Laser guidance system for crop spraying aircraft

• US 4,225,226 A
• Filed: 12/29/1978
• Issued: 09/30/1980
• Est. Priority Date: 12/29/1978
• Status: Expired due to Term

• Current Assignee: Spectra Precision Inc. (Trimble Inc.)
• Original Assignee: Spectra-Physics Incorporated (MKS Instruments Incorporated)
• Inventors: Teach, Ted L., Davidson, Richard W., Rando, Joseph F.
• Primary Examiner(s): Buczinski, Stephen C.
• Application Number:
  US05/974,369
• Time in Patent Office: 641 Days
• Field of Search: 340/27 NA, 356/4, 356/5, 356/141, 356/152, 356/1, 364/456, 364/449
• US Class Current: 356/3.01
• CPC Class Codes: G01S 17/87 Combinations of systems using electromagnetic waves other than radio waves
• CPC Class Codes: G05D 1/0202 specially adapted to aircraft

Abstract

This invention provides a method for controlling the path of a crop spraying aircraft in making repeated traverses over a field to insure that each traverse is laterally spaced from the adjacent traverse by the proper distance to assure adequate coverage of the crop land with the material being sprayed and avoiding over-lapping or insufficient coverage of any portion of the crop land. In accordance with the method of the invention, the crop spraying aircraft carries a rotating laser beam transmitter and receiver, and the transmitted beam is reflected from a plurality of reflectors located on the ground at known positions relative to each other to provide successive reflections of the transmitted laser beam from which the angular positions of the aircraft relative to the reflectors may be continuously determined. After an initial pass over the field to establish the spray path, the position of the aircraft may be continuously computed by a microprocessor and an error signal generated during each subsequent pass to indicate to the aircraft operator whether the aircraft should be steered more to the right or left to stay on the desired spraying path.

Claims

1. A method of guiding crop spraying aircraft in a desired path across a field, comprising the steps of:

a. locating a plurality of laser reflectors in a linear array in the vicinity of the field with a known spacing between such reflectors;

b. emitting from the aircraft a laser beam, fan-shaped in a vertical plane and rotating about a vertical axis, thereby periodically traversing said reflectors;

c. receiving on the aircraft the laser beams reflected from said reflectors;

d. determining the angular relationship between the reflected laser beams from each successive reflector;

e. continuously computing from said angular relationships the horizontal position of the aircraft relative to said reflectors; and

f. continuously comparing the actual horizontal position of the aircraft with a desired horizontal position and generating signals representing any differences therebetween, whereby the aircraft can be returned to the desired horizontal position relative to said reflectors by an aircraft operator utilizing said signals.

2. The method of claim 1 wherein said reflectors are disposed in a line parallel to the desired traverse paths of the plane over the field.

3. The method of claim 1 including the step of making an initial pass across the field to establish the initial horizontal position of the aircraft relative to said reflectors.

4. The method of claim 3 including the step of computing at least one desired horizontal position for said aircraft from said initial horizontal position.