[Question] Usage of retain_accelerations in RigidBodyPropertiesCfg?

[Soappyooo]

My RL env looks different when running on CPU and GPU.

Simply speaking, I apply a constant external force to a floating robot, and the env resets when robot fly out of boundary. I'm using dt=1/60 and render_interval=1, in a DirectRLEnv. I reset the robot root pose and velocity in _reset_idx function. I checked robot.data.body_acc_w and it's always all zero after reset.

However, with retain_accelerations=True in my robot's RigidBodyPropertiesCfg and using CPU, the acceleration seems to add up between resets. This does not happen when using GPU or retain_accelerations=False.

So, I'm wondering the usage of retain_accelerations. In example tasks, some of them use True and some of them use False, when should I use True or False? Does it works differently on CPU and GPU? Or is it a bug? I'm using IsaacLab 2.2.0 and IsaacSim 5.0.0. Thanks in advance.