Breaking physic change with CoppeliaSim 4.1

[HLalogeLC]

Hello,

We are experiencing strange behavior of our robot since version 4.1 for Ubuntu 20.04 of CoppeliaSim: movements are unpredictable, and the robot keeps moving back-and-forth because of a inacurate odometry. If I go back in 4.0, it works well (I used the Ubuntu 18.04 version and compiled the simExtension for ROS myself).
We are using the Newton engine.

Now, we are using a custom script to make our wheels work (holonomic wheels) with an invisible sphere, using sim.resetDynamicObject, sim.setObjectPositon/Rotation, and we use ROS to communicate with CoppeliaSim to control the robot. It is possible that the root of the problem is in this script.

I looked at the CoppeliaSim 4.1 changelog, and didn't find any changes that could cause this bug. So, I see three possibilities:

- Our wheel script relied on a bug that was fixed in 4.1.
- There is an unannounced breaking change in 4.1
- There is a new bug in 4.1.

Do someone experience the same breaking change in 4.1 ?

Regards,
Hugo Laloge

[HLalogeLC]

I found the problem by looking at the code of the KUKA Omnirob: I was missing the new flag sim.handleflag_reljointbaseframe when using sim.setObjectPositon/Rotation.