Abstract

A mobile sprinkler irrigation system comprising an elongate sprinkler supply pipe supported at one end by a self-propelled pace carriage and along the length thereof by a plurality of spaced self-propelled follower carriages. A tower on the pace carriage supports a laser projection system that projects a laser plane parallel to and along the length of the sprinkler supply pipe. The follower carriages carry laser sensor units deposed to intercept the laser plane whenever a follower carriage falls out of alignment with the pace carriage. Control circuitry operates in response to the sensors to control the propulsion wheels for the follower carriages so that the carriages follow the laser plane. Thus, the follower carriages follow the path of the laser plane, as defined by the pace carriage, whether the path be curvilinear, or rectilinear.