Search found 57 matches

by steven
Mon Jul 01, 2019 12:47 pm
Forum: PyBullet Support and Feedback
Topic: What accuracy to expect for trajectory tracking using position control
Replies: 6
Views: 600

Re: What accuracy to expect for trajectory tracking using position control

in the second case, the robot collides with the ground which will impact the links and joints of the robot.
by steven
Sun Jun 30, 2019 5:45 am
Forum: PyBullet Support and Feedback
Topic: What accuracy to expect for trajectory tracking using position control
Replies: 6
Views: 600

Re: What accuracy to expect for trajectory tracking using position control

thanks for your sharing. why did you said "maximum of 0.01 for some joint"? i add the following to print the max delta, the value is about 0.006. how much tracking accuracy do you need? the accuracy is very high if don't care about the velocity. print("max value=", np.max(robotlog[mask,17:23] - qeva...
by steven
Fri Jun 28, 2019 1:39 am
Forum: PyBullet Support and Feedback
Topic: What accuracy to expect for trajectory tracking using position control
Replies: 6
Views: 600

Re: What accuracy to expect for trajectory tracking using position control

Could you provide a complete simple test? i can work with you to find the root cause.
by steven
Wed May 29, 2019 11:51 am
Forum: General Bullet Physics Support and Feedback
Topic: Incorrect results when simulating multiple bodies
Replies: 8
Views: 675

Re: Incorrect results when simulating multiple bodies

hi tgreif,
sorry, it is hard for me to reproduce your issue. hope next time i can help you. good luck!
by steven
Mon May 27, 2019 12:21 pm
Forum: General Bullet Physics Support and Feedback
Topic: Incorrect results when simulating multiple bodies
Replies: 8
Views: 675

Re: Incorrect results when simulating multiple bodies

Could you tell me the initial postion of these two meshes, as well as some parameters, such as the initial velocity, friction, mass or other values? thanks.
by steven
Mon May 27, 2019 11:19 am
Forum: General Bullet Physics Support and Feedback
Topic: Incorrect results when simulating multiple bodies
Replies: 8
Views: 675

Re: Incorrect results when simulating multiple bodies

Could you attach your stl files and code snippet of how did you create your world? i want to reproduce it and then debug it to find the root cause.
thanks!
by steven
Sun May 26, 2019 2:12 pm
Forum: PyBullet Support and Feedback
Topic: Issues with velocity control
Replies: 5
Views: 702

Re: Issues with velocity control

update the procedure of this case. 1. apply the gravity to the multibody then will change the velocity, 2. apply the constraints, including 1> jointMotor constraint that will try to change the velocity back to the targetVelocity, 0 for your case; 2> Fixed constraint 3> contact constraint and frictio...
by steven
Thu May 23, 2019 6:36 pm
Forum: PyBullet Support and Feedback
Topic: Issues with velocity control
Replies: 5
Views: 702

Re: Issues with velocity control

Could you also attach all the mesh files? thanks.

Code: Select all

b3Printf: ur5_free_base.urdf:24: cannot find 'meshes/ur5/visual/base.dae' in any directory in urdf path
by steven
Thu May 23, 2019 7:21 am
Forum: PyBullet Support and Feedback
Topic: Issues with velocity control
Replies: 5
Views: 702

Re: Issues with velocity control

Could you attach a complete simple test? i can debug it with you to find what happened there. so far my understanding about the procedure: 1. apply the gravity to the multibody then will change the velocity, 2. apply the jointMotor constraint that will change the velocity back to the targetVelocity,...
by steven
Tue May 21, 2019 11:27 am
Forum: General Bullet Physics Support and Feedback
Topic: SoftBody: modeling a rope from trimesh
Replies: 6
Views: 783

Re: SoftBody: modeling a rope from trimesh

i find that there are duplicated vertex in the array of gVerticesRope, the engine will create a node for each vertex when this array is passed to the btSoftBody(), so there will be more than one node for a same point that is not what we expect. i think you need to re-design your gVerticesRope/gIndic...
by steven
Mon May 20, 2019 1:53 am
Forum: General Bullet Physics Support and Feedback
Topic: SoftBody: modeling a rope from trimesh
Replies: 6
Views: 783

Re: SoftBody: modeling a rope from trimesh

Could you first change your mesh? i would like to work with you to find the root cause.
i also noted that the first and last note are not located at the end of this rope.
by steven
Sun May 19, 2019 10:42 am
Forum: PyBullet Support and Feedback
Topic: Joint friction
Replies: 5
Views: 480

Re: Joint friction

you can google the damping then you can know what the damping is used for. the damping force is a resistence that proportional to the velocity but in the opposite direction. as for the implementation in this engine, honestly so far i still don't understand what that equation below comes from. for mo...
by steven
Fri May 17, 2019 9:12 am
Forum: PyBullet Support and Feedback
Topic: Joint friction
Replies: 5
Views: 480

Re: Joint friction

1. p.setJointMotorControl2(obj,1,p.VELOCITY_CONTROL,targetVelocity=0,force=frictionForce)
2. p.changeDynamics(obj,j,linearDamping=value1, angularDamping=value2)

for my understanding, these two get the similar result with different methods. you can try it and see if get what you want.
by steven
Fri May 17, 2019 1:45 am
Forum: PyBullet Support and Feedback
Topic: Joint friction
Replies: 5
Views: 480

Re: Joint friction

self._p.setJointMotorControlArray(self.kuka_uid, self._motor_indices, self._p.VELOCITY_CONTROL, forces=np.zeros(len(self._motor_indices))) i think this is a method to simulate the joint friction, like the angularDamping. self._p.changeDynamics(self.kuka_uid, self._motor_indices, lateralFriction=fri...