Abstract: An irrigation system that includes multiple interconnected spans that are supported by multiple tower structures. Each intermediate tower structure and end tower structure may include a dual-controller drive assembly that may include both a fixed-speed drive controller controlling the speed of movement of the dual-controller drive assembly when the fixed-speed drive controller is selected and a variable-speed drive controller controlling the speed of movement of the dual-controller drive assembly when the variable-speed drive controller is selected, and one or more selector switches configured to either manually, based on manual operator input, or automatically, based on automatic sensor input, select between the fixed-speed drive controller and the variable-speed drive controller.

Abstract: An irrigation system with transient state speeds of movement achieves and maintains substantial straight alignment of multiple interconnected spans with continuous movement over a range of speeds in a forward and reverse movement direction. A variable-speed drive controller monitors and processes the output of the corresponding alignment detector and, based on the output of the alignment detector, selects from memory and continuously furnishes to the corresponding span motor a predetermined progressively increasing speed profile or a predetermined progressively decreasing speed profile.

Abstract: An irrigation system with steady state speeds of movement achieves and maintains substantial straight alignment of multiple interconnected spans with continuous movement over a range of speeds in a forward and reverse movement direction. A variable-speed drive controller monitors and processes the output of the corresponding alignment detector and, based on the output of the alignment detector, selects from memory and continuously furnishes to the corresponding span motor a predetermined progressively increasing speed profile, a predetermined progressively decreasing speed profile, or a new fixed current speed.