diff --git a/embodichain/data/enum.py b/embodichain/data/enum.py
index c4643a82..2902045c 100644
--- a/embodichain/data/enum.py
+++ b/embodichain/data/enum.py
@@ -24,12 +24,14 @@ class SemanticMask(IntEnum):
     Attributes:
         BACKGROUND (int): Represents the background region (value: 0).
         FOREGROUND (int): Represents the foreground objects (value: 1).
-        ROBOT (int): Represents the robot region (value: 2).
+        ROBOT_LEFT (int): Represents the left robot region (value: 2).
+        ROBOT_RIGHT (int): Represents the right robot region (value: 3).
     """
 
     BACKGROUND = 0
     FOREGROUND = 1
-    ROBOT = 2
+    ROBOT_LEFT = 2
+    ROBOT_RIGHT = 3
 
 
 class EndEffector(Enum):
diff --git a/embodichain/lab/gym/envs/managers/observations.py b/embodichain/lab/gym/envs/managers/observations.py
index 1eb83fa4..24be9d99 100644
--- a/embodichain/lab/gym/envs/managers/observations.py
+++ b/embodichain/lab/gym/envs/managers/observations.py
@@ -180,10 +180,11 @@ def compute_semantic_mask(
     """Compute the semantic mask for the specified scene entity.
 
     Note:
-        The semantic mask is defined as (B, H, W, 3) where the three channels represents:
-        - robot channel: the instance id of the robot is set to 1 (0 if not robot)
+        The semantic mask is defined as (B, H, W, len(SemanticMask)) where these channels represents:
         - background channel: the instance id of the background is set to 1 (0 if not background)
         - foreground channel: the instance id of the foreground objects is set to 1 (0 if not foreground)
+        - robot left-side channel: the instance id of the robot left-side is set to 1
+        - robot right-side channel: the instance id of the robot right-side is set to 1
 
     Args:
         env: The environment instance.
@@ -209,13 +210,30 @@ def compute_semantic_mask(
     else:
         mask = obs["sensor"][entity_cfg.uid]["mask"]
 
-    robot_uids = env.robot.get_user_ids()
+    left_robot_uids = torch.cat(
+        [
+            env.robot.get_user_ids(link_name)
+            for link_name in env.robot.link_names
+            if link_name.startswith("left_")
+        ],
+        -1,
+    )
+    right_robot_uids = torch.cat(
+        [
+            env.robot.get_user_ids(link_name)
+            for link_name in env.robot.link_names
+            if link_name.startswith("right_")
+        ],
+        -1,
+    )
 
     mask_exp = mask.unsqueeze(-1)
 
-    robot_uids_exp = robot_uids.unsqueeze_(1).unsqueeze_(1)
+    left_robot_uids_exp = left_robot_uids.unsqueeze_(1).unsqueeze_(1)
+    right_robot_uids_exp = right_robot_uids.unsqueeze_(1).unsqueeze_(1)
 
-    robot_mask = (mask_exp == robot_uids_exp).any(-1).squeeze_(-1)
+    left_robot_mask = (mask_exp == left_robot_uids_exp).any(-1).squeeze_(-1)
+    right_robot_mask = (mask_exp == right_robot_uids_exp).any(-1).squeeze_(-1)
 
     asset_uids = env.sim.asset_uids
     foreground_assets = [
@@ -239,9 +257,11 @@ def compute_semantic_mask(
 
     foreground_mask = (mask_exp == foreground_uids_exp).any(-1).squeeze_(-1)
 
-    background_mask = ~(robot_mask | foreground_mask).squeeze_(-1)
+    background_mask = ~(left_robot_mask | right_robot_mask | foreground_mask).squeeze_(
+        -1
+    )
 
-    masks = [None, None, None]
+    masks = [None, None, None, None]
     masks_ids = [member.value for member in SemanticMask]
     assert len(masks) == len(
         masks_ids
@@ -249,7 +269,8 @@ def compute_semantic_mask(
     mask_id_to_label = {
         SemanticMask.BACKGROUND.value: background_mask,
         SemanticMask.FOREGROUND.value: foreground_mask,
-        SemanticMask.ROBOT.value: robot_mask,
+        SemanticMask.ROBOT_LEFT.value: left_robot_mask,
+        SemanticMask.ROBOT_RIGHT.value: right_robot_mask,
     }
     for mask_id in masks_ids:
         masks[mask_id] = mask_id_to_label[mask_id]