Let's Make Robots!

Ball-E (Bugs worked out!)

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Base_Bottom.JPG1.58 MB
Insides_Out.JPG1.41 MB

This is my second robot. It's going to run off of an Arduino Diecimila. It will have 3 servos, used for movement. I currently have 2 of them up and running. My plan is to take a 3rd, and suspend weight (about a pound of polymorph or lead) from it. I will use it to keep the base paralell with the ground.

It will drive in a wierd way: the 2 servos I already have will rotate, trying to turn the platform. As the platform is weighed down by the 3rd servo and its load, the platform will stay steady, as the ball turns forward or backward around it. To turn, the 3rd servo tilts the weight towards either drive servo, while the ball is spinning forward or backward. If you don't get this, think about the Earth. The north and south poles are where the F/B servos are. The equator is the line where the bottom of the ball touches the floor. As the ball tilts to one 'pole', it will rotate the platform inside. Then when the weight evens out again, the ball goes back on the equator, but with the orientation different, it will be facing a new direction.

Base%20Bottom.JPGIts only sensor so far will be a long distance Sharp IR, as I have heard they can see through plastic.



 

 


Update: August 13, 2009

My Arduino Diecimila came! I'm working full tilt to ge this 'bot done now. I can order new parts, such as my 3rd servo, and the handful of sensors...

ArduinoDiecimila400.jpg


I now have all I need to finish it. its only a matter of time...

rotundus-diagram.gif

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I plan on having some sort of actuator, near each 'pole' of the robot, then having cheap IRs or 2 ultrasonics pop out every so often. OR, I could make some sort of linkage to the ball that lets it spin, as well as not tangling wires around an axis screw. Then, I permanently aim them forward, and send it on its way.

Assuming that your IR emitter/detector pair will be in the same relative postiion in the ball at all times - i.e. the same height off the ground, and pointing in the same direction - then the optics shouldn't change from time to time. So can you not simply either calculate, estimate, or empirically measure some kind of fudge factor to scale up the distance you measure from the IR sensors?

 

This project is parked until I get my Mr. General Competition robot done, and my Xmos started. But that's an excellent Idea, I think I'll use it.

Drilling holes to put  IR emitter and detector for a simple IR detector should be fairly easy.. well you'll need a few, and compare all the values.

 

 Take a total of about 8 I believe to cover all angles of the ball. Maybe less depending on what kind of angle you get.

So when are you releasing the video for this?

After the laws of physics change. Apparently, the ball acts as a 'fresnel lens', making readings from IR sensors seem closer then they really are. Once I get some better hardware, and another handful of servos, it will have an extending PING))) from the sides, to take readings there.
Have you thought of trying a different type of sensor, maybe ultrasonic, to see if they get through the "lens" of the ball better than IR?

ignoble the ultrasonic sensor couldnt be able to escape the ball 

i read the same article in popular science!

Popular Science has a "Future of..." series. Last night was "Future of Security" and it included an autonomous rolling ball robot. Very cool application of the type of bot you are trying to build.

I can't find any decent links to it yet.I found this article from much earlier on the bot. Here is another one that includes a video.The company making the bot is calling it "Rotundus".

The bot was originally developed for exploration on other planets, so it is completely sealed and able to go through/over sand, water, ice, snow, etc. 

It has two gyro-stabilized cameras on domed pods on either side of it. The rolling surface was black and looked like rubber with nubs for traction. It can be remote controlled or use GPS waypoints to navigate autonomously.