diff --git a/robomaster_pi/pup_position.py b/robomaster_pi/pup_position.py
index d6df093d0f3f9b6323673408146d42aeaa34919c..ec5a670b94ab4acdf1914e0c08519aa056d1d649 100644
--- a/robomaster_pi/pup_position.py
+++ b/robomaster_pi/pup_position.py
@@ -13,7 +13,7 @@ class RobotPosePublisher(Node):
         self.tf_listener_ = TransformListener(self.tf_buffer_, self)
         self.timer_ = self.create_timer(1.0, self.publish_robot_pose)
 
-    def quaternion_to_z_angle_deg(rotation):
+    def quaternion_to_z_angle_deg(self, rotation):
         x = rotation.x
         y = rotation.y
         z = rotation.z