RWI B12B Explorer robot

machine27 · December 30, 2011, 3:55pm

Up for sale is an RWI B12B Explorer robot. All the original electronics in the base are in tact. Last time I powered the robot up I was able to drive it around with the included wired joystick. It has two large batteries 12v 4ah (gel cell I think) batteries that may or may not hold a charge.
I had originally planned to update the robot with a Basic Stamp but I couldn’t bring myself to do it as it’s in very original condition.
The B12 is a omni directional synchronous drive robot meaning one motor steers all three wheels and one motor drives all three wheels. From a mechanical stand point, it took some amazing engineering to come up with this drive system. The top plate is also mechanically linked to the wheels so the plate rotates whenever the wheels change direction. Hence a camera mounted on the plate facing the direction of travel would always stay pointed towards the direction of travel.
I believe the robot is from the early 90’s as it has the upgrade removeable bump sensor panels which enclose the robot in the pictures.
The sale will include the robot, the joystick and the original charger. I’ve mis-placed the charge cable but it should be fairly easy to construct one as it’s a two conductor cable with a barrel type plug at each end.
I’m asking $1000 for it plus shipping. It originally was about 4 times that price when new.
If you have a T-hex and want to trade, message me.

Thanks.
rwi 4.JPG
rwi 3.JPG
rwi 2.JPG
rwi 1.JPG

km6vv · December 30, 2011, 6:29pm

Interesting drive system. Any more pictures of the drive train?

Alan KM6VV

machine27 · December 30, 2011, 10:09pm

I’ll snap a couple pictures and post them tomorrow.
Happy Holidays everyone.

machine27 · January 1, 2012, 12:10am

Here’s a couple more pictures of the drive system on the robot. I made a sad discovery when I turned him over to snap pictures of the wheels. Two wheels have cracked rubber tires making the robot impossible to drive. I can’t sell him like this and expect to get anything out of him. I’ll put him back on the shelf until I can figure out how to buy/make replacement tires. Maybe large o-rings might work well. Darn!

A quick description of the how the drive works. Two timing sprockets are stacked up on each wheel module. The top one drives a center shaft down to a bevel gear. The oposite bevel gear is attached to the drive wheel making the drive wheel rotate. The lower timing sprocket attaches to the drive wheel module through a second outer shaft, this sprocket turns the module.
The last two pictures show the plug which goes through a set of rotary contacts allowing electrical connections to be made to the servo drives from the top plate.
Enjoy the pictures!