Hello.
I'm writing because I've been having problems with the interaction between the parts in a box and the environment. There's a UR5 that's supposed to pick up objects in this box, but as it approaches the objects start to move, causing the arm's vaccum gripper to pick up the object incorrectly.
Even after increasing mass, inertia and density, the robot still manages to lift the object without it falling, as would be the case in real life.
Attached are the captures I made and various documents to better present my problem.
https://drive.google.com/file/d/1SFadwN ... sp=sharing
https://drive.google.com/file/d/1KqvD22 ... drive_link
Also already consulted this:
https://forum.coppeliarobotics.com/view ... ing#p36295
https://manual.coppeliarobotics.com/en/ ... erties.htm
https://forum.coppeliarobotics.com/viewtopic.php?t=7385
I look forward to hearing from you, and thank you in advance for your help and time.
Trouble with Object Dynamics and UR5 Gripper in Box Setup
Re: Trouble with Object Dynamics and UR5 Gripper in Box Setup
Hello,
what physics engine are you using?
what physics engine are you using?
- Make sure that the end-effector does not accidently touch the part before having the chance the attach it. Sometimes there are collisions occuring with invisible objects (when the models are not properly built)
- Depending on the engine you use, try to add some damping (linear and/or angular) to the parts to pick.
- When releasing the part, it first stays as a static object in the air (and often collides with the end-effector) before it falls again. How come? Do you have some custom code for that?
- Are you using the suction cup from the model library, or something else?
Re: Trouble with Object Dynamics and UR5 Gripper in Box Setup
Hello,
As a physics engine, I use Bullet, because it's the only one with which we've seen the least problems with dynamic objects.
To keep things simple, I thought a scene with as few elements as possible would allow us to solve one problem at a time. So here's the new scene and the experiments carried out in it:
https://drive.google.com/file/d/15Chmsp ... drive_link
https://drive.google.com/file/d/1C3-7Z8 ... drive_link
https://drive.google.com/file/d/1AiWGKH ... drive_link
https://drive.google.com/file/d/1UxAUM5 ... drive_link
https://drive.google.com/file/d/1nqEdKd ... drive_link
Et le nouveau model: https://drive.google.com/file/d/1GbCbNb ... drive_link
I'd also like to apologize for my late reply, i was sick, i'm recovering now.
Edit: i noticed the access was not available, i changed it, now public access.
As a physics engine, I use Bullet, because it's the only one with which we've seen the least problems with dynamic objects.
- Yes you're right, but for this case we don't build our models all maked from Coppelia. These boxes were created with custom dimensions via a script.
- Compared to linear/angular damping, we can add it manually, but not via scripts. Until now, we found no documentation for its properties in the doc https://manual.coppeliarobotics.com/en/ ... Parameters nor https://manual.coppeliarobotics.com/en/ ... htm#engine.
- We don't even know why, because we just disable the vaccum gripper. But instead of physics applying to the object, we notice that it's the script that does it: in fact, the next time the robot moves, the object suddenly becomes dynamic again, an effect we didn't include in our various scripts.
- The suction cup is Coppelia's in the Equipments section under the name suction Pad
To keep things simple, I thought a scene with as few elements as possible would allow us to solve one problem at a time. So here's the new scene and the experiments carried out in it:
https://drive.google.com/file/d/15Chmsp ... drive_link
https://drive.google.com/file/d/1C3-7Z8 ... drive_link
https://drive.google.com/file/d/1AiWGKH ... drive_link
https://drive.google.com/file/d/1UxAUM5 ... drive_link
https://drive.google.com/file/d/1nqEdKd ... drive_link
Et le nouveau model: https://drive.google.com/file/d/1GbCbNb ... drive_link
I'd also like to apologize for my late reply, i was sick, i'm recovering now.
Edit: i noticed the access was not available, i changed it, now public access.
Re: Trouble with Object Dynamics and UR5 Gripper in Box Setup
To add Bullet angular/linear damping, do this (in CoppeliaSim V4.8):
Almost everything is a property now.
If your end-effector is not dynamically enabled, then the suction cup might behave in a funny way. If you can post a self-contained, minimalistic version of your scene, then that would be most helpful.
Cheers
Code: Select all
sim.setFloatProperty(cylinderHandle, 'bullet.angularDamping', 0.99)
sim.setFloatProperty(cylinderHandle, 'bullet.linearDamping', 0.99)
If your end-effector is not dynamically enabled, then the suction cup might behave in a funny way. If you can post a self-contained, minimalistic version of your scene, then that would be most helpful.
Cheers
Re: Trouble with Object Dynamics and UR5 Gripper in Box Setup
Thanks, we will let you as soon as, a mimified version.
Have a nice day.
Have a nice day.
Re: Trouble with Object Dynamics and UR5 Gripper in Box Setup
Hello again,
Thanks a lot for your previous advice, it really helped me refine my setup! I’ve simplified the scene and updated the script to focus on the core issue. Like you will see, despite these improvements, I’m still encountering the same challenges.
Here are these files:
https://drive.google.com/file/d/192FBU- ... p=sharing
https://drive.google.com/file/d/1V7eqmn ... p=sharing
Thanks again for your time and support. I’m looking forward to hearing your thoughts!
Cheers,
Andrew.
Thanks a lot for your previous advice, it really helped me refine my setup! I’ve simplified the scene and updated the script to focus on the core issue. Like you will see, despite these improvements, I’m still encountering the same challenges.
Here are these files:
https://drive.google.com/file/d/192FBU- ... p=sharing
https://drive.google.com/file/d/1V7eqmn ... p=sharing
Thanks again for your time and support. I’m looking forward to hearing your thoughts!
Cheers,
Andrew.
Re: Trouble with Object Dynamics and UR5 Gripper in Box Setup
I am sorry, but I fail to understand what the problem is or what you are trying to do in those 2 scenes. In the first scene the approach to the cylinder is not correct (i.e. the end-effector is not vertical, but has a 90 degree angle. Also, the end-effector slightly touches the body that holds the clinders, and since that box is not static, it might move).
In the second scene the robot just does one motion and that's it. The cylinders move by themselves back and forth, but that is a specificity of most physics engine when you have a cylinder on a flat surface and no damping. If that is really that problematic, add damping, and if that doesn't have the desirec effect with your engine, model the cylinder as a compound of several cuboids: that model of a cylinder won't roll anymore.
Cheers
In the second scene the robot just does one motion and that's it. The cylinders move by themselves back and forth, but that is a specificity of most physics engine when you have a cylinder on a flat surface and no damping. If that is really that problematic, add damping, and if that doesn't have the desirec effect with your engine, model the cylinder as a compound of several cuboids: that model of a cylinder won't roll anymore.
Cheers
Re: Trouble with Object Dynamics and UR5 Gripper in Box Setup
Additionally, in scene 2, the base of the robot is touching and colliding with one of the tables...
Cheers
Cheers
Re: Trouble with Object Dynamics and UR5 Gripper in Box Setup
Hello,
I am writing to let you know that the issue is still not resolved even after I applied everything you said. Could you please provide a solution or additional steps to follow? Thank you in advance for your assistance.
Best regards and best wishes,
https://drive.google.com/file/d/1rd1VBF ... drive_link
https://drive.google.com/file/d/1-KwOWr ... sp=sharing
https://drive.google.com/file/d/1C96dnf ... sp=sharing
I am writing to let you know that the issue is still not resolved even after I applied everything you said. Could you please provide a solution or additional steps to follow? Thank you in advance for your assistance.
Best regards and best wishes,
https://drive.google.com/file/d/1rd1VBF ... drive_link
https://drive.google.com/file/d/1-KwOWr ... sp=sharing
https://drive.google.com/file/d/1C96dnf ... sp=sharing