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Postby GordsM8 » Tue Feb 09, 2016 9:42 am

My 12 year old son and I have started out first project to build a remote controlled car.

We have built the basic chassis using some Meccano. it has 2 wheels at the back which are driven by a Meccano motor and two steerable wheels at the front.

We haven't bought any Pi kit yet. Will probably get the latest Pi 2 as the main device (will then get used on other projects).

The question is: what controller board, or boards, do we need to control the motor(s) and servo (for steering)? I don't mean to state the obvious but we would need to control the speed and direction of the motor.

I don't know if the Meccano motor will be suitable - it is encased in a plastic box so don't know any details about it. I have a small servo from my helicopter days, but yet know how to mount it or connect it to the Meccano (for steering).

We haven't bought a kit as we wanted the fun of working it out for ourselves!

GordsM8
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Postby Dave » Tue Feb 09, 2016 1:25 pm

Ok well first thing I would say is, make sure you don't try and power the motors from your Pi! Motors tend to be very current intensive which will burn out your Pi's GPIO ports. So make sure you get an external power source for your motors.

As for controlling your motors.

If you can get away with simple on/off with your motors, and only want to drive forward. You could use the PiBorg PicoBorg - http://www.modmypi.com/raspberry-pi/bre ... ontroller/

If you want more control over your motors (forward and backwards) you'll probably want to upgrade to the PiBorg PicoBorg Reverse - http://www.modmypi.com/raspberry-pi/bre ... ontroller/

As for your servo, any of the following should do, each of them have their own benefits, so make sure to read the description to check which one will suit your needs the best :)

Servo Controllers:
http://www.modmypi.com/raspberry-pi/bre ... e-support/ - Support for 4x servos - Support for 4x Ultra Sonic Range Sensors
http://www.modmypi.com/raspberry-pi/bre ... t-pca9685/ - Support for 16x servos - Stack multiple boards to support up to 992 servos!
http://www.modmypi.com/raspberry-pi/bre ... servo-hat/ - Support for 16x servos - Stack multiple boards to support up to 992 servos! - HAT format

Please note, if you decide to use the Servo HAT, and the PiBorg PicoBorg, you'll need to use an extended header so you can plug the PicoBorg on top of the HAT:
http://www.modmypi.com/raspberry-pi/gpi ... xtra-tall/

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Postby GordsM8 » Tue Feb 09, 2016 4:29 pm

OK, thanks.

This is our very first project and will lead onto other things, so getting the PiBorg PicoBorg Reverse seems sensible.

Also, the ability to add ultrasonic range sensors makes the PiBorg UltraBorg very interesting!

Regarding the Meccano motor - is it likely to work with the controller above, or will we need to test it? It runs on 4 x 1.5v AA batteries.

GordsM8
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Postby Dave » Wed Feb 10, 2016 10:02 am

The motor controllers should work with most motors. I think (don't quote me on this) the limiting factor of the motor controllers is simply how much current they can handle. Really big motors can use a ton of current.

The PicoBorg Reverse can handle up to 5 Amps which is loads!

I suspect the Meccano motors are fairly low current, so shouldn't be a problem to use.

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