Laptop Robot

[maitri]

Hi All,

I am new here and fairly new to robotics having never built\owned one.  I am an AI software programmer and have created some interesting vision processing algorithms I want to test in real world robot scenarios.

So here is what I want to do...my laptop would be on a robot base that I make of plywood or some other material.  All i want to be able to do is to control the wheels.  The laptop will have a webcam and based on that input I will navigate the robot.  So I assume all i need is a microcontroller board that I can connect to my laptop perhaps via RS232 or USB to which I can issue commands to tell each wheel what to do.

Pretty simple, eh?  So can anyone recommend the easiest board for me to work with that I can simply plug in some motors, a battery and my laptop and be off and running?  I do want to possibly add some other peripherals to the board in the future that I could receive inputs from, but for now the webcan directly connected to the laptop is all I need...and the ability to control the wheel motors.

Best,
Kevin

[definitionofis]

I would pick a motor controller based on the type of motors,
for example, these:

http://www.robotshop.ca/motor-controllers.html

For a low budget approach, you could run any low amp DC motor
with this self-solder board and parts:
http://www.robotshop.ca/solarbotics-l298-motor-driver-kit-2.html

It would be a three wheeler, with two separately motorized wheels for steerability.

You could toggle the on/offs on the motor controller by directly wiring them to a parallel port.

Since those parallel ports aren't available much these days,
I'd pick a controller with a USB connector to run to the laptop.
Probably something like this one would be simple enough to program the outputs:

http://www.robotshop.ca/arduino-usb-microcontroller-board-1-1.html

Check out the excellent torque tutorial page for weight and torque requirements for your motor choice.
http://www.societyofrobots.com/mechanics_dynamics.shtml

[maitri]

Thanks Def,

Thanks for the help...

I am not concerned about budget and I am not electronics guy.  So I just want to take a board, plug it into my PC via USB\Serial.  Plug in some motors to the board and a power supply and be off and running.

Can anyone recommend a  motor type?  Brushless? stepper? etc...

Thanks!

Kevin

[parallax]

Another really good source of PC interfaces are Phidgets:

http://www.phidgets.com/

They make a wide range of motor/servo controllers, I/O boards, and sensors that use USB or serial connections, and support a large variety of programming languages. Plus there is a TON of documentation out there in regard to them.

As far as what sort of motors and actuators you might want to use, here are some (very) general thoughts:

*Stepper motors will give you a higher degree of accuracy as far as position
*Servos typically have a limited range of motion unless you modify them
*Brushed/Brushless motors will give you more oomph

All the aforementioned require their own kind of controllers, and all have a different workflow. Why don't you look into some of these options and propose something? Then we can tell you what you would need to make it work, and what further things you might want to consider. 

Cheers!
parallax     

[z.s.tar.gz]

Have you looked into the arduino? I've heard a lot of good things about them from "non electronics" type of people.

[maitri]

Thanks for pointing me to Phidget...they have excellent manuals and they look to have what I need.  This in particular:

http://www.phidgets.com/products.php?category=10&product_id=2007

The problem is that I don't really know the size motors I need to haul my laptop around on their back.  It is not too heavy and I can make the frame rather lightweight, so maybe the above setup will be fine.

Any thoughts?

Kevin

[definitionofis]

I like phidgets, too. They are easy to program.

I still think you should run the mass, slope and velocity numbers through
that link, which I gave and pick your motor torque requirement first
to see how many amps you will be running through the controller.

[parallax]

Good choice! I have actually used this exact motorcontroller (the 1060) and was thrilled with the results. I would imagine that this particular combo deal should be fine. However, one point of concern... I didn't see any specifications for the DC motors so we have no way of knowing their output. 

For what you are talking about doing I imagine they will probably be fine though. You don't need a significant amount of power to move a laptop on wheels, especially with a light frame/chassis. Even better if it was a netbook of some sort. Kinda nifty that those motors are in servo casings as well! The only way to be sure would be to e-mail the company and ask for the specs.

If you were to find out that they weren't strong enough, DC motors aren't incredibly expensive so it would be a relatively small thing to swap them out. Also, the 1060 can handle a wide array of motor choices so you pretty much have a free reign in your selection. For example I'ved used it with two modified 12 volt 1100gph bilge pumps (they drew about 4 amps on full blast). They make great watertight motors