Can Bullet import Solidworks model completely?

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sajjjjad
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Joined: Mon Sep 17, 2012 8:09 am

Can Bullet import Solidworks model completely?

Post by sajjjjad »

Hi,
I have been working on the Humanoid Robot Simulation project for quite a while now and I have some difficulties linking exported model from Solidworks and Catia into my project and linking them with bullet physics engine.
In order to do that I used Collada Export plugin in Solidworks to export my model and import it in bullet engine, however it did not work. Kinematics and articulated systems and mess of objects was distorted, for example the mass of objects were zero and all the rigid bodies were static. Also it could not recognize any of model's joints.

Does Colloda Export plugin have any problem exporting models or is it Bullet which can not import the Collada exported model?

I have to say that I used the Collada 1.4, since I have heard there is some problem in exporting kinematics and articulated systems which are solved in collada 1.5, is it correct?

I tried Blender too, I exported wrl and stl files from solidworks and gave them to Blender, then I used the .bullet file exported from Blender in my program. Unfortunately it could not recognize kinematics and articulated systems and mess of objects.

Does solidworks export these properties to wrl or stl files?
And is Blender capable of importing these properties from wrl or stl files?

In order to get better view of what is going on I created a simple model in solidworks and exported it to Blender. I used triangleMesh for modeling the rigid bodies. The problem with Blender was the rotation of the joints, they did not rotate with specific pivot points that I had entered.

I imported the .bullet file from Blender into my project. But Bullet just ignored some of rigid bodies and deleted them, gave following error:
"Overflow in AABB, object removed from simulation
If you can reproduce this, please email bugs@continuousphysics.com
Please include above information, your Platform, version of OS."

After doing all this I came to ask this and appreciate it if you could answer me, is there any way which you can export the Solidwokrs or Catia model into Bullet correctly?
And more importantly is Bullet a proper tool for simulating these kind of project (Humanoid Robot Simulation)?
I mean if you could import the model correctly into the Bullet, can Bullet simulate these model similar to the real physical objects?
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Erwin Coumans
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Re: Can Bullet import Solidworks model completely?

Post by Erwin Coumans »

Can you share some Solidworks COLLADA files and attach them (zipped) to this topic?

What version of Solidworks are you using exactly?
I mean if you could import the model correctly into the Bullet, can Bullet simulate these model similar to the real physical objects?
Yes, Bullet can simulate robots, but to get high quality accurate results, you have to use a very small timestep, many solver iterations and double precision (#define BT_USE_DOUBLE_PRECISION in all C++ projects)

Code: Select all

world->getSolverInfo().m_numIterations=1000;
world->stepSimulation(1./1000.f,0);
Thanks,
Erwin
sajjjjad
Posts: 5
Joined: Mon Sep 17, 2012 8:09 am

Re: Can Bullet import Solidworks model completely?

Post by sajjjjad »

SolidWorks 2012 x64
Collada file : http://mowlaei.com/collada.zip
Thanks
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Erwin Coumans
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Re: Can Bullet import Solidworks model completely?

Post by Erwin Coumans »

You might want to try Solidworks to URDF and then convert URDF to Bullet (that code is not written yet).

See http://www.willowgarage.com/blog/2012/1 ... solidworks
sajjjjad
Posts: 5
Joined: Mon Sep 17, 2012 8:09 am

Re: Can Bullet import Solidworks model completely?

Post by sajjjjad »

What do you suggest for converting URDF format to COLLADA? May I use the ROS (Robot Operating System) to convert URDF to COLLADA?
Please take a look at this link: http://www.ros.org/wiki/collada_urdf/Tu ... %20COLLADA
Is ROS converter compatible with Bullet? Will you publish the URDF importer in the next version of the Bullet?
Thanks in advanced
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