diff --git a/aist_plusplus/features/utils.py b/aist_plusplus/features/utils.py
index 8b57cc5..5a2c968 100644
--- a/aist_plusplus/features/utils.py
+++ b/aist_plusplus/features/utils.py
@@ -126,8 +126,8 @@ def calc_average_acceleration(
         ) / frame_time
         v1 = (
             positions[i + j][joint_idx]
-            - positions[i + j - 1][joint_idx] / frame_time
-        )
+            - positions[i + j - 1][joint_idx] 
+        ) / frame_time
         average_acceleration += (v2 - v1) / frame_time
         current_window += 1
     return np.linalg.norm(average_acceleration / current_window)
@@ -180,4 +180,4 @@ def calc_average_velocity_vertical(
         )
     else:
         raise NotImplementedError
-    return np.linalg.norm(average_velocity)
\ No newline at end of file
+    return np.linalg.norm(average_velocity)