diff --git a/NP_Implementation/test/test_aPID_np.py b/NP_Implementation/test/test_aPID_np.py
index eff1e01..c500e84 100644
--- a/NP_Implementation/test/test_aPID_np.py
+++ b/NP_Implementation/test/test_aPID_np.py
@@ -15,5 +15,20 @@ class TestAdaptivePIDNP(unittest.TestCase):
         self.rbf = RBFNetwork(self.input_dim, self.n_centers)
         self.apid = AdaptivePIDNP(Kp, Ki, Kd, self.rbf)
 
+    def test_update(self):
+        """Test the update method."""
+        target = 10.0
+        measured_value = 8.0
+        dt = 0.1
+        
+        control_signal = self.apid.update(target, measured_value, dt)
+        
+        self.assertIsInstance(control_signal, float)        
+        self.assertGreater(control_signal, 0)
+        
+        measured_value = 9.0
+        control_signal_2 = self.apid.update(target, measured_value, dt)
+        self.assertNotEqual(control_signal, control_signal_2)
+
 if __name__ == '__main__':
     unittest.main()