Latest creation ...

Dimitri · Super Member Joined: Nov 25, 2005 Posts: 5946

Well I had a issue, I needed to test, and reverse engineer some motors that were given to us for our electric car. A 1,000$ each bike wheel with a integrated motor. But needed a stationary test bed that could "mimic" the wheel driving, but also simple enough it can be considered "disposable" once the project is done.

So I came up with, and built this today at my college. There is a hinge to push that center 1x6 up onto the tire to make the tire think its got resistance. Mimicking the road somewhat. Its a lot simpler then using a conveyor belt, which I was thinking of doing.

And yes its the first day of Christmas holidays for me and I was at my college. Confused

Dimitri

Elvis · Posted: Mon Dec 20, 2010 8:05 pm Post subject: Re: Latest creation ...

very good if it doesnt work you could try bike brakes on the rim.

Dimitri · Super Member Joined: Nov 25, 2005 Posts: 5946

It takes bike disk breaks. However, to maintain consistency in use, a constant pressure would be preferable. Especially one that need not be user controlled like breaks.

Hence a piece that can be adjusted to apply varying pressures on the wheel.

Dimitri

Suzanne · Posted: Mon Dec 20, 2010 9:06 pm Post subject: Re: Latest creation ...

Ok call me dumb, but that is not going to simulate a tire on the road. That's going to simulate breaking because of the friction. You need another rolling surface on that 1x6, like a roller on a boat trailer. Actually 2 rollers, and place the tire between them so that you have one in front and one behind. Then to simulate going up hill or a heavy load, you would put the breaks on the roller or make it harder to turn. The friction on the rollers will not effect the tire, like the wooden timber will, because they'll both be turning.

What you have set up is going to make friction on the wood and the tire and that will make heat which will cause varying resistance, because of what heat does to wood and what happens to rubber when heated.

Just a suggestion, I know my wording sounds harsh, I'm not in a literate mood or something.....forgive me? WAY WAY WAY COOL wheel integrated motor thingy too!!

yeah I built lots
of those things (not)
Suz

Dimitri · Super Member Joined: Nov 25, 2005 Posts: 5946

Suz,

Your close, but remember, there is friction caused by the fact there is a load on the tire in use.

The heavier the guy on a bike, the more the load on the tires, the more energy required to turn the wheels.

Dimitri

Suzanne · Posted: Mon Dec 20, 2010 9:35 pm Post subject: Re: Latest creation ...

Well all I'm sayin is that I think the friction you are about to make is more severe and more heat producing. I"d bet that if you use it as it is, with the board up against the tire and you fix the board there in one spot to create a load effect, the heat on the rubber and wood will cause a greater and greater friction, rubber getting sticky as it heats up, causing it to create an escalating amount of resistance. You'd have to keep moving the board up and down to allow the rubber and wood to cool. Static resistance and rolling resistance.

I think using rollers would give you a more consistent resistance.

Suz

Vince · Posted: Mon Dec 20, 2010 11:31 pm Post subject: Re: Latest creation ...

I think you are right Suz.

An arrangement a bit like a dyno they use to measure power output on a car would do the job. The dyno uses a powered roller setup that is "loaded" to simulate the road.

'Mitri...it would be an easy setup to make mate. Looking at your current arrangement, I think it would be a fairly simple matter to arrange boat trailer rollers onto your existing frame, one to the front and rear of the wheel so that it runs on the two rollers. To put load on the roller, you could then use the arrangement you have now to put load on one of the rollers...possibly with an adjustable bolt under the hinged plank so that the load is constant.

Cheers, Vince

gelandangan · Posted: Tue Dec 21, 2010 1:21 am Post subject: Re: Latest creation ...

how about use the rim to run a belt onto the rollers?
you can adjust the roller resistance by whatever..

Pumpkinslinger · Posted: Tue Dec 21, 2010 1:44 am Post subject: Re: Latest creation ...

I'd lean toward the rolling resistance too. Use an air cylinder with a regulator to control the braking consistently.

Aloysius · Posted: Tue Dec 21, 2010 2:14 am Post subject: Re: Latest creation ...

Dimitri wrote:

The heavier the guy on a bike, the more the load on the tires, the more energy required to turn the wheels.

Dimitri

Are you sure? Think about bicycleraces. When racing on their own for the shortest time, a lot of them are using full, heavy wheels. It seems that once they are turning, momentum helps to keep them turning and it doesn't cost extra energy...

and I also have a warm feeling about Suz's rolling resistance...

Ominivision1 · Posted: Tue Dec 21, 2010 3:11 am Post subject: Re: Latest creation ...

The rolling resistance force increases in a linear line with load increases. For example, you have a tire rated at x, and that a load increase leads to an increase of the deformation and thus energy losses.

Another example is the train, steel wheels and steel track provide lower rolling resistance then a car with rubber tires on asphalt or concrete.

Btw Dimi are them bridgeport mills in the background?

Dimitri · Super Member Joined: Nov 25, 2005 Posts: 5946

They are actually Taiwanese copies my college bought. With a converted head done up by the Canadian importer.

They are not bad machines. Taiwan can really produce some good stuff.

Dimitri

Dimitri · Super Member Joined: Nov 25, 2005 Posts: 5946

Been working on it all week.

I connected my cheaper multimeter onto the system, and ran it for the whole 3+ hours I was running the wheel, multiple times, ran the batteries till they died 3 times so far, gaining data with different control variables put into the system. I used a ESD PCI card to read the CAN Bus data (my own personal purchase including the computer its inside of), and well things went pretty successfully.

Believe it or not, knowing even my basic level of Hexadecimal paid off, I manage to notice patterns in the code and I started to understand what was going on. And the variables that appear from experimentation so far to be the ones I am mostly after (to get the car going), I already have a understanding of. The other system variables with time can be tackled one at a time however.

The screen is not doing the card's output justice, the codes believe it or not are going at approximately 9 milliseconds each. So the code flys and all you see is very quick "snap shots" staring at it.

Dimitri

PaulS · Posted: Mon Jan 10, 2011 7:34 pm Post subject: Re: Latest creation ...

Nice work Dimitri! I like the tension roller for drag too.
How many poles are on the rotor / stator?

Dimitri · Super Member Joined: Nov 25, 2005 Posts: 5946

I think you might be interested in this Paul, a run down of that motor.

www.youtube.com/watch?v=33uCs_awBJk

Dimitri