Patent ID: 8116977

Claim:
A method for guiding a passive implement along a desired path comprising: providing a tractor guided by an autopilot having a nudge input; introducing a test input to the tractor autopilot; providing a GNSS receiver fixed to the passive implement; towing the passive implement behind the tractor via a hitch; using a model of the tractor-hitch-implement system to provide feedback to a control system that provides nudge inputs to the autopilot-controlled tractor and to the model; wherein, the model estimates the immediate passive implement offset from the path; tractor, hitch and implement elements within the model are arranged such that nudge inputs from the control system are applied to the implement element directly; the tractor element of the model includes information obtained from measurements of the motion of the tractor in response to the test input; and, the control system nudge inputs cause the difference between the actual implement path and the desired path to be minimized.