Quote:
Originally Posted by Richard Wallace
How important is scrub? Will overhung motor mass and fat treads be significant factors?
what do you think are the window motor attributes that kept this from being a problem in the past? Can a motor engineer help with this?
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My previous post was a little from the hip so I used some numbers loosely. My intent was to point out that trying to start moving a load with higher powered motors takes a lot of energy. The Denso window motors are rated at 23 watts and the AM9015 is rated 179 watts. The latter is rated at 69 amps stall current. I haven't tried metering them individually but steering is a significant hit on the battery. We use wedge-top tread and 1" wide wheels because they seemed to cause less turning force on carpet. Those things were more important with the limited torque of the window motors. We are getting the performance we want out of the current steering motors but the energy hit on the battery was a surprise. I didn't mention that the drive train is geared about 9:1 which is around 12 fps actual top speed. It takes quite a bit of energy to accelerate a 145 lb to that speed. The battery just isn't an infinite supply.
One thing I blew over was whether the strategy is to turn to the intended direction before driving the wheels. Our main driving mode relies on constantly correcting the direction which means running all motors at once.