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A Di Wheel called......

'THE TRINITY'


A TEAM FROM THE UNIVERSITY OF ADELAIDE HAVE GOT AN ELECTRIC DIWHEEL WORKING ~click here for details

Need to wire up the control boxes. they will be separate to the battery boxes to allow the battery placement to be used to effect the centre of gravity. Also need to 'adapt' the brake levers to use micro switches for the 'inhibit' signal to the controllers and to switch the contactor to switch out the motor.

Discovered I had the gearing totally wrong on the 'monowheel' test ~ it was geared for 22MPH! need to get new sprockets ordered to bring it down to a more sensible 13MPH.

Need to get the tyres and sort out the batteries ~ I would like to go for some LIFEPO4 ones due to the size and weight but they are expensive so it may be normal sealed ones.


Back ground to the project (or why the hell did I build it!)

Much like the mono wheel the idea came from  Douglas Self's site along with a fascination with 'Gerbiling*' ~ safer in a di wheel than a mono wheel,. if safer is the right word.

All the di wheels I have found details of use a petrol engine and presumably some sort of differential drive. Now petrol engines don't like running upside down so continuous 'gerbiling'  would stall the engine. Electric motors on the other hand don't give a damn which way up they are! Having built a few electric vehicles, this, for what I want it to do, is the way forward. This would also allow independent drives to each wheel, doing away with the need for a differential and (in theory) allowing for a very, very manoeuvrable machine.

The whole thing will have to come apart since my idiot neighbour has left just enough room to get a motorcycle or monowheel out the back but not quite enough for a di wheel - some people have no foresight....... this does however, lead to the interesting possibility of two electric mono wheels!

* ~ going completely over the top ( nothing to do with rodents). By applying the brakes the inner frame is locked to the wheel so over you go!

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 Initial drawings and ideas

Unlike the Red Max, the di wheel has been fully designed before I get near my shed!!!!!!! there are some pictures of it lower down, the inner frame is stronger than the mono wheel.!

Whilst designing it a few things started to become clear...........

The controls are two joysticks, one for the left wheel, one for the right. The joysticks work with the electronic speed controller such that as the stick is moved forward the forward speed increases ; as it is pulled back the reverse speed increases. The centre (or neutral) position is stop. This means that if one stick is pushed full forward and one full reverse the driver (rider?) spins around a central vertical axis. The result of this degree of controllability should be a highly manoeuvrable vehicle!

Each joystick has a brake lever. This lever has two functions;  firstly it operates the disc brake on the drive wheel, secondly it 'disconnects' the motor. This means (hopefully) some spectacular multiple gerbiling! FORWARD OR BACKWARD!

And now for the really scary bit. Stick with me on this one because it is hard the explain..........

You pull both joysticks full reverse, then pull on the brakes. This will cause you and the di wheel to roll over backwards. When you are completely upside down you release the brakes and push one joystick forward and the other back. This should cause a 'half spin'. Now since you are still rotating backwards you should come out of this rotation facing forwards! it seems right in theory.......... This would work going forwards and coming out backwards as well!

The more you think about it the more bazaar manoeuvres you come up with.......

The gearing has been calculated to give a top speed of 20MPH. yikes!

A four or five point harness is going to be used by the way! from the designs I think my head will miss the ground by about three inches so a helmet might also be useful.

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Parts used and suppliers

The wheel - 5' diameter hoop of 2" steel tube. wall thickness 1/8".  They have arrived, made by Barnshaws bending in Audenshaw

The inner frame - 4.5' diameter hoop of 3/4" steel tube. wall thickness 1/8". See above

The rollers - ready and waiting!!!!!!!!

The motors - 1000watt, 36 volt DC motors from TNC scooters in the USA

The drive wheel - mini moto wheel with sprocket for larger chain. disc brake.

The name plaques - will be made by CS Engraving.

The tyre - Three 19" mountain bike tyres, cut to size and pop riveted on. may be better with something with a 'squarer' section.

The seat - probably a kart one. EBay again?

The harness - a five or six point racing/rally type.  from EBay

The shocks - not used as shocks but keep the drive wheel pressed to the outer wheel. Mountain bike units from EBay.

The batteries - these are  expensive, but vital! probably three (or six) 12volt 18AH ones (or bigger). would like to use LIFEPO4 ones; I am using them on the uniboard but they are expensive!!!!!!!!!

The controllers - Curtis programmable ones! thanks again Tony.

All other parts are going to be made by me, in my shed, again.

 

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Pictures

                

         

I have started the build!

Here are the drive wheels and swing arms, with brakes

         

new pictures! Note there are only three rollers!

 

 

 

 

 

pictures of the monowheel conversion ~ the handlebar/seat unit comes off on four bolts!

 

 

 

 

 

 

 

see my head will just miss the floor!

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Movies

a bit of testing of the electric drive! gearing is to high and the batteries needed charging!

test 1

test 2

test 3

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What's it like to ride ?

    Probably bloody terrifying! but that is kind of the idea!

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Questions

Q1. Couldn't you design some 'electronics' that would prevent 'Gerbiling' ?

A1. Yes. but why would I? that would remove all the fun.

 

Q2. Couldn't you use just one central joystick?

A2. Yes. I thought about this but decided to have two separate ones since the brakes need to be separate. Also this allows the possibility of two electric monowheels.

 

Q3. Why not make the wheels 'tilt' to allow better cornering?

A3. Nice idea! but lets not run before we can walk eh?

 

Q4. The actual construction does not seem to follow the CAD design?

A4. You noticed that? As soon as I get the actual metal in my hand the little grey cells set to work and plans change!

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EDWARD ~ The University of Adelaide Di wheel

for more details  http://www.mecheng.adelaide.edu.au/robotics/robotics_projects.php?wpage_id=44&title=60&browsebyauthor=115

The videos are great take a look!

video1

video2

video3

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