diff --git a/qspace.py b/qspace.py
index 0ad6862..75533f1 100644
--- a/qspace.py
+++ b/qspace.py
@@ -87,6 +87,29 @@ class QSpace3D(Device):
         for name, value in kwargs.items():
             setattr(self.dc.cons, name, value)
 
+    def hard_constraints(x):
+        if x["betain"]<0:
+            return False
+        if x["betaout"]<0: 
+            return False
+        if x["nu"]<0: 
+            return False
+        if x["nu"]>180:    
+            return False
+        if x["mu"]<0:    
+            return False
+        if x["mu"]>90:    
+            return False
+        if x["chi"]<-30:
+            return False
+        if x["chi"]>30:
+            return False
+        if x["phi"]<-60:
+            return False
+        if x["phi"]>60:
+            return False
+        return True
+
     # if I understand the examples/code correctly, then some more method calls are mandatory?
     # those should probably all get shortcuts...