I am part of a team, which is working on an autonomous RC-Car. Im trying to figure out, if we should use a brushed or brushless motor. The car we are using is the MIT-Racecar. It comes with an VESC 4.12 and a sensorless brushless motor. The problem we are facing is the control at start up and low speeds.
I have spent some time to get myself familiar with e-motors and the vesc, but I am still discovering new things every day about the issue, which makes the decision even harder the more I discover about motors and esc . As mentioned above, we want a car, that can be controlled at start up and at low speeds(for parking and other slow stuff).
This is how I see the situation:
- How the behavior of the motor will be, depends on the motor itself, the controller and the configured software.
- The choice of the motor can be brushed or brushless. Brushed has better low speed-control and smoother start up, but I need an additional encoder to get the necessary odometry.
- With a sensored brushless motor, I can get almost as good as with a brushed motor at start up and low speeds, but it is more complex on the software side. The upside is, I don't need additional sensors( if the sensors are good enough). Here is a video of a sensored brushless motor at very low speeds, just to give you an idea of what I have in mind:https://www.youtube.com/watch?v=0Vv_fWZATPk
Additional things to consider for the brushless motor (in my opinion):
- The torque should be high.
- It should be a 4 Poles motor( 4 Poles referring to the magnets on the rotor) for smoother rotations at low speed
- The more steps the better for smoother rotations at low speed
- Are my assumptions correct?
- Did I miss some points I should consider? (Like what are additional benefits when using brushless vs brushed)
- How difficult is it to configure a brushed vs. a brushless motor with VESC?
- Should we get the newer VESC Version?
- Can I use external odometry in VESC in combination with a brushed motor?
- Can I get a result like in the video with FOC? ( I am guessing, they are using the same technology)
Any input you can contribute would be appreciated greatly :)
Thanks for reading and answering.