Search found 4221 matches
- Wed Mar 11, 2020 11:56 pm
- Forum: PyBullet Support and Feedback
- Topic: Documents for creating environments for grasping
- Replies: 1
- Views: 7055
Re: Documents for creating environments for grasping
First, you need to learn how to create an OpenAI Gym environment with PyBullet: https://medium.com/@gerardmaggiolino/creating-openai-gym-environments-with-pybullet-part-1-13895a622b24 then you should investigate how this script works: https://github.com/bulletphysics/bullet3/blob/master/examples/pyb...
- Tue Mar 10, 2020 4:05 am
- Forum: PyBullet Support and Feedback
- Topic: Maximum number of multibody links?
- Replies: 2
- Views: 8078
Re: Maximum number of multibody links?
There is currently a maximum of 128 links (see MAX_DEGREE_OF_FREEDOM)
The intention was for typical robots, which usually have only tens of links.
The intention was for typical robots, which usually have only tens of links.
- Fri Dec 20, 2019 12:12 am
- Forum: PyBullet Support and Feedback
- Topic: JOINT_PLANAR/SPHERICAL problem
- Replies: 2
- Views: 8329
Re: JOINT_PLANAR/SPHERICAL problem
We only tested spherical joints in deep_mimic through URDF, not programmatically. Have you tried that? Here is a patch that enables spherical joint creation through the API (instead of URDF): https://github.com/bulletphysics/bullet3/pull/2551 Attached is an example that works after applying this pat...
- Fri Dec 20, 2019 12:08 am
- Forum: PyBullet Support and Feedback
- Topic: Inaccurate RayTest in Pybullet
- Replies: 2
- Views: 7751
Re: Inaccurate RayTest in Pybullet
Yes, by default we use convex hulls. Best to create a convex decomposition for moving objects (using VHACD, there are utils from obj -> vhacd). See this example: https://github.com/bulletphysics/bullet3/blob/master/data/teddy_vhacd.urdf For concave static trangle meshes, you can mark them as 'concav...
- Mon Dec 09, 2019 5:32 pm
- Forum: General Bullet Physics Support and Feedback
- Topic: curved trajectory(rolling Friction) fix for bullet in unity
- Replies: 6
- Views: 11198
Re: curved trajectory(rolling Friction) fix for bullet in unity
Good point, I will create a 2.89 release soon (in October was just a file change, not a real 'tag')
- Fri Nov 22, 2019 4:56 am
- Forum: General Bullet Physics Support and Feedback
- Topic: Maximum angular velocity
- Replies: 5
- Views: 12001
Re: Maximum angular velocity
>> I know how to shift CoM before the simulation starts with createMultibody, but how to do it during the simulation I recommend to create an additional link (without visual shape, but with some collision shape) along a slider joint, and move that link. You can change the mass of that link using pyb...
- Wed Nov 20, 2019 5:56 pm
- Forum: General Bullet Physics Support and Feedback
- Topic: Collision detection failed for Ellipsoid shapes
- Replies: 7
- Views: 14861
Re: Collision detection failed for Ellipsoid shapes
drleviathan makes good points.
Aside from that, you could provide a full working small example (single c++ file, no dependencies other than Bullet) and file an issue here:
https://github.com/bulletphysics/bullet3
it accepts zip file attachments, or just add the code inline.
Aside from that, you could provide a full working small example (single c++ file, no dependencies other than Bullet) and file an issue here:
https://github.com/bulletphysics/bullet3
it accepts zip file attachments, or just add the code inline.
- Thu Oct 24, 2019 1:58 am
- Forum: PyBullet Support and Feedback
- Topic: What's the best way to pin a rigid body to another rigid body?
- Replies: 1
- Views: 7884
Re: What's the best way to pin a rigid body to another rigid body?
The best way is to create a new URDF and attach them as a fixed joint. You can use the URDF editor to do this. See this example how to combine a car and a kuka: https://github.com/bulletphysics/bullet3/blob/master/examples/pybullet/gym/pybullet_utils/examples/combineUrdf.py Alternatively, you get so...
- Thu Oct 24, 2019 1:56 am
- Forum: PyBullet Support and Feedback
- Topic: How to convert rotation matrix to quaternion in PyBullet
- Replies: 2
- Views: 12885
Re: How to convert rotation matrix to quaternion in PyBullet
Only Euler <-> Quaternion conversions are exposed in PyBullet, not the Matrix <-> Quaternion yet.
- Thu Oct 24, 2019 1:55 am
- Forum: PyBullet Support and Feedback
- Topic: Segment-wise collision detection
- Replies: 1
- Views: 7019
Re: Segment-wise collision detection
You could use getClosestPoints to get a better conservative answer how far you can safely move, and then use bigger steps along your trajectory.
- Thu Oct 24, 2019 1:53 am
- Forum: PyBullet Support and Feedback
- Topic: The difference between setJointMotorControl2 and resetJointState
- Replies: 1
- Views: 7439
Re: The difference between setJointMotorControl2 and resetJointState
reset* functions teleport the robot into some state, ignoring all dynamics. setJointMotorControl2 will set some targets and let the simulation try to achieve those, so they obey the laws of physics. The examples may use one or the other. It is best to never use reset* functions while simulating, onl...
- Thu Sep 05, 2019 2:35 pm
- Forum: PyBullet Support and Feedback
- Topic: Dynamically attached fixed joint is not fix
- Replies: 2
- Views: 10622
Re: Dynamically attached fixed joint is not fix
Mouse forces are very strong and possibly stronger than the fixed joint constraint forces. It is better to attach a fixed joint as part of the urdf instead of using a constraint.
- Thu Sep 05, 2019 2:34 pm
- Forum: General Bullet Physics Support and Feedback
- Topic: Chain of constraints is very unstable if masses differ
- Replies: 2
- Views: 6557
Re: Chain of constraints is very unstable if masses differ
You can use btMultiBody instead, together with some velocity motors to model joint friction/damping. It is easiest to prototype this directly in PyBullet first, see its quickstart guide . For btRigidBody, using a smaller time step would help more than increasing the number of iterations, but btMulti...
- Sat Aug 24, 2019 12:26 am
- Forum: PyBullet Support and Feedback
- Topic: Connecting pybullet to a C++ Bullet Physics instance?
- Replies: 1
- Views: 7879
Re: Connecting pybullet to a C++ Bullet Physics instance?
Yes, you can create a PyBullet server and client and also connect to this from a C++ client using the C-API, which is pretty much identical to the PyBullet API (PyBullet uses this same C API). The API header file is here: https://github.com/bulletphysics/bullet3/blob/master/examples/SharedMemory/Phy...
- Sat Aug 24, 2019 12:23 am
- Forum: General Bullet Physics Support and Feedback
- Topic: Create bullet shape from .obj mesh
- Replies: 5
- Views: 13947
Re: Create bullet shape from .obj mesh
PyBullet has some examples that create a mesh (convex or concave) from an .obj file or from vertices in memory. See https://github.com/bulletphysics/bullet3/blob/master/examples/pybullet/examples/createMesh.py https://github.com/bulletphysics/bullet3/blob/master/examples/pybullet/examples/createText...