Walking with physics

[galok]

I wanna make an algorithm that use physics for walking in 2D. Like in Euphoria engine (Rockstar) or like in this video:
https://www.youtube.com/watch?v=tb-t4j9wt7E
I think i should manage revolute or hinge joint velocity, but i haven't precise idea how it should be done. I think maybe you can point me at code or a book or anything else, so practically any related information would be very helpful.

[galok]

first serious progress, i found research with source code:
https://www.cs.ubc.ca/~van/papers/Simbicon.htm

[Ñuño Martínez]

Cool. If you find more stuff, please share it too.

[galok]

well, first of all i compile it and i must admit it was very easy with VS 2008 Express Edition (as was said in README), but README was telling the truth and it's very not user friendly, actually a first thing i found out - it's doesn't working and i found out an error that occurs - it's heap corruption, but if you start application from VS 2008 - heap corruption still occurs, but after this - app doesn't care about it. I dont know why this happening, but i must mention this to be precise.
And next step was found out that there is no controls to do something with rendered skeleton, after few minutes i figured out that there is a GUI but coordinates of it is out of my screen space, so i adjust it manually in "\src\AppGUI\init\setup.tcl" file. After this GUI is appear and i played an animation, learned how to throw obstacles and after more few minutes i figured out that there is no animation change menu. Animation can be changed only manually in "\src\AppGUI\init\input.conF" file by commenting and uncommenting loads, after this i read comment about 2D and i learned that there is no 2D, but instead there is a 3D biped with toes (?).

# Define the rigid bodies that will make up the character - this is the same as the normal bip3d, but has toes

so i posting a video and hope i could manage read their code and translate it to 2D environment. yeah...
i need to mention that there is comments everywhere, so they must be helpful, but when i run debug build with debugger - fps slows down to 5-7 and that is increase difficulty in understanding

[galok]

i'm tried as hard as i can translate simulation parameters to box2d, i translated object sizes, mass, inertia and positions of joints, after this i created fixed step loop procedure (200 iterations with Dt = 0.00005) and run simulations in zero gravity to step 33, but results is still far from good, i think i'm mistaken somewhere...

and values of variables are different
(torque hash, root velocity, relative angles)

Simbicon:
--- 33 ---


384,45


0,47 -0,09


-1,80
-0,23
-0,70
-0,01
-30,86
1,43
-0,01

Box2D:
--- 33 ---


287,05


0,40 -0,07


-1,48
0,10
0,79
0,46
-31,42
14,11
9,78

[SilverWarior]

The cause might be in different floating point precision between your and original program.

[galok]

The cause might be in different floating point precision between your and original program.

I tried to do less iteration in order to decrease precision error, 20 iterations with 0.0005 Dt give same results. simbicon use single precision float for calculations. i'm not sure, but it seems box2D use single precision float as well.

i tweak simbicon a little and the only way i got something that looks like what i've seen in box2d is when i manually decrease left shin torque by 10 times, don't know what this mean

[galok]

i found 2D demo on java applet and i make a Delphi port of it (i'm using XE7), here is not so stable build and source, and frankly it's scary .
instead of a physics engine they use something that no carbon-based life form could ever understand, but it seems that balancing and walking part is present in normal code

SimbiconDelphi.zip

[galok]

first try to port it to box2d, this doesn't seem right

[Roland Chastain]

Hello! This isn't really what you asked for, but you may be interested in this FlashPascal demo:

http://flashpascal.execute.re/CubeMan3D.php

The source code is included in the examples shipped with the compiler.