Instructables

DC Motor Control Help?

A very long story short, I desperately need assistance in knowledge with some motor control. I need to control 2,DC 6v motors with encoders that include 6-pin 2.0mm pitch PH JST cables that break out motor inputs. The bottom line would be what do I need to control these motors, to go forward and reverse, and operate it from a wireless controller? I appreciate any and all help!

Also, this is our motor:
http://www.trossenrobotics.com/p/Robot-DC-Gearhead-Motor-6v180rpm.aspx

steveastrouk5 months ago

What will you be using to drive the motor controller ?

NickWeav (author)  steveastrouk5 months ago

Well this is part of our problem, we don't know.

...so you bought a motor for WHAT ?

NickWeav (author)  steveastrouk5 months ago

It's all part of a design project for a pre-engineering class, and in the class we go over the primary areas of engineering and a lot of parts got cut out because of inclement weather this year and we haven't learned much of what we were supposed to and it makes it difficult to finish this rover project.

Ah, so its a "rover project". Now we're getting somewhere. Is this thing supposed to be autonomous, or are you controlling it with a remote control ?

NickWeav (author)  steveastrouk5 months ago

We're controlling it from the other side of a room by means of a camera that relays into a TV.

"controlling it" - by telepathy ?

NickWeav (author)  steveastrouk5 months ago

Controlling it by a wireless controller that we need to build.

RIGHT. Now we're getting somewhere. So, could you build a nice standard RC car transmitter and receiver ? Or do you think you need to use a computer, and an RF link ? Or Wi-fi ?

NickWeav (author)  steveastrouk5 months ago

It would probably make the most sense to use a standard RC car transmitter and receiver.

Then just use one of these

http://www.dimensionengineering.com/products/sabertooth2x5

NickWeav (author)  steveastrouk5 months ago

I'm definitely going to take a look into it, thank you! Now another question, because I need to control one side at a time to make it turn, would I need to purchase 2 drivers?

If you read the link, you would see its DUAL CHANNEL

NickWeav (author)  steveastrouk5 months ago

Thank you.

I would use an arduino. But any reciever would work even the cheap $5 27mhz ones.
steveastrouk5 months ago

First rule of engineering: Define the problem.

rickharris5 months ago

I am worried you don't know enough about what your trying to do which always suggests a lack of research!

However if all you need to control is forward and back movement a so called H bridge arrangement will do the job.

As your drawing quite a lot of current I suggest relays will be a good way to go at least for a start. Linking these to your radio control receiver may be another problem.

Really if your using a standard radio control then a brushless ESC for each motor and a relay to reverse the connections for back and forward is the easiest way to go.

See diagram

There are electronic ways to do this and searching for H bridge is a good way to find them. IC's exist that provide this function BUT be aware that in many cases they won't directly carry the current you need.

For speed control you need to look at a brushed ESC arrangement - you are using RC equipment - or PWM type control.

BipolarHBridgeSchematic.gifH bridge again.jpg
NickWeav (author)  rickharris5 months ago

As much as I don't like to say it, you're absolutely right, my team and I really don't know enough about this project to finish it properly. Everything we were supposed to learn that could help us, got cut because of inclement weather. I have been looking at the H-Bridges however, and it's what I'm leaning towards right now. Never the less, thank you for the comment! This has been the most helpful so far!

steveastrouk5 months ago

Do you JUST want to go "forward" and "reverse", or do you want to control speed and/or position ? These are very strong motors, and are capable of drawing 6A from the supply.

What are you intending to use the encoder for ?

NickWeav (author)  steveastrouk5 months ago

One motor will power two wheels, that will allow turning if one side is operating at a time. I'm unsure if speed control is a necessity but if it's recommend I'll get something to control it. For the encoder, my team and I aren't educated enough with electronics to put it to full use though it came with the motor and we thought we could use it for a wireless controller.

robo103025 months ago

Well you can use a L239D but its not going to provide the power that your motors need. You can try adding a high voltage transistor after the L239D.