Ask Engadget: best robot platform for under $400?

We know you've got questions, and if you're brave enough to ask the world for answers, here's the outlet to do so. This week's Ask Engadget question is coming to us from Ryan, who reckons it's about time he stopped playing with Lego blocks and began playing with a real man's robot platform. Just kidding about the Lego bit. If you're looking to send in an inquiry of your own, drop us a line at ask [at] engadget [dawt] com.

"I am an aspiring roboticist who has been using Lego Mindstorms NXT for a few years and I am looking for the next step up. I have a budget of about $400. I am looking for something that has more motors, more sensors, and a way to have it live feed video back to a computer. I would also like a platform that has a large amount of building that can be done on top of it, such as adding an arm or another array of sensors, or a different drive base. I'm new to the world of robotics outside of the NXT, so any tips would be appreciated as well. Thanks!"

Come on over, robot lovers. Toss those gloves and goggles aside for a moment and throw this guy some advice. What platform keeps you up in the garage at night?

[stevetravel Posted Aug 13th 2010 2:27PM]

I have use the lynxmotion unit. They have a pretty nice family of parts and we were able to make a nice little demo without a ton of effort.

Here's our demo - http://www.iso-tip.com/pro50-robotic-marshmallow-roaster/

It has some nice low level triggering and programming but also nice high level train and repeat positioning if you want to get it to move without getting into the micro controller level.

Here the robot arm we used for $360. We added a wrist and an IR sensor to for a few buck more after we started working with it.
http://www.lynxmotion.com/c-124-al5a.aspx

[someguy7234 Posted Aug 15th 2010 1:09PM]

The elephant in the room should be GUMSTIX... the overo series is really powerful. Beagleboard is another good option that will meet your video requirement (since both have a full USB stack and will install ubuntu)... I would recommend Gumstix more, as it has a DSP on board.

For hardware... cheap out dude... get some sparkfun motor controllers and line level shifters. Platforms get boring quickly, so make something out of a project box and some tamiya gearboxes to start.

For feedback, I would avoid encoders, your cost and debug complexity skyrockets for no good reason. Take a look at the IMU module offered by sparkfun. Separate your motor contol and analog though or they WILL TALK!.... For power, go AA rechargable. you will slap yourself in the head if you spend $30 on a LiIon and charger and then realize you need to isolate the grounds. They are easy enough to swap out and cheap and accessible.

$400 goes quickly when you are doing robotics. Good luck!
-PS, I'm a graduate student in mobile robotics, and I spend a fair bit of my stipend at sparkfun.