Automatic guidance of a farm tractor along curved paths, using a unique CP-DGPS

Precision agriculture involves very accurate farm vehicle control along recorded paths, which are not necessarily straight lines. We investigate the possibility of achieving this task with CP-DGPS (carrier phase differential GPS) as the unique sensor. The vehicle heading is derived according to a Kalman state reconstructor, and a nonlinear velocity independent control law is designed, relying on chained systems properties. Field experiments, demonstrating the capabilities of our guidance system, are reported and discussed.