brushless dc motor with myRIO

[todd1402]

Hi Guys,

I'm trying to control a brushless DC motor using a myRIO board in conjunctions with an ESC.  I know that in theory it should be able to be controlled like a servo, however the sample servo VI does not work with the motor.  Does anyone know how to fix this? Or even better have a working VI?

thanks

[Tanner!]

What ESC are you using? What kind of commands is it expecting?

[todd1402]

Im using a venom V2 http://www.competitionx.com/pdf/esc/venom-pro-brushless-esc-manual.pdf it is designed for radio control however, which i thought could lead to problems

[Tanner!]

Okay, I'm confused. How is the ESC and your myRIO connected? How are you envisioning them communicating? The Venom Pro ESC doesn't seem to have any comm ports. There is a BEC that comes in that you could possibly reverse engineer, but there isn't a direct way to communicate with this device.

[todd1402]

The manual shows the ESC being controlled via the throttle channel of the remote control. Given that ESC use PWM generally, I was assuming that by having the myRIO send PWM signals in place of the radio controller the ESC would operate the same way. However my knowledge of the workings of radio controllers is limited, so they may operate totally differently. I am not concerned if I need to get a different type of ESC, i just wanted to know if it was possible to control one using myRIO the same way as a servo is controlled, given I have used this method before with a raspberry pi (with a different ESC) and it worked perfectly.

[Tanner!]

This could be possible. I can't find any documentation on the signals between the two devices, but if you have an oscilloscope you could probably get to the bottom of it. It wouldn't surprise me if it were just PWM.

[Wayne.C]

You should be able to use a DIO and FPGA to output the PWM signal you need.  Just make sure that the voltage levels are compatible and you get the pulse widths right.

[todd1402]

How can I find out what the voltage and pulse levels should be? or is it trial and error?

[Wayne.C]

Trial and error will most likely end up damaging something.  Contact the manufacturer of the ESC directly ( tech line ) and ask.  An O-scope to monitor signals between radio receiver and esc would be the quickest.

[Jack_R]

I would like to apply PWM (12 V) to a DC motor.  I am applying torque with it to control its position against a return spring and external forces, similar to a throttle body.  I will need to apply PWM up to ~20 kHz and will need to suddenly reverse polarity at times.  Throttle body controllers use an H-bridge for this.  Is there a module for cDAQ-9174 or for compact RIO that will do this?