An angularity sensor is disclosed for incorporation within center pivot irrigation systems for providing a signal to respective controllers controlling the rotational driving force of respective span units in response to angular deviation between adjacent span units. The angularity sensor disclosed resists erroneous signals from roll, pitch, longitudinal extensions and contractions, and traverse dislocations between adjacent span units. It responds only to angular deviations between adjacent span units regardless of the other movements caused by the terrain being traversed. Parallel extensible members under tension are attached to opposite sides of one span unit and connected on the opposite end to a horizontal member rotatably mounted for rotation in a horizontal plane on the opposite span member. The rotatable member is connected to the input of the controller whereby only rotational forces of the rotating member are transmitted to the controller as angularity deviation signals. All other movements are absorbed by the extensible members.
