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700 points elipsitz | 3 comments | | HN request time: 0.001s | source
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TaylorAlexander ◴[] No.41194755[source]
This is very exciting! For the last several years I have been developing a brushless motor driver based on the RP2040 [1]. The driver module can handle up to 53 volts at 30A continuous, 50A peak. I broke the driver out to a separate module recently which is helpful for our farm robot and is also important for driver testing as we improve the design. However this rev seems pretty solid, so I might build a single board low cost integrated single motor driver with the RP2350 soon! With the RP2040 the loop rate was 8khz which is totally fine for big farm robot drive motors, but some high performance drivers with floating point do 50khz loop rate.

My board runs SimpleFOC, and people on the forum have been talking about building a flagship design, but they need support for sensorless control as well as floating point, so if I use the new larger pinout variant of the RP2350 with 8 ADC pins, we can measure three current signals and three bridge voltages to make a nice sensorless driver! It will be a few months before I can have a design ready, but follow the git repo or my twitter profile [2] if you would like to stay up to date!

[1] https://github.com/tlalexander/rp2040-motor-controller

[2] https://twitter.com/TLAlexander

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sgu999 ◴[] No.41195045[source]
> for our farm robot

That peaked my interest, here's the video for those who want to save a few clicks: https://www.youtube.com/watch?v=fFhTPHlPAAk

I absolutely love that they use bike parts for the feet and wheels.

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HeyLaughingBoy ◴[] No.41195126[source]
I have given some thought to a two-wheeled electric tractor for dealing with mud -- horse paddocks turn into basically a 1-foot deep slurry after heavy rain and it can be easier to deal with something small that sinks through the mud, down to solid ground than something using large floatation tires. Additional problem with large tires is that they tend to throw mud around, making everyone nearby even more dirty.

I haven't actually built anything (been paying attention to Taylor's work, though), but I came to the same conclusion that bike wheels & tires would probably be a good choice. It also doesn't hurt that we have many discarded kids' bikes all over the place.

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1. littlestymaar ◴[] No.41199609[source]
Your description fit what I've seen for rice farming, whose machines usually use bike-like tires.
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2. vintagedave ◴[] No.41200613[source]
I’m curious there. I’ve seen rice paddies plowed in Vietnam and the tractors used wide paddle-like wheels. I saw two varieties: one with what looked like more normal wheels but much wider, and one which was of metal with fins, very much akin to a paddle steamer, though still with some kind of flat surface that must have distributed weight.

Would they be more effective with thin wheels? Both humans and cattle seem to sink in a few inches and stop; I don’t know what’s under the layer of mud and what makes up a rice paddy.

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3. littlestymaar ◴[] No.41200955[source]
What I saw was in Taiwan, but I guess it must depends on the depth of the mud and the nature of what's below.