View Full Version : Laptop Powered RC car

07-26-2007, 03:10 PM
Obviously, we can't enter projects in our own contest! But we are going to post some old ones we did ourselves in here so people can check them out.

The laptop controlled RC car was something we built a few years ago. It was part of the evolution to a full blown RC car robot with a mini-PC on it.

As we worked out the software for the robot we first wanted to get used to controlling it. The easiest way to do that is to use good ole human input for testing your output. So we built the base of the robot and tethered it to a laptop which took input from manual control via some mini-joysticks. (You will notice in more recent projects that we never use this archaic method anymore, opting instead to use normal joysticks and DirectX to read form them.)

Parts Used:
(2) Phidget Mini-Joysticks (http://www.trossenrobotics.com/store/p/3255-Mini-Joy-Stick.aspx)
(1) 8/8/8 Phidget Interface Kit (http://www.trossenrobotics.com/store/p/3202-InterfaceKit-8-8-8.aspx)
(1) laptop
(1) USB to Ethernet Extender (http://www.trossenrobotics.com/store/p/3462-USB-to-RJ45-Extender.aspx) (+ long ethernet cable)
(1) 4 servo Phidget Controller (http://www.trossenrobotics.com/store/p/3188-Servo-4-Motor-Controller.aspx)
(1) Hacked up RC car

Here's the video, and yes, I was being sarcastic in the beginning. Microsoft and Google would NEVER fund the same project!


07-27-2007, 11:33 AM
We looked under Dave's desk and actually found the little RC car curled up under there. Here are some pics of him in his latest state.

(PS: a tip for people thinking about making RC car robots. If you plan to load some weight on the bot then you should stuff the tires with something like foam. You can buy a can of Great Stuff (it's a hardening foam insulate) and squirt that into the tires.)

07-27-2007, 12:58 PM
Could you comment on the power supply and the power requirements for this type of project. I understand the control side but not the power for the servo's & the overall drive unit, thanks ...

07-30-2007, 03:35 PM
Sure thing, the car itself still drove off the rechargeable battery that came with it. We did run a power line down the tethered cable to power the Phidget 4-servo controller. We just took a 6V power supply and spliced in a long run of speaker cable to do that and taped it to the RJ45 Cable.

Recently Dave has told me that there are ways to get around powering the Phidget controller. I'll ask him to post on that next.


08-01-2007, 02:09 PM
Regarding powering the servo controller:

The circuitry is all powered by the USB 5V line. This 5V line also powers servo channel 0. If you want to use the additional 3 servo channels, power must be supplied either to the DC input jack on the controller board, or directly to the servos. I prefer powering the servos diretly, because this bypasses the servo controller's current limitations.

I described my technique for powering servos in this thread:

10-21-2008, 06:01 PM
Okay people, I am very much interested in getting a laptop. I am planning for buying this within a month or so. I prefer HP laptop but I don't know alot about buying laptops. I would like one that has a big memory,built in wireless internet connection thing, built in webcam, and one that's fit for a girl. I really need your advice. What is the best Hp laptop for me to buy and why? Thanking you,

10-21-2008, 06:54 PM
I love lamp.

10-21-2008, 07:13 PM
Why was this car never USB powered?!

10-21-2008, 07:16 PM
Because USB power can't power motors like that, not enough current? More than a hundred milliamp or so and you're done.

10-21-2008, 07:19 PM
Because USB power can't power motors like that, not enough current? More than a hundred milliamp or so and you're done.

Seeing that Microsoft sponsored it....?

10-21-2008, 08:04 PM
What, the USB standard? No.

The USB standard doesn't allow for that much current to be carried.

10-21-2008, 08:25 PM
Then Microsoft should tell Google to make an "extra high power USB hub". Intel can then send the servers for Google to design it on. Microsoft can make the drivers. And Trossen Robotics can make a claw for the robot to grab beer from the fridge!

lol, really though, I would think you could power a small robot from USB power. I am thinking of those USB fans... I wonder if you could strip a few down and gear them to drive the laptop around?

You could control the robot over an I/O board, then run the power over a few other USB ports.

A little dumb, the only thing you'd gain is the robot being "USB Powered" (aka running off a laptop battery). Still, if I had the parts, I'd try it just for the fun of saying that my laptop drives itself around! :)

Edit --

The robot would be very slow, and may not make it back to the charging dock in time.

10-22-2008, 12:42 AM
Yea, if you want several hours/inch, you could probably even do it... 5v @ 50m/A per motor, with NOTHING else on the bus.

Oh, btw, if it were "super powered", you couldn't call it "USB". It would be uncompliant and therefore you'd get sued. "USB" means something very very specific.

BTW: You know that "gullible" is in the dictionary twice, right?

Matt writes: "and yes, I was being sarcastic in the beginning. Microsoft and Google would NEVER fund the same project!"