Sum of energy increase
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Sum of energy increase
Hi,
I have a problem, sum of energy of a free system in space increase more and more. I tested with a lot of scenes. The bug appears only when there is friction. Energy is higher with a spring. With friction the energy increase around 0.1 J each second. I send the scene.
If you have any idea what I need to do in my scene for have a realistic energy ?
thanks
I have a problem, sum of energy of a free system in space increase more and more. I tested with a lot of scenes. The bug appears only when there is friction. Energy is higher with a spring. With friction the energy increase around 0.1 J each second. I send the scene.
If you have any idea what I need to do in my scene for have a realistic energy ?
thanks
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- tests resssorts v1 - start - avec forces - envoi Al.phz
- File to test where energy increase more and more
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- vk4
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- Joined: Sun Dec 22, 2013 5:14 pm
Re: Sum of energy increase
I've just set 1x sim speed and energy stops increasing.
Dream of Algodoo as game development engine...
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Kilinich - [Best bug reporter 2010]
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Re: Sum of energy increase
I downloaded my own file and tested it, the speed of simulation (0.1X or 1X) don't change the result. I tested this better scene more stable. The scene watch y/x position for each object and sum of energy. Like trajectories are differents, the force from spring don't give the same energy to the object 1 compare to object2.
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- ste22 al.phz
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Re: Sum of energy increase
Interesting research
I believe energy leak/increase is a limitation of step by step calc of contacts. Nothing you can do to stops it.
I believe energy leak/increase is a limitation of step by step calc of contacts. Nothing you can do to stops it.
Dream of Algodoo as game development engine...
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Kilinich - [Best bug reporter 2010]
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- Joined: Mon Aug 31, 2009 8:27 pm
- Location: South Russia
Re: Sum of energy increase
I tested with a range of frequency (900 to 1800 Hz) and the result don't change until forces are stable. I think I understood the error of Algodoo. Center of gravity of Object1 (green color) has a force perpendicular to its movement. In the contrary, the force on Object2 (red+orange) has a force that works. I compute the power = 0.026/2 (radius) * 88*cos(60°) (force) * 18.5 (angular velocity) = 10.5 W. Algodoo find 6.5 W. I added an axis on object 1, this don't change the result. Look at image :
I added the scene.
I optimized the result and I can have more than 30 W on the second scene. I think the sum of force on big object act on the linear trajectory and add more and more energy because the system increase its angular velocity in the same time. Small object (2 objects) has a different trajectory, it's a rotation and the last translation. The rotation increase more and more due to the difference of distance I think.
I added the scene.
I optimized the result and I can have more than 30 W on the second scene. I think the sum of force on big object act on the linear trajectory and add more and more energy because the system increase its angular velocity in the same time. Small object (2 objects) has a different trajectory, it's a rotation and the last translation. The rotation increase more and more due to the difference of distance I think.
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- cc7-masses4-good parameters-2.zip
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- cv6 - Al.phz
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- vk4
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Re: Sum of energy increase
Aaaaand ?
It''s an approximation. What we should do now?
It''s an approximation. What we should do now?
Dream of Algodoo as game development engine...
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Kilinich - [Best bug reporter 2010]
- Posts: 2098
- Joined: Mon Aug 31, 2009 8:27 pm
- Location: South Russia
Re: Sum of energy increase
It's not an approximation, the torque exist. I understood where the energy come from and why Algodoo give more energy. Center of gravity of Object1 (green) is not the same than Object2 (red/orange). This create a torque in the direction of rotation. Now, what is the compensation of this torque ? And why Algodoo don't find it ? I tested from 800 to 5000 Hz (after forces are unstable), the energy is very stable. I added the scene and an animated gif file.
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- cc7-masses4-good parameters-3-fr - Alf.zip
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- anigif.gif
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- vk4
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Re: Sum of energy increase
This is the phase angle the problem. The center of gravity of green object in not at 180° in front of red object. Click on image please, they are larger than the site can do.
The center of gravity don't move, it is very stable, move sometimes of 0.1 mm. The phase angle is in this example of 16.5°.
The center of gravity don't move, it is very stable, move sometimes of 0.1 mm. The phase angle is in this example of 16.5°.
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- ns4.phz
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Re: Sum of energy increase
WOW! I don't recall anyone putting this much time and energy into researching an issue in Algodoo! I don't understand all of it, but I am totally impressed by it!
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Xray - Posts: 500
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Re: Sum of energy increase
In this scene if I compute the error it's 1 cm ! The energy added each second is 26 J at 12000 Hz so with the sum of forces at 151 N and an angular velocity of 19 rd/s this give 26/151/19 = 0.9 cm. It's a great error. Sure the system has energy but it's only a kinetics energy. With big distance Algodoo give error ?
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- 9r.phz
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