Adds scene update to ManagerBasedEnv and DirectRLEnv initialization (#1809)

# Description

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This PR fixes execution of imu (and other sensor) based observation by
updating the scene at the initialization of ManagerBasedEnv and
DirectRLEnv. This ensures the Imu._dt (and any other scene buffers) are
set before extracting Imu.data.

Fixes #1423 

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## Type of change

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- Bug fix (non-breaking change which fixes an issue)

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## Checklist

- [x] I have run the [`pre-commit` checks](https://pre-commit.com/) with
`./isaaclab.sh --format`
- [x] I have made corresponding changes to the documentation
- [x] My changes generate no new warnings
- [ ] I have added tests that prove my fix is effective or that my
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---------
Signed-off-by: James Tigue <166445701+jtigue-bdai@users.noreply.github.com>
Signed-off-by: Kelly Guo <kellyg@nvidia.com>
Co-authored-by: Kelly Guo <kellyg@nvidia.com>

source/isaaclab/config/extension.toml

 [package]
 
 # Note: Semantic Versioning is used: https://semver.org/
-version = "0.33.16"
+version = "0.33.17"
 
 # Description
 title = "Isaac Lab framework for Robot Learning"

source/isaaclab/docs/CHANGELOG.rst

 Changelog
 ---------
 
+0.33.17 (2025-02-13)
+~~~~~~~~~~~~~~~~~~~~
+
+Fixed
+^^^^^
+
+* Fixed Imu sensor based observations at first step by updating scene during :meth:`~isaaclab.envs.ManagerBasedEnv.init`
+
+
 0.33.16 (2025-02-09)
 ~~~~~~~~~~~~~~~~~~~~
 
@@ -27,6 +36,7 @@ Fixed
 
 * Fixed not updating the timestamp of ``body_link_state_w`` and ``body_com_state_w`` when ``write_root_pose_to_sim`` and ``write_joint_state_to_sim`` in the ``Articulation`` class are called.
 
+
 0.33.13 (2025-01-30)
 ~~~~~~~~~~~~~~~~~~~~
 

source/isaaclab/isaaclab/envs/direct_rl_env.py

@@ -139,6 +139,7 @@ class DirectRLEnv(gym.Env):
             print("[INFO]: Starting the simulation. This may take a few seconds. Please wait...")
             with Timer("[INFO]: Time taken for simulation start", "simulation_start"):
                 self.sim.reset()
+                self.scene.update(dt=self.physics_dt)
 
         # -- event manager used for randomization
         if self.cfg.events:

source/isaaclab/isaaclab/envs/manager_based_env.py

@@ -139,7 +139,8 @@ class ManagerBasedEnv:
             print("[INFO]: Starting the simulation. This may take a few seconds. Please wait...")
             with Timer("[INFO]: Time taken for simulation start", "simulation_start"):
                 self.sim.reset()
-            # add timeline event to load managers
+                # add timeline event to load managers
+                self.scene.update(dt=self.physics_dt)
             self.load_managers()
 
         # make sure torch is running on the correct device