Fixes the tensor shape for contact sensor's force matrix data (#195)

# Description

This MR changed the shape of
`omni.isaac.orbit.sensors.contact_sensor.ContactSensorData.force_matrix_w`
in
[ContactSensor#L215-L217](https://github.com/NVIDIA-Omniverse/orbit/blob/963f3045367be3ccdac4f0902ac2103fcbb6070f/source/extensions/omni.isaac.orbit/omni/isaac/orbit/sensors/contact_sensor/contact_sensor.py#L215-L217)
from `(num_envs, num_bodies, num_shapes, num_filters, 3)` to `(num_envs,
num_bodies, num_filters, 3)`. This makes the returned tensor shape valid
with the data obtained from PhysX.

Fixes #193 

## Type of change

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

## Videos

I have implemented this in an ORBIT environment and now get the expected
behaviour
Before | After (resets only the robot collides with obstacles) 
--|--
<video
src="https://github.com/NVIDIA-Omniverse/orbit/assets/56405924/96dee42f-d84b-4a52-9480-77e800ab7f23"
width="600" />|<video
src="https://github.com/NVIDIA-Omniverse/orbit/assets/56405924/4112a941-87e2-43fd-a63b-19154cf6040f"
width="600" />

## Checklist

- [x] I have run the [`pre-commit` checks](https://pre-commit.com/) with
`./orbit.sh --format`
- [ ] 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
feature works
- [ ] I have run all the tests with `./orbit.sh --test` and they pass
- [x] I have updated the changelog and the corresponding version in the
extension's `config/extension.toml` file
- [x] I have added my name to the `CONTRIBUTORS.md` or my name already
exists there

---------
Signed-off-by: Mayank Mittal <12863862+Mayankm96@users.noreply.github.com>
Co-authored-by: Mayank Mittal <12863862+Mayankm96@users.noreply.github.com>

source/extensions/omni.isaac.orbit/config/extension.toml

 [package]
 
 # Note: Semantic Versioning is used: https://semver.org/
-version = "0.10.13"
+version = "0.10.14"
 
 # Description
 title = "ORBIT framework for Robot Learning"

source/extensions/omni.isaac.orbit/docs/CHANGELOG.rst

 Changelog
 ---------
 
+0.10.14 (2024-01-22)
+~~~~~~~~~~~~~~~~~
+
+Fixed
+^^^^^
+
+* Fixed the tensor shape of :attr:`omni.isaac.orbit.sensors.ContactSensorData.force_matrix_w`. Earlier, the reshaping
+  led to a mismatch with the data obtained from PhysX.
+
+
 0.10.13 (2024-01-15)
 ~~~~~~~~~~~~~~~~~~~~
 

source/extensions/omni.isaac.orbit/omni/isaac/orbit/sensors/contact_sensor/contact_sensor.py

@@ -208,12 +208,11 @@ class ContactSensor(SensorBase):
         if self.cfg.track_air_time:
             self._data.last_air_time = torch.zeros(self._num_envs, self._num_bodies, device=self._device)
             self._data.current_air_time = torch.zeros(self._num_envs, self._num_bodies, device=self._device)
-        # force matrix: (num_sensors, num_bodies, num_shapes, num_filter_shapes, 3)
+        # force matrix: (num_envs, num_bodies, num_filter_shapes, 3)
         if len(self.cfg.filter_prim_paths_expr) != 0:
-            num_shapes = self.contact_physx_view.sensor_count // self._num_bodies
             num_filters = self.contact_physx_view.filter_count
             self._data.force_matrix_w = torch.zeros(
-                self._num_envs, self._num_bodies, num_shapes, num_filters, 3, device=self._device
+                self._num_envs, self._num_bodies, num_filters, 3, device=self._device
             )
 
     def _update_buffers_impl(self, env_ids: Sequence[int]):
@@ -234,12 +233,11 @@ class ContactSensor(SensorBase):
 
         # obtain the contact force matrix
         if len(self.cfg.filter_prim_paths_expr) != 0:
-            # shape of the filtering matrix: (num_sensors, num_bodies, num_shapes, num_filter_shapes, 3)
-            num_shapes = self.contact_physx_view.sensor_count // self._num_bodies
+            # shape of the filtering matrix: (num_envs, num_bodies, num_filter_shapes, 3)
             num_filters = self.contact_physx_view.filter_count
             # acquire and shape the force matrix
             force_matrix_w = self.contact_physx_view.get_contact_force_matrix(dt=self._sim_physics_dt)
-            force_matrix_w = force_matrix_w.view(-1, self._num_bodies, num_shapes, num_filters, 3)
+            force_matrix_w = force_matrix_w.view(-1, self._num_bodies, num_filters, 3)
             self._data.force_matrix_w[env_ids] = force_matrix_w[env_ids]
         # obtain the pose of the sensor origin
         if self.cfg.track_pose:

source/extensions/omni.isaac.orbit/omni/isaac/orbit/sensors/contact_sensor/contact_sensor_data.py

@@ -49,8 +49,8 @@ class ContactSensorData:
     force_matrix_w: torch.Tensor | None = None
     """The contact forces filtered between the sensor bodies and filtered bodies in world frame.
 
-    Shape is (N, B, S, M, 3), where N is the number of sensors, B is number of bodies in each sensor,
-    ``S`` is number of shapes per body and ``M`` is the number of filtered bodies.
+    Shape is (N, B, M, 3), where N is the number of sensors, B is number of bodies in each sensor
+    and ``M`` is the number of filtered bodies.
 
     Note:
         If the :attr:`ContactSensorCfg.filter_prim_paths_expr` is empty, then this quantity is None.