US2586817A - Stabilization system for gunfire control apparatus and the like - Google Patents

Description

Feb. 26, 1952 H. HARRIS, JR 2,586,817

STABILIZATION SYSTEM FOR GUNFIRE CONTROL. APPARATUS AND THE LIKE Filed NOV. 20, 1945 2 SHEETS--SHEET l T0 COM/ll TER L /L/Z Mmm.

Feb. 26, 1952 H. HARRIS, JR 2,586,817

STABILIZATION SYSTEM FOR GUNF'IRE CONTROL APPARATUS AND THE LIKE Filed Nov. 2o, 1945 2 SHEETS- SHEET 2 .N .mvg

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Patented Feb. 26, 1952 STABILIZATION SYSTEM FOR GUNFIRE CONTROL APPARATUS AND THE LIKE Herbert Harris, Jr., Cedarhurst, N. Y., assig'nor to lhe Sperry Corporation, a corporation of Delaware Application November 20, 1945, Serial No. 629,859

My invention particularly relates to a system adapted for use in stabilizing re control apparatus such as gun sights and turrets mounted on aircraft. For the purposes of illustrating one adaptation of this invention, I will refer to a particular type of ordnance and to a gun turret mounted for stabilization on an aircraft. However, it is to be understood that this invention is not to be considered as limited thereto, but may be applied to any type of apparatus or body which is mounted for stabilization about one or more axes in space.

Gun turrets, in accordance With present practices, are usually mounted on a craft, such as an airplane, for movement about ytwo mutually perpendicular axes of support, one thereof being termed the azimuth axis, being normally vertical, and the other thereof being termed the elevation axis, being normally horizontal. Servomotors and associated control apparatus, which may be responsive to remotely positioned, manually operable handle bars, or, handle bars mounted Within the turret, are employed for driving the turret carrying the gun and sight in azimuth and also in elevation, or the turret in azimuth and the guns and sight in elevation relative to the turret. In such installations, the gun sight is provided for the use of the operator in tracking a target and suitable computing and gun control mechanisms are included for the purpose of offsetting the line of sight and the gun for target'interception purposes.

Heretofore, where such gun turrets are unstabilized, the handle bars or manual controls function to operate control signal generators, for example, potentiometers, one of which controls the azimuth servo and the other the elevation servo, the handle bars being movable in the directions in which it is desired to drive the turret. The voltage derived from the potentiometers are respectively applied to suitable amplifiers which, in turn, control the direction and rate of operation of their associated servomotors. This control voltage ordinarily functions to accelerate the servomotor until the speed thereof is such that the voltage output of a permanent magnet generator, driven by said servo, bucks out the potentiometer voltage or modifies the original signal voltage, so that the rate of operation of the servo is proportional to the manually applied, initial signal. -In this manner, the servo will drive the turret at the established rate with respect to the craft or plane but, of course, not necessarily so with respect to space. If the plane has no angular movement about an axis paralleling the axis Claims. (Cl. 318-489) about which the turret is driven, then the turret will be driven at a rate with respect to the plane and with respect to space which is proportional to the potentiometer voltage, and the voltage output of the permanent magnet generator will be a measure of the angular rate of the turret with respect to space or a true measure of the angular rate of a target. assuming that under these conditions a target is being tracked by the use of the sight.

However, should the plane carrying the turret dive or roll, this motion of the craft will affect that motion of the turret which occurs about the same or a parallel axis and as a result thereof, the turret optics or sight will move olf the target and must be brought back thereon by manipulating the hand-control. Assuming that under these conditions, the angular rate of the target remains a constant, the change in the voltage output from the potentiometer. because of movement of the hand-control, will change the turret rate. Therefore, since the angular rate of the target has not changed, the new turret rate, or the turret rate under transient conditions of dive or roll as measured by the permanent magnet generator, Will be an erroneous measure of the target rate and not a measure of the turret rate relative to space.

In the present invention, I propose to use a system of the general character of that above described which is adapted to control the rates of a gun turret about its two axes of support, but, in connection with each servomotor, instead of employing a permanent magnet generator or similar generator which is driven by the servo and provides a voltage output proportional to the speed thereof, I propose to provide a means for measuring the true rate of the turret about its axes of support relative to space, and to supply signals proportional to this measurement of true angular rate with respect to space which may be supplied to a computer, thereby providing correct and accurate input data, and which are also applied further to control the servos, whereby to provide stabilization of the turret. In my proposed system, the angular rate at which the turret is driven about its axes of support under the control of the potentiometer voltage derived from the handle controls and the signal proportional to angular rate relative to space may vary with respect to the aircraft, but, will remain substantially constant relative to space for a given setting of the handle controls for all movements of the aircraft in dive and roll. In other Words, the angular rate of the turret relative to space is dependent upon the setting of the handle controis and will remain constant for a given setting irrespective of movements of the craft in pitch. roll or azimuth.

It is, therefore, the primary object of the present invention to provide a stabilizing system for a first body mounted for stabilization about an axis of support on a second movable body or aircraft in which means are provided for controlling the angular rate of the first body relative to the second, a measurement of the angular rate of the first body relative to space is taken, and the control exercised by said control means over the angular rate of the first body is modified in accordance with the measure of angular rate relative to space.

Another obiect resides in providing a stabilizing system of the foregoing character in which a gun sight or the like is stabilized, tending to remain on target during movements of tile craft in pitch and roll; and in which true rates of the sight with respect to space are obtained, thereby providing a true measurement of the angular rate of the target which may be supplied as accurate input data to an associated computing mechanism.

Still another object of the present invention resides in providing a stabilizing system for a turret in which the initial control signal controls the rate of movement of the turret relative to the craft and a second control signal, which is proportional to a measure of true angular rate of the turret relative to space, is used to modify the initial control signal, so that the turret rate with respect to space is substantially a constant when no change in the initial signal occurs, and the movement of the turret in tracking a target is substantially unaffected by movements of the craft.

A still further object resides in-providing a stabilizing system in which an initial control signal, which may be manually adyusted or otherwise, directly controls a servo for driving the body or turret to be stabilized while a gyroscope is caused to precess about an axis paralleling the axis about which said body is stabilized, so that the gyro follows the movements of the body or turret, and a signal derived from the torque-exerting means, which causes precession of the gyro, is derived as a true measure of the angular rate of the body with respect to space and is used to modify the initial control signal so as substantially to effect stabilization of the body thereby affording accurate control thereover by the initial signal.

The invention in another of its aspects relates to novel features of the instrumentalities described herein for achieving the principal objects of the invention and to novel principles employed in those instrumentalities, whether or not these features and principles are used for the said principal objects or in the said eld.

A further object of the invention is to provide improved apparatus and instrumentalities embodying novel features and principles, adapted for use in realizing the above objects and also adapted for use inother fields.

With the foregoing and other objects in view, my invention includes the novel method and the novel combinations and arrangements of elements described below and illustrated in the accompanying drawing, in which- Fig. 1 schematically illustrates the system of the present invention as applied to the control of a turret or other object about a single axis of support;

Fig. 2 schematically represents the system of the present invention as applied to a gun turret for stabilizing it about its two axes of support;

Fig. 3 is a fragmentary perspective view of a gun turret and sight therewithin mounted for stabilization in accordance with the present invention about mutually perpendicular axes on a craft; and

Fig. 4 schematically shows a modified manner in which to derive signals proportional to precession rates of a gyro.

In the drawings, I have shown a gyroscope as the means which normally provides a substantially :dxed reference with respect to space but which may be caused to move or precess at an angular rate corresponding to the rate at which the turret or other obJect is rotated by the servomotor.

In Fig. 1 of the drawings, I have shown one embodiment of my invention wherein a gyroscope is arranged to stabilize and provide an accurate measurement of the rate of rotation of the turret about one of its axes of support relative to space, while in Fig. 2, a system is shown for complete stabilization of the turret by means of a single gyroscope which also functions to provide accurate measurements of rates of operation of the turret relative to space about both of its axes of support.

Referring first to Fig. 1, 1 indicates generally the schematically illustrated turret, mounted for movements in elevation about an axis 2 and for rotation in azimuth about an axis 3. In the schematic illustration, the turret I is supported on trunnions 4 in a gimbal ring 5 which in turn vis mounted on trunnions 6 to rotate in bearings 1 lwhich, it will be understood, are mounted on the airplane or other craft carrying the turret.

A servomotor 8, which may be of any suitable conventional design and which may be of the character of those more particularly shown in Fig. 2, is arranged through its output shaft 9 and associated gearing I0 to drive the turret I in azimuth about the axis 3. A manual control such as the handle bars illustrated in Fig. 2, and indicated at II, enables the operator or gunner to control a potentiometer I2 comprising the resistance element I3 and the wiper arm I4 operated by the handle control II. A battery I5 or other suitable source of voltage is connected across the potentiometer winding I3 and a midtap on the potentiometer winding is connected through lead I6 to the amplifier I1, while the arm or wiper I4 is connected through lead I8 to the amplifier.

The amplifier functions to supply an output voltage which is proportional to the signal voltage derived from the potentiometer and the output of the amplifier reverses in polarity, or in phase sense if the servomotor is of an alternating current type, upon reversal of the polarity of the signal Voltage supplied thereto. The signal voltage derivedfrom the handle bar control may be of an alternating character, if desired. The signal voltage derived from potentiometer I2 constitutes the initial or primary signal controlling the rate and direction of operation of the servomotor and, hence, in view of the additional voltage signal derived from the gyroscope as hereinafter described, the rate of the turret I about axis 3 will be dependent upon the setting of the handle bar control II relative to the aircraft on which the turret is mounted.

In accordance with my invention and in lieu of the feedback signal voltage from a permanent magnet generator which is proportional to speed of rotation of the servomotor, I supply a feedback voltage which is proportional to rate of turn or precession of a gyroscope which is caused automatically to precess at the rate of turn of the turret established by the handle bar controls.

In the embodiment illustrated in Fig. 1, a gyro indicated generally at I9 is mounted within the t1 'et and is free to precess about the axis 20 thereof which preferably parallels the axis of supports 3 of the turret. The gyroscope may be of a conventional character including a gyro rotor case 2| within which the rotor is mounted to rotate about the spin axis 22. The rotor case 2| in turn is supported on trunnions 23 in the gimbal ring 24. Gimbal ring 24 is in turn supported on trun nions 25 to rotate in suitable bearings 26 (oni,y one of which is shown) about the axis 2U. It will be understood, although' otherwise shown for clearness in illustration, that the gyro and its bearings 26 are mounted within the turret I.

In order to cause the gyro to precess about its axis 20 at the same rate that the turret is caused to rotate about its axis 3, I have schematically shown a pick-off or signal voltage generator ar-V ranged to control the precession of the gyro in accordance with movements of the turret. In the embodiment illustrated, I have shown an E-type signal transformer or generator indicated generally at 21. This signal transformer is of a wellknown type comprising an E-shaped core 28 which in the embodiment illustrated is mounted to move with the gyro or gimbal ring 24 thereof about the axis 20, and an armature 29 which is rotated about the axis 20 of the gyro and in timed relation with rotation of the turret about the axis 3. This may be accomplished as schematically shown by means of bevel gears 30, one of which is keyed to rotate through the output shaft 9 of the servomotor and the other of which is connected through shaft 3| with the armature 29 of the signal transformer.

It will be understood that the core and armature of the transformer 21 are formed of suitable magnetic material and that the core carries an exciting winding on the middle leg thereof and a pickup winding on each end leg. The exciting winding, which is not illustrated but is schematically represented as connected with a suitable source of alternating current 32, functions to pass equal amounts of ux through the end legs thereof when the armature is so positioned as to provide two balanced parallel magnetic circuits. When the armature moves from this position in one direction or the other, the voltages induced in the pickup windings, which are not illustrated but are connected in series across the leads 33 and 34, provide a resultant voltage output having one phase sense when the armature moves relative to the core in one direction and of the opposite phase sense when this motion is reversed from the zero voltage output position of he armature. To accomplish this result, of course, the two pickup windings are connected in voltage bucking relation.

Leads 33 and 34 are connected to a suitable amplifier 35 which is preferably of a phase-sensitive nature when a transformer of the character of il at indicated at 21 is employed to provide a reversible phase alternating voltage signal input thereto. The amplifier is connected with a suitable source of alternating reference voltage 32a which is preferably the same source as source 32, above referred to, for the signal transformer 21. The amplifier preferably functions, at least in the embodiment herein illustrated, to provide a direct current output differentially to control a torque motor indicated generally at 38. For illustration purposes, I have shown in Fig. 1 the output stage of the amplifier as including the electron tubes 31 and4 38 connected respectively in the two parallel channels of the amplifier and having plates or anodes connected through the differential eld windings 39 and 40 of torque motor 36. A mid-tap between these windings constitutes a common return to the amplifier as shown, tube 31 serving to control the current in winding 39 and tube 38 similarly serving to control the current in winding 40. The amplifier may be adjusted so that when no signal is supplied thereto, the currents in the windings 39 and 40 are equal and opposite and, therefore. no torque output is derived from torque motor 36. When, however, a signal voltage of one phase sense or the other is supplied to amplifier 35, the current in winding 39 or 40 predominates over the other, depending upon the phase sense of the signal, therefore, producing a torque output from motor 36 in such a direction as to cause the gimbal ring 24 of the gyroscope to precess in the same direction and at the same rate as that at which the armature 29 of the signal transformer is rotated by the servomotor.

It will be understood that the torque applied about the axis of trunnions 23 of the gyro will cause precession of the gimbal ring about axis 20 of the gyro and that the rate with respect to space of this precession will be proportional to the torque so applied. Furthermore, the resultant current or the difference between the currents flowing in the eld windings 39 and 40 of the torque motor will be a measure of the torque exerted by the torque motor or a measure of the rate of precession of the gyroscope. In the embodiment shown in Fig. 1, and for purposes of illustrating one manner in which this torque may be measured, I have shown the cathode circuits of the tubes 31 and 38 as including resistors 4| and 42, and I have also shown a battery 43 as a source of plate potential. Hence, the currents iiowing in the plate circuits of tubes 31 and 38 will produce a differential voltage drop across resistors 4| and 42 and the resultant or net voltage drop between the cathodes of these tubes or across the resistors 4| and 42 will be a measure of the torque applied to the gyro and the rate of precession thereof. Hence, leads 44 are connected to the cathode ends of the resistors 4| and 42, so that a signal voltage will be developed thereacross which is proportional to the rate of precession of gyroscope |9.

Leads 44 may be connected, as indicated, to a computer to supply thereto a signal voltage which, as hereinafter more particularly pointed out, is an accurate measure of the angular rate of turret about axis 3 and relative to space. In accordance with this invention, leads 44 are in turn connected to leads 45 to the amplier I1 and, by means of leads 45, the signal voltage across leads 44 is supplied to amplifier |1 in bucking relationship to the signal supplied thereto from the potentiometer I2.

The operation of the embodiment of my invention shown in Fig. 1 is as follows: First, let us assume that the aircraft on which turret is mounted has no angular movement relative to space, and let us further assume for description purposes that the sight, handle control and operator are within the turret. In order to track a chosen target, vthat is, maintain theline Iof sight of the turret optics on the target while the target moves relative to the aircraft, theoperator manipulates the handle bars or manual controlsA to supply a signal voltage outputv from potentiometer I2. The potentiometer I2 may be considered as the source of a first or primary signal voltage or the initial signal employed in controlling the servo, and the polarity thereof is dependent upon the direction in which the handle controls are turned. This initial signal functions to cause the servomotor to drive theturret about its axis 3 in the desired direction to track the target .At the same time, the armature 29 of signal transformer 21 moves relative to the core 28 thereof and supplies a signal voltage to the amplifier 35, the outputs of the amplifier Vbeing such asY to apply a torque on the gyro by means of the torque motor 36 which will cause it to precess in the same direction in which the armature 29 is moved and at the same rate. In other words, the gyro is caused to precess about its axis 20 which parallels the axis 3 of the turret and to follow the turret in its rotation thereabout.

The rate signal derived across the cathode resistors 4I and 42, which is a measure of the angular rate of precession of gyroscope I9, is supplied in bucking relation to amplifier I1. It is assumed for purposes of illustration that the servomotor herein employed is of the Vickers hydraulic type, wherein the control signals so control the servo that it will continue to operate at a rate proportional to the setting of the handle controls II when the signal voltage derived therefrom is reduced to zero by the rate signal fed back from the torque motor control circuit. This type of servo is Well known in the art and a detailed description thereof is not believed necessary but reference may be made to U. S. Patents Nos.'2,l77,098, issued to T. B. Doe, et al., and 2,189,823, issued to H. P. Vickers et al. Obviously, other types of servos may be employed wherein the difference between the initial control signal such as that derived from the potentiometer I2 .and the feedback rate signal such as that derived from the torque motor circuit is of such value as to drive the servo at the desired rate or at a rate proportional to the handle bar setting.

Therefore, assuming that the handle bar control II is moved to some predetermined position, the repeat-back signal voltage will, in the type of servo system herein assumed, equal and oppose the signal derived from potentiometer I2, reducing the resultant signal voltage supplied to amplifier I1 to zero, and servomotor 8 will drive the turret I at a rate proportional to the handle bar setting. Since the gyroscope precesses at the same rate as the turret and at the same rate at which the line of sight is angularly moved, so long as the line of sight remains on the target, the gyroscope will provide an accurate measure of the angular rate of the target in space.

If, during this operation with the handle bar control set, the aircraft should rotate about lthe axis 3 or 20, it would be necessary for the operator to readjust the setting of the handle controls because of the added movement of the craft if the gyroscope and its associated repeat-back circuit were not employed. However. the gyroscope will tend to maintain its position in space and, therefore, the rate signal which is derived from the torque motor circuit will normally control the servomotor in such a manner that angular movement of the turret about its axis 3 will be synchronized with angular movement of the gyro about its axis 20. Hence, the repeat-back of the ratesignal functions to stabilize the turret under the control of the gyro and to maintain the rate of the turrent relative to space as prescribed by rate` dependent upon the setting of the handle control, but at a diierent rate relative to the craft. Therefore, the repeat-back signal derived from the control for the torque motor of the gyroscope will tend to maintain the line of sight on the target, even though movement of the craft about the same or parallel axis occurs, so that it is unnecessary for the operator to adjust the handle'bar setting except to maintain the desired rate of the sight or turret as though no movement of the craft had occurred.

In Fig. 2, I have schematically shown my invention as applied to the stabilization or control of the gun turret about two of its mutually perpendicular axes of support, as clearly illustrated in Fig. 3. Referring first to Fig. 2, the manually operable handle bars 46 are movable by the operator about the azimuth axis 41 and also about the elevation axis 48. In the embodiment illustrated, the handle bars together with the gyroscope are mounted within the turret indicated generally at 49 in Fig. 3. Movement of the handle bars about the azimuth axis 41 serves to rotate the wiper arm 50 of the potentiometer 5I which may be generally similar to potentiometer I2, hereinbefore described; and which is employed to provide a signal voltage for controlling the azimuth servo.

Operation of the potentiometer 5I may be .accomplished through the medium of gears 52, one of which is secured on the shaft of the wiper arm and the other of which is directly coupled with the handle bars 46. Similarly, a second potentiometer indicated generally at 53 is connected for operation by the handle bars when they are moved about the elevation axis 48. The wiper arm 54 of potentiometer 53 is secured to shaft 55 which is driven by gear 5B which, in turn, is operated by cylindrical rack 51. Rotation of handle bars 46 about axis 48 produces axial translation of rack 51 through the medium of gear 58, meshing with cylindrical rack 59. Hence, movement of handle bars 46 about axis 41 produces a corresponding movement of wiper 50 over the resistance element of potentiometer 5I and rotation of handle bars 46 about axis 4B produces a corresponding rotation of wiper 54 over the resistance element of potentiometer 53. Potentiometer 53 is employed to provide a signal for controlling the elevation servo. Each of the resistance elements of potentiometers 5I and 53 is connected across a suitable source of current such as battery 60 and a center tap on each resistance element together with the wiper arm of each potentiometer are respectively connected to output leads 6I and 62, leads 6I being connected with the azimuth servo amplifier 63 for controlling the azimuth 9 servo, and leads 62 being connected to the eleva tion servo amplifier 64 for controlling the elevation servo.

The azimuth and elevation servomotors are re- Vspectively initially controlled by the handle bars 46 in response to signal voltages derived from the potentiometers and 53, substantially in the same manner as the servomotor 8 hereinbefore described in connection with Fig. 1.

In the embodiment of my invention shown in Fig. 2, I employ a single gyroscope for measuring the angular rates of the turret about its two axes of support on the craft. For example, as shown in Fig. 3, the turret 49 is supported on trunnions 65 for movements in elevation about the axis 66 and relative to the yoke or gimbal ring 61. Ring 61 in turn is supported to rotate in azimuth about the azimuth axis 6B by means of suitable trunnions 69 or the like, journalled in suitable bearings in parts of the craft structure, such as the bearing support 10 illustrated in the upper por-r tion of Fig. 3 and the bearing supports 'H appearing at the bottom of Fig. 3. The gyroscope indicated generally at 12 in Fig. 2 is mounted for movement about the axes 13 and 14. These axes are, in accordance with the invention, disposed in parallel relation to the axes of support 66 and 68 of the turret. In other words, axis 13 parallels the turret axis 66 and axis 14 of the gyroscope parallels the turret axis 68.

'I'he spin axis 15, of the gyroscope may, therefore, parallel the line of sight provided by the optical system represented generally at 16 in Fig. 3. The rotor bearing case 11 of the gyro is mounted on trunnions 10, aligned with the axis 14, and supporting the rotor case in gimbal ring 19. The gimbal ring 19, in turn, is supported on trunnions 80 in supports 8| whichI are fixed to the casing of the instrument, trunnions 80 being aligned with the axis 13 of the gyroscope. In order to afford free movement of the gyroscope about both of these axes and at the same time to operate signal generators or pick-offs for detecting such movements of the gyroscope, the rotor bearing case is connected through stem 82 with a yoke 83 mounted to rotate about an axis normally coincident with the axis 14 of the gyro. In this manner, rotation of the rotor case of the gyro about the axis 14 will be imparted to the yoke 03 and will serve to move the armature 84 of an E-tyne transformer or pick-01T 85 relative to the core 86 thereof, which core is mounted in xed relation to the casing of the instrument. The stem 82 is movable within a slot 81 in the yoke 83 which is of a length suilicient to permit the necessary movement of the gyro casing and gimbal ring 19 about the axis 13. The trunnion 80 is arranged to operate the armature 88 of a second pick-01T or signal transformer 89, the core 90 of which is mounted in fixed relation to the casing of the instrument. Since the casing of the instrument .is xed within the turret. pickoffs 85 and 89 will detect movements of the turret relative to the gyroscope and vice versa.

It is herein assumed that axis 14 of the gyroscope parallels the azimuth axis of the turret and therefore when the handle bar controls 46 are operated to cause the turret to rotate in azimuth at a prescribed rate relative to the craft, the casing of the gyroscope will move the core 86 of pick-off 85 relative to the armature 84. As a result thereof, a signal voltage output will be supplied across the leads 9| supplying an alternating signal voltage to amplifier 92. functions in the same manner as amplifier 35 This amplier.

hereinbefore describedin connection with Fig. 1 to control torque motor 93 which is mounted on trunnion to exert a torque about the axis ,13 and thereby cause the gyro to precess in the same direction as the casing thereof or in which the core 96 of the pick-off had been turned relative thereto. Leads'94 serve to connect the output of amplifier 92 with the torque motor 93. and it will be understood that the torque exerted thereby will be suiiicient to cause the gyroscope to precess about the axis 14 at the same rate as that at which the azimuth servo drives the turret as hereinbefore described.

'I'he signal voltage, which is proportional to rate of precession of the gyro, and which is derived from the output of the torque motor amplier 92, as described in connection with the ampliiler 35 in Fig. 1, is fed back to servo amplifier 63 by leads 95 and this signal may also be supplied through leads 96 as accurate rate input data to a computer as indicated.

In the embodiment of my invention herein illustrated, the azimuth servomotor is indicated generally at 91 and comprises an A end or variable displacement pump 98 which is driven by preferably a constant speed motor 99. The fluid or oil pumped from the A end is delivered through one of the pipes |00 and returned through the other to and from a hydraulic motor |0|, termed the B end. The displacement of the pump or A end 98 is controlled by a lever |02 which is positioned by the piston in a stroke cylinder |03. As is well known in the hydraulic servomotor art, the lever |02 controls the displacement within the pump 98 and both the rate and direction of operation of the B-end. Therefore, the position of the piston within the stroke cylinder |03 is determinative of the direction of rotation of the azimuth servo. Control valve |04 serves to control the admission and exhaust of oil or other fluid to the interior of the stroke cylinder |03 and to produce movement of said piston in either direction depending upon the direction of movement of the valve member within the valve |04 which is actuated by torque motor |05 which, in turn, is controlled by the output of amnlier 63. In brief, through the above-described servo system components, the azimuth servo i nl will drive the turret in azimuth about its axis 68 in a direction and at a rate dependent upon the two signals derived from the potentiometer 5| and the amnlier controlling the toroue motor 93 of the gyroscope as hereinbefore described in connection with Fig. 1. In Figs. 2 and 3, I have schematically represented the azimuth servo |0| as driving the turret through the medium of internal ring gear |06 and pinion |01. The internal gear may be secured to the craft and in this case, as shown, the servo moves with the turret.

As hereinbefore indicated, I have herein illustrated the servomotors as of the Vickers hydraulic type wherein the rate of the servo output is proportional to the signal derived from the control handle potentiometers when this signal is bucked out by a signal proportional to the speed of the servo. Obviously, other types of servos may be employed with the rates thereof dependent upon the signals derived both from manual controls and a gyroscopic follow-up system of the character herein described.

The system embodiying the gyroscope 12. handle bars 46 and the elevation servomotor indicated generally at |08 is substantially the same as above described in connection with the azimuth servo. Briefly, a ring gear |09 or a gear segment as shown may be secured to the turretv in concentric relation to the elevation axis 66.`

In this case, the B-end of the servomotor is mounted on the yoke or gimbal ring 61 to control elevation movements of the turret or gun relative to the gimbal ring. The A-end of servomotor |08 is controlled by the piston within stroke cylinder I2 and the position of said piston is controlled by the valve ||3, in turn. actuated by the torque motor Ill. The torque motor ||4 is controlled by the output of the elevation ampller 64 to which an initial control signal voltage is supplied from the potentiometer 53 associated with the handle bars 46 and the leads 62. 'I'he pick-off 89 for detecting relative movement between the gyroscope and turret about the axis I3 of the gyro supplies a control signal voltage to amplier ||5 which is similar to ampliers 35 and 92 hereinabove described and the output thereof is supplied to control a torque motor IIS or the rate of precession of the gyro about axis 13. A signal voltage proportional to the torque 'applied or rate of precession of the gyro about axis 'I3 is supplied thro-ugh leads I I'I to the elevation servo amplifier 66 and through leads I I8 to a suitable computing mechanism.

The ampliers 63, 64, 92 and I I5 are preferably phase-sensitive amplifiers in view of the nature of the alternating voltage signals supplied thereto, and are preferably all connected to the same source of alternating reference voltage, indicated at I I9, from which the signal transformers are excited.

The elevation servomotor functions like the azimuth servomotor to drive the turret in elevation about its axis of support 6B at a rate dependent upon the setting of the wiper of potentiometer 53, and also under the control of the signal voltage derived from the torque motor amplifler ||5. With this arrangement and assuming that the spin axis of the gyro parallels the line of sight from the optics into space, the gyroscope will precess about its axes I3 and 'I4 in accordance with movements of the turret about the axes 66 and 68 substantially to maintain parallelism between the line of sight and the spin axis of the gyro. The computing mechanism, of course, offsets the bore axis of the gun relative to the line of sight for target interception purposes.

It should be evident from the above descrip- .tion of the system shown in Fig. 2 that the single gyro 'I0 will function to provide true and accurate measurements of the angular rates of the turret or the line of sight relative to space, and about the axes of support 66 and B8. Likewise, the gyroscope 12 functions to maintain or to tend to maintain the line of sight upon a target while being tracked and during roll, pitch and like movements of the craft so that the rate of movement of the sight relative to space is substantially unaffected by these movements of the craft and the gunner or operator has no greater problem in keeping his sights on the target than he would have if the system were mounted on a stationary support.

In Fig. 4, I have schematically shown an alternative construction for deriving signals proportional to rates of precession of a gyroscope wherein a rate gyro, indicated generally at |20, is employed. In conventional manner, this gyro is spring constrained about its axis of precession dened by trunnions |2| which are, of course, journalled in suitable bearings (not shown).

The tension of spring |22 may be adjusted by knob |23 to control the magnitude oi.' precession The spin or angular rotation of gimbal ring |24. axis of the gyro rotor is indicated at |25 and the axis about which the angular rate is measured is indicated at |26.

A gyro of this character will precess or turn about the axis of trunnions |2| an angular distance proportional to the rate of turn thereof about axis |26. This angular displacement may be measured by an electrical pick-off or signal generator or by any other type of pick-oft whether electrical or otherwise to supply a signal proportional to said angular displacement of the gimbal ring from its initial, spring constrained position.

In the present case, I have illustrated an induction type pick-off or signal generator |21 having a fixed stator winding |28 energized from a suitable source of alternating current and a rotor winding |29 which is mounted on or rotated by trunnion |2|. This pick-oil may be wound to provide a linear output. potentiometer, for example, may be used to supply alternating or unidirection signal voltage outputs.

When using-a rate gyro to supply a signal output proportional to rate of turn in the present invention, one thereof is mounted to turn with the turret or sight and with the axis |26 thereof coincident or parallel with the axis 68 of the turret mounting shown in Fig. 3, and a second rate gyro is likewise mounted to turn with the turret or sight but with the axis |26 thereof coincident with or paralleling the axis 66 of the turret mounting or sight shown in Fig. 3. Hence. the signal output of one rate gyro unit will constitute a measure of turret rate in azimuth relative to space while that of the other rate gyro unit will constitute a measure of turret and/or sight rate in elevation relative to space. These rate signals may be used as hereinabove described to control the respective servomotors and effect substantial stabilization of the turret and sight and also as input data to the associated computing mechanism.

Advantages of the present system are as follows: f

1. The angular rates of a target are accurately and correctly measured with respect to space as above described.

2. The line of sight is stabilized in that it tends to remain on the target during dive, roll or other angular movements of the craft.

3. Errors in measuring rate due to the bearingsand friction of the gimbal rings of the gyroscope are substantially eliminated because at a constant rate of turn of the turret, the gyroscope which is mounted therein turns at substantially the same rate.

4. Any instability which may otherwise be caused by-gmbal lock is eliminated because the gyro follows the line of sight or turret.

5. Additionally, a single gyro may be employed. and in View of the nature of its use a comparatively small gyro is sufficient.

Although in the foregoing I have illustrated and described the manually operable control as a means for deriving an initial or primary control signal to which the servos are primarily responsive, it will be understood ,that other means for supplying such a signal, such as radar systems for automatic target tracking purposes, may be used to supply the primary control sig- On the other hand, a

nal, are contemplated as within the broad scope of the present invention.

While I have described my invention in its preferred embodiments, it is to be understood that the words which I have used are words of description rather than of limitation and that changes within the purview of the appended claims may be made without departing from the true scope and spirit of my invention in its broader aspects.

What is claimed is:

1. In a stabilizing system for a rst body mounted for'stabilization about an axis of support on a second movable body, a servomotor for turning said rst body about said axis, a source of iirst control signal and an amplifier responsive thereto for controlling said servomotor, a gyroscope, means for causing said gyroscope to precess at a rate corresponding to the rate of turn of said first body, means for deriving a second signal proportional to the rate of precession of said gyroscope, and means for applying said second signal to said amplifier in bucking relation to said first signal.

2. In a stabilizing system for a first body mounted for stabilization about an axis of support on a second movable body, a source of first signal, an amplier responsive to said signal and a servomotor controlled by said amplifier for turning said body about said axis, said servomotor being so constructed and arranged as to drive said first body relative to said second body at a rate proportional to the magnitude of the signal supplied by said amplifier and at a constant rate when the signal supplied by said amplifier is reduced to zero, a gyroscope, means for causing said gyroscope to precess at a rate corresponding to the rate of turn of said rst body, means for deriving a signal proportional to the rate of precession of said gyroscope, and means for supplying said last recited signal to said amplifier in bucking relationship to said rst signal.

3. In a stabilizing system for a first body mounted for stabilization about an axis of support on a second movable body, driving means for turning said rst body about said axis, control means for said driving means, a gyroscope free to turn about an axis parallel to the axis of support of said first body, means for applying a precessing torque to said gyroscope, signal generating means responsive to relative movement between said first body and said gyroscope for controlling said gyro-precessing means whereby to cause said gyroscope to follow said first body and to precess at a rate corresponding to the rate of turn of said first body, means for deriving a signal from said gyro-precessing means proportional to the rate of precession of said gyro, and means responsive to said signal for further controlling said driving means.

4. In a system for determining the rate of movement with respect to space of a body mounted to turn about an axis of support on a second body movable in space, a gyroscope free to move about an axis paralleling said axis of support, means for deriving a signal proportional to relative displacement between said body and said gyroscope, torque-producing means responsive to said signal for precessing said gyroscope at a rate corresponding to the rate of turn of said body, and means for deriving from said torque-producing means a signal proportional to the rate of precession of said gyroscope.

5. In a system for determining the rate of movement with respect to space of a first body carried on a second body and movable about an axis relative thereto, driving means for turning said first body about said axis relative to said second body, a source of first control signal, control means responsive to said first signal and to a second signal for controlling said driving means, a gyroscope free to precess about an axis paralleling said first-mentioned axis, means for precessing said gyroscope at a rate corresponding to the rate of turn of said first body, means for deriving a second signal proportional to the rate of precession of said gyroscope, and means for further controlling said driving means by said second signal whereby said first body will rotate at a constant rate with respect to space when said first control signal is unaltered.

HERBERT HARRIS, JR.

REFERENCES CITED The following references are of record in th flle 0f this patent:

UNITED STATES PATENTS Date l Germany Aug. 1,1935

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