Search found 4101 matches

by Erwin Coumans
Thu Sep 13, 2018 3:32 am
Forum: PyBullet Support and Feedback
Topic: How to disable collisions?
Replies: 2
Views: 326

Re: How to disable collisions?

I just implemented a few ways to do it: Disable collisions per object pair / link: enableCollision= 0 pybullet.setCollisionFilterPair(objectUniqueIdA, objectUniqueIdB, linkIndexA, linkIndexB, enableCollision) or disable collisions per group of objects: group = 0#other objects don't collide with me m...
by Erwin Coumans
Thu Sep 13, 2018 3:27 am
Forum: PyBullet Support and Feedback
Topic: Getting simulation time in pybullet
Replies: 1
Views: 45

Re: Getting simulation time in pybullet

It is not exposed, you have to keep track of it yourself at the moment.
by Erwin Coumans
Wed Sep 12, 2018 6:16 pm
Forum: General Bullet Physics Support and Feedback
Topic: Bullet MediaWiki and online documentation is not accessible.
Replies: 1
Views: 142

Re: Bullet MediaWiki and online documentation is not accessible.

We had to move to a new server (after 15 years!) and only the forum and the wordpress frontpage are fully ported.

The online doxygen generated documentation should be working now (check it).
There is no wiki on the server at the moment, most of the information on the wiki was very out-of-date anyway.
by Erwin Coumans
Wed Sep 12, 2018 4:14 pm
Forum: PyBullet Support and Feedback
Topic: Inverse Dynamics Algorithm
Replies: 1
Views: 46

Re: Inverse Dynamics Algorithm

The computation of the joint space inertia (mass) matrix matrix is using the Composite Rigid Body Algorithm. // The algorithm is essentially an implementation of "method 3" // in "Efficient Dynamic Simulation of Robotic Mechanisms" (Walker and Orin, 1982) // (Later named "Composite Rigid Body Algori...
by Erwin Coumans
Thu Aug 16, 2018 5:12 pm
Forum: General Bullet Physics Support and Feedback
Topic: Precision of getClosestPoints calculation ?
Replies: 2
Views: 243

Re: Precision of getClosestPoints calculation ?

Using an extremely small margin and changing the setEqualVertexThreshold is not supported. Also, make sure to use the double precision version. Also, I made some fix in the btGjkPairDetector.cpp related to degenerate cases here. You may want to share a small reproduction case based on a modified exa...
by Erwin Coumans
Mon Jul 09, 2018 7:27 am
Forum: General Bullet Physics Support and Feedback
Topic: When building URDF models, which visualizer do you use?
Replies: 3
Views: 397

Re: When building URDF models, which visualizer do you use?

Well, we use PyBullet for that, is can visualize URDF, SDF and MJCF etc. Also, it has utilities to show inertial boxes and in wireframe mode it can show joint axis etc.

You can see a few screenshots in the PyBullet Quickstart Guide.
by Erwin Coumans
Thu Jun 14, 2018 6:48 pm
Forum: PyBullet Support and Feedback
Topic: How well suited is PyBullet to Domain Randomization for Sim-to-Real?
Replies: 1
Views: 228

Re: How well suited is PyBullet to Domain Randomization for Sim-to-Real?

Various projects inside Google use PyBullet with domain randomization, there are plenty of PyBullet Python APIs to change dynamics and visuals. Aside from PyBullet APIs, you can also use the UrdfEditor to modify any URDF setting (link sizes, joint pivot location etc). >> PyBullet to handle texture r...
by Erwin Coumans
Wed Jun 06, 2018 3:49 pm
Forum: PyBullet Support and Feedback
Topic: Position control for robot base?
Replies: 4
Views: 406

Re: Position control for robot base?

Indeed, you should not call resetBasePositionAndOrientation during the simulation, since it is an abrupt change that ignore and violates all dynamics, and likely give bad simulations and artifacts. If you reset the simulation (right after loading the URDF file or when teleporting a robot back to its...
by Erwin Coumans
Wed May 09, 2018 12:54 am
Forum: General Bullet Physics Support and Feedback
Topic: stepSimulation freezes for large number of multi body objects.
Replies: 2
Views: 319

Re: stepSimulation freezes for large number of multi body objects.

Is this C++ or PyBullet? You should be able to profile timings and gradually increase the number of robots.

We are not clearvoyant: try to file an issue in the tracker and provide a simple reproduction case.

https://github.com/bulletphysics/bullet3/issues
by Erwin Coumans
Thu May 03, 2018 2:56 pm
Forum: General Bullet Physics Support and Feedback
Topic: CPU multithreading is working!
Replies: 145
Views: 45649

Re: CPU multithreading is working!

Thanks for the reply. Can you report the issue in the Bullet https://github.com/bulletphysics/bullet3/issues tracker, so we can track progress on fixes? 1. My program using single-threaded btDiscreteDynamicsWorld crashed because of btSequentialImpulseConstraintSolver::getOrInitSolverBody method retu...
by Erwin Coumans
Thu May 03, 2018 2:52 pm
Forum: General Bullet Physics Support and Feedback
Topic: Maximum angular velocity
Replies: 2
Views: 275

Re: Maximum angular velocity

You can override the maximum angular velocity using btMultiBody::setMaxCoordinateVelocity

This maximum velocity is a safety mechanism, to avoid energies going to infinity.

What are you trying to achieve with a very high velocity?
by Erwin Coumans
Thu May 03, 2018 1:38 pm
Forum: General Bullet Physics Support and Feedback
Topic: Is diagonlize/extractRotation broken, i.e., does nothing? see 3 lines of example code and try yourself
Replies: 3
Views: 225

Re: Is diagonlize/extractRotation broken, i.e., does nothing? see 3 lines of example code and try yourself

The original btMatrix3x3::diagonalize method should work for symmetric matrices. Recently (2017) I replaced it with a diagonalize method based on the "A Robust Method to Extract the Rotational Part of Deformations" paper and its extractRotation implementation, but the resulting rotation still includ...
by Erwin Coumans
Thu May 03, 2018 1:26 pm
Forum: General Bullet Physics Support and Feedback
Topic: Someone familiar with btMultiBody please let me know if this is correct.
Replies: 3
Views: 521

Re: Someone familiar with btMultiBody please let me know if this is correct.

I strongly recommend first using the PyBullet Python bindings, and loading URDF or SDF files, it is documented in the https://docs.google.com/document/d/10sXEhzFRSnvFcl3XxNGhnD4N2SedqwdAvK3dsihxVUA/edit#heading=h.2ye70wns7io3 . Our recent RSS paper (Sim-to-Real: Learning Agile Locomotion For Quadrup...
by Erwin Coumans
Wed Apr 11, 2018 7:14 am
Forum: PyBullet Support and Feedback
Topic: pyBullet vs Gazebo
Replies: 3
Views: 817

Re: pyBullet vs Gazebo

Ultimately you can try out both and decide for yourself. It seems that Gazebo uses Bullet Gazebo uses btRigidBody from Bullet (maximal coordinate rigid bodies) which is not necessary the best way for robotics, it allows for joint gap. PyBullet uses Featherstone articulated rigid bodies (btMultiBody)...