4 Wheels 4 More Fun

[rocketman468]

just so awsome :D

[nattavision]

this is great but it seems to be wobbling alot, looks like it would fall over as soon as u touch it!

[Appelsappel]

awesome

[fedekaare]

I've got a budy. him and i have been playing with the idea of a RC AH-64 Apache. This would be flyed FPV with remote camera and headtracking goggles. this model would be made with fly by wire and this is where we lack the expertise that you have. would it be possible to make you balancing software transferable to flying a helicopter or/and a plane?

Hope you still read this... : )

[Vegakade]

This robot uses light sensors and pid controlers. The light sensors won't be much use for you. Maybe the PID controlers will. Better sensors for a helicopter will be gyro and accelerometers (look also for my other robot NXT-body balance). But you better search for IMU and Helicopter on a search engine.

Good luck

[RoboTekno]

i love it, especially since it is made form legos

[Limpfittz]

Amazing

[jvpommeren]

Absolutely a great robot!

How did you tune the PID controller parameters? Trial and error or some advanced technique?

Did you measure what the maximum recoverable angles of your model are? In both (tilt and roll) directions?

[Vegakade]

Thx, I started with manualy tuning(Lego Remote Control) while a supervised learner on the PC watched the process(through the IR-tower). The Learner(LWPR) could do the tuning quite well. No angles were calculated, only light sensor values.

[Vegakade]

look on google for:

Locally Weighted Statistical Learning Software download

[zedomax]

nice dude!

[unijamo5]

pretty dam cool

[davesum99]

please post the code!!

Also, what is the back wheel doing? What light sensors are you using?

[Vegakade]

The tilt is compensated with the wheel on the ground.

The roll is compensated with the one wheel in the air. The weight of this wheel changes the centre of gravity of the unicycle. But to move this wheel in the air you have to compensate for the moving force. There are the two turning wheels for. They compensate the force of moving the one wheel in the air.

I used the same sensor's as Steve Hassenplug(Hitechnic). And two RCX's to get a very small measure and control cycle.

[pintpi]

Oh, I was way off then. I assumed you were using some type of incremental encoder sensors and I thought the wheel on the back was being used to sense roll but now I see the wheel in the back and the two spinning wheels banace each other's torsional forces.

[davesum99]

Can you make this clearer? I've done some simulations with just the two turning wheel type of setup. I don't see what the third wheel in the back accomplishes; the two windmill-like wheels should be able to correct for roll by themselves.

BTW this is very impressive, so I'm not arguing with success! Just trying to understand.

[Vegakade]

Youre remark about the two windmill-like wheels will be able to correct for roll by themselves is correct. But the issue is that not the two windmill wheels correct the roll but the acceleration of this two. First the lego motors cant accellerate t0o much thats a problem because the cause of the roll is not solved. Cause of the roll are for example the instable rubber wheel or not a good offset from the sensors. So before the maximum acceleration is reached the centre of gravity is changed.

[Vegakade]

Actualy the coding is quite simple. Just three PID-controlers in two RCX's. The construction was the challenge!

[pintpi]

It seems the wheel in the back is being used to sense roll but what type and where is the pitch sensor? Doesn't look like it has any yaw control but do you plan on trying to get it to go anywhere? Not that balancing on a single wheel isn't cool enough but since you got the balancing working, it shouldn't be much more work getting it moving. Nice work though. I can only imagine how many hours of coding went into that :-)

[desiredusername]

Is that balanced on a single wheel?

[Vegakade]

Yep, a single wheel

[desiredusername]

So the lateral balancing is from the arm? And this is all stock RIS (except for firmware)??