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Robot traction drive application

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cjmssmd
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Joined: 2022-05-14 22:36
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Robot traction drive application

Vehicle is a skidsteer robot with Pixhawk autopilot.  Autopilot drives left & right motors via PPM (driving duty cycle mode on the fsescs).  Pack is 460Ah 15S LiFePO4 (i.e., 50v pack).  

ESC: fsesc6.7 

Motor: FreeRCHobby 6384 motor, 50Kv, 14 Poles w hall sensors.  Motor connected to a 20" diameter lawn mower wheel through 16:1 reduction gearbox (from https://banebots.com/)

Firmware version BETA 55

My problem is that I am not getting as much torque at low RPM as I think I should.  If I run the motor at 10% duty cycle and hold the motor it stalls showing only about 16-18 amps motor current.  See from t=5999-6002:

On setup wizard I use Generic, Medium Outrunner and get the following results (for one side)

Under General settings I set motor current limits to +50 and -50.

Under FOC the Kp, Ki and Gain are:

First questions:  Do these R, L, Ld-Lq, lambda, Kp and Ki numbers look right?  Must I run the motor detection with the motor disconnected from gearbox and wheel?

cjmssmd
Offline
Last seen: 3 months 4 days ago
VESC Free
Joined: 2022-05-14 22:36
Posts: 2

Running in erpm mode at 1500 erpm, if I try to stop the motor by hand, I can't stop it - see from t=7177 to 7122; speed controller properly ramps duty cycle to maintain erpm.

 

Running at 1000 erpm, however, is a different story.  The motor doesn't spin smoothly and rather jerks/cogs.