Feeler

Following devices have been in use for many years primarily as implement steering or hitch shifting guidance mechanisms.

More recently these systems have been adapted to steer using GPS postioning. These GPS based implement guidance products can further increase accuracy by reducing guidance errors caused roll, yaw and implement misalignment. The errors can be significant on trailed implements and are further accentuated by slopes, uneven soil and rough ground conditions, as illustrated below:

The implement tracking error is seldom mentioned in the literature of gps guidance systems. to measure the guidance accuracy of any guidance product, measure the actual error is simply a case of of measuring the distance between the implement tracks/marks of adjacent runs where the direction of travel was in opposite directions. Halve the measured error to get the implement guidance error. Even on the highest accuracy RTK guidance systems, the following results are not unusual for trailed implements.

Feeler Guidance Manufacturers

The following links list manufacturers of feeler guidance products:
AgGuide
AgNavigation Ultra Guide (no longer active?)
Automatic AG
Claas
Fleischer Manufacturing inc.
John Deere
Orthman
Smucker Manufacturing
Sunco Marketing