Automatic lawn mower

Claim 2

Guidance apparatus for a self-propelled mower comprising: first sensor means, including several photosensitive receptors and light source means for directing light towards said receptors, for producing output signals associated with each said receptor dependent upon the light received by each said receptor; first comparator means for comparing predetermined combinations of said output signals and for producing comparator output signals dependent upon said comparisons; and control means for producing guidance signals for a self-propelled mowing apparatus in response to the content of said comparator output signals, said photosensitive receptors being in an array whose principal dimension is essentially transverse to the normal direction of travel of the mower, the path of light from said light source means to said receptors being such that the presence of a substance to be mowed in the vicinity of one of said receptors affects the amount of light received by said receptor, said control means and said first comparator means including means responsive to said several receptors for detecting a boundary between mowed and unmowed vegetation.

Claim 3

The apparatus of claim 1 in which the light source of the sensor means comprises a plurality of columnized light compartments and each photosensitive receptor is in a corresponding compartment.

Claim 4

The apparatus of claim 2 in which the photosensitive receptors are photosensitive resistors.

Claim 5

The apparatus of claim 1 in which the sensor means includes a first sensor assembly and a second sensor assembly, each said assembly comprising a plurality of photosensitive receptors and light source means for directing light toward said receptors.

Claim 6

The apparatus of claim 4 in which the control means includes logic circuit means for producing guidance signals for the mowing apparatus in response to comparator output signals associated with the first sensor assembly of the sensor means and for establishing a priority over comparator output signals from outputs associated with the second sensor assembly.

Claim 7

The apparatus of claim 5 in which the control means further includes means for responding to signals associated with the first sensor assembly when said signals indicate a transition between mowed and unmowed substance between the receptors and light source means of the first sensor assembly, and for otherwise responding to the signals associated with the second sensor assembly.

Claim 8

The apparatus of claim 1 in which the comparator means includes means for sequentially comparing predetermined pairs of sensor means outputs.

Claim 9

The apparatus of claim 1 in which said control means includes means for producing signals representing the position beneath and array of the existence of and the location of the boundary between the mowed and unmowed areas.

Claim 10

The apparatus of claim 8 in which said transverse array includes more than ten photosensitive receptors.

Claim 11

The apparatus of claim 8 in which the sensor means includes a first sensor assembly and a second sensor assembly, each said assembly comprising a plurality of photosensitive receptors and light source means for directing light toward said receptors.

Claim 12

The apparatus of claim 1 in which said light source means and said receptors are contained in a dust protective enclosure having a non-glare window allowing light to traverse out of and reflect back through the window to said receptors.

Claim 13

The apparatus of claim 11 in which said light source means is operable to emit light through a first light polarizer, said light being directed at said non-glare window at the Brewster angle for the window material resulting in attenuation of the reflected portion of said light by orthogonally polarizing it from the direction of said first light polarizer, said window transmitting the remaining portion of said light.

Claim 14

The apparatus of claim 11 in which the extent of light reflected back through said window to said receptors is determined by several light reflective elements, said elements positioned to be deflected to an extent dependent upon the height of vegetation in the vicinity of said elements, deflection of said elements resulting in a change of light reflected back through the window.

Claim 15

The apparatus of claim 1 in which said photosensitive receptors are in a linear array, there being at least six photosensitive receptors in the array and in which said comparator means compares receptors spaced apart from one another by at least two spaces.

Claim 16

The apparatus of claim 1 which further comprises: second sensor means, including several second photosensitive receptors and second light source means for directing light toward said second receptors, for producing second output signals associated with each of said second receptors; and second comparator means including means for producing second comparisons of predetermined combinations of said second output signals and for producing second comparator output signals dependent upon said second comparisons, and in which said control means includes means for giving (1) first priority to said first sensor means and first comparator means when a mowed-unmowed substance interface is detected by said first sensor means and first comparator means, (2) second priority to the second sensor means and second somparator means when a mowed-unmowed substance interface is detected by said second sensor means and second comparator means, and (3) third priority to a preprogrammed control routine.

Claim 17

The apparatus of claim 1 in which said comparator means includes means for producing output signals which are indicative of the presence of a mowed-unmowed substance interface between two of said receptors spaced apart from one another and in which said control means also includes means for producing guidance signals based upon a plurality of said interface comparator output signal indications from a preselected number of said comparator output signals.

Claim 18

The apparatus of claim 1 which includes means for making the comparator means unresponsive to a false indication from an error output condition of one of said receptors.

Claim 19

Guidance apparatus for a self-propelled mower comprising: first sensor means for detecting a differential of vegetation height of a first boundary of a mowing area; second sensor means for detecting a differential of vegetation height at a second boundary of a mowing area; and control means for producing guidance signals for a self-propelled mower suitable for use in tracking either said first or second boundary in response to detection of a differential of vegetation height by said second sensor means when said first sensor means does not detect a boundary but said second sensor means does detect a boundary and by said first sensor means when said first sensor means does detect a boundary.

Claim 20

Guidance apparatus for a self-propelled mower comprising: first sensor means for detecting a differential of vegetation height of a first boundary of a mowing area; second sensor means for detecting a differential of vegetation height at a second boundary of a mowing area; and control means for producing guidance signals for a self-propelled mower suitable for use in tracking either said first or second boundary in response to detection of a differential of vegetation height by said second sensor means when said first sensor means does not detect a boundary but said second sensor means does detect a boundary and by said first sensor means when said first sensor means does detect a boundary.

Claim 21

The apparatus of claim 18 wherein said first sensor means and said second sensor means include several photosensitive receptors and light source means for directing light toward said receptors for producing output signals associated with each said receptor dependent upon light received by each said receptor.

Claim 22

Guidance apparatus for a self-propelled mower comprising: first sensor means positioned to the side of the mower in its normal direction of travel nearest the outer boundary of a mowing area; second sensor means positioned to the side of the mower in its normal direction of travel farthest from the outer boundary of a mowing area; multiple detector means within each of said first and second sensor means, said detector means including detectors positioned to monitor an assigned area of vegetation within its path, said detectors positioned in an array whose principal sensing dimension is essentially transverse to the normal direction of travel of the mower, each of said detectors including means for producing a detector output signal dependant upon the vegetation height within its path; comparator means for producing comparisons of predetermined combinations of said detector output signals and for producing comparator output signals dependent upon said comparisons, said comparator means coupled to said first and second sensor means; processing means for converting comparator output signals to control signals, said processing means coupled to said first and second sensor means, said processing means including means for providing a status indication signal of the presence of a vegetation height differential within the monitored areas of the detectors within an array, said processing means also including means for providing a location indication signal dependent upon the location of transition of vegetation heights within the monitored areas of said detectors; and control means for producing guidance signals for a self-propelled mower from the status indication signal and the location indication signal of said processing means.

Claim 23

Guidance apparatus for a self-propelled mower comprising: first sensor means positioned to the side of the mower in its normal direction of travel nearest the outer boundary of a mowing area; second sensor means positioned to the side of the mower in its normal direction of travel farthest from the outer boundary of a mowing area; multiple detector means within each of said first and second sensor means, said detector means including detectors positioned to monitor an assigned area of vegetation within its path, said detectors positioned in an array whose principal sensing dimension is essentially transverse to the normal direction of travel of the mower, each of said detectors including means for producing a detector output signal dependant upon the vegetation height within its path; comparator means for producing comparisons of predetermined combinations of said detector output signals and for producing comparator output signals dependent upon said comparisons, said comparator means coupled to said first and second sensor means; processing means for converting comparator output signals to control signals, said processing means coupled to said first and second sensor means, said processing means including means for providing a status indication signal of the presence of a vegetation height differential within the monitored areas of the detectors within an array, said processing means also including means for providing a location indication signal dependent upon the location of transition of vegetation heights within the monitored areas of said detectors; and control means for producing guidance signals for a self-propelled mower from the status indication signal and the location indication signal of said processing means.

Claim 24

The apparatus of claim 22 wherein: said processing means includes means for producing a status indication signal and a location indication signal for each of said first sensor means and said second sensor means; and said control means includes means for giving priority of control to the status indication signal and the location indication signal of the first sensor means over the like signals of the second sensor means.

Claim 25

Guidance apparatus for a self-propelled vehicle comprising: sensor means including a plurality of switches in an array whose principal dimension is essentially transverse to the normal direction of travel of the vehicle, said sensor means operable to produce output signals associated with each switch dependent upon the closed or open status of said switch; a plurality of actuator means each for controlling the closed or open status of one of said plurality of switches dependent upon the height of vegetation within its path; comparator means operable to produce comparisons of predetermined combinations of said output signals and for producing comparator output signals dependant upon said comparisons; and control means operable to produce guidance signals for a self-propelled vehicle in response to the content of said comparator output signals.

Claim 26

Guidance apparatus for a self-propelled vehicle comprising: sensor means including a plurality of switches in an array whose principal dimension is essentially transverse to the normal direction of travel of the vehicle, said sensor means operable to produce output signals associated with each switch dependent upon the closed or open status of said switch; a plurality of actuator means each for controlling the closed or open status of one of said plurality of switches dependent upon the height of vegetation within its path; comparator means operable to produce comparisons of predetermined combinations of said output signals and for producing comparator output signals dependant upon said comparisons; and control means operable to produce guidance signals for a self-propelled vehicle in response to the content of said comparator output signals.

Claim 27

The apparatus of claim 22 in which said comparator means includes a scanner for sequentially sampling output signals of said comparator means.

Claim 28

The apparatus of claim 22 wherein said comparator means includes means for making the comparator means unresponsive to a false indication from an error output condition of one of said detectors.

Claim 29

The apparatus of claim 22 wherein said plurality of switches are of a light sensing type and said plurality of actuator means are movable and have a reflective surface positionable to control light reaching said switches.

Claim 30

The apparatus of claim 22 in which the sensor means includes a first sensor assembly and a second sensor assembly, each assembly comprising a plurality of switches in an array whose principal dimension is essentially transverse to the normal direction of travel of the vehicle, said comparator means includes a first comparator means for processing output signals from said first sensor assembly and a second comparator means for processing output signals from said second sensor assembly, each of said first and second comparator means producing output signals.

Claim 31

The apparatus of claim 26 in which said control means includes means for establishing priority for said first comparator means over said second comparator means.

Claim 32

Guidance apparatus for a self-propelled mower comprising: sensor means, including several detectors positioned in an array whose principal sensing dimension is essentially transverse to the normal direction of travel of the mower, each of said detectors positioned to monitor an assigned area of vegetation within its path, each of said detectors producing a detector output signal dependent upon the vegetation height within its path; comparator means operable to produce comparisons of predetermined combinations of said detector output signals and for producing comparator output signals dependent upon said comparisons; processing means for converting comparator output signals to control signals, said processing means providing a status indication signal of the presence of a vegetation height differential within the monitored areas of the detectors within the array, said processing means also providing a location indication signal dependent upon the location of transition of vegetation heights within the monitored areas of the detectors; control means for producing guidance signals for a self-propelled mower from the status indication signal and the location indication signal of the processing means.

Claim 33

Guidance apparatus for a self-propelled mower comprising: sensor means, including several detectors positioned in an array whose principal sensing dimension is essentially transverse to the normal direction of travel of the mower, each of said detectors positioned to monitor an assigned area of vegetation within its path, each of said detectors producing a detector output signal dependent upon the vegetation height within its path; comparator means operable to produce comparisons of predetermined combinations of said detector output signals and for producing comparator output signals dependent upon said comparisons; processing means for converting comparator output signals to control signals, said processing means providing a status indication signal of the presence of a vegetation height differential within the monitored areas of the detectors within the array, said processing means also providing a location indication signal dependent upon the location of transition of vegetation heights within the monitored areas of the detectors; control means for producing guidance signals for a self-propelled mower from the status indication signal and the location indication signal of the processing means.

Claim 34

The apparatus of claim 28 in which said comparator means includes a scanner for sequentially sampling output signals of said comparator means.

Claim 35

The apparatus of claim 28 wherein said comparator means includes means for making the comparator means unresponsive to a false indication from an error output condition of one of said detectors.