Hello hoping I can get some support on here as I purchase all my parts through Robot Shop.
I’m currently working a building a BB8 robot and need some assistance with the electrical part of it. I want to drive it using DC motors connected to a Flysky Receiver. I have a PDF file showing the math and parts I’d like to use however, it won’t allow me to add an attachment on this forum.
Regards
Paul
Hello @ppecch and welcome to our forum!
You can put your files on WeTransfer and then post link here:
Thank you.
To which email can I send the file to?
Thank you the file has been sent.
Was my file received?
To whom did you send it?
As I mentioned above, get the transfer link and post it here so users can download your pdf file.
Thank you.
@ppecch Welcome to the RobotShop Community. If your main question is how to drive DC motors using a handheld RC transmitter, note that you only need a DC motor controller which accepts RC input, and meets the voltage and current requirements of your motors. No real need to send large files as only the motors are important in the choice of a motor controller.
Thanks for the response @cbenson
I’m looking at using a FlySky Controller and FS-IA6B Receiver with the Sabertooth Dual 5A R/C 6-18V Regenerative Motor Driver (R/C) and two 6 Volt 150:1 Micro Gearmotor 100 RPM. I think this makes sense?
No problem with that combination, but not sure about the size of the motors you selected - those will relate to the size of your BB-8. Although you didn’t provide the current or voltage requirements of the motor, it’s more than likely less than 5A. Note too that the Sabertooth PROVIDES 5V on the center red pin to the receiver, so you don’t need to power the receiver using a separate battery - the Sabertooth takes care of that.
BB8 Robot Cal.pdf (256.5 KB)
@cbenson This was extremely helpful, thank you. I didn’t realize that the receiver did not require into own battery source. As far as my numbers, I’ve attached a PDF showing the math. Hopefully it makes sense.
Drive Speed = 0.25 m/s
Torque = 0.1 Nm
Rpm ~ 80 rpm
At 6 V with the 100 rpm motor using two motors I’m drawing 0.69 amp
It all outlined in my PDF. That being said I also think this combination should work:
I might consider using a 150 RPM motor.
Thoughts?
The Scorpion is also RC, and with a max current of 6.5A, it’s well above what your motors will draw. It also has a BEC
“Receiver battery eliminator circuit (BEC) standard - may be disabled. This can provide up to 100 mA of current at 5V to the RC receiver and other attached electronic circuits.”
So is it safe to say I have a solution? And would you recommend the 150 RPM motors?
Regarding the motor specs (torque, speed, voltage), that’s a separate question entirely. BB-8 is a ball robot, where the equations to get the perfect values are likely different than for a balancing or multi-wheeled robot. There are a few BB-8 projects here, but the choice of motors will really depend on the size of the robot, its weight, the inclines and terrain you want it to tackle etc.
Attached is a pick of my BB8 to put things in perspective. The ball is 200 mm in diameter and I’ll have two motors mounts on a pendulum type counter weight. I have no intentions of driving him to quickly as long as I get enough torque out of the motors I should be fine. My numbers are based on a total weight of 2.7 lbs. At 100 PRM I’ve already built in a safety factor of 2 so I’ll keep my fingers crossed.
If this is the kind of motor you’re considering, you’ll see that it’s physically tiny for the size of robot you have in the photo. It’s not much larger than the joystick.
Continuous torque: ~1/4 stall = ~0.3Kg-cm
You’d likely need something considerably larger like:
Continuous torque: ~1.3 Kg-cm (almost 4x more)
Are there any options in a 12V Micro Gear Motor from Robot Shop? Can I use this one below and I’m assuming these run CW/CCW? Based on what my numbers work out to I need 1.1 kg.cm torque, these are rated at 1.5 kg.cm torque.
I’m a bit doubtful about the specs for that last product being 200:1 and also 500rpm and 1.5Kg-cm rated.
There are 12V variations of those small motors. Examples:
They would mostly be in the following category:
No filters for voltage yet, but that’s all in the works.
