Search found 4180 matches

by Erwin Coumans
Sat Mar 09, 2019 1:26 am
Forum: PyBullet Support and Feedback
Topic: Spherical Joints
Replies: 10
Views: 1878

Re: Spherical Joints

The humanoidMotionCapture.py example shows how to use spherical drives. Also one of the humanoids in that example use resetJointStateMultiDof to set its state. Both modes works just fine with me. Please check it.
by Erwin Coumans
Sat Mar 09, 2019 1:24 am
Forum: PyBullet Support and Feedback
Topic: Position control for robot base?
Replies: 13
Views: 3158

Re: Position control for robot base?

You can attach the base to the (fixed) world frame with a couple of degrees of freedom. Then you can apply setJointMotorContro2 in POSITION_CONTROL mode, or VELOCITY_CONTROL mode to those degrees of freedom to move the base.
by Erwin Coumans
Sat Mar 09, 2019 1:21 am
Forum: PyBullet Support and Feedback
Topic: Simulating indirect drives
Replies: 1
Views: 431

Re: Simulating indirect drives

We currently don't have an API to exceed the maximum RPM of 100, but we probably should add it.

There is an old issue here, I should implement it:
https://github.com/bulletphysics/bullet3/issues/1890
by Erwin Coumans
Sat Mar 09, 2019 1:18 am
Forum: PyBullet Support and Feedback
Topic: Moving from Bullet 2 to Pybullet
Replies: 5
Views: 1280

Re: Moving from Bullet 2 to Pybullet

>> The visualization will be done using a 3D engine. >> - Motion states. Is your 3d engine also Python or C++? How do you want to synchronize the graphics transforms? Through C++ / shared memory, or using Python? If it happens in Python, we could add a method that receives only the updated objects. ...
by Erwin Coumans
Sat Mar 09, 2019 1:13 am
Forum: PyBullet Support and Feedback
Topic: PyBullet and ROS?
Replies: 1
Views: 890

Re: PyBullet and ROS?

It should be reasonably easy to write a bridge between ROS and PyBullet, for example in Python. PyBullet can already load URDF and SDF files and you can get all information and control through Python. Python can communicate to a PyBullet simulator and share ROS topics. There is no out-of-the box sol...
by Erwin Coumans
Thu Mar 07, 2019 4:15 am
Forum: General Bullet Physics Support and Feedback
Topic: Friction problem - Sphere isnt rolling on a straight line.
Replies: 8
Views: 2711

Re: Friction problem - Sphere isnt rolling on a straight line.

@Steven: Rolling friction works fine now, as long as you use btMultiBody, since we clamp against an implicit cone now, not against a pyramid. The fix is here: https://github.com/bulletphysics/bullet3/blob/master/src/BulletDynamics/Featherstone/btMultiBodyConstraintSolver.cpp#L116 The fix hasn't been...
by Erwin Coumans
Mon Mar 04, 2019 1:15 am
Forum: General Bullet Physics Support and Feedback
Topic: Friction problem - Sphere isnt rolling on a straight line.
Replies: 8
Views: 2711

Re: Friction problem - Sphere isnt rolling on a straight line.

OK, I got around implementing cone friction for rolling friction, so the two rolling friction directions are coupled and clamped against the friction cone together (instead of each rolling friction direction clamped against a friction pyramid).

https://github.com/bulletphysics/bullet3/pull/2138
by Erwin Coumans
Fri Mar 01, 2019 4:22 am
Forum: General Bullet Physics Support and Feedback
Topic: Friction problem - Sphere isnt rolling on a straight line.
Replies: 8
Views: 2711

Re: Friction problem - Sphere isnt rolling on a straight line.

Rolling friction indeed has an issue. We need to use cone friction for rolling friction (as we do for lateral friction). Will be fixed in a little while, see this issue: https://github.com/bulletphysics/bullet3/issues/2117 For now, disable rolling friction and manually apply some force (or use dampi...
by Erwin Coumans
Wed Feb 27, 2019 6:06 pm
Forum: PyBullet Support and Feedback
Topic: Spherical Joints
Replies: 10
Views: 1878

Re: Spherical Joints

This PR exposes the torques: https://github.com/bulletphysics/bullet3/pull/2130 Thanks for the report! By the way, the DeepMimic humanoid can be trained using stable PD control now: https://www.youtube.com/watch?v=aiWxIjtMMFI When switching to spherical joint motors, the policy doesn't train. See th...
by Erwin Coumans
Wed Feb 27, 2019 4:22 pm
Forum: PyBullet Support and Feedback
Topic: Pybullet not rendering correctly
Replies: 9
Views: 1345

Re: Pybullet not rendering correctly

This is likely some Intel OpenGL driver issue
~~~~~~
Version = 3.3 INTEL-10.4.14
Vendor = Intel Inc.
Renderer = Intel HD Graphics 3000 OpenGL Engine
~~~~~~~
by Erwin Coumans
Wed Feb 27, 2019 4:19 pm
Forum: General Bullet Physics Support and Feedback
Topic: Can i help Bullet to resolve collisions
Replies: 2
Views: 407

Re: Can i help Bullet to resolve collisions

A few things to try: * use a smaller simulation step * increase the number of solver iterations * use a direct solver, Bullet provides Dantzig MLCP solver, see some of the examples in the ExampleBrowser * Use a btBoxShape for the ground * Enable SAT, separating axis test if you use btConvexHullShape...
by Erwin Coumans
Tue Feb 26, 2019 12:52 am
Forum: PyBullet Support and Feedback
Topic: Remove Collision from an entire MultiBody
Replies: 4
Views: 970

Re: Remove Collision from an entire MultiBody

Good to hear it is fixed!
by Erwin Coumans
Tue Feb 26, 2019 12:52 am
Forum: PyBullet Support and Feedback
Topic: Spherical Joints
Replies: 10
Views: 1878

Re: Spherical Joints

Spherical joints still need a bit more work indeed. I'll add the getJointStateMultiDof for spherical joints soon. setJointMotorControlMultiDof indeed sets the maxForce. It is not misnamed: if you set a target velocity of 0, the joint motor can model joint friction given the maximum (friction) force....
by Erwin Coumans
Tue Feb 26, 2019 12:44 am
Forum: PyBullet Support and Feedback
Topic: Pybullet not rendering correctly
Replies: 9
Views: 1345

Re: Pybullet not rendering correctly

Do the regular Bullet examples work? For example, what do you see if you run
~~~~~~~
python3 -m pybullet_envs.examples.testBike
~~~~~~~
(its implementation is testBike.py)

I see this, on Mojave 10.14.3:

bike.png
bike.png (358.08 KiB) Viewed 1301 times
When I run your script, it shows the R2D2 indeed, on the ground plane.
by Erwin Coumans
Fri Feb 22, 2019 7:45 pm
Forum: PyBullet Support and Feedback
Topic: Simulating closed loop structure in PyBullet
Replies: 1
Views: 439

Re: Simulating closed loop structure in PyBullet

SDF and URDF files need to be tree structure/ open loop. PyBullet provides user constraints to close loops. See our Minitaur example how to add such constraint. https://github.com/bulletphysics/bullet3/blob/master/examples/pybullet/gym/pybullet_envs/minitaur/envs/minitaur.py#L391 See createConstrain...