ODrive for 300kg AGV?

Projects
1

At a high level is ODrive the right controller for my application?

I’m building a 300kg Autonomous Ground Vehicle with a dual wheel traction drive. 48V pack. According to our calcs it needs on the order of 500watts (approx 10 amps) per wheel to cruise on level ground at 3 m/sec, and peak power requirements (2 m/sec up a 20 degree incline) are on the order of 1.5kw (30 or so amps) per wheel. Plus or minus. The autopilot is ardurover on pixhawk hardware (so, R/C PPM output commanding velocity; we plan on running the ODrive in velocity mode with external encoders).

We’re in the process of selecting BLDC motors with KV on the order of 75-80, so, max motor RPM in the 3500 range. Motors will drive a 1:25 reduction gear for output (wheel) RPM around 140rpm.

It seems from the specs including the temperature stress test here that the ODrive should have sufficient power capabilities for this application. And the ODrive velocity mode seems to support our autopilot and application.

Yet on the Projects discussion I found no projects that use the ODrive for vehicles of this mass.

Is there something I’m missing here? I realize there’s no 100% right or wrong answer but I’m interested in whatever thoughts group members (or @Wetmelon ) might share.

Thank you-

Chris

2

Yep, sounds good to me. Honestly it’s a lightish load for the ODrive, but it’ll work great. Note that you only get ~ 75% of the voltage to the motor right now, so you need to calculate max speed as

0.75 * V * Kv = RPM

3

Thanks!

Is the 75% because of the two shunts issue described here?

If so, is the solution available in v4, and, is v4 the same as ODrive Pro?

4

Yes, sorta, and yes.

The Pro has 3 shunts, which allows us to go to 100% modulation. That’s still in validation internally. And v4 was split into multiple products, one of which is Pro. We’ll also be doing a lower price tier version called S1.

1 Like
5

Is the 75% voltage issue specific to all motors? Only being able to access 75% of the power from my motors could be problematic.

6

It’s an issue inherent to the design of the ODrive V3. We’ve already started testing 100% modulation on the V4 / Pro hardware