Variable-speed irrigation system

Abstract

An irrigation system is disclosed that is configured to maintain a near straight alignment. In an implementation, an irrigation system includes multiple interconnected spans which are supported by multiple tower structures. Each tower structure includes a variable-speed drive unit for selectively driving a tower structure at a selected speed. The irrigation system also includes multiple sensors that are each associated with a corresponding span to determine an alignment of the corresponding span with respect to adjacent spans. Each of the sensors is in communication with a corresponding variable-drive control unit. Each of the variable-drive control units are configured to control the selected speed of a corresponding variable-speed drive unit to maintain the interconnected spans in a substantially linear orientation with respect to adjacent ones of the plurality of interconnected spans along a generally longitudinally oriented axis (e.g., maintain alignment of the spans with respect to each other).

What is claimed is: 
     
         1 . An irrigation system comprising:
 a plurality of interconnected spans;   a plurality of tower structures for supporting the interconnected spans, each one of the plurality of tower structures including a variable-speed drive unit for selectively driving a tower structure at a selected speed;   a plurality of sensors, each one of the plurality of sensors associated with a corresponding one of the plurality of interconnected spans and configured to determine an alignment of a corresponding one of the plurality of interconnected spans; and   a plurality of variable-drive control units, each variable-drive control unit of the plurality of drive control units in communication with a corresponding variable-speed drive unit and a corresponding sensor, each variable-drive control unit configured to control the selected speed of the corresponding variable-speed drive unit to maintain the plurality of interconnected spans in a substantially linear orientation with respect to adjacent ones of the plurality of interconnected spans along a generally longitudinally oriented axis,   wherein the selected speed of the corresponding variable-drive control unit is based upon the alignment.   
     
     
         2 . The irrigation system as recited in  claim 1 , wherein at least one sensor is configured to determine an angle between a first corresponding interconnected span of the plurality of interconnected spans and a second corresponding interconnected span of the plurality of interconnected spans; wherein the corresponding variable-drive control unit is configured to determine a selected speed to maintain the plurality of interconnected spans in a substantially linear orientation with respect to adjacent ones of the plurality of interconnected spans along a generally longitudinally oriented axis, the selected speed based upon the angle. 
     
     
         3 . The irrigation system as recited in  claim 1 , wherein each sensor of the plurality of sensors is in direct communication with a corresponding variable-drive control unit of the plurality of variable-drive control units. 
     
     
         4 . The irrigation system as recited in  claim 1 , wherein the variable-speed drive units comprise switched reluctance motors. 
     
     
         5 . The irrigation system as recited in  claim 1 , wherein the plurality of sensors comprise at least one of a potentiometer, a captive alignment sensor, a laser based alignment sensor, or a non-contact proximity sensor. 
     
     
         6 . The irrigation system as recited in  claim 1 , wherein at least one sensor of the plurality of sensors is configured to continuously furnish a signal to the corresponding variable-drive control unit, wherein the variable-drive control unit is configured to continuously furnish a signal to a variable-drive unit of the corresponding interconnected span to continuously modify a speed of the corresponding tower structure to re-align the corresponding tower structure with the adjacent tower structure. 
     
     
         7 . An irrigation system comprising:
 a center pivot structure;   a main section assembly coupled to the center pivot structure, the main section assembly including a plurality of interconnected spans;   a plurality of tower structures for supporting the interconnected spans, each one of the plurality of tower structures including a variable-speed drive unit for selectively driving a tower structure at a selected speed;   a plurality of sensors, each one of the plurality of sensors associated with a corresponding one of the plurality of interconnected spans and configured to determine an alignment of a corresponding one of the plurality of interconnected spans; a plurality of variable-drive control units, each variable-drive control unit of the plurality of drive control units in communication with a corresponding variable-speed drive unit and a corresponding sensor, each variable-drive control unit configured to control the selected speed of the corresponding variable-speed drive unit to maintain the plurality of interconnected spans in a substantially linear orientation with respect to adjacent ones of the plurality of interconnected spans along a generally longitudinally oriented axis,
 wherein the selected speed of the corresponding variable-drive control unit is based upon the alignment. 
   
     
     
         8 . The irrigation system as recited in  claim 7 , wherein at least one sensor is configured to determine an angle between a first corresponding interconnected span of the plurality of interconnected spans and a second corresponding interconnected span of the plurality of interconnected spans; wherein the corresponding variable-drive control unit is configured to determine a selected speed to maintain the plurality of interconnected spans in a substantially linear orientation with respect to adjacent ones of the plurality of interconnected spans along a generally longitudinally oriented axis, the selected speed based upon the angle. 
     
     
         9 . The irrigation system as recited in  claim 7 , wherein each sensor of the plurality of sensors is in direct communication with a corresponding variable-drive control unit of the plurality of variable-drive control units. 
     
     
         10 . The irrigation system as recited in  claim 7 , wherein the variable-speed drive units comprise switched reluctance motors. 
     
     
         11 . The irrigation system as recited in  claim 7 , wherein the plurality of sensors comprise at least one of a potentiometer, a captive alignment sensor, a laser based alignment sensor, or a non-contact proximity sensor. 
     
     
         12 . The irrigation system as recited in  claim 7 , wherein at least one sensor of the plurality of sensors is configured to continuously furnish a signal to the corresponding variable-drive control unit, wherein the variable-drive control unit is configured to continuously furnish a signal to a variable-drive unit of the corresponding interconnected span to continuously modify a speed of the corresponding tower structure to re-align the corresponding tower structure with the adjacent tower structure. 
     
     
         13 . An irrigation system comprising:
 a center pivot structure;   a main section assembly coupled to the center pivot structure, the main section assembly including a plurality of interconnected spans;   a plurality of tower structures for supporting the interconnected spans, each one of the plurality of tower structures including a switched reluctance motor for selectively driving a tower structure at a selected speed;   a plurality of sensors, each one of the plurality of sensors associated with a corresponding one of the plurality of interconnected spans and configured to determine an alignment of a corresponding one of the plurality of interconnected spans;   a plurality of variable-drive control units, each variable-drive control unit of the plurality of drive control units in communication with a corresponding variable-speed drive unit and a corresponding sensor, each variable-drive control unit configured to control the selected speed of the corresponding switched reluctance motor to maintain the plurality of interconnected spans in a substantially linear orientation with respect to adjacent ones of the plurality of interconnected spans along a generally longitudinally oriented axis,   wherein the selected speed of the corresponding variable-drive control unit is based upon the alignment.   
     
     
         14 . The irrigation system as recited in  claim 13 , wherein at least one sensor is configured to determine an angle between a first corresponding interconnected span of the plurality of interconnected spans and a second corresponding interconnected span of the plurality of interconnected spans; wherein the corresponding variable-drive control unit is configured to determine a selected speed to maintain the plurality of interconnected spans in a substantially linear orientation with respect to adjacent ones of the plurality of interconnected spans along a generally longitudinally oriented axis, the selected speed based upon the angle. 
     
     
         15 . The irrigation system as recited in  claim 13 , wherein each sensor of the plurality of sensors is in direct communication with a corresponding variable-drive control unit of the plurality of variable-drive control units. 
     
     
         16 . The irrigation system as recited in  claim 13 , wherein the plurality of sensors comprise at least one of a potentiometer, a captive alignment sensor, a laser based alignment sensor, or a non-contact proximity sensor. 
     
     
         17 . The irrigation system as recited in  claim 15 , wherein at least one sensor of the plurality of sensors is configured to continuously furnish a signal to the corresponding variable-drive control unit, wherein the variable-drive control unit is configured to continuously furnish a signal to a variable-drive unit of the corresponding interconnected span to continuously modify a speed of the corresponding tower structure to re-align the corresponding tower structure with the adjacent tower structure.