Quadruped Robot

hardware support
1

Hi can anyone help me with finding the schematic or gerber files of the MIT mini cheetah motor controller if that it is open source. Any help would be appreciated thank you

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Hi i am a newbie , do you recommend any other board ? Do you know any other open source boards that would be fun to work with?

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It depends on your usecase: small gimbal motors to washmachine motors, anything goes.

You can find many BLDC controller boards on AliExpress. Odrive or VESC clones and general purpose controllers, which also run with simpleFOC (i.e. MKS )
Other guys have openSourced their controllers and you find their links here in the forum.

5

i’m planning on using a flycat 5010 360kv motor can you share me the link of any one of the open source boards that you may prefer

6

So, you expect me to lookup specs of your motor and find a matching driver?
I’m a fan of DIY, which is meant literally. I never copy anyones ideas or concepts without building my own opinion.

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im sorry if i offended you in anyway

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@KAVIN_G - we get a lot of people asking for advice and sometimes it feels like not much research has been done before clicking ‘post’.

I remember what it was like when i got into bldc first, took me a while to realise that board selection is hard!

Best place to start is to do a bit of rough ohms law. Start with the voltage you are intending to give the motor (look at spec of motor). Do you need to give it max motor voltage? If you only need half the motors max speed you may only need to provide half the voltage.

Now divide voltage by phase resistance (again motor spec) to give a rough guide to the current you’ll need from your driver.

Phase resistance can vary between 0.01 ohm (for high speed motors) to 15ohms (for gimbal motors. At a guess your motor probably has a resistance of about 0.5ohm (do check!).

Your motor choice means that you’ll probably be looking at a board/driver with external mosfets as your currents will be greater than 2A.

How about you do some maths and come back and ask for a driver that can provide voltage x and current y, then you look like you’ve done your research :grinning:

You may also want to add what sensor (if any) you intend to use for closed loop as not all boards support all sensor interface (spi/i2c/hall/encoder interrupts)

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The Phase resistance of the motor is 0.5 ohms and the current will be 24A since im planning on using 12v also and i’ll be using a AS5600 magnetic rotary position sensor. I’m in india i can’t get assembled boards because the price is too high for shipping plus the import duties here so can you please recommend me a open source board that can drive flycat 5010 360kv motor with the above mentioned specs.

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Have you seen David Gonzales’ Dagor? It’s designed specifically for quadrupeds, though it is several years old so you’ll have to check if all the components are still available.
https://community.simplefoc.com/t/esp32-brushless-controller-dagor/132

Or if you want lowest possible cost and are able to order from JLCPCB, you could use my stripped-down version of Valentine’s Lepton, which is the cheapest driver I’m aware of at around $6 per board. But it doesn’t have hardware current sense so you won’t be able to control it quite as accurately, and it doesn’t have enough flash space for the SimpleFOC Commander interface so it’s a bit more fiddly tuning the motor.
https://community.simplefoc.com/t/lepton-deku-mod/2641

And for cheapest position sensing, you can use two analog hall sensors with a 3D-printed mount to hold them at the appropriate distance from the motor magnets
https://community.simplefoc.com/t/40-cent-magnetic-angle-sensing-technique/1959

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But i dont think that the Dagor Brushless Motor Controller is open source??

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Oh, I think you’re right. I always thought it was open source, but I guess it’s only the firmware. There is a github page for the project, but I don’t see any files for making the PCB.

Valentine recently made a new design for a medium-cost board (around $14) with current sense, but I don’t think anyone has fully tested it yet so you’d be somewhat on your own figuring out how to use it.
https://community.simplefoc.com/t/qvadrans-v1-0-fka-lepton-3-0/3376

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13

The cost for the drivers is neglectible against the cost for a (mobile) power source for that beast.
A quadruped bot needs 2 or 3 motors per leg. Each 5010 motor can consume ~290W max.

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Will a two 4s battery will be suffice , even for a fewer span of time?

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If I said: yes would you blame me for burning down your house?
Of course there are (some) LiPO batteries which can handle 200-300A peak.

But if you have to ask such question, you are not the right person to start this project.

  • Are you able to wire the motors and battery in a safe way? Select the best wire gauge?
  • What about inrush current protection?
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Sorry i;m a newbie but i have some guidance i’ll definitely not hook things up without someone’s guidance can you suggest me a optimal way ?

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What do u need to know exactly?
By the way 2 battery 4s will be enough!

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i want know much power do i need to give to operate 12 Flycat 5010 360kv motors and also if you could give me a link of any open source bldc controller boards it would be really helpful

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I am also lookimg at using a moter like this. Beware, many 5010 moters are not usable for this purpose. I find you want one with more pole-piars then usual. 360kv might be low enough. As I found, you will need to buy different moters and run them on a test jig. Build and test the reductive system too. You need about 9:1 for a robot usinfg a motor like this. As for controller’s. Buy one that is grossly over spec’d for testing. There are any number of them. But for the actual robot. You will need to design a custom controller. EVERY one I have found is just the wrong shape or size or something. A walking robot is a very tight balance and needs a very high power to weight ratio. So expect to use custom controllers but you hav e a LONG way to go. My test rig uses some belts and a drum. A cord is wrapped around the drum and a weight is hung. This simulated the weight and inertia of the actual robot.

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20

For a robot, we think in terms is “average power”. What we care about is the temperature of the motor. You can put 40 amps into a 5010 310kv motor nd be fine for a fraction of a second. You might need this to do a jump and a landing. But while airbord the current would be near zero so the average could be low. What makes the controller hard is they have to be able to supply huge peak currents but maybe only a few amps on average and of couse every gram of mass matters a lot on a walkking robot. So you have to do custom stuff likeuse the robot’s structural frame as a heat sink for the MOSFETs. The PCB has to be designed for this kind of mounting. Robots can also moderate their activity based on the motor and mosfet temperature so unlike some other use cases (like a flying quad copter), it is OK to just stop and do nothing. The robot says “I just did a back-flip, I need to rest for 5 minutes”.

I would be very interrested in lookimmgat your overall design.

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