Adroit hand dense reward fixes

* fix hand-to-object dense reward component sign in adroit hand door, hammer, and relocate scenarios

gymnasium_robotics/envs/adroit_hand/adroit_door.py

@@ -294,7 +294,7 @@ def step(self, a):
             palm_pos = self.data.site_xpos[self.grasp_site_id].ravel()
 
             # get to handle
-            reward = 0.1 * np.linalg.norm(palm_pos - handle_pos)
+            reward = -0.1 * np.linalg.norm(palm_pos - handle_pos)
             # open door
             reward += -0.1 * (goal_distance - 1.57) * (goal_distance - 1.57)
             # velocity cost

gymnasium_robotics/envs/adroit_hand/adroit_hammer.py

@@ -305,7 +305,7 @@ def step(self, a):
         # override reward if not sparse reward
         if not self.sparse_reward:
             # get the palm to the hammer handle
-            reward = 0.1 * np.linalg.norm(palm_pos - hamm_pos)
+            reward = -0.1 * np.linalg.norm(palm_pos - hamm_pos)
             # take hammer head to nail
             reward -= np.linalg.norm(head_pos - nail_pos)
             # make nail go inside

gymnasium_robotics/envs/adroit_hand/adroit_relocate.py

@@ -294,7 +294,7 @@ def step(self, a):
 
         # override reward if not sparse reward
         if not self.sparse_reward:
-            reward = 0.1 * np.linalg.norm(palm_pos - obj_pos)  # take hand to object
+            reward = -0.1 * np.linalg.norm(palm_pos - obj_pos)  # take hand to object
             if obj_pos[2] > 0.04:  # if object off the table
                 reward += 1.0  # bonus for lifting the object
                 reward += -0.5 * np.linalg.norm(