moteus r4.5

Meet the newest revision of the moteus controller!

Yes, it does look mostly the same as the r4.3 that has been getting a lot of use lately. This revision exists mostly to improve manufacturability, but I snuck in a minor design improvement while at it. Now, the maximum voltage input is rated up to 44V from the 34V of the r4.3! (Note though, that the pi3hat and power_dist still are limited to 34V). Otherwise the new controller is fully electrically, mechanically, and software compatible with the r4.3.

It is now the default in the mjbots store, only $5 more than the old version at $84.

And, by popular demand, it still has a devkit!

8 thoughts on “moteus r4.5

  1. Do any of the debug pins breakout an adc or i2c on this controller? Can the planetary gear reduction on the servo version be easily removed to run the motor at full rpm? As i recall you have a 130kv 700w motor
    Thanks

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    1. Three easy answers:

      1. There are no free ADC resources.
      2. I2C is broken out on a connector which is currently unused.
      3. The servo cannot be converted into direct drive easily.

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  2. Thanks. The controller devkit says ‘semi-random brushless motor’. Any guarantee that it will be around 100kv? I need to spin up to 200 rpm_min to 3-4k rpm_max

    I briefly glanced at the .sch on github by skimming the raw file and it seemed there were 2 temperature sensors using ADC’s. Perhaps I could cut one of those for an extra ADC? The STM G4 shows x5 adc and 3 of those seem to be used for the current shunts on the motor board.
    I was hoping to experiemnt with an external fluid pressure sensor as feedback to the motor control. Most robust/stainless sensors I’ve found are 0-5v analog or 4-20ma, so looking for an easy way to experiment with your board.

    I have a VESC 6 that offers similar ADC feedback, but is likely more power/size than I need for my application.

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    1. The motor that is shipping with the devkits is currently a 5008 class 330Kv motor. I’ve run similar ones up 7,000rpm on the 24V devkit supply. If you want the devkit to get all the accessories but don’t want the motor, you can either desolder it, or ask in order comments and we can ship the pieces not put together.

      There are two temperature sensors, and one, the motor sense, is not used other than to report its value. However, it is time multiplexed on ADC5 with the FET temperature, which is used. You could could depopulate R7 (which is a 10k pulldown), and then the motor temperature input goes directly to ADC5. Then you just have to be careful to not disrupt the FET temperature sensing. Or you could leave the 10k pulldown and use it as part of the required resistor divider for a 0-5V signal.

      FYI: To make a 100Kv motor go 4,000 rpm, you’d need to power the r4.5 at just about the absolute maximum voltage of 44V.

      Liked by 1 person

  3. I’m planning a 40v system.

    Could the 130 kv motor used in your servo replace the 330kv in the kit with an upcharge? I understand the 24v supply is matched to the 330kv motor, but I plan to use a 60v adjustable lab supply.

    Thanks for the ADC details. The resistor divider option sounds ideal – I’ll look into it further. Seems a sampling/timing dependancy from the fet temp polling is the only potential concern. I didn’t look at the rate in the code, but the G4 has high speed adc, so I assume it’s not a limit for my application (<1kHz).

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    1. The rotor and stator from the servo only exist in a frameless configuration. If you’re OK with that, then sure, we can include the parts instead of the devkit motor for an upcharge, but you’d have to build a motor to go around them. If you want that, send an email to info@mjbots.com and we’ll quote. moteus is compatible with a wide range of motors, so any ~100-130Kv motor you find in the same power class should work fine.

      Each of the temperature sensors are currently sampled at 20kHz, so that might be just fine.

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  4. Thanks for the explanation. I should have known you were just buying frameless versions.

    I’ll buy your standard dev kit and test with the 330kv. I don’t know much about motors, but tmotor seemed to have the nicest low kv motors. Hobbyking also has interesting low kv motors, but they’re always out of stock. Let me know if you have any other suggestions. I’d prefer something protected similar to your qdd servo, or some of the tmotor designs.

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    1. I’m not aware of any off the shelf solutions for housing a controller and motor in a 100Kv class motor with a direct drive. https://www.iq-control.com/ has some smaller motors, and you might be able to dig around on aliexpress and find something, although they’d typically come with their own not-so-good controller. (AFAIK iq-control’s controllers are very good)

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