US2377589A

US2377589A - Automatic aiming control

Info

Publication number: US2377589A
Authority: US
Publication date: 1945-06-05
Anticipated expiration: 1962-06-05

Description

f y a U June 1945. w. M. SUTCLIFFE 2,377,589

AUTOMATIC AIMING CONTROL Filed NOV. 20, 1940 2 Sheets-Sheet 1 mriiiiiuii' mm;

I [III II flumi llllllllllIllllilllllllllllllwllllllllllllllIlimllllllllllllllllllllllllllllllllllll I! I r II I INVEN'FOR ATTOR NEYS June 1945-- w. M. SUTCLIFFE 2,377,589

AUTOMATIC AIMING CONTROL Filed Nov. 20, 1940 2 Sheets--Sheei 2 W/LLMM M SuTcL/FFE INVENTOR ATTOR N EYS in these fields, and

Patented June 5, 1945 UNITED STATES PATENT OFFICE- AUTOMATIC AIMING CONTROL William M. slimline, Bay Village, Ohio Application November 20, 1940, Serial No. 366,423

14 Claims.

be embodied in directional control means of marine or aerial torpedos, .and in means for directing searchlights, motion picture cameras,

and the like. In general, the invention may be embodied in any apparatus in which a member is to be aimed at an object under circumstances in whichthere is relative motion as between the member to be aimed and the object aimed at. The principal object of my invention is to provide new and improved automatic aiming control of these types.

The novel features of my invention will appear from this specification and the accompanying drawings, showing one embodiment of-the in vention, and forming a part thereof, and all these novel features are intended to be pointed. out in the claims. v In the drawings 1 Figure l is a more or less diagrammatic side I elevation of a gun having associated therewith parts of an automatic aiming control embodying my invention,

Figure 2 is a partly fragmentary view of a part of the apparatus shown in Figure 1,,looking into the plane 2--2 of Figure 1, in the direction of the arrows.

Figure 3 is a section taken along the line 3-3 of Figure 1, looking in the direction of the arrows,

Figure 4 isa plan view diagram of a pair of light transmitting tubes and their light gathering fields,

- Figures 5 and 6 are transverse diagrams respectively of certain light gathering fields,

Figure 7 is an electrical diagram of a'motor control system which may be embodied in apparatus in accordance with my invention,

Figure 8 is a transverse diagram of .certain light gathering fields, showing an object included Figure 9 is a-diagram showing images which may be formed by apparatus embodying my invention. c

Referring to Figure 1 there is here shown one form of what may be termed anaiming means 20 which in any desired suitable way is so constructed and arranged that it will movesynchronously with some desired member or apparatus. In this instance, for purposes of simplification, the aiming means 20 is-shown as movable synchronously with a gun by reason of the fact that it is mounted directly on the gun barrel 2|, but, obviously, the aiming means need not be mounted on the gun barrel itself to have it move synchronously therewith. Accordingly,- it will be apparent that the gun barrel 2| may be taken to represent any member the direction of which is to be controlled or any member movable in synchronism therewith.

The aiming means 20 comprises, in the instance shown in Figures 1 through 3, four

tubes

22, 23, 24, 25 mounted in a yoke 26 comprising four connetced U-shaped portions, the tubes being pivotally supported in the respective U- I tube 23, and the'axis of the pivots 21 of the tube v 24 is parallel to the axis of the pivots 21 of the tube 25.

In Figure 2 a portion of the tube 25 is broken away, and as best seen in this figure, means is provided for adjusting the

tubes

22, 23 so that their axes extend in a desired direction, and to this end each

tube

22, 23 has disposed aboutit a ring 28 of desirably larger-internal diameter than the outside diameter of the respective tubes, the rings 28 being pivotally mounted on the tubes respectively by pivots 29, and the rings 23 being connected by screw-threaded studs 30, one having a right hand thread and the other a left hand thread, carried by the rings 28 respectively, and the screw-threaded studs 30 cooperating with a turn buckle 3i. Accordingly, it, will be apparent that by rotation of the turn buckle 3i the

tubes

22, 23 may be simultaneously swung about their respective pivots 21 in opposite directions of-rotation as viewed in Figure 2. a

The

tubes

24, 25 are adjustable bymeans of rings 28a, screw-threaded studs 30a, and a turn.

buckle 3m, in the manner already described in connection with the

tubes

22, 23, rotation of the turn buckle 31a of course adjusting the

tubes

24, 25 in a plane at right angles to the plane of the

tubes

22, 23.

The yoke 23 is hereshown as provided with The axis of the pivots 21 of the tube keyed to the stud as or fastened some support as is a gear 38 meshing with a pinion 39 which may be manually rotated or rotated by an electric motor 45. Keyed to the trunnion 33 is a gear segment 4| meshing with a pinion 42 which may be rotatable manually or by an electric motor 43 (see Figure 3) suitably carried by the support 35. The pivot stud 35 and the trunnions .32, 33 permit the aiming means 25 to be adjusted relatively to the barrel 2| in a vertical plane and in a plane at right angles to the vertical plane, but it will be understood that the amount of adjustment necessary is relatively small since in this instance it serves to adjust the aiming means 25 in accordance with the range of the gun, the trajectory of the projectile fired thereby, and relative movement of the objective.

The

tubes

22, 23, 24, 25 have disposed therein photo-

electric cells

44, 45, 45, 41 respectively.

External terminals 48 are provided,-mounted on connection boxes at the ends of the

tubes

22, 23, 24, 25, each pair of terminals 48 being connected to the anode and cathode of the respective

photoelectric cells

44, 45, 45, 41. The lower ends of the tubes, as viewed in Figure 2, are closed light tight whereas the other ends are open. Preferably, in order to increase the range and accuracy of the aiming means 25, lens means is provided for each

tube

22, 23, 24, 25 adapted to provide an image in its respective tube at the planeof the cathode of the respective photo-

electric cell

44, 45, 45, 41. In this instance each

tube

22, 23, 24, 25 is provided with a single lens 43 the principal focus of which is at the cathode of the respective photo-electric cell, 45, 45, 41.

The gun barrel 2| is pivotally mounted by trunnions 55 in a support so that it may be swung about a horizontal axis, and an electric motor 52 having a pinion 53 meshing with a gear 54 keyed to one of the trunnions 55 is adapted to swing-the gun barrel 2| about the axis of the trunnions 55. The support 5| is pivotally mounted by a pivot 55 on a base 55, so that the support 5| and hence the gun may be swung about a vertical axis, and a motor 51 having a pinion 58 meshing with a gear 59 keyed to the support 5| is adapted to swing the support about the axis of the pivot 55.

The operation of the motor 51 is controlled by the photo-

electric cells

44, 45, and the operation of the motor 52 is controlled by the photo-

electric cells

45, 41. A description oi the control oi one of the motors will serve for both. Accordingly reference may now be had to Figure 7 which shows the manner in which the motor 51 may be controlled by the photo-

electric cells

44, 45. Desirably, the anodes and cathodes oi the cells are connected to amplifiers respectively. Current flowing through the cell 44 is amplified by an amplifier 55 provided with any suitable source of electric current 5| and the amplified current is text by conductors 52, 53 to the coil 54 of amelectro-magnet. In like manner current flowing through the cell 45 is amplified by an amplifier 55 provided with a source of electric current 55, and the amplified current is ted by conductors 51, 58 to the coil 55 of an electro-magnet. The magnet coils 54, 55 are adapted to act in opposition on an armature or armaturescarried-by a movable element 1|..of a reversing switch 12, the movable element being swingable about a pivot 13. The movable element 1| carries a pair or contacts 14, 15 insulated therefrom andfrom each other and connected by a conductor 15 to oneterminal of a field winding 51] of the motor 51, the other terminal of the field winding 511 being connected to one of the line wires,-15, of a pair of line wires 15, 85 leading to a source of electric current (not shown).

The movable element 1| also carries a contact 19 in this instance electrically connected, thereto, and when the movable element isswung counter clockwise the contacts 15, 19 are adapted to engage

contacts

85, 8| connected by

conductors

82, 83 to the movable contacts 84 of a manually operable reversing switch 85. When the movable element 1| is swung in a clockwise direction the contacts 14, 15 are adapted to engage

contacts

85, 81, the contact 85 being connected to the conductor 83 and the contact 51 being connected to the conductor 82.

The movable element 1| of the electromag- -netically operated reversing switch 12 is conposed in this connection resistance means controlled by a switch 89, which as here shown comprises a movable element 95 swingable about a pivot 9 I, the movable element 95 being connected by a conductor 92 to the movable element 1|. Mounted on and desirably insulated from the movable element 95 are a pair of arcuate cores 93 adapted to cooperate with a pair of solenoids 94, 95. The terminals of the solenoid 94 are connected by conductors 95, 91 to the conductors 52, 53 respectively, and the terminals of the solenoid 95 are connected by conductors 95, 89 to the conductors 51, 58 respectively. The. movable element 95 is adapted to cooperate with either a resistor I55 or a resistor I5I depending on which way the movable element is swung. The adjacent terminalsof the resistors I55, I5I are free but the outer terminals are connected to each other and through a conductor I52 to the line wire 88.

The movable elements 1| and 95 are here shown as biased to their open positions by their own weight but any other suitable biasing means may be provided.

connected to the conductor I54, so that when the movable contacts 84 of thereversing switch are swung. clockwise to engage the contacts I 51, I55 respectively, the connections of the-conductors- 52, 53 to the armature 510 are reversed.

The photo-electric cells '45, 41 are connected to a control system C for the motor 52. The armature 52a and field 52 of the motor 52 are-ted from line wires 15a, 85a (which may be the same as line wires 18, 88). posed between the motor 52 and the photo-

electric cells

45, 41 is identical with the system hereinbefore described in connection with the motor 51 and the photo-

electric cells

44, 45.

As shown diagrammatically in'Figure 4, the light gathering field of the tube 22 defines a conical surface indicated by the diametrically opposite generatrix lines I58, I53, and in like manner the-lines II5, indicatediametrically opposite generatrix. lines of the light gathering field oi the tube 23. The angle between the respective pairs of generatrix lines I 58,- I55, and H5, III will depend, as is evident; on such factors as the length of the tubes or the length of an object will form a shadow or an image on the cathode of the photo-electric cell of the re- The control system C interspective tube only if the object is included in the light gathering field.

As adjusted in Figure 4, the light gathering fields are so related that the generatrix lines I99, Ilfl are parallel or substantially parallel. The tubes 24, 25 (omitted from Figure 4 for the sake of clearness) may be adjusted the same as the

tubes

22, 23, and the relationship between the

tubes

22, 23 and the tubes 24,' 25, as hereinbefore described, is accordingly such that a transverse section of thefour light gathering fields of the four tubes at some distance from thetubes would accordingly be defined by a pair of circles 2, tier the fields o'fthe

tubes

22, 23, and a pair of circles H4, M5 for the fields of the

tubes

24, 25; and at some-further distance from the tubes a transverse section would be defined by a pair of circles ll2a, ll3a for the fields of the

tubes

22, 23, and a pair of circles l I411, 511 for the fields of the

tubes

24, 25. The circles H2, 2:1 and H3, Ilia are transversely tangent to thegeneratrix lines I99, Illl respectively, and the circles II4, H411 and 5, 5a are transversely tangent to the parallel generatrix lines 9a,

IIOa respectively of the light gathering fields of the

tubes

24, 25.

It will be evident that the circles defining the sections of the light gathering fields of diametrically opposite tubes do not overlap in Figure 5' but that the circles defining the sections of the light gathering fields of circumferentially adjacent tubes do overlap and that the amount of overlap increases with the distance from the tubes. The amount of overlap may, if desired, be increased 'or decreased by adjustment of either or both of the turn buckles 3|, Ma. If desired the tubes may also be adjusted so that the light. gathering fields of diametrically opposite tubes by the photo-electric cells- 45, 41.

lines lll9a, l l|a and so be not included in any of the light gathering fields depends on whether the lines I 99. H0 and "Na, Illla respectively diverge very slightly and in that case how far the airplane is from the aiming meansfle A very slight divergence of the lines I09, I10, and of the lines l09a, llfla is assumed inFigure 8 but this is' not essential and depends on the conditions and results desired. I I when the light gathering fields of the

tubes

22, 23, 24, 25 are directed for-example on the, sky in the daytime all of the cathodes of the photoelectric cells 44 to 41 inclusive receivethe same amount of light and accordingly the coils 64, 59

controlled by the

cells

44, 45 are balanced and the reversing switch 12 is in its openposition; also, the coils 94, 95 are balanced and the movable element 99 of the resistance control switch 99 is in its open position. The same is true with respect to the corresponding switches controlled Accordingly, the

motors

52 and 51 are not in operation. Assuming now that an airplane P is included in thelight gathering fields of the four tubes as shown in Figure 8 then the cathodes of the photoelectric cells 44 to 41 inclusive will be shadowed by the images 5 to H9 inclusive, respectively, andconsequently less current will fiow through 3 the cells. In theccase, of the cells, 4 1, the

- coil 69 than fiows throughthe coil 54, thereby ing fields at some remote point from the

tubes

22, 23,- 24, 25 so that a section of the four fields wouldbe defined by the circles ll2b, ll3b. and

7 I14b, Il5b. The object included in the circle ll2b is almost the entire wing of the airplane and this object will result in an ima e -I I5 (Figure 9) on the. cathode of the photo-electric cell 44. There being in the illustrated instance but a single .objective lens 49 foreach tube" this image H5 will bereversed, it beingunderstood that ill-Figure 9 all images there shown are considered as though viewed from the rear ofthe focalxplane,

though of course the cathodes ofthe photo-electric cells are opaque and in the case of theimage I I5 this-may be considered as formed onthe cath- .ode of the photo-electric cell 44 ofthe tube 22'.

The object includedv in the circle 3b is the tail and part of the fuselage of the airplaneand this "will form an. image 1 on the cathode of the photo-electric cei; 45. The-objectincluded in the circle ll.4b is 1:. considerable part of the wing of the airplane and this will form an image III on thecathode 0:5" the photoelectric cell 45. It

will be noted that because the circle Il4b overlaps the circle 'II2b, the image 8 willinclude also a portion ofv theairplane included in the image 6. In like'manner the portion of the airplane included in the circle I 15b will form an image II9 on the cathode of 'the'photo-electric cell. 41 and this image'will include also a portion of the airplane included in the image 5.

causing th'ev movable member .II to swing to the right as viewed in Figure '7, the contacts-'15, 19 engaging the contacts 89', 3|; At the-same time the coil 95 will over-balancethe coil 94 and the movable contact element 90 will engage the resistor Illl and move overand in contact with the resistor, cutting out anamountof resistance depending on the amount or unbalance. The motor ,51 is thereby caused toro'tate and turnthe gear 59:10, that the aiming means '29 will be so moved that the. images 5, II11will move toward the left as viewed in Figure 9, whereby less of the air- .plane appears. inthe-imag'e I I6 and more of the airplane appears in'the; image 1, this motion continuing untilthe cathodes ofthe photo-

electric cells

44 and 45 are shadowed an equal amount; whereupon the switches 12 and 89 return to theiropen positions. However this condition is notjnecessarily-reached, because the airplane ismoving' and tends to maintain anunbalanced condition in the

cells

44, 45 and consequently the motor 51 may continue in operation, the aiming means following the airplane continuously.

It will be noted that as' the amount of unbalance. as between the photo-

electric cells

44 and 45 decreasesthe amount of unbalance between coils It will be understood that whether or not any" part or an of an. airplane, for example, might. e disposed between the lineal, and

.94 -,and also decreases so that more of the resistance I9I iszinserted in the motor circuit as the current fiow through the coil '94 increases, thereby causing the motor 51 to operate more and more" slowly as abalancefis'approached. The switch 12' is desirably so adjusted, that a minimum amount, of unbalance between the coils 64; and. will causeithemovable element 1| to move to either cheer the other offits'operatiiig positions,'depending on the directionjofthe 'un'- balance, the movable element being majintained in such operatingposition as'long asthefiamount olunbalance remains above the predetermined more than the other shadows the cathode of its respective photo-electric cell, the switches of the control C for the motor 52, corresponding to the switches 12 and 09 of the control for the motor 51, will come into action and the motor 52 will be caused to rotate in such direction that the amount of shadowing caused by the images 1 I0, I I9 is again equal, whereupon the motor 52 stops, or continues to rotate. at such a speed as to maintain a substantial balance.

Accordingly, it will be evident that the aiming means 20 is maintained directed at the airplane, the general axis of the aiming means being maintained so directed that it intersects the approximate center of gravity of the total outline of the airplane. Of course it follows that since the gun barrel 2| and the aiming means are moved synchronously, the gun barrel will be likewise so aimed that when the gun is fired the shell will hit or burst at or near the airplane. The operator oi the gun may adjust the relationship between the aiming means 20 and the gun barrel 2| while these parts are being automatically controlled by the

motors

52, 51. The operator may observe where the shells from the gun are bursting and cause operation of either or both of the motors 40, 43 until the shells burst at the objective. Such adjustment is particularly adapted to allow for relative movement of the objective with respect to the projectile. s

. It will be evident that to begin with, when the aiming means 20 is directed at an airplane, it may be that the entire airplane is included in one of the circles 2b, 3b, 4b, 5b, in which case there'will be a large unbalance as between the photo-electric cell shadowed by the image of the airplane and whichever one 01' the photo-electric cells is diametrically opposite the one which is being shadowed by the airplane, so that the contact 90 of the switch 09 will cut out a comparatively large amount of the resistor I00 or light sky and the object aimed at shadows the light gathering fields, then these reversing switches will be thrown into the other position when the aiming means is directed at a dark sky and the object to be aimed at is an illuminated one or emits invisible radiation.

The photo-electric cells may if desired be of a form responsive to invisible light. For example, they may be responsive to infra red rays from an object included in a dark sky.

It will be apparent that when the invention is embodied in a directional control for a marine torpedo, or the like, in which case there is relative movement as between the torpedo and the object aimed at in substantially only one plane, then two tubes only such as the

tubes

22, 20, need be utilized.

From what has been stated hereinbefore it will be apparent that the aiming means may be relatively stationary and the object aimed at movable, or the aiming means may be relatively movable and the object aimed at may be stationary, or both the aiming means and the object may be mov'able. Thus, whenever there is relative movement as between an object and the aiming means the aiming means and the member which it controls will be maintained directed at the object.

In general, it will be noted that the entire image of whatever object may be included in any one of the light gathering fields of the aiming means is projected onto the cathode of the photo-electric cell associated with that light gathering field.

the'resistor I01, as the case may be, thereby causing the associated motor to operate rapidly to bring the diametrically opposite photo-electric cells in balance; the same of course applying also to the other two photo-electric cells and their associated motor. e

- As he'reinbefore mentioned, the apparatus may be so adjusted that'the entire object aimed at when at'a given range may be entirely or sub-' stantially entirely within the spaces bounded by the light gathering fields (see Figure 5) and the motors 02 and 51 will stay out of operation as long as the object is maintained in that space,

one or the other or both motors operating as soon as the object entersone or more or the light gathering fields. I

The reversing switch. ing reversing switch in the control C are provided so that the motorsjg and I! may be caused to be operated in-r the direction. lore:-

Consequently the relative position oi such image and the cathode on which it is cast is not material. The same image cast anywhere on the cathode will produce exactly the same effect. Furthermore, an advantage of having circumterentially adjacent light gathering fields produce images at least portions of which are duplicates of each other makes more accurate aiming possible. I

In Figures 8 and 9 it has been assumed that the object aimed at is a single airplane. However, the object aimed at may be a plurality of airplanes flying in formation or otherwise. My inventiorr is particularly advantageous in aiming at such a composite object. The range may be such that when'the aiming means 20 is aimed in a the airplanes included in one field may also be included in the adjacent overlapping field. .The

result'is that when the aiming means 20 is directed at such a composite object, .the photoelectriccells .44 to 41 inclusive will so control the motors 02, II that the opposed cellswill be brought into balance when 'the general axis oi the aiming means ll intersects the approximate center 01 gravity of thecomposite object con- "llj'and thecorrespondh ample it the reyersing switches are set so that the motors 02, I1 operate in the correct directionwhen the means 20 is direc'wd at a stituted by the plurality of, airplanes then included in the light gatheringfields. One or more of the airplanes will be within the range of shrapnel from a shell bursting at this center of gravity.- I

Under some eonditionsot duirable to have diametrically opposite light gathering fields overlap. as shown in Figure 6.

a, a is feasible and In' such cas an object included in both of two diametrically opposite fields will result in images, on'the' cathodes of the photo-electric cells associated with these fields respectively, at least portions of which images are duplicates of each other. Each cathode is thus shadowed more than it would be if there were no overlapping of the light gathering fields, thereby increasing the sensitivity of the difierential response of the switch 12, and of the switch 89.

From the foregoing it will be apparent to those skilled in the art that the illustrated embodiment of my invention provides a. new and improved automatic aiming control, and accordingly accomplishes the principal object of my invention.

On the other han'd,it also will be obvious to those skilled in the art that the illustrated embodiment of my invention may be variously changed and modified, or features thereof, singly or collec-- tively, embodied in other combinations than those illustrated, without departing from the spirit of my invention, or sacrificing all of the advantages thereof, and that accordingly, the disclosure here- I in is illustrative only, and my invention is not linited thereto. "Iclaim: 1 d I f. In combination: means for aiming at an object, including at least two separate, light ca ering units, eachunit comprising a light transmitting tube and light responsive means in said tube responsive to light provided by the light gathering field of the unit; means so mounting said units for movement in unison that said tubes are in generally parallel relation and the light gathering fields of said units are substantially displaced in space; and means controlled by saidlight responsive means for maintaining said aiming mean directed at an vobject tending to move relatively across said light gathering field; said controlled means including an electric motor, having an armature, a normally open reversing switch for controlling the current through said armature, and means controlled by said light responsive means for selectively actuating said reversing witch.

2. In combination; means for at an object including means providing a light gathering field and light responsive means responsive to ,light provided by said lishtsathering field; and means controlled by said light responsive means for maintaining said'aiming means di-'- rected at an objecttending to move relatively across, said light gathering fields; said controlled *means including an electric motor having directed at an object tending to move relatively across said light gathering fields; said controlled means including an electric motor having an armature, a normally open reversing switch for controlling the current through said armature, means controlled by aid light responsive means for selectively actuating said reversing switch, a resistor connectable in the circuit of said motor armature to adjust the speed thereof, and means controlled by said light responsive means. constructed and arranged to vary the amount of said resistor connected in said motor circuit.

4. In combination: means for aiming at an object, including at least two separate light gathering units each providing a separate objective light gathering field, each unit comprising a light transmitting tube and light responsive.

, means for maintaining said aiming means directed at an object tending to move relatively across said light gathering fields.

5. In combination: means for aiming at an object, including at least two separate light gathering units each providing aseparate obarmature, a normally open reversing switch for controlling current through said armature,

means controlled by said light responsive means for selectively said reversing switch, a

rsistonconnectable in the circuit of said motor mature to adjust the speed thereof, and means controlled by said light responsive means constructedand arranged to vary amountof said resistor connected in said a. Incombinatlonz. Iron at anobject including atleasttw separate light goth-- erlng units, each, unit colnpnsingja'flight transmitting-tube. and light rsponsiie mean in said tube responsive to lieht tov dbythe light gathering I field of the unit; means so-lnounting said units for movement in unison that'said tubes gathering fields of said units displaced in s e; and means controlled by said lightresponare in generally Parallel-relation and the light jective light gathering field, each unit comprising a light transmitting tube and light responsive means, in said tube responsive to light provided by the objective light gathering field of the unit; means so mounting sai units for movement in unison that said tubes are in generally parallel relation and the objectivelight gathering fields V of said units are substantially displaced in space,

overlapping each other in part, so that the optical fields aimed at by said units respectively are substantially displaced in !space and have a part in common; and means controlled'by said light responsive means for maintaining said aiming means directed at an object tending to move relatively across said light gathering fields.

6. In combination: means for aiming at an object, including four separate light gathering units each providing a separate objective light gathering field, each unit comprising a light transmitting tube and light responsive means in I said tube'responsive to light provided'by theobjective light gathering field of the unit; means so mounting said units tor movement in unisonthat said tubes are in generally parallel rela'-- tion circumferentially spaced from each' other and the objective light gathering fields of said units are substantially displaced in space from each other so that the optical fields aimed at by said units respectively are substantially circumrerentlally displaced in space, the axes of two diametrically opposite object, including four separate light gathering I separate objective light--- unlts each providing a, gathering field, each unit comprising alight transmitting tube and light responsive means in .said tuberesponsive to light provided by the defining a plane at right angles to a plane defined by the axesof j ering objective light gathering field of the unit; means so mounting said units for movement in unison that said tubes are in generally parallel relation circumferentially spaced from each other and the objective light gathering fields of said units are substantially displaced in space from each other and the objective light gathering fields of each pair or circumferentially adjacent units overlap each other in part, so that the optical fields aimed at by said units respectively are substantially circumferentially displaced in space and at least those. aimed at by circumferentially adjacent units have a part in common, the axes of two diametrically opposite tubes defining a plane at right angles to a plane defined by the axes of the other two diametrically opposite tubes; and means controlled by said light responsive means for maintaining said aiming means directed at an object tending to move relatively across said light gathering fields.

8. In combination: means for aiming at an object, including at least two separate light gathering units eachproviding a separate objective light gathering field, each unit comprising means, including an objective lens, constructed and arranged to provide an optical image of an object included in the objective light gathering field of the unit and comprising means respone sive to the image so provided; means so mounting said units for movement in unison that the objective light gathering fields of said units are generally collateral but substantially displaced in space, said light gathering fields overlapping each other in part, so that the optical fields aimed at by said unitsrespectively are substantially displaced in space and have a part in common; and means controlled by said image responsive means :for maintainin said aimin means directed at an object tending to move relatively across said light gathering fields.

9. In combination: means for aiming at an object, including four separate light gathering units each providing a separate objective light gathering field, each unit comprising means, including an objective lens, constructed and arranged to provide an optical image of an object included in the objective light gathering field of the unit and comprising means responsive t the image so provided; means mounting said units in circumferentially spaced relation for movement in unison so that the objective light gathering fields or said units are substantially displaced in space from each other and the objective light gathering fields of at least-the circumferentially adjacent units overlap each other in part, so that the optical fields aimed at by said units re-- spectively are substantially circumferentially displaced in space and at least those aimed at by ci'rcumferentially adjacent units have a part in commo and means controlled by said image responsive means for maintaining said aiming means directed at an object tending to move relatively across said light gathering fields.

10. In combination: means for aiming at an object, including at least two separate light gathunits each providing a separate objective light gathering field, each unit comprising a light transmitting tube, lens means including at least an objective lens for said tube,- and photo-electric means in said tube disposed approximately at the plane of an image provided by said lens-means of an object included in the objective light gathering fil'd'of the unit; means so mounting said units for movement in in generally parallel relation and. the objective unison that said tubes are object, including four separate light gathering.

units each providing a separate objective light gathering field, each unit comprising a light transmitting tube, lens means including at least an objective lens for said tube, and photo-electric means in said tube plane of an image provided by said lens means or an object included in the objective light gathering field of the unit; means mounting said units in circumferentially spaced relation (or movement in unison so that said tubes are in generally parallel relation and the objective light gathering fields of said units are substantially displaced in space from each other so that the optical fields aimed at by said units respectively are substantially circumferentially a plane at right angles axes of the other two diametrically opposite tubes; and means controlled by said photoelectric means for maintaining said aiming means directed at an object tending to move relatively across said light gathering fields.

12. In combination: means for aiming at an object, including at least two separate light gathering units each providing a separate objective light gathering field, each unit comprising a light transmitting tube and light responsive means in said tube responsive .to light provided by the objective light gathering field of the unit; means so mounting said tubes for movement in unison that said tubes are in generally parallel relation and the objective light gathering fields or said units are substantially displaced in space so that the optical fields aimed at by said units'respectively are substantially displaced in space: means for adjusting the angle between the axes of said tubes to adjust the amount of displacement or said light gathering fields; and means controlled by said light responsive means for maintaining said aiming means directed at an object tending to move relatively across said light gathering. fields.

13. In combination: meansfor aiming at an object, including at least two separate light gathering units each providins a separate objective light gathering field, each unit comprising a light transmitting tube, lens means including at least an objective lens for said tuba-[and photo-electric means in said tube disposed approximately at the plane of an image provided by said lens means of an object included in the objective light gathering field of the unit; means mounting said units for movement in unison so that said tubes are in generally parallel relation and the objective light gathering fields of said units are substantially displaced in space so that the optical fields aimed at by said units respectively are substantially displaced in space; means for adjusting the angle between the axes of said tubes to adjust the amount of displacement of said light gathering fields; and means controlled by said photo-electric means for maintaining said aiming means directed at an object tending to move relatively across said light gathering fields.

14. In combination: means object, including four separate lisht gathering disposed approximately at the displaced in space the axes of two diametrically opposite tubes defining to a. plane defined by the for aiming at an units each providing a separate objective light gathering iield, each unit comprising a light transmitting tube, lens means including at least an objective lens for said tube, and photo-electric means in said tube disposed approximately at the plane of an image provided by said lens means of an object included in the objective light gathering field of the unit; means mounting said units in circumferentially' spaced relation for movement in unison so that said tubes are in generally 10 parallel relation and the objective light gathering fields of said units are substantially displaced in space from each other so that the optical fields aimed at by said units respectively are substantially oircumierentially displaced in space, the axes of two diametrically opposite tubes defining a plane at right angles to a plane defined by the axes oi the other two diametrically opposite tubes; means for adjusting the angle between the axes of diametrically opposite pairs of said tubes respectively to adjust the amount of displacement of the corresponding diametrically opposite pairs of light gathering fields respectively; and means controlled by said photo-electric means for maintaining said aiming means directed at an object tending to move relatively across said light gathe'ring fields.

\ WILLIAM M. SUTCLIF'FE.