US3844196A

US3844196A - Fire control system

Info

Publication number: US3844196A
Application number: US00292934A
Authority: US
Inventors: J Brandstadter; J Taylor
Original assignee: Pneumo Dynamics Corp
Current assignee: Pneumo Dynamics Corp
Priority date: 1972-09-28
Filing date: 1972-09-28
Publication date: 1974-10-29
Anticipated expiration: 1991-10-29
Also published as: IT996694B; DE2348098A1; JPS4973163A; JPS5630881B2; DE2348098B2; GB1442822A; FR2201774A5

Abstract

A stabilization system for the turret and cradle of an armored vehicle for maintaining the orientation of a weapon supported therein in an inertial frame of reference, thereby correcting for disturbances of the hull of the vehicle caused by steering in a direction other than directly at the desired target as well as for variations in pitch, roll and yaw caused by movement over uneven terrain. Two rate gyros mounted on the cradle, a rate gyro on the hull cooperate in pairs to provide inertial control signals in elevation and traverse to modify servo loop dynamic response and to maintain a stabilized position with respect to a preselected frame of reference. In each axis signals developed by integration of one cradle rate gyro output, by a servo valve position transducer, a tachometer coupled to the hydraulic motor and a paired rate gyro, and by differentiation of the tachometer and paired rate gyro output are combined with the manually introduced signal derived from the gunner''s station for control of the servo valve and the motor for positioning either the turret or the cradle supporting the weapon. Automatic drift compensation is included for correction of electronic offsets and mechanical variances within the system, consisting of a potentiometer mechanically coupled into the system at the option of the operator to produce a continuous signal, thereby providing correction to the combined control signal applied to the servo valve.

Description

United States Patent Taylor et al.

[ Oct. 29, 1974 FIRE CONTROL SYSTEM [75] Inventors: John E. Taylor, Kalamazoo; Jack M.

Brandstadter, Royal Oak, both of Mich.

[73] Assignee: Pneumo Dynamics Corporation,

Cleveland, Ohio 22 Filed: Sept. 28, 1972 21 Appl. No: 292,934

Primary Examiner-Stephen C. Bentley Attorney, Agent, or Firm--Donnelly, Maky, Renner & Otto [57] ABSTRACT A stabilization system for the turret and cradle of an 46 WORTH POT.

WEAPON armored vehicle for maintaining the orientation of a weapon supported therein in an inertial frame of reference, thereby correcting for disturbances of the hull of the vehicle caused by steering in a direction other than directly at the desired target as well as for variations in pitch, roll and yaw caused by movement over eqeveat reia- TWO rate reemoqm d on the ratl e a rate gyro on the hull cooperate in pairs to provide inertial control signals in elevation and traverse to modify servo loop dynamic response and to maintain a stabilized position with respect to a preselected frame of reference. In each axis signals developed by integration of one cradle rate gyro output, by a servo valve position transducer, a tachometer coupled to the hydraulic motor and a paired rate gyro, and by differentiation of the tachometer and paired rate gyro output are combined with the manually introduced signal derived from the gunners station for control of the servo valve and the motor for positioning either the turret or the cradle supporting the weapon. Automatic drift compensation is included for correction of electronic offsets and mechanical variances within the system, consisting of a potentiometer mechanically coupled into the system at the option of the operator to produce a continuous signal, thereby providing correction to the combined control signal applied to the servo valve.

12 Claims, 4 Drawing Figures SERVOVALVE PATENTED I18? 29 89M 45 DRIFT DRIFT POT.

2 WEAPON POS. GYRO j CONTROL 32 POT. ssRvovAL\ E" 35 2e a 34 2ND STAGE vewcnv LVDT 36 4% TAOHOMETER m 5r- HULL 42 i E cvno FIRE CONTROL SYSTEM This invention relates to inertial guidance and stabilization systems and more particularly to the stabilization system for the weapon of an armored vehicle subject to movement in plural axes.

Many systems have been devised for the powered control and stabilization of weapons and the like in military vehicles, for example, naval vessels and aircraft which mount rotatable turrets for the orientation of weapons supported thereby, however significantly different problems are encountered in the application of these systems to land oriented vehicles including the relatively high amplitudes and frequencies occurring in movement and the heretofore unappreciated degree of structural resonances encountered which affect the accuracy and response of such systems.

Difficulties are encountered in providing a sufficiently wide dynamic range for the servo system as well as providing for the necessary frequency response in order to be sensitive to a wide range of conditions, so that both a highly responsive and accurate system can be provided for tracking at close ranges while moving rapidly over rough terrain as well as accommodating therelatively slight deviations encountered when long range tracking from a stationary vehicle is required.

For example, it is apparent that any control and stabilization system for the weapon of a vehicle must be able to execute maximum excursions of the weapon within a minimal time interval in order to achieve an attack advantage while at the same time being able to track a distant target at extremely low rates which may be on the order of 0.15 mils/sec. Further, under such extremely low tracking conditions it is apparent that accuracy is of utmost importance when deviations due to an uneven terrain cause major effects in the orientation of the weapon.

Even though different inertias, structural resiliences, and damping ratios are inherent in the mechanical construction of the hull and turret of the vehicle and require some difference in the control parameters of each system in order to obtain optimum performance, other than for differences in electrical gains and mechanical gear reductions, the control and stabilization systems for the two axes are essentially the same.

Prior art systems of control for the stabilization of a tank weapon include the R. J. Barlow et al, US. Pat. No. 3,405,599 entitled Weapon Stabilization System which shows the utilization of gun and hull gyros for stabilization of the weapon in azimuth, and gun and turret gyros for stabilization in elevation. Integration and differentiation of the gyro signals are employed to obtain position and acceleration signals which are combined in a particular manner for control of a servo valve, in turn controlling fluid flow to the stabilizer for the respective axes. Such system is similar in showing compatibility with manual control handles, however, such control is effected in the hydraulic portion of the system wherein a synchronizer unit is employed and an overriding effect is obtained to control the fluid flow to the actuator mechanism. Thus such system may be described as an alternate type of system wherein control of the actuator is either by conventional hydraulic flow techniques or in alternate periods under the automatic control of the electromechanical servo system.

In the apparatus of the instant invention a pair of gyros are similarly employed for each axis of stabilization being mounted respectively on the weapon cradle and turret and the weapon cradle and hull of the vehicle, each gyro developing either a position or acceleration signal in addition to the directly available rate signal for a combined control of the servo valve directing fluid flow to a hydraulic motor. Manual input is supplied by a potentiometer coupled to the gunners control handle, providing the command signal to the servo loop and being continuously connected in the loop when the weapon is in a stabilization condition.

A position transducer coupled to the second stage of the servo valve generates an electrical signal proportional to the displacement of the valve spool and a tachometer coupled to the hydraulic motor provides an electrical signal proportional to the angular rate of same, both signals being utilized in feedback, as a portion of the servo loop.

Thus essentially the rate gyros mounted on the gun cradle, by means of integration circuits, provide an inertial positional frame of reference as an input to the servo loop for stabilization of the weapon in each axis of motion and the manually operated potentiometers provide command signals for correcting the orientation of the weapon and for acquiring new targets. The various feedback elements mentioned and the rate gyros mounted on both the hull and the turret as supporting structure, serve to alter the characteristics of the servo loop to achieve optimum performance.

in addition a drift correction signal is continuously applied as an inputto each servo system, being developed from a potentiometer intermittently coupled to the driving element of the servo loop at the option of the operator to correct for hysteresis, friction, electrical imbalances and the like.

Additionally in lieu of operating in the stabilized mode, the system is compatible with a power control and manual mode of operation, the former providing hydraulic actuation of the drive motors by way of fluid coupling between hydraulic flow control valves contained in the gunners control and the respective drive motors, while in the manual mode direct engagement with the traverse and elevation mechanism is possible by use of suitable gearing, no-back clutch elements and hand cranks.

Therefore it is one object of this invention to provide an improved stabilization system which includes inherent synchronization between manually applied inputs and the closed loop control system.

It is another object of this invention to provide an improved stabilization system for a vehicle mounted weapon system having improved target acquiring capabilities allowing the rapid slewing of the weapon to position and the laying on of the target without overshootmg.

It is another object of this invention to provide an improved weapon stabilization system in which a very high gain position loop is provided, being accommodated by the utilization of components which provide improved damping.

It is a further object of this invention to provide an improved stabilization system having very high gain and feedback for improved damping, in which additional inertial signal members are utilized to modify dynamic response of the system in order to reduce transient errors.

It is a still further object of this invention to provide a weapon stabilization system including drift control mechanism therein which alleviates a manual function of the gunner and provides a system having improved accuracy.

To the accomplishment of the foregoing and related ends, the invention, then, comprises the features hereinafter fully described, the following description and the annexed drawings setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the various ways in which the principles of the invention may be employed.

In the drawings:

FIG. 1 is a partial perspective view of a vehicle equipped with the apparatus of this invention showing a weapon positionable in traverse and elevation;

FIG. 2 is a simplified schematic showing in block diagram form of one axis of stabilization for the control system;

FIG. 3 is a schematic showing in block diagram form of the complete control system for stabilization of a weapon in elevation and traverse; and

FIG. 4 is a schematic showing in block diagram form of the mechanical and hydraulic arrangement employed in conjunction with the stabilization system.

Referring now to the FIG. 1 perspective view there is shown a vehicle 10, equipped with the weapon 11 under stabilization, consisting of a turret structure 12 and hull structure 13. The weapon 11 is capable of being positioned in elevation with respect to the turret l2 and the turret is in turn rotatable with respect to the hull 13 for positioning in traverse, the combined movement providing orientation of the weapon 11 with respect to a remote target. The turret and hull of the vehicle comprise the supporting structure for the weapon and are movable as a unit under the conventional drive system of the vehicle 10, operated under control of the driver for movement in any direction over the terrain, either directly at the target or at any angle of attack with respect thereto.

In a conventional arrangement the weapon 1! is mounted in a cradle M for pivotal movement with respect to the turret R2 of the vehicle and is capable of limited arcuate movement. In this embodiment the cradle 14 is supported by a trunnion l6 journalled in the turret and in turn supports the weapon ll thereon. The cradle 14 further supports the

weapon gyros

18, 19 for movement with the cradle, the gyros being oriented to be responsive to the elevational and traverse movements of the weapon 11. Also mounted on the cradle is a gear segment 20 which is engaged by the output pinion of a gear box containing a hydraulic drive motor, in turn receiving fluid impetus from the stabilization system or by way of manually introduced flow as will be described in greater detail hereinafter. In a third and fully mechanical mode of operation, the output pinion may be engaged by a manually operable hand wheel through a no-back mechanism and appropriate gear reduction.

Similarly the turret 12 of the vehicle is mounted on the hull 13 for rotation in traverse about a substantially vertical axis in a conventional manner, the movement mechanism including a ring gear and hydraulic motor driven gearbox and output pinion which receives fluid flow through a second stabilization system in either the automatic or manually controlled modes of operation previously described. Still further a traverse hand crank and suitable mechanical driving mechanism provide manual control over the traverse motion of the turret 12.

The

gyros

18, 19 mounted for movement with the cradle 14 may be conventional units providing electrical signal outputs related to the movement of the structure on which mounted, in this embodiment the gyros 118, 19 being orthogonally oriented to provide indications in the elevation and traverse planes of motion and providing signals of the rates of movement of the weapon Ill in each coordinate axis. The gyros are interconnected with electronic circuitry forming a part of the stabilization system for control of movement of both the cradle l4 and turret l2 and serve to maintain the orientation of the weapon 11 with respect to a position in space selected by the gunner of the vehicle 10.

The gunner provides such orientation commands by the movement of control handles which are mechanically linked with the hydraulic system for manually controlling the flow of fluid to the respective drive motors and simultaneously to potentiometers for develop ing electrical signals for alternate control from the stabilization system. Such control elements are depicted schematically in FIGS. 2-4 but it will be clear that any suitable mechanism and control devices may be employed to perform this function.

In the stabilized mode, of operation by virtue of suitable interlocks, the displacement of the control handles in each axis provides an output from only the electrical control elements, i.e., the potentiometers, which elements command a proportional velocity for the control system. The gunner in looking through his sight recognizes any displacement between his line of sight and the desired target and displaces his control handles accordingly for reorientation of the stabilization system, by rotation of a handle in the direction he wishes to displace the line of sight in traverse and by tipping same in the direction he wishes to displace the line of sight in elevation.

While the rate gyros mounted on the weapon cradle 14 are the primary elements for providing stabilization of the weapon 11 in an inertial frame of reference, rate gyros are mounted on the turret and hull of the vehicle respectively for providing additional inputs to the individual servo drive systems for the respective axes of control, in accommodation of the movement of the supporting structure of the vehicle 10 over terrain as directed by the driver. It is desired that the stabilization system provide extremely high gain for rapid and responsive movement of the weapon 11 and the signals derived from the rate gyros on the supporting structure are applied as inputs to the stabilization system to improve the response of same in compatibility with maintaining accuracy for the servo system.

The turret and hull gyros are mounted on suitable portions of the vehicle 10 and are also of the rate gyro type providing electrical output signals representative of the rate of movement of the portions of the vehicle in the elevation and traverse planes respectively. These rate gyros are also electrically interconnected with the stabilization system and are operative during the stabilized mode of operation of the vehicle.

Referring now to the FIG. 2 simplified showing of the stabilization system there are indicated the essential elements forming the traverse axis of stabilization. Included in this showing are the control potentiometer 24, being that device coupled to the gunners control handles which provides a desired command signal for the weapon to allow the gunner to track the target. The output of the control potentiometer 24 is a signal indicative of the desired rate of movement of the weapon 11 and is applied to first and

second combiner units

25, 26 which serve to algebraically add applied signals.

Position feedback for the stabilization system is developed from the weapon gyro 27, this being one of the rate gyros l8, 19 mounted on the weapon cradle 14 and providing a rate signal output as the second signal applied to the first combiner unit 25. The combined signal output is then applied to an integrator circuit 28 to provide a signal proportional to the angular error displacement of the weapon 11 in space from the commanded line of orientation, such-signal then being applied via line 29 to the main combining unit 30 for development of the signal applied on line 31 to the servo valve 32 for control of the hydraulic motor driving the turret in traverse.

An LVDT 34 (linear variable differential transformer) serves as a sensor for the servo valve 32 being mounted on the servo valve housing to generate an electrical signal proportional to the displacement of the second stage spool, such signal being applied as one input on line 35 to the second combiner unit 26. Further feedback for the servo loop is developed in a tachometer 36 coupled to the hydraulic motor which serves as the servoactuator, generating an electrical signal proportional to the angular rate of displacement of the hydraulic motor, such signal being applied as one input to athird combiner unit 38. Also in the servo system is the hull gyro 39 being a rate gyro mounted on the vehicle to generate an electrical signal proportional to the angular rate of displacement in space of that structure, such signal being applied as the second input to the third combiner unit 38. As will be described in greater detail the tachometer 36 and hull gyro 39 signals are applied in opposition so that a difference signal on line 40 is obtained, this signal being applied to a differentiating circuit 41 to develop an acceleration signal on line 42 in turn applied to the main combiner unit 30 for development of the control signal for the servo valve 32. The difference signal on line 40 is also applied as one input to the second combiner unit 26 thereby developing a resultant velocity signal on line 44 for application to the main combiner unit 30, such resultant signal being a function of the difference between the velocity of the structure on which the gyro 39 is mounted and the velocity of the hydraulic servo actuator.

The fourth input to the main combiner unit 30 is the drift signal on line 45 developed from the drift potentiometer 46 providing the automatic drift control which compensates for offsets and changes in the null of the system components.

Thus, in operation of the stabilization system the gunner looks through his sight and recognizes displacement between the line of sight and the desired target. He displaces his control handles and thus the control potentiometer 24 to command proportional velocity of the control system asa correction for the orientation of the weapon 11. The output of the potentiometer 24 is shaped to provide low sensitivity around center, allowing the gunner to track a moving target accurately and to lay on a stationary target without overshooting. At either end of travel of the potentiometer 24, sensitivity is progressively increased so that the gunner can rapidly slew the system to acquire a target.

To affect the necessary velocity commanded by the control potentiometer 24 the servo valve 32 must be displaced the proper amount to provide the desired flow to the hydraulic motor. The resultant rotation of the motor by way of mechanical coupling with the ring gear coupled to the turret 12 will drive the latter at the desired speed to provide the correction. The LVDT 34 on the servo valve 32 is an electrical position sensor providing an output voltage proportional to the direction and magnitude of the flow from the servo valve 32. The tachometer 36 mounted on the hydraulic motor provides an output proportional to the direction of rotation and angular velocity of the motor. Both are in the feedback loop and provide voltages to resist motion of the system, being combined in

combiner units

38 and 26 to provide a velocity signal on line 44. The voltage from the control potentiometer 24 which is also directed to combiner 26 must be calibrated to be equal to the sum of these two signals at the desired system velocity in order to achieve equilibrium. Additionally such voltage from the control potentiometer 24 must also be equal to the output of the weapon gyro 27 so that the system can be repositioned at the desired rate of change. In this manner the gunners inputs are synchronized with the control system.

Disturbances of the hull 13 due to steering and suspension inputs due to movement over terrain tend to cause the line of sight to be displaced from the target and in order for the stabilization system to accommodate this, the turret l2, and the cradle 14 in its own stabilization system, must be moved at a velocity equal and opposite to these inputs. In order to accomplish this and to obtain a system with a high degree of static accuracy, the voltage output from the rate gyro 27 mounted on the cradle is electrically integrated to provide a reference position in space about which the system operates. It is desirable also to select the system components so that the resultant position loop operates stably at the highest possible gain, this being necessary since the position error required to produce a velocity of the servo actuator is inversely proportional to the gain of the position loop.

To further aid in increasing the system gain additional components are provided to improve the damping. These include the LVDT 34 on the second stage of the servo valve 32 and the tachometer 36 mounted on the hydraulic motor, the former providing an accurate linear long stroke valve with extremely high pressure gain while the output of the tachometer 36 is utilized in feedback both in a direct velocity mode and by differentiating the velocity signal to provide a voltage proportional to the acceleration of the motor. The effect of these compensating feedbacks is to allow the gain of the position loop to be increased thereby improving the static accuracy of the system but at the expense of a reduction of the systems dynamic response.

The reduced dynamic response causes transient errors that are greater than desired and in order to reduce these errors to an acceptable level, additional rate gyros mounted on the hull and turret are utilized. The rate gyro 39 on the hull senses the angular velocity of the hull 13 in the plane of the ring gear as a result of steering inputs from the driver. The rate gyro in the turret senses the angular velocity of the turret 12 in the plane of the cradle as a result of pitch or roll inputs from the suspension and terrain.

Thus in FIG. 2 the output voltage from the hull gyro 39 is calibrated such that disturbances of the vehicle 10 generate voltages which are equal to the sum of the LVDT 34 and tachometer 36 outputs when the hydraulic motor rotates its output member at a velocity equal and opposite to the disturbing velocity. in addition, the hull gyro 39 signal is added to the tachometer 36 signal in such a manner as to eliminate the effects of the acceleration feedback as a result of vehicle disturbance. It does not theoretically require a steady state error in the position of the weapon gyro 27 to produce the required response. Instead, the open loop velocity and acceleration commands from the additional hull gyro 39 performs this function. It is only necessary for the position loop to contend dynamically with those errors in the system due to miscalibration, systems dynamics, and the various system nonlinearities and to provide the necessary static accuracy.

The automatic drift control introduced by the drift potentiometer 46 is utilized to accommodate for the hysteresis and friction in the weapon gyros and the offsets in the demodulators and integrators which cause the system to drift from the desired line of sight. The automatic drift control consists of an appropriate gunner operated on-off circuit, the drift potentiometers 46 and a solenoid operated brake and clutch mechanism. In operation when the vehicle comes to rest, the operator may cause energization of the clutch and engagement of the potentiometer 46 with the output shaft of the hydraulic motor for a limited period of time by pressing the reset button. If drifting of the system occurs during this period of time, any motor rotation will be coupled to the drift potentiometer 46 to generate a signal which opposes that signal which caused the drift. Since the output of the potentiometer 46 is continuously coupled into the main combiner unit 30, the motor will come to rest when the signals are of equal magnitude. Upon releasing the reset button the clutch and the potentiometer 46 will be mechanically locked in this position by a spring loaded brake. Under drift control the hydraulic motor and drift potentiometer 46 form an additional integrator in the system which balances out any drift and then accurately holds this balancing voltage until the next time the drift control is operated.

Referring now to the block diagram of FIG. 3, an understanding of the complete stabilization system for a vehicle mounted weapon may be obtained. The affects upon the system are indicated by the blocks labeled gunner 48, driver 49 and terrain 50, the latter two providing inputs via the steering 51 and suspension 52 for the vehicle to the hull 54, in turn rotatably mounting the turret 55 and the latter the cradle 56, for movement of the weapon 57. This also moves the sight 58 which provides a means for feedback to the gunner 48 as indicated by line 59. The gunner 48 independently maneuvers the elevation and traverse

controls

60, 61, these being the potentiometers which provide proportional velocity commands while the hull gyro 62, turret gyro 64. and

cradle gyros

65, 66 provide continuous feedback signals representative of motion of the respective elements as affected. The cradle motor 67 as directed by servo valve 68 and the turret motor 69 as directed by its servo valve 70 are mechanically coupled via

appropriate reducer mechanisms

71, 72 respectively, to provide the impetus to the cradle 56 and turret 55.

In the elevation axis of stabilization, with corresponding elements in the traverse axis indicated by the same reference numeral with the subscripts b, the valve position sensor 74a provides the signal proportional to the flow magnitude through the servo valve 68 and a tachometer 75a is coupled to the hydraulic motor 67 to provide the angular velocity signals. An integrator 76a and differentiating circuit 77a receive inputs as shown utilizing appropriate combiner units 78a, 79a, 80a, 81a in the manner similar to that set forth in the description of the FIG. 2 simplified showing of one axis of the stabilization system.

The automatic drift control is included independently in each axis of stabilization comprising the drift potentiometer 82a providing a correction signal, a clutch 84a coupling the shaft of the potentiometer 82a with the motor 67 output shaft, a solenoid 85a for actuating the clutch 84a and a manually operated reset button. The combiner units 78a-81a indicated in the FIG. 3 showing of the invention are only slightly modified from those depicted in the FIG. 2 simplified schematic of the system but the same function obtains, i.e., the tachometer 75a and turret gyro 64 are combined in opposition in combiner unit 81a while the output of the drift potentiometer 82a is directed to the integrator circuit 76a via combiner unit 780 prior to application to the main combiner unit 88a, such signal variations being minor and readily accommodated by suitable impedance networks and the like.

Thus, it may be seen that when in the stabilization mode the orientation of the weapon 57 may be maintained in spite of driver 49 introduced or terrain 50 introduced effects upon the disposition of same and may be continuously altered by the gunner 48 who applies a visual correction to the system. It is also to be noted that the stabilization system is compatible with a completely mechanical mode of operation for orientation of the weapon 57 or a hydromechanical mode of operation for backup or auxiliary purposes whereby the gunner 48 can manually orient the weapon as desired.

Referring to FIG. 4 showing of the mechanical and electrohydraulic portion of the control system, the same control handles 90 coupled to the control potenti ometer 24 of FIG. 2 and the elevation control 60 and traverse control 61 of FIG. 3 are mechanically coupled to the traverse control valve 91 and the elevation control valve 92 providing fluid flow to the respective hydraulic motors 93a, b. By means of appropriate clutches 94a, b and gear reducers 95a, b output motion can be supplied to the ring gear 96 for the turret 12 of the vehicle 10 and to the gear sector 97 for controlling the elevational orientation of the cradle 14 and thus the weapon 11 mounted thereon.

Power for the system is obtained from the vehicle DC supply 100 by means of a power relay 101 for driving a DC motor 102, in turn actuating a pump 103. A pressure relief valve 104, accumulator 105, pressure regulator 106 and pressure switch 107 are utilized in a conventional manner to provide fluid to the selector valve 108, in turn coupled to the control handles 90 and as indicated to the servo valves 68, 70 for the stabilization system.

A pair of gunners palm switches 110a, b are provided for control of solenoid valves 111a, b, in turn controlling the actuation of clutches 112a, b for selecting the hydromechanical or mechanical modes for driving the weapon. The latter system includes a pair of hand cranks 114a, b for the traverse and elevation mechanisms respectively, being coupled through noback devices 115a, b and the solenoid actuated clutches 1120, b for drive of the reducer mechanisms 95a, b and thus the ring gear 96 and gear sector 97 for movement of the weapon.

ln the hydraulic power control mode of operation displacement of the control handles 90 in each axis operates the

hydraulic valves

91, 92 having shaped metering orifices providing an output similar to that of the potentiometers in the elevation and traverse

controls

60, 61. In the closed center four-way

hydraulic valves

91, 92 the rate of change of metering area around center is verylow allowing the gunner to track the moving target accurately and to lay on a stationary target without overshooting. The rate .of change of .metering area at the ends of the valves travel is progressively increased so that the gunner can rapidly slew the system to initially acquire a target or change to a different target. By way of the clutches 94a, b and reducers 95a, b, the axial piston hydraulic motors 93a, b operate the turret and cradle .at velocities proportional to the control handles displacement in response to the gunners inputs.

When the gunner desires to change the line of sight he depresses the palm switches 11011, b which are an integral part of the control handles 90 to selectively operate the solenoid valves llla, b and engage either or both of the hydraulically operated clutches 94a, b. These clutches 94a, b engage the hydraulic motors 93a, b with the gear reducers 95a, b and the clutches 1112a, b disengage theno-backs 115a, b and hand cranks 114a, b so that the hydraulic motors 93a, b can then drive the gear sector 97 or ring gear 96 as a function of control valve displacement with the clutch acting as a safety overload device.

In the manual mode of operation of the system when the palm switches 110a, b are not actuated, a spring in the clutches 94a, b disengages the hydraulic motors 93a, b from the gear reducers 950, b and engages the no-backs 115a, b and hand cranks lllda, b. The nobacks 115a, b act as a brake to ground preventing the output from reversibly driving the hand cranks 114a, b and the clutches 112a, b as overload safety devices. The hand cranks 114a, b allow the gunner to accurately position either the turret or cradle but are limited in speed capabilities by the operators physical output power.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. Apparatus for stabilization with respect to an inertial reference axis of a movable member mounted on supporting structure subject to random deviations from a predetermined aligned position comprising a rate gyro mounted on said movable member for developing electrical signals representative of the rate of movement of said member in the elevational plane, means for integrating the electrical signals of said rate gyro to develop position signals representative of the disposition of said element in the elevational plane with respect to an inertial axis of reference, a second rate gyro mounted on said supporting structure for developing electrical signals representative of the rate of movement of said structure in the elevational plane, a motor for imparting motion to said movable member in response to fluid flow at a rate proportional to a control signal, a tachometer coupled to said motor for providing electrical signals representative of the rate of rotation of same, means for differentially combining said tachometer signals and said second rate gyro signals to produce a resultant signal, means for differentiating said resultant signal to provide an acceleration signal, a servo valve for controlling fluid flow in response to electrical signals, a transducer coupled to the second stage of said servo valve to provide signals representative of the displacement of same, and means for combining said resultant signal, said transducer signal, said acceleration signal and said position signals to provide a combined signal for control of said servo valve.

2. Apparatus as set forth in claim 1 further including a manually adjustable control potentiometer for developing electrical signals representative of desired rate of movement of said movable element, means for combining said potentiometer signals with the signals of said first rate gyro for application to said integrating means, said potentiometer signals being separately applied to said last-named combining means to introduce a manual adjustment signal in the combined signal applied to said servo valve.

3. Apparatus as set forth in claim 1 further including a second adjustable potentiometer for developing drift signals for correction of offset errors, friction effects and the like in the stabilization system, said drift signals being applied to said combining means for summation with said combined signal for control of said servo valve.

4. Apparatus for stabilization of a member movable with respect to supporting structure, comprising a motor for imparting movement to said member in response to an applied input, a first rate gyro mounted for movement with said member for developing electrical signals representative of such movement, means for integrating the electrical output of said first rate gyro to provide signals representative of the position of said member, a second rate gyro mounted on said supporting structure for developing electrical signals representative of the rate of movement of said supporting structure due to external influences, said second rate gyro being oriented'to be responsive to influences affecting the position of said movable member in the manner sensed by said first rate gyro, means for manually introducing electrical command signals for control of movement of said movable member, and means for combining said command, position and rate signals to produce a combined electrical output signal for control of said motor.

5. Apparatus as set forth in claim 4 further including a tachometer coupled to said motor for providing electrical output signals representative of the rate of rotation of same, said tachometer output signals being applied to said combining means for control of the motor running characteristics.

6. Apparatus as set forth in claim 5 wherein said motor is a hydraulic motor and further including a servo valve for controlling fluid flow to said motor as a function of the combined signal of said combining means.

7. Apparatus as set forth in claim 6 further including a transducer coupled to said servo valve for monitoring the positioning of same, said transducer providing an electrical signal representative thereof, and further in cluding means for coupling said transducer signal to said combining means.

8. Apparatus as set forth in claim 7 wherein said combining means comprises first means for combining said tachometer and said second rate gyro signals, and second means for combining the output of said first combining means, said transducer signals and said manual command signals for application to said first named combining means.

9. Apparatus as set forth in claim 8 wherein said movable member is the weapon of a tank, mounted for movement in elevation in the tank turret, said turret in turn mounted for movement in traverse in the tank hull, said first rate gyro being operatively mounted on said weapon and said second rate gyro being operatively mounted on said turret.

10. Apparatus as set forth in claim 9 further including third and fourth rate gyros respectively operatively mounted on said weapon and said hull for monitoring movements of traverse, means for integrating the signals of said third rate gyro, means for differentiating the signals of said fourth rate gyro, a motor for controlling movement of said turret in traverse, means for introducing manual command signals for control of said turret, and means for combining said turret command signals, said integrated signals and said differentiated signals for application to said turret motor for control of traverse movements.

11. A drift control mechanism for stabilization systems and the like wherein a closed loop servo maintains disposition of an object by means of a motor driven, gyro stabilized, error compensating system, comprising means coupled to the motor for providing indications of the actuated and non-actuated conditions of the same, a transducer for providing an electrical signal in response to a mechanical variation in same, normally disengaged coupling means for coupling said transducer to the motor in response to an electrical signal, a manually operated reset button to engage said coupling means for sensing deviations of the motor due to offset error, drift and the like by driving said transducer through said coupling means and generating a signal opposing any signal causing drift, means for locking said transducer in its position upon release of said manually operated reset button, and means continuously connecting the electrical signal of said transducer to the error compensating system as a drift compensation signal.

12. The drift control mechanism as set forth in claim 11 wherein said transducer is a potentiometer and said coupling means is a solenoid-actuated clutch interconnecting the motor and said potentiometer.

Claims

4. Apparatus for stabilization of a member movable with respect to supporting structure, comprising a motor for imparting movement to said member in response to an applied input, a first rate gyro mounted for movement with said member for developing electrical signals representative of such movement, means for integrating the electrical output of said first rate gyro to provide signals representative of the position of said member, a second rate gyro mounted on said supporting structure for developing electrical signals representative of the rate of movement of said supporting structure due to external influences, said second rate gyro being oriented to be responsive to influences affecting the position of said movable member in the manner sensed by said first rate gyro, means for manually introducing electrical command signals for control of movement of said movable member, and means for combining said command, position and rate signals to produce a combined electrical output signal for control of said motor.

7. Apparatus as set forth in claim 6 further including a transducer coupled to said servo valve for monitoring the positioning of same, said transducer providing an electrical signal representative thereof, and further including means for coupling said transducer signal to said combining means.