Didn’t put a category since this is between electrical and mechanical.
I’m looking to make a Solo12 but can’t quite stomach the cost at 900 for just the motors from T-motor. Has anyone else here looked into using different BLDC motors? I was looking at RCTimer’s GBM4108 46KV hollow shaft Gimbal Brushless Motor which would come out to about 360 for all 12 of the motors.
Since it’s a gimbal motor with a much lower KV rating I’m guessing this would actually be a better QDD candidate right out of the box requiring less of a gear down and might have bearings that are up to the task of dealing with the radial loads.
Are there any glaring reasons why these wouldn’t work? I messaged RCTimer asking for a more detailed spec sheet. It looks like the motors weigh about twice as much but I’m hoping that they proportionally pack more of a punch as far as max watts goes.
I’m currently in the final stages of building a SpotMicro (all the mechanical bits are done) and I’d really like to build a proper quadruped with a QDD BLDC setup that’s within my price range. I probably would end up using the same motor drivers as the Solo12 but want to try and go with a jetson nano or pi with a coral TPU and try to keep the rest pretty simple.
It would be very interesting to test alternative motors for ODRI.
Gimbals motor seems a nice solution for robotics since they tend to offer better performances at low speed and have less torque ripple. On the other side, the power density seems to be less, meaning that for similar performance the motor will be heavier.
In terms of motor controller, Gimbals motor also change things. My understanding is that because of the lower Kv, you will have to apply lower current / higher voltage to produce a same power. It seems more challenging to close the loop on the small current, because of noise level, resolution etc.
Some people prefer to servo the voltage, since at low speed, the high coil resistance make the correlation between current (torque) and input voltage more important. To me, these motors are better suited to position control operation, but I never got the chance to play with one.
You can read the explanation of the Odrive team (another motor controller project) on the subject here: Is gimbal mode like stepper motor control? - Support - ODrive Community
A last point to consider if that the maximum velocity will be determined by your motor’s Kv and bus voltage (24v on ODRI robots)
Unfortunately, the motor you propose do not say anything about the power / stall torque the motor can provide, so motor control apart, it is difficult to say if it’s a good match for ODRI.
Finally, the mechanics will need to be redesigned to accommodate the new motor attachment.
Please lt us know if you plan to test a motor like this one.