Guidance assist system for agricultural machines

DETAILED DESCRIPTION The present invention comprises guidance assist apparatus for directing the lateral movement of an agricultural machine with respect to the severed edge of the crop material being harvested.
The crop directly preceding the machine is periodically scanned by an optical sensing device in cooperation with a scanner.
The output therefrom provides a representation of the crop as viewed during the scan with a discontinuity therein corresponding to the severed crop edge.
The output from the sensing device is filtered and coupled to circuitry wherein the location or phase of the discontinuity is matched or compared against a predetermined point in the scan.
The apparatus thereafter provides an error signal representative of the deviation of the discontinuity from the predetermined point.
The error signal may be coupled to utilization means for directing the lateral movement of the machine so that the error signal is reduced towards zero.
The apparatus further includes means for maintaining the polarity and magnitude of the error signal independent of whether the relatively more intense illumination is scanned prior or subsequent to the severed crop edge.
Additionally, the apparatus further includes means for providing an indication when the contrast between the severed and unsevered crop is insufficient to maintain reliability with the system.