MIT Cheetah / Hobby King Cheetah Motor Testing

[@wei1224hf]

That GUI software looks so cool! It will be very popular if you opensource it.

[@rob10856]

The angle is 6 times a full revolution in radians because the encoder is on the motor not the output shaft and there is a 6:1 gear ratio.

[@engserve]

Right, but it is a simple setting in firmware that could be changed.

[@engserve]

With the current firmware and CAN protocol, the motor is not setup to run many revolutions. The firmware suggests the limit is +/12.5 radians (about 4 total revs) mapped to the 16 bit position. That does not appear to be working right, so I requested clarification from Steady Win. With an application like the Cheetah robot, you don't need many revolutions. A CNC machine like a delta bot would be the same. Unneeded revolutions, eat into the resolution of the 16 bits. My 24 revs/16 bits is not great.

[@marklagana2769]

Rob is right. Try turning it off, turning it MORE than 1/6th of a revolution and then turn it back on - its new position will be shifted by 60 degrees

[@jontscott]

So at only 250 watts I guess this would not work well for driving a heavy robot wheel? 250 watts sounds weak but maybe not since it had gears? That is one cool motor either way and nice that it can be controlled over CAN. Looking forward to seeing what you do with it!

[@SgtBurned]

You probably want the un-modified version which is the U8 motor.

[@CarlosFilho20014]

Hello, could you share the design of this delta 3d printer?

[@Build_the_Future]

Nice. I'm building a 2 legged robot using 6 Odrives check it out and let me know what you think thanks.

[@한성동-f3k]

I bought a motor and did not know how to operate it during the test, so I ask for help. Where can I get the HobbyKing Cheetah Test Program?

[@wei1224hf]

So this motor's velocity control can't work at all? I have bought a motor like yours , I found it hard to do the velocity control. The pramater 'velocity' did not work

[@skipper5811]

I'm newbie kinda, are you changing torque by applying more current? I mean you aren't applying external loads at all.

[@qingchengsui1636]

Why didn’t I get any response after typing the initials of the mode? Using it on Putty,

[@J_gumbainia]

Holy cow, this is awesome, can be used on humanoid robots.

[@juanpablocanguro]

Hi! question: have you been able to implement some kind of "ramp-up"? Would it be possible to make this motor move with a trapezoidal or S curve to achieve a "soft start"? thanks!

[@engserve]

With a step and direction input it will follow the curve set by the step generator.

[@juanpablocanguro]

@@engserve Thanks Ill give it a go and let you know! maybe you will like my channel, specially my latest video :)

[@FilmFactry]

Very cool. Out of my budget , but I'll keep an eye out. I'm sure these will dive below $100 somerime soon.

[@engserve]

I think the biggest cost factor is the housing and gearbox. If you just want a motor/controller/encoder combo, I am sure these will be below $100 very soon.

[@byungjaelee5110]

It would take a long time to get the price down. The machining process of the gears and the body is not easy to do. These are the things that rarely go down in price. Computer hardware and technology has been accelerating very fast these days. For computer parts it's mass produced for alot of people. So that is why for something like a robotics actuator is expensive.

[@engserve]

@@byungjaelee5110 The $100 would be a motor with integrated driver...no reduction.

[@byungjaelee5110]

@@engserve yup. The problem is the gearbox...

[@byungjaelee5110]

@@engserve Will you make a video for DIR/Pulse interface? It's too difficult communicating via CAN bus.

[@kamiabyazdi2091]

I dont understand, you changed the torque value and the motor position changed. I am working with the same motor and the reaction of the motor is the same and i dont know why?! i would be glad if i can contact you with email to get some information.

[@santoshkumar-yh2bc]

Hi Kamiab Yazdi, I'm currently working on the same motors and unable to interface it with Transceivers. I would be glad if you can help. Please email me at [e-mail] so that we can get in touch.

[@Frankx520]

Thank You for posting this. Like it! I want to learn more :)

[@bratwizard]

Me Too

[@dieselphiend]

Can anyone tell me how hard it would be to wire these in such a way that they reversed direction when they detected a load? I guess that's more of a function of the drivers- so, with the right drivers, can these detect a load?

[@byungjaelee5110]

Nice video! Can you do a video on step/dir interface?

[@engserve]

Here is a blog post. www.buildlog.net/blog/2020/03/adding-step-and-direction-cnc-control-to-the-cheetah-motor/

[@tttuberc]

When motor moves, it sounds like some pneumatic system. It moves so fast.

[@gedr7664]

Are you making any progress on this?

[@engserve]

Yes

[@gedr7664]

@@engserve looking forward to your videos! subbed

[@FilmFactry]

In looking at the website, can you report back, how well it works on much slower moves confined to a few degrees? I'm guessing with an encoder it would be.

[@engserve]

You can play with the velocity a little, but for a real application you probably want precise control of position, speed and acceleration. The controller is not designed to do that. I think the best way to achieve that is via rapid positional control, like a CNC machine does with a stepper motor or closed loop servo.

[@usicchauras]

Hi Barton I just purchased one of these...Is it ok to directly connect 24V to the motor as the documentation says that it might get destroyed?

[@engserve]

I did it. I used heavy gauge, short and tightly twisted wires.

[@usicchauras]

@@engserve Help me out Bart...I'm unable to understand how to give the position command....i.e. how do I move it to zero degree.90 degree,270 degrees etc...I just want a single rotation back and forth...Thanks in advance

[@lingxuanzhao7172]

Thank You for this. Did you write the C# test program yourself？

[@engserve]

Yup

[@ezequielfarina4559]

Hi, im working with the same motors and i was wondering if you can send me the technical specification of it cause the instructions i send dont work in my case and maybe its because i have the wrong datasheet.

[@engserve]

See the document in the description

[@advince]

hi, how can i find the ESP32 code for that? thanks a lot.

[@santoshkumar-yh2bc]

Hi did you find the code. Kindly share.

[@lazyartist2358]

Hey, great video. I have a question concerning this app that you've written in 4:10. Did you write this in C++, If so can you give me articles, websites where I can learn how to write similiar app and also implement it with a robotic project? Many thanks, I'm starting my EEE degree this year!

[@wei1224hf]

It's in C#

[@vycka7360]

Can be written both in C# and C++ using windows forms

[@shlomishitrit6287]

Hi, I'm trying to figure out how to control this motor with Arduino and CAB-BUS shield. Please, let me know if you can help me. Thanks in advance.

[@engserve]

See the doc in the description

[@shlomishitrit6287]

@@engserve Thank you. I would like to get your email for specific questions.

[@engserve]

@@shlomishitrit6287 There is a link to a Slack channel at the end of the doc

[@engserve]

There is a link to a Slack Channel at the end of the doc.

[@dunichtich100]

Is there PID tuning? Because one can see it swinging around the desired position before it comes to a hold.

[@engserve]

Yes

[@dunichtich100]

@@engserve thx

[@zhangyichao4612]

Great demo video! Hi,Why does the position of the motor change when you set kp and kd?

[@engserve]

The kp value has a big affect on the final target value. I will be reprogramming it soon. I want to improve that and play with the resolution vs range.

[@shlomishitrit6287]

I Have the same problem to. maybe its related to steady state error. make sure that the velocity command is zero when you compare between different kp.

[@lingxuanzhao7172]

@@engserve Hi，I still have some questions about kp and kd. How should I set these values to get a accurate output? I really want to communicate with you ,thanks!

[@lingxuanzhao7172]

@@shlomishitrit6287 Hi, do you have any progress on it? I have some problem on kp and kd ,too. I I look forward to talking to you.Thanks

[@张宁-v9o]

@@lingxuanzhao7172 hi， are u also reappearing mini cheetah？

[@kipkerluke2508]

How is the backlash on the gearbox?

[@engserve]

I think I saw a spec of about 0.25° of backlash. I have not measured it, but it feels to be a little more. Maybe a full degree.

[@chenhan91]

@@engserve that seems like a very terrible gearbox for robot

[@engserve]

@@chenhan91 The Cheetah robots are awesome!