Automatic guidance system for farm tractors and method of plowing

Claim 2

An automatic guidance system as defined in claim 2 wherein said means for turning the forward wheels comprises: a hydraulic pump; a source of hydraulic power fluid connected to said hydraulic pump; a cylinder and piston assembly having the piston thereof adapted for connection to the steering mechanism of the tractor; conduit means connecting said hydraulic pump to said cylinder for driving the piston in or out of said cylinder when hydraulic power fluid is applied to said cylinder; and valve means connected in said conduits and responsive to said first and second sensing devices for directing power fluid to an end of said cylinder dependent on the signal communicated to said valve means by one of said first and second sensing devices.

Claim 3

An automatic guidance system as defined in claim 3 wherein said means for applying the brake and for simultaneously turning the forwArd wheels comprises: a hydraulic pump; a source of hydraulic power fluid connected to said pump; a valve connected to said pump for receiving power fluid therefrom, and connected to said third sensing means to be thrown by said third sensing means when said third sensing means moves from plowed to unplowed land; a first piston and cylinder assembly connected to said valve for receiving power fluid therefrom, and having the piston thereof adapted for connection to the steering system of the tractor; and a second piston and cylinder assembly connected to said valve for receiving power fluid therefrom, and having the piston thereof adapted for connection to the brake of one of the rear wheels of the tractor.

Claim 4

An automatic guidance system as defined in claim 4 and further characterized as including means for compensating said sensing devices for anomalous characteristics of the earth.

Claim 5

An automatic guidance system as defined in claim 5 wherein said means for compensating said sensing devices comprises: a background -sensing device for sensing a background characteristic of the earth; and means for adjusting the sensitivity of at least one of said first, second or third sensing devices in response to variations in said background characteristic as sensed by said background-sensing device.

Claim 6

An automatic guidance system as defined in claim 6 wherein said automatic guidance system further comprises: fourth and fifth sensing devices mounted on said frame in horizontal alignment with said first and second sensing devices, and said first and second sensing devices being positioned between said fourth and fifth sensing devices, said fourth and fifth sensing devices each being capable of sensing the difference between plowed and unplowed land; coarse steering control means connected to said fourth and fifth sensing devices and adapted for connection to the forward wheels of the tractor for turning the forward wheels in one direction when said fourth sensing device moves across a boundary between plowed and unplowed land, and for turning the forward wheels in an opposite direction when said fifth sensing devices moves from a position over unplowed land to a position over plowed land, the turning movements of said forward wheels effected by said coarse steering means being greater than the turning movements of said forward wheels effected by said first mentioned turning means.

Claim 7

An automatic guidance system as defined in claim 1 wherein said sensing devices are photoelectric sensors.

Claim 8

An automatic guidance system as defined in claim 1 wherein said means for turning the forward wheels comprises: a hydraulic pump; a source of hydraulic power fluid connected to said hydraulic pump; a cylinder; a piston rod extending from said cylinder and adapted for connection to the steering mechanism of the tractor; a first valve connected to said first sensing device and openable when said first sensing device moves from plowed to unplowed land; fluid conduits connected through said first valve between one end of said cylinder and said pump; a second valve connected to said second sensing device and openable when said second sensing device moves from unplowed to plowed land; and fluid conduits connected through said second valve between a second end of said cylinder and said pump.

Claim 9

An automatic guidance system as defined in claim 1 wherein said means for applying a brake and turning the forward wheels comprises: a hydraulic pump; a source of hydraulic power fluid connected to said pump; a valve connected to said pump for receiving power fluid therefrom, and connected to said third sensing means for responding thereto by shifting said valve; a first piston and cylinder assembly connected to said valve for receiving power fluid therefrom, and having the piston thereof adapted for connection to the steering system of the tractor; and a second piston and cylinder Assembly connected to said valve for receiving power fluid therefrom and having the piston thereof adapted for connection to the brake of one of the rear wheels of the tractor.

Claim 10

An automatic guidance system as defined in claim 1 and further characterized to include means for compensating said sensing devices for anomalous characteristics of the earth.

Claim 11

An automatic guidance system as defined in claim 11 wherein said means for compensating said sensing devices comprises: a background-sensing device for sensing a background characteristic of the earth; and means for adjusting the sensitivity of at least one of said first, second or third sensing devices in response to variations in said background characteristic as sensed by said background-sensing device.

Claim 12

An automatic guidance system as defined in claim 1 and further characterized to include means for reducing hunting due to overresponsiveness of said means for turning said wheels.

Claim 13

An automatic guidance system as defined in claim 13, wherein said means for reducing hunting comprises: fourth and fifth sensing devices mounted on said frame in horizontal alignment with said first and second sensing devices, with said first and second sensing devices positioned between said fourth and fifth sensing devices, said fourth and fifth sensing devices each being capable of sensing the difference between the plowed and unplowed land; coarse steering control means connected to said fourth and fifth sensing devices and adapted for connection to the forward wheels of the tractor for turning the forward wheels in one direction when said fourth sensing device has crossed the boundary between plowed and unplowed land, and for turning the forward wheels in an opposite direction when said fifth sensing device moves from a position over unplowed ground to a position over plowed ground, the turning movements of said forward wheels effected by said coarse steering means being greater than the turning movements of said forward wheels effected by said first mentioned turning means.

Claim 14

In a farm tractor having a plow pulled thereby, and having a pair of rear wheels, brakes for each of said rear wheels, and at least one forward wheel, the improvement which comprises: first sensing means for contacting the earth along opposite sides of a relatively straight boundary between plowed and unplowed earth; means mounting said first sensing means on said tractor for contacting the earth on opposite sides of said boundary when said tractor is steered along said boundary in a direction of travel which is aligned with, or parallel to, said boundary; means mounted on said tractor and responsive to signals developed by said first sensing means when said first sensing means contacts the earth on only one side of said boundary for turning said forward wheels in a direction to return said sensing means to a position in which it contacts the earth on opposite sides of said boundary; second sensing means mounted on said tractor in spaced relation to said first-mentioned sensing means and contacting the earth on one side of said boundary at a location which is forward of said first sensing means and on opposite sides thereof from said forward wheels; and means mounted on said tractor and responsive to a signal developed by said second sensing means when said second sensing means crosses a boundary between plowed and unplowed land and for applying a brake to one of said rear wheels and simultaneously turning said forward wheels in a direction with respect to said boundary corresponding to the direction which the point of earth contact of said second sensing means lies with respect to said first-mentioned relatively straight boundary to thereby pivot the tractor about said one rear wheel.

Claim 15

The improvement defined in claim 15 wherein said first sensing means comprises: a first sensing device for sensing electromagnetic radiation transmitted thereto from the earth and developing a signal prOportional to the amplitude of the sensed radiation; and a second sensing device horizontally spaced from said first sensing device for sensing electromagnetic radiation transmitted thereto from the earth and developing a signal proportional to the amplitude of the sensed radiation.

Claim 16

The improvement defined in claim 16 wherein said means responsive to signals developed by said sensing means comprises: a bidirectional servomotor; and drive means drivingly connecting said motor to the front wheels of a tractor for turning the wheels as the motor is turned.

Claim 17

The improvement defined in claim 16 wherein said first sensing means comprises: a first feeler blade mounted pivotally on said mounting means and extending downwardly therefrom below a plane tangent to said rear wheels and front wheels; and a second feeler blade pivotally mounted on said mounting means and extending downwardly therefrom below a plane tangent to said rear wheels and front wheels.

Claim 18

The improvement defined in claim 16 wherein the first sensing means further comprises: means for resiliently biasing said first feeler blade to a first position when said first feeler blade is in plowed land, and for yielding when said first feeler blade is in unplowed land and is in a second position; means for resiliently biasing said second feeler blade to a first position when said second feeler blade is in plowed land, and for yielding when said first feeler blade is in unplowed land and is in a second position; a first valve connected to said first feeler blade and having a first, open position when said first feeler blade in in said second position, and having a second, closed position when said first feeler blade is in said first position; and a second valve connected to said second feeler blade and having a first, open position when said second feeler blade is in said first position, and a second, closed position when said second feeler blade is in said second position.

Claim 19

An automatic guidance system for farm tractors having a pair of rear wheels and at least one forward wheel comprising: a supporting frame adapted for mounting on the forward portion of the tractor; first and second horizontally spaced sensing devices mounted on said supporting frame and facing downwardly therefrom, said sensing devices being positioned on opposite sides of a line extending substantially parallel to the line of desired forward travel of said tractor, and each sensitive to a characteristic which varies between plowed and unplowed ground; means adapted for connection between at least one wheel of the tractor and the first and second sensing devices and responsive to signals developed by said sensing devices for turning said one wheel in one direction when said first sensing device moves from a position over plowed ground to a position over unplowed ground, and for turning at least one wheel of the tractor in an opposite direction when said second sensing device moves from a position over unplowed land to a position over plowed land; a third sensing device mounted on, and facing downwardly from, said frame and spaced horizontally from said first and second sensing devices, said third sensing device being disposed on the same side of said line parallel to said line of desired forward travel as is said second sensing device, and being sensitive to a characteristic which varies between plowed and unplowed land; and means adapted for connection between the braking system of the tractor, at least one wheel of the tractor, and said third sensing device for applying a brake to one of the rear wheels of the tractor and simultaneously turning the tractor in a direction to move said third sensing device away from said line parallel to said line of desired forward travel by wheel movement when said third sensing device moves from a position over unplowed ground to a position over plowed ground.