diff --git a/perls2/controllers/ee_imp.py b/perls2/controllers/ee_imp.py
index 82f449df..48346426 100644
--- a/perls2/controllers/ee_imp.py
+++ b/perls2/controllers/ee_imp.py
@@ -123,7 +123,10 @@ def __init__(self,
         self.output_min = np.array(output_min)
 
         # limits
-        self.position_limits = position_limits
+        if position_limits is not None:
+            self.position_limits = np.array(position_limits)
+        else:
+            self.position_limits = position_limits
         self.orientation_limits = orientation_limits
 
         # kp kv