Understanding Motor Wires for Hacking

Hi, I'm fairly new to Arduino, having completed all of the Starter Kit projects, I've moved onto my first project. The plan is to modify a Classic Roamer Robot to run on an Arduino device. Loved it as a kid and managed to pick up one in fairly good working order, wanted to expand the capability and get it to run on a little more standard batteries.

I'm doing a lot of research and trying to figure out as far as possible what's going on through exploring, but there are a few questions I have along the way that I've got as far as I can...

Current Question is: Why are there four additional wires coming out of the area with the cogs on each motor? Not what they do but why are they placed at the point they are, placed attached to the cogs?

To expand: They don't seem to directly connect to the motor but seem to be part of the circuit. I traced the wires and circuits and two connect to each other, one connects to the sound, two to the rest of the circuit, one to the U2. The motors themselves link to the switch, circuits and two CNs. I kinda get how things work but I don't quite understand everything runs through the place they do. Is there a reason why they may run through that area (like they are powering the cogs when it turns), or is any other reason?

The aim: Is to switch out the PCB board with an Arduino as far as possible using the existing wires and attaching them to an Arduino (potentially with shields). I haven't got far enough to know for definites if this will be possible but am taking things one step at a time.

The Functionality: The Roamer is programmed through the buttons at the top and can go forwards, backwards, turn 365 degrees, make sound. Sensors and a stepper motor can be attached as well.

The Setup:

The Motors:

The wires:

The brief 'what is what' |500x373

Any advice as to why it may be like this would be appreciated.

Thanks

Hi, what is your electronics, programming, arduino, hardware experience?

The motors require a driver circuit to operate because they need more current than can be supplied by the microcontroller chip. The unit you have there will probably be custom made so the driver may be integrated into the controller IC

The four extra wires are used to detect rotation of the gearbox, speed. If you look closer you can see that the two places that they connect to are opposite each other, one is a LED and the other a Photo-transistor, in between there is a gear probably with a hole in it to let the LED shine on the transistor as it rotates.

Tom....... :)

Cool, ok this makes sense and I hadn't noticed that!

My knowledge at the moment isn't good enough. I know coding but not hardware so this is part of a far longer learning circle where I'll build up the knowledge, which may take a short time but I understand can take a far longer time as this isn't exactly simple stuff.

Ok so this makes sense as why it's connected where it is. So I've begun to learn about motors more powerful than the Arduino, shall bring in rotating motor Arduino robots, use of LED + Phototransistor in motors. Let me know if you know any resources you think may be useful to read, I'm still in electronics basic books. I had started the inkling that it would be the turning that may be something to do with it.

Thanks so much for the pointing in direction so far :)