use first EE or gripper, with warning petercorke#243

jhavl · jhavl · commit d58b5f7ccb90 · 2021-09-13T12:31:57.000+10:00
diff --git a/roboticstoolbox/robot/ERobot.py b/roboticstoolbox/robot/ERobot.py
@@ -892,20 +892,19 @@ def _get_limit_links(self, end=None, start=None):
         tool = None
         if end is None:
 
-            # if we have a gripper, use it
-            if len(self.grippers) == 1:
+            if len(self.grippers) > 0:
                 end = self.grippers[0].links[0]
                 tool = self.grippers[0].tool
-            elif len(self.grippers) > 1:
-                # if more than one gripper, user must choose
-                raise ValueError("Must specify which gripper")
+                if len(self.grippers) > 1:
+                    # Warn user: more than one gripper
+                    print("More than one gripper present, using robot.grippers[0]")
 
             # no grippers, use ee link if just one
-            elif len(self.ee_links) == 1:
+            elif len(self.ee_links) > 0:
                 end = self.ee_links[0]
-            else:
-                # if more than one EE, user must choose
-                raise ValueError("Must specify which end-effector")
+                if len(self.ee_links) > 1:
+                    # Warn user: more than one EE
+                    print("More than one end-effector present, using robot.ee_links[0]")
 
             # Cache result
             self._cache_end = end
