LHD sim using BGE for forward kinematics with collision

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lcdumais
Posts: 1
Joined: Mon Jan 19, 2009 3:33 am

LHD sim using BGE for forward kinematics with collision

Post by lcdumais » Mon Jan 19, 2009 3:50 am

Hi,

I'm trying to build an E-learning simulator using blender game engine for the operation of a LHD machine (It's like a low profile construction loader). A good video presentation for these machines is located at: http://ca.youtube.com/watch?v=a06BhehuzdE .

I have been trying to do a model of the machine in the game engine without success. I tried many things but each time something didnt work. (If the forward kinematics works, than the collision detection model is wrong. If the collision dectection model works, then the forward cinematics does'nt work).

I would like to know if someone has a suggestions about the "best" way to model the machine in blender(maybe it's impossible with the current state of the software). I present here some approaches I used:

1. The simpler method that I tried was to use a tree of objects(parent and children). The child would rotate according to local coordinates using the classics kinematics approach for positioning an object:
parent->position + parent->rotation+ object->position + object->orientation

I had the following hierarchy

"cn_full" (the parent node)
.|
.+----cn_rframe
.........+
..........|
..........+---cn_fframe
...............+
...............|
...............+----cn_boom
......................+
......................|
......................+----cn_bucket

This approach worked fine but the collision model is wrong. I submitted a bug about this on the blender bug tracker(see the image attached).
problem_collision_simulation_running.png
problem_collision_simulation_running.png (102.25 KiB) Viewed 2581 times
Maybe there is a way to force a collision model regeneration?


2. The second promising attempt is to use all separate object using the RigidBody joint approach. However, I could not find a way for the boom and the bucket to stay horizontal.
problem_constraint_20090118a.png
problem_constraint_20090118a.png (99.69 KiB) Viewed 2581 times
I tried to add hydraulic without success (the physics engine went crazy).

(I would like to provide a .blend file, just write to lcdumais()hotmail!com).

I'm running a little bit out of options. Maybe a pure python script approach could solve my problem. I'm looking for any suggestion you could have.

Sincerely,
louis

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