Dec 16, 2006

Technical Question

Yesterday while doing some shopping I was in the Discovery store and saw this remote control motorcycle. The thing was very cool and the only thing that kept me from buying it was knowing the look on my wife's face if I brought it home, wrapped it, and wrote my name on it :)

Question: inside the motorcycle is a gyroscope that keeps the motorcycle upright at high speeds. But even at low speed, the thing balanced pretty well. Now, the motorcycle was a little wider than a real motorcycle (if scaled up), but the thing really did run like a motorcycle without training wheels or other support.

Any thoughts on how fast you'd have to get a NXT bot's speed up to keep it up OR how difficult would it be for LEGO or HiTechnic to create a gyroscope? I should add that this has been a discussion on "another board" but not available to the general public. I'm interested in thoughts on the reality/cost/usefulness of this item.

Jim

5 comments:

Brian Davis said...

I'd be curious exactly how the model worked. You can use a gyroscope with a large angular momentum to reduce the rate you "fall over" at... and if you can manipulate the axis of this gyroscope, you can actively balance (on a real bike, the wheels themselves help perfomr this function). But it still needs some "intelligence" to correct.

As to how big it has to be, well... it's the angular momentum that counts; you can get a large angular momentum be using a massive wheel, a big (large diameter) wheel, or spinning it very fast. So you are not neccessarily limited to large gyroscopes (although, again, you might have them in the wheels).

As to gyros, well... it's easy (well, it's easy for other people, not this author) to make a gyroscopic *sensor*, to determine how fast the angular rate is changing. This could be very useful for a number of things, and I believe it probably is being worked on.

--
Brian Davis

Christopher R. Smith (Littlehorn) said...

I found a couple of interesting patented methods...I'm still looking for a picture of the insides.

Chris

The long one...Here

...and the short one:
Gyro stabilized remote controlled toy motorcycle having good stability and controllability without using ground contacting auxiliary wheels or the like. The motorcycle comprises a chassis supporting a fixed angle rear wheel drive and associated motor and a castered front wheel. A gyro wheel having an axis nominally parallel to the axis of the rear wheel is mounted in a gimbal with a vertical axis in the forward part of the chassis and connected to the front wheel fork and post to turn the front wheel responsive to the rotation of the gimbal relative to the chassis. The chassis further includes a radio receiver, battery power and a steering device, such as a motor and slip clutch for torquing the gyro wheel gimbal. To turn in a first direction the gyro gimbal is torqued in the opposite direction, initially causing the front wheel to also turn in the opposite direction. As the motorcycle and the gyro lean into the turn, a correcting torque is generated by the gyro and caster of the front wheel, overcoming the initial steering torque to maintain the proper steering angle and balance for the motorcycle.

Jim Kelly said...

I'm continually amazed at what one can find on the Internet!

Thanks for posting, Chris.

Jim

Ian said...

I found this Gyration gyroscope sensor a few weeks ago: http://www.gyration.com/en-US/GyroTech.html

Christopher R. Smith (Littlehorn) said...

Ian,

Thats a Very Cool Sensor! I really can't tell how sensitive it is but... Please, someone stick this into a LEGO sensor shell and sell it to me? I'm sure I could stuff it into my NXT MonoWheel and give it a spin.

Christopher

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