mass decelerated, the error spiked in the other direction before settling down. The brushed graph was tighter and of lower magnitutde than the brushless.

This was very surprising to me. I thought the lower inertia of the brushless would tip the test in its favor. Any suggestions or comments? I cannot see switching to the brushless unless I can get comparable performance.