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JointMotor for urdf robot franka_panda

Posted: Fri May 29, 2020 4:24 pm
by cutman2593
Hello,

I'm working on a C++ project about a robotic arm and I chose Bullet to handle the IK/FK of the robot and some physics besides it.

I use python for my tests and my workspace corresponds to the panda_sim of the repository 'pybullet'. I tweaked it a little to apply a motor on the first joint using the function 'SetJointMotorControl2' and I also set the initial joint/rest positions for all links to 0. So in the method 'panda_sim.py::step', there is only one line used to apply the motor :

Code: Select all

self.bullet_client.setJointMotorControl2(self.panda, 0, self.bullet_client.VELOCITY_CONTROL, 
							targetVelocity=-1, force = 1000)
The motor starts alright and is steady, however when time passes by, the other joints starts to rotate as well and in the end, everything goes wrong and the motor doesn't rotate the first joint anymore. Is there a way to block revolute positions of other joints to allow the rotation movement joint by joint (which corresponds to simple FK) ?

Thanks for reading.
Johann NOVAK

Re: JointMotor for urdf robot franka_panda

Posted: Tue Jun 16, 2020 5:54 pm
by Erwin Coumans
It appears as if you are driving a strong motor against a joint limit, this won't work properly so try to avoid doing that.