Search found 81 matches

by steven
Sun Jul 05, 2020 7:07 am
Forum: PyBullet Support and Feedback
Topic: setJointMotorControl2 won't assign correct force value to certain joints
Replies: 5
Views: 272

Re: setJointMotorControl2 won't assign correct force value to certain joints

thanks for you reply.
this issue is caused by that the mass of the lower legs are too small, so far i don't know how to fix this. i just increase the mass to workaound this.
by steven
Sun Jul 05, 2020 3:18 am
Forum: PyBullet Support and Feedback
Topic: setJointMotorControl2 won't assign correct force value to certain joints
Replies: 5
Views: 272

Re: setJointMotorControl2 won't assign correct force value to certain joints

Can't reproduce your issue? Could you provide all the files? thanks.

cannot find 'MQ_SIM_ASEM/meshes/Chassis.STL' in any directory in urdf path
by steven
Sat May 09, 2020 1:26 am
Forum: PyBullet Support and Feedback
Topic: calculateMassMatrix inconsistent with RBDL
Replies: 6
Views: 834

Re: calculateMassMatrix inconsistent with RBDL

http://www.doc88.com/p-9833547094235.html
not sure if you can access this link, also wanted to attach the pdf for your reference but it is too large about 32M for this web. i can email to you if you need.
by steven
Fri May 08, 2020 11:10 am
Forum: PyBullet Support and Feedback
Topic: calculateMassMatrix inconsistent with RBDL
Replies: 6
Views: 834

Re: calculateMassMatrix inconsistent with RBDL

adding this 'flags=pb.URDF_USE_INERTIA_FROM_FILE' when loading the urdf can fix this.
by steven
Thu May 07, 2020 1:59 pm
Forum: PyBullet Support and Feedback
Topic: calculateMassMatrix inconsistent with RBDL
Replies: 6
Views: 834

Re: calculateMassMatrix inconsistent with RBDL

thanks for your reply, i have found the orignal paper for bullet and i will check it and try to find the cause.
by steven
Thu Apr 30, 2020 3:36 am
Forum: PyBullet Support and Feedback
Topic: bot gets unstable and blows away after some time
Replies: 4
Views: 692

Re: bot gets unstable and blows away after some time

i find the velocity will oscillate and the amplitude will get bigger and bigger. i think it should be the issue of the PD parameters.
adding a velocity boundary of [-10,10] can fix this. just for your reference.
by steven
Wed Apr 29, 2020 1:54 am
Forum: PyBullet Support and Feedback
Topic: calculateMassMatrix inconsistent with RBDL
Replies: 6
Views: 834

Re: calculateMassMatrix inconsistent with RBDL

Do you have any progress? Could you tell me why did you compare the MassMatrix between them? thanks.
by steven
Tue Nov 26, 2019 12:52 am
Forum: General Bullet Physics Support and Feedback
Topic: Collision detection failed for Ellipsoid shapes
Replies: 7
Views: 1330

Re: Collision detection failed for Ellipsoid shapes

temp = (*pos) + m_localScaling * (vec * m_localScaling).normlized() * (*rad) - vec * getMargin(); feel it should be like this: temp = (*pos) + m_localScaling * (vec / m_localScaling).normalized() * (*rad) - vec * getMargin(); i will check if the points on the ellipsoid can be expressed by this func...
by steven
Mon Nov 25, 2019 2:38 am
Forum: General Bullet Physics Support and Feedback
Topic: Collision detection failed for Ellipsoid shapes
Replies: 7
Views: 1330

Re: Collision detection failed for Ellipsoid shapes

adding this shape->setMargin(0) can avoid this issue but i still can't understand what caused this issue. i have some questions when review this code below in line 76 of btMultiSphereShape.cpp. temp = (*pos) * m_localScaling + vec * m_localScaling * (*rad) - vec * getMargin(); 1. why the origin pos ...
by steven
Thu Nov 14, 2019 7:14 am
Forum: General Bullet Physics Support and Feedback
Topic: What parameters to tune to stabilize collisions
Replies: 8
Views: 1588

Re: What parameters to tune to stabilize collisions

hi JJJK,
i still suspect that this is caused by the non-suitable actions. i find the every joint of the human description with URDF format doesn't have any limitation while in the MJCF format it does.
hope you can update your latest demo.
thanks.
by steven
Tue Nov 12, 2019 7:53 am
Forum: General Bullet Physics Support and Feedback
Topic: What parameters to tune to stabilize collisions
Replies: 8
Views: 1588

Re: What parameters to tune to stabilize collisions

hi all,
i have another question not specific to this case, where does the motor constraint force come from? this force will increase the system energy? thanks.
by steven
Tue Nov 12, 2019 12:55 am
Forum: General Bullet Physics Support and Feedback
Topic: What parameters to tune to stabilize collisions
Replies: 8
Views: 1588

Re: What parameters to tune to stabilize collisions

did you only change the robot description to the pybullet_data/mjcf/humanoid.xml then it can work now? did you have any other changes? could you also attach them also? thanks.
by steven
Mon Nov 11, 2019 9:37 am
Forum: General Bullet Physics Support and Feedback
Topic: What parameters to tune to stabilize collisions
Replies: 8
Views: 1588

Re: What parameters to tune to stabilize collisions

looks not so reasonable. I will check it again later.
by steven
Mon Nov 11, 2019 9:00 am
Forum: General Bullet Physics Support and Feedback
Topic: What parameters to tune to stabilize collisions
Replies: 8
Views: 1588

Re: What parameters to tune to stabilize collisions

i just take a test that change the gravity acceleration to setGravity(0, 0, -0.981) and set robot initial position to robot_init_pos=(0, 0, 200) and then after a while we can find that the base velocity sometimes become very large. i also debug this case and find the acceleration of the base and joi...