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Author Topic: Jhula principle - increase speed by applying brakes.  (Read 55122 times)

prajna

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Jhula principle - increase speed by applying brakes.
« on: March 25, 2007, 06:19:38 PM »
I posted in http://www.overunity.com/index.php/topic,1763.msg26525.html#msg26525 about (what is for me at least) a new idea that folows on from Mikovic's system.  I thought that rather than cluter up the Mikovic thread I would start a new one, so here it is.

Examining the Mikovic arrangement and modelling it in wm2d I noticed that if the balance beam is free to rotate then there are periods in the oscillation of the system where latching the pendulum to the balance beam would increase the momentum.  Basically, I began to see that we could increase the energy in a system not by investing more energy into it but by putting on the brakes, as it were.

For a more detailed explaination take a look at http://declarepeace.org.uk/jhula/

If someone has time to reduce the size of the animated .gif I have linked from that page then I would be most grateful.

bitRAKE

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Re: Jhula principle - increase speed by applying brakes.
« Reply #1 on: March 26, 2007, 09:57:17 PM »
What ideas do you have on a braking system - both with regard to extracting power and minimizing wear? This is very similar to Mikovic's device (I still believe it is equivalent to a double pendulum) as two measured positions are needed to the trigger (lock, in the case of Jhula) the pendulum.

prajna

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Re: Jhula principle - increase speed by applying brakes.
« Reply #2 on: March 26, 2007, 11:19:59 PM »
Sadly, regenerative braking would not be suitable for latching this system since at the point when you want to engage the brake the pendulum is not moving with respect to the counterweight.  So the latch/unlatch mechanism would simply be used to increase the momentum in the system and energy would be extracted from the counterweight axle. Or at least that is how it appears to me at this stage.  There may be other parts of the cycle where regenerative braking could be used (where the pendulum has greater angular momentum than the counterweight) but I believe that the main driving force is in taking advantage of the asymmetric centre of mass when it occurs in our favour.

I predict that there comes a speed beyond which we can no longer increase the momentum because the pendulum will be flung out to its maximum extent whilst it is rising against gravity.  To extract energy we might use regenerative braking to keep the machine operating in the RPM band between that maximum and the point where the counterweight is swinging rather than spinning.

prajna

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Re: Jhula principle - increase speed by applying brakes.
« Reply #3 on: March 27, 2007, 04:08:30 PM »
Oooh, this is getting really fun!  I have just added a very rudimentary latching system to Jhula and it looks excellent.  I have attached a wm2d model for anyone who would like a preview.  I want to tidy it up somewhat before making an .avi and animated .gif and posting them to the website.

The model breaks eventually (something that wm2d isn't handling correctly) but it works better than I had expected with this rough model.

prajna

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Re: Jhula principle - increase speed by applying brakes.
« Reply #4 on: March 28, 2007, 02:45:23 AM »
Here is a screenshot of the graphs and a new model with a redesigned latch.  I am still experimenting but I guess I should do a neater job of the latching system. The output is rather extraordinary and I don't feel entirely confident that wm2d handles polygons well but it looks good.

Want2Invent

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Re: Jhula principle - increase speed by applying brakes.
« Reply #5 on: March 28, 2007, 04:01:16 AM »
Hi!

I've been skimming over the threads on Mikovic and now Jhula. I just came to me this morning that what you're looking for is what we might have known all along since we were kids.

Do you remember playing on a swing? There is a way of somehow maintaining the momentum by shifting one's weight on the swing and extending or retracting one's legs. Seems to be very simple.

I'm not into this very seriously. I'm working in an office, but I stumbled on this forum and just got very interested. I don't know if I'll every be able to do the experiments here since I don't have the skills...for now.

God bless you!

Teddy  :)

prajna

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Re: Jhula principle - increase speed by applying brakes.
« Reply #6 on: March 28, 2007, 04:09:19 AM »
Similar to swinging, Teddy, but swings don't generally swing themselves.  As you say, you have to shift your weight and that takes some energy to do. Jhula may be able to swing itself once it is started and the hope is that there will be a way for the mikovic device to feed energy from its output back into its pendulum.  I'm glad you're interested.

Want2Invent

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Re: Jhula principle - increase speed by applying brakes.
« Reply #7 on: March 28, 2007, 04:26:35 AM »
Hello Prajna,

Just a suggestion. It might be better if you could convert your AVI to MP4 or flash so they download faster. That's if you have the software, but GIF and AVI is fine.

Teddy

xnonix

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Re: Jhula principle - increase speed by applying brakes.
« Reply #8 on: March 28, 2007, 01:20:18 PM »
Hi all,
I have simulated the latches on the lever and on the pendulum by two motors.

The motor on the pendulum simulates hte latch that only make it move clockwise and block it when it want to go anticlockwise. The power on this motor is the power that we could obtain by extractin power from the latch.

The motor on the lever makes it move only anticlockwise. The power generated when it want to go clockwise is measured as well.

Here is a graphic and the model

prajna

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Re: Jhula principle - increase speed by applying brakes.
« Reply #9 on: March 28, 2007, 01:57:24 PM »
xnonix, that is fantastic! I am still not entirely sure how you worked out the formula but it certainly seems to work.  I am a little dissapointed that there does not seem to be as much acceleration as I had hoped.  I added a rotation graph for the counterweight and the slope seems pretty flat to me (except during periods when the system seems to find a 'sweet spot').  I had hoped that graph might curve upwards.

xnonix

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Re: Jhula principle - increase speed by applying brakes.
« Reply #10 on: March 28, 2007, 02:25:09 PM »
In the graphics: the latch torque of the lever an pendulum shows you when the latch is on. When is 0 the system is free.

About the formulas they are easy to explain...

If i want a force +F when the body(x) is rotating clockwise:
F * (Body(x).v.r > 0)

the part (Body(x).v.r > 0) is a conditional that is 1 when is true and 0 When is false.

Something like this is what i did on the two motors to simulate the latches. The system seems to work.

Now let's make it in reality.

prajna

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Re: Jhula principle - increase speed by applying brakes.
« Reply #11 on: March 28, 2007, 02:31:06 PM »
Yes, nothing is more convincing than something that works in real life.  :) It looks like it should be very easy to build.  I am still playing around with designs to find out the optimum relationship between the counterweight and pendulum mass, the length of the pendulum and the position of the two bearings.  Small adjustments in any of these seem to make quite a difference in how it performs.

bluesgtr44

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Re: Jhula principle - increase speed by applying brakes.
« Reply #12 on: March 28, 2007, 05:18:00 PM »
Hmmmm....interesting. I have used WM2D for quite awhile now. I do not trust the polygon functions very much and try to avoid them. I also believe that if one was to build this that they would find the 3rd deminsion kicking in and it would take away from the system in the form of attempting to also oscillate in and out. I downloaded your set ups and increased the air resistance to what I would think are more realistic levels. The first one made two revolutions and died....you had air resistance set to "none", I changed it to the default low setting of .3....the second one you had a low setting of .07, I raised that to .2 and this made the set up more erratic, but it did keep going and maintain an increase. I feel this was in part due to the use of the polygon function in WM2D...I just don't have a lot of faith in it.

Draw a circle or disk about 4ft. in diameter.....pin it in the center and then use the curved polygon function and draw another circle of 1ft. in diameter.  Set the two to "collide" and then set the polygon circle inside the regular circle. Hit RUN! This thing will accelerate itself to oblivion! Why? My understanding is that the polygon circle thinks it is on the outside of the circle and  rolling off....it just keeps trying to roll off....a software glitch...one reason why I do not trust them....


Steve

prajna

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Re: Jhula principle - increase speed by applying brakes.
« Reply #13 on: March 28, 2007, 05:32:15 PM »
Yes, I notice glitches too, Steve; sudden accelerations. I have noticed that there are a number of parameters that need to be balance. It seems to be a balanced unbalance that makes this system work. :)

bluesgtr44

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Re: Jhula principle - increase speed by applying brakes.
« Reply #14 on: March 28, 2007, 06:26:25 PM »
My apologies, Prajna....I do not think this system will work at all. My main point was....there is no 3rd deminsion in WM2D. Very much like Milkovich, the pendulum is going to want to go backwards and forwards to stop the motion....gravity always wants to win. Think about it, a constant downward force will utilize any means to achieve that point of rest. Even if you try to brace it, this produces friction in the hard mechanics of the system and decreases the output and the whole thing comes to a stop.


Steve