A DEVICE COMPRISING A LEVEL LINE DETECTOR SELECTIVELY ORIENTED IN REFERENCE TO A SURFACE A MOVEABLE ARM AND A PROCESSOR IN COMMUNICATION WITH THE DETECTOR AND ARM TO SELECTIVELY MOVE THE ARM, TO MAINTAIN THE ARM IN SURFACE REFERENCE. IN ANOTHER EMBODIMENT, A SYSTEM COMPRISING A LEVEL LINE DETECTOR SELECTIVELY ORIENTED IN REFERENCE TO A SURFACE A MOVEABLE ARM A PROCESSOR IN COMMUNICATION WITH THE DETECTOR AND ARM TO SELECTIVELY MOVE THE ARM, TO MAINTAIN THE ARM IN SURFACE REFERENCE AND A LEVEL LINE TO COMMUNICATE WITH THE DETECTOR. IN ANOTHER EMBODIMENT, A METHOD COMPRISING: SELECTIVELY ORIENTING A LEVEL LINE DETECTOR IN REFERENCE TO A SURFACE DETECTING A LEVEL LINE COMMUNICATING DETECTION DATA TO A MOVEABLE ARM AND MOVING THE ARM BASED ON THE DATA, TO MAINTAIN SURFACE REFERENCE.
