EP0580701B1

EP0580701B1 - A device for aiming at a mobile target and directing an anti-aircraft gun or the like at same

Info

Publication number: EP0580701B1
Application number: EP92909132A
Authority: EP
Inventors: Hans-Arne Nilsson
Original assignee: Saab Instruments AB
Current assignee: Saab Instruments AB
Priority date: 1991-04-17
Filing date: 1992-04-08
Publication date: 1994-12-07
Anticipated expiration: 2012-04-08
Also published as: WO1992018823A1; DE69200849T2; DE69200849D1; NO306579B1; NO933737L; SE468330B; SE9101148L; SE9101148D0; FI934557A7; AU1659892A; FI107295B; FI934557A0; EP0580701A1

Abstract

A device for aiming at a mobile target and to direct an anti-aircraft gun is comprising servomotors for directing the barrel, an aiming unit with field glasses (8) and a device for ranging as well as a calculating unit. The aiming unit is pivotally held on a support (2, 5) fixated to the barrel. Means (11) are provided for directly and indirectly measuring the sight line angular velocity. The calculating unit calculates the required lead angle and offset angle of the barrel and is sending corresponding signals to the servomotors. The device is functioning in three phases: during a phase I the barrel angular velocities have a fixed relationship with the sight line angular pivoting achieved by manual action from a neutral position, a series of range measures are taken and the calculating unit is calculating a preliminary target path and target speed, during phase II the range measuring is stopped and the barrel is directed corresponding to the preliminary target path and target speed, during phase III another series of range measures is taken and the calculating unit is calculating definitively the target speed and thereby the correct lead angle and offset angle of the barrel direction, whereby the servomotors are directing the barrel.

Description

The present invention relates to a device for aiming at a mobile target and to directing an anti-aircraft gun or similar with the same, the barrel direction of the anti-aircraft gun being adjustable in azimuth and elevation by means of servomotors with an aiming unit incorporating a sight for optical aiming at the target along an aiming line, preferably field glasses, a device for ranging to the target, preferably a type of laser, the aiming unit being held by a support and being swivelling by manual action in azimuth and in elevation, the support being fixed to said barrel, where the aiming unit also comprises means for measuring the angle in azimuth and in elevation between the aiming line and the barrel direction, and the device comprising means for measuring directly or indirectly the angular velocity of the aiming line in azimuth and in elevation, said means being arranged to send signals in accordance with their corresponding measured values to a calculating device being adapted to calculate according to said received signals as well as to supplied information on correction values such as data regarding the ballistics of the missile been fired from the anti-aircraft gun, pervailing wind vectors, the required lead angle and offset angle of the barrel direction and sending corresponding signals to said servomotors to have a fired projectile hitting the target.
Such devices are already known by several designs. Common to them is that they are using advanced techniques with a high level of costs. The ranging of the target is usually performed by a radar or a laser range meter with a high frequency measuring in combination with a television camera with an automatic target tracking device.
The present invention has as an object to propose a device of the kind mentioned above, which device allows for shorter reaction periods between a target observation and its fighting, high hitting probability when used repeatedly, a passive target tracking function, easy manipulating, training and service and which device has a low cost profile for capital, service and operation.
According to the invention, as defined in claim 1, a device of the kind mentioned above is characterized by being adapted to operate in three phases, wherein;

Phase I
is comprising that said servomotor at a first initialisation of the aiming unit and the calculating unit are adapted to be activated, so that the angular velocity of the barrel in azimuth ω_Ae and in elevation ω_Ee has a defined correlation to the angular deflection in azimuth and elevation of the aiming line from a neutral position, achieved by manual action in following the target with the aiming line and during a second initialisation of the aiming unit and the calculating unit a series of range measures are taken intermittently, the calculation unit registering corresponding values of the aiming line azimuth angle ψ_s and elevation angle Θ_s with in space fixated reference values as well as range and measuring time, the calculating unit calculating on basis of said corresponding values a first preliminary target path and target speed and precalculating preliminary directions, i.e. angles in azimuth ψ_e and in elevation Θ_e and angular velocities in azimuth ω_Ae and in elevation ω_Ee of the barrel for a fired projectile to hit the target;
Phase II
is comprising that at a third initialisation of the aiming unit and the calculating unit the range measuring is stopped and said servomotors are activated to direct the barrel direction with said angles ψ_e and Θ_e and simultaneously provide the barrel direction with angular velocities ω_Ae and ω_Ee corresponding to the angles precalculated during phase I, and the angular velocities corresponding to said calculated target path and target speed;
Phase III
is comprising that at a fourth initialisation of the aiming unit and the calculating unit a series of range measures are performed intermittently, the calculating unit registrering correlated values of the aiming line azimuth angle ψ_s and elevation angle Θ_s as well as of the range, the calculating unit basing on these correlated values calculating a definite target speed and thereby correct barrel directions and angular velocities in azimuth and in elevation for a fired projectile to hit the target, whereafter the calculating unit is activating the servomotors to adjust these angles and angular velocities.

By this embodiment of the device according to the invention measured data are collected during phase I during a relatively short first time period. During phase II, the coarse target aiming phase, the barrel directing is performed to a preliminary offset and lead. During this phase no dectecing af measure points is performed. During phase III, the fine measuring and fine directing phase, further measure data are collected. During the intermediate phase II and, thereby, an extended time period, in which the target has moved on further, the calculating unit can calculate a relevant medium speed of the target. The barrel is finely directed according to the last measured data and the firing of the projectile can be performed.
With the dividing into three phases as desbribed above the range measuring can be performed by a laser which only has to create a restricted number of laser pulses for an exact target ranging, and thus enabling the use of a laser without any special cooling and with a resulting high reliability and low service costs with the function simultaneously being almost passive.
According to a preferred embodiment of the invention, rate gyros are incorporated for measuring the barrel angular velocities in azimuth ω_Ae and in elevation ω_Ee. The output signals from these are integrated to corresponding angles. Simultaneously the angles between the sight line and the barrel direction are measured in azimuth Δψ and in elevation ΔΘ, whereby the calculating unit is correlating the range measure values with the corresponding angle positions for the sight line to the target in a system with in space fixated references.
The rate gyros are in fact in space fixated references for all measure values being the basis for the directing of the barrel. By using the same rate gyros for the control of the barrel direction and the angular velocities a highly relative accuracy is obtained of the actual target position of the flight path. The adaption of in space fixated references enables a sustained stability in repeated use, such as repeated firing. The subsidence of an anti-aircraft gun relatively to the ground is not inflicting on the hitting result. Any play and roughness due to wear and similar in the anti-aircraft gun machinery is eliminated by the rate gyros directly measuring the barrel velocities.
In principle it is also possible according to another embodiment of the invention to adapt the rate gyros for directly measuring the sight line angular velocities in azimuth ω_As and in elevation ω_Es. Accordingly, means have to be adapted for measuring the angular velocities between the sight line and the barrel direction in azimuth and in elevation, i.e. Δ ψ and ΔΘ. As the angles between the sight line and the barrel direction are already being measured this means that the signal for Δ ψ and for Δ Θ is derivated. This arrangement, however, is less efficient from a technical viewpoint compared with the rate gyros measuring the barrel angular velocities.
According to a preferred embodiment the device according to the invention is adapted to direct the barrel angles during said phase II with the servomotors being activated in azimuth ψ_e and in elevation Θ_e with an accelerated movement. During directing of the barrel in phase II the operator is risking to drop the target out of sight. Of course this can be compensated by him by leading the sight line in the opposite direction to the one, in which the barrel is directed, but said acceleration is in a suitable embodiment of the device according to the invention restricted correspondig to the difference between the angles of the barrel direction and the sight line in azimuth Δ ψ and in elevation Δ Θ.
To obtain the best achievable precision in directing the barrel the servomotors should direct it in azimuth and in elevation with feedback, i.e. in closed control loops.
The device according to the invention can also be achieved in many apparative ways within the scope of the appending claims.
In a convenient embodiment, where the unit can be swivelled relatively to the onto the support fixed barrel in azimuth and in elevation by means of two handles to be gripped by the right and left hand respectively, the three phases I-III are initiated by a series of switches being activated and kept activated in series.
Of special importance is that the initiating of phase II can be achieved by activating another switch first when an initiation has occurred by activating a first switch and keeping it activated.
The invention will now be described in detail in connection with the enclosed drawings, on which

Figure 1 is a perspective view of an embodiment of the aiming unit mounted on a support with a control device; and
Figure 2 is a perspective view of a handle for the control device in figure 1.

The aiming unit is supported to be swivelled in azimuth and in elevation on a support, which by means of a beam 1 is fixed to a barrel, not shown in the figure. The support comprises a basis plate 2 supported by the beam 1 by means of rubber isolators 3 with the function to protect the aiming unit from shocks having a high level of acceleration. They are dimensioned and designed in such a way as not to effect the angular direction of the aiming unit in relation to the barrel. Onto the basis plate 2 a vertical shaft 4 is pivotally mounted, supporting on its upper end a yoke 5, into whose uprising arms a platform 6 is mounted by means of a shaft 7 pivoting in elevation. The platform 6 is supporting a laser range meter 8 also performing as field glasses. The latter is provided with hair lines representing the optical axis of both the visual sight and the range meter. The laser range meter 8 is also equipped with a coarse sight 9 and a forehead support for protection during firing. Onto the basis plate 2 a gyro unit 11 is mounted comprising two rate gyros measuring the angular velocity, one for measuring the barrel movements in azimuth and the other for measuring the barrel movements in elevation. Onto the basis plate 2 is further mounted an angle detector 12 for measuring the barrel elevation angle. To measure the angle between the sight line of the aiming unit and the barrel direction there is an angle detector 13 provided for measuring in azimuth Δ ψ, the stationary part of which is fastened underneath the basis plate 2 and the vertical axis of which is connected to the shaft 4, supporting the yoke 5 and thereby the laser range meter. The angle Δ Θ in elevation between the sight line and the barrel direction is measured by means of an angle detector 14 connected to the shaft 7.
The guiding of the aiming unit is performed by means of guiding device 15 incorporating a number of links and shafts. A vertical shaft 16 is pivotally mounted onto the underside of the basis plate 2. Into the shaft 16 a vertical shaft 17 is fastened. Around the shaftt 17 a yoke 18 is pivotally mounted with one end supporting on the underside a vertical rod 19, which in turn is helding a switching unit 20 provided with handles 21 and 22 for each hand. The yoke 18 is presenting on its other end a vertical shaft 23 pivotably mounted and presenting a vertical rod 24, which at its upper end by a ball joint 25 is connected to the platform 6. The dimensioning of the parts appertaining to the guiding device 15 is made in such a way as to change down movements being performed by an operator by moving and turning the rod 19 respectively back and forth in comparison to the movements of the platform 6 and thus the movements of the laser range meter/field glasses 8. Thus, the target tracking by manual action is facilitated considerably. The shape of the switching unit 20 can clearly be seen in figure 2. The handles 21, 22 are on the upper side provided with switches 26, 27. When the operator is gripping the handles with the switches the means is activated as to actuate the barrel direction via the servomotors by the moving of the rod 19 forwards and backwards by the operator. Moreover, the switching unit is comprising four switches 28-31, their shape and function being described in the following.
The device functions as follows:
As already mentioned, the operator is activating the device by gripping the handles 21, 22 and thereby pressing in the switches 26, 27. Thereby said phase I is initiated. When the operator by means of the handles 21, 22 is pivoting the field glasses and thereby the sight line at the target, the barrel is automatically directed in the same direction with an angular velocity in azimuth and in elevation being proportional to the sight line by manual action achieving the angle pivoting in azimuth and in elevation from a neutral position. The device is performing a slave function during the target tracking phase. The target tracking is achieved by the operator after perception of a target with the eye fixed through the coarse sight 9 guiding the fields glasses so that the sight line approximately coincides with the direction to the target. The operator is then moving his eyes to the field glasses eye piece 32 and is directing the field glasses so that its hair lines representing the optical axis of the field glasses, i.e. the sight line is coinciding with the target. The laser range meter 8 of the aiming unit is initiated by the operator with his right thumb lifting the switch 28. The range metering is then performed by the laser range meter sending a short period light impulse being reflected by the target lying in the sight line. The reflected energy is detected by the range meter registering the time interval between the output and the reflected light impulse and converting it to a corresponding range value, which then is transmitted to the calculating units calculating circuits. This value is coordinated with the sight line angular position with in space fixed references, ψ_s and Θ_s. The angles ψ_s and Θ_s are obtained the subtracting the difference angles between the sight line and the barrel direction Δ ψ and Δ Θ, respectively from the existing barrel angles ψ_eand Θ_e.
In the initial position, when the first range value is obtained, the azimuth angle is set ψ_so = 0, the starting value of the elevation angle being given by the output signal from the angle detector 12, Θ_eo - ΔΘ. ψ_s is thereafter calculated as an integrated value of ω_Ae - Δψ, and Θ_s as integrated value of ω_Ee - ΔΘ. The laser range meter 8 is thereafter ranging automatically in a fast sequence in continually aiming at the target a number of target ranges. During this aiming the feeding into the calculating unit is performed of the corresponding range values and correlated time periods and angular values ψ_s and Θ_s. In the calculating circuits of the calculating unit a calculation is made of the target range for each measure occasion. After two registrations the target speed is also calculated and continually the actual target position. After at least three registrations the medium value of the target speed and of the calculated target position is obtained. Each further measure value provides a better background for calculating the actual target position. The spreading of the target, the spreading of the laser energy as well as the the sweeping of the sight line over the target, however, is creating scattering faults between the measure points. The laser range meter has for reasons of costs an embodiment which is limiting the number of sent energy impulses per time period and thus the target tracking has to be extended in time. After the first phase I is completed phase II, the coarse target aiming phase, is initiated as follows:
The operator holds with his right thumb the switch 28 still lifted and is pressing down the switch 29, to the right. This can only be achieved with the switch 28 in a lifted position. The laser range measures are stopped and the directing of the barrel is changing from a directing by means of the angular velocity in proportion to the directing value, being adapted in phase I, to an automatic directing by means of calculated angles ψ_e, Θ_e and angular speeds ω_Ae, ω_Ee so that the barrel direction willl have the right lead angle and the right offset angle to have a fired projectile hitting the target. In changing to an automatic directing an accelerated movement of the barrel is created, which is slowed down, when the barrel is moved to the commanded direction and angular speed.
During the relatively fast movement of the barrel to the new direction the operator should try to sustain the field glasses' aiming at the target to be able to proceed to the next phase as fast as possible to collect further measure values. The operator is compensating the movement by pivoting the field glasses in an opposite direction to not drop the target out of sight. To enable even untrained operators with a longer reaction time to manipulate the device, a function has been introduced to limit the barrel directing speed during phase II so that it is limited in relation to the prevailing angular difference between the sight line and the barrel, Δψ and ΔΘ. This function results in that the directing is performed more slowly when the operator is reacting more slowly and is performing faster, if the operator is reacting faster. After the phase II is completed phase III, the fine target aiming phase, is initiated as follows:
The switches 28, 29 are kept lifted and pressed down respectively. The operator is lifting with his left thumb switch 30. New measure values for the target range and correlated time periods and angular values for ψ_s and Θ_s are registered in the same manner as during phase I. The calculation of the required offset angle and of the lead angle are thus updated, the barrel direction being immediately directed in a corresponding way. Due to the elapse of time between phase I and phase III, being occupied by phase II, the precision in calculation of the target position and the target speed will be high. The time period for phase II is about 1 to 3 seconds.
The firing of the projectiles is achieved by the operator in keeping the remaining switches 28, 29, 30 in their lifted resp. pressed down positions pressing down switch 31 with his left thumb. The firing is continuing as long as the switch 31 is pressed down. During the firing sequence the barrel is directed in the same way as previously, i.e. automtaically by the servomotors with closed control circuits, incorporating the rate gyroes.

Claims

A device for aiming at a mobile target and to direct an anti-aircraft gun or similar at the same, the barrel direction of the anti-aircraft gun being adjustable in azimuth and elevation by means of servomotors with an aiming unit incorporating a sight for optical aiming at the target along an aiming line, preferably field glasses (8), as well as a device (8) for ranging the target, preferably a type of laser, the aiming unit being held by a support (2, 5) and being swivellable by manual action in azimuth and in elevation, the support being fixed to said barrel, the aiming unit also comprising means for measuring the angle in azimuth (13) and in elevation (14) between the aiming line and the barrel direction, and the device comprising means (11) for measuring directly or indirectly the angular velocity of the aiming line in azimuth and in elevation, said means being arranged to send signals in accordance with their corresponding measured values to a calculating unit which is adapted to calculate on the basis of the said received signals and on the basis of supplied information on correction values such as data regarding the ballistics of the missile been fired from the anti-aircraft gun, prevailing wind vectors, the required lead angle and offset angle of the barrel direction and wherein the said calculating unit sends corresponding signals to said servomotors to fire a projectile at the target,
characterized in that the device is adapted to operate in three phases, wherein;
In phase I at a first initialisation of the aiming unit and the calculating unit said servomotors are activated so that the controlled angular velocity of the barrel in azimuth ω_Ae and in elevation ω_Ee has a defined correlation to the angular deflection in azimuth and elevation of the aiming line from a neutral position, the said deflection of the aiming line being achieved by manual action in following the target with the said aiming line and in that during a second initialisation of the aiming unit and the calculating unit a series of range measures are taken intermittently by the ranging device (8), the calculation unit registering corresponding values of the aiming line azimuth angle ψ_s and elevation angle Θ_s in relation to reference values fixed in space, the calculating unit also registering range and measuring time and calculating on the basis of said corresponding values a first preliminary target path and target speed and precalculating preliminary directions, i.e. angles in azimuth ψ_e and in elevation Θ_e and angular velocities in azimuth ω_Ae and in elevation ω_Ee of the barrel in order to direct a projectile toward the target;
In phase II at a third initialisation of the aiming unit and the calculating unit the range measuring is stopped and the said servomotors are activated to control the barrel direction on the basis of said angles ψ_e and Θ_e and angular velocities ω_Ae and ω_Ee precalculated during phase I, and corresponding to said calculated target path and target speed;
In phase III at a fourth initialisation of the aiming unit and the calculating unit a series of range measures are performed intermittently, the calculating unit registrering correlated values of the aiming line azimuth angle ψ_s and elevation angle Θ_s as well as of the range, the calculating unit then, on the basis of these correlated values, calculating a definite target speed and thereby obtaining correct barrel directions and angular velocities in azimuth and in elevation for a fired projectile to hit the target, whereafter the calculating unit activates the servomotors to adjust the barrel angles and angular velocities.
Device according to claim 1, characterized in that rate gyroes are incorporated for measuring the barrel angular velocities in azimuth ω_Ae and in elevation ω_Ee.
Device according to claim 1, characterized in that the rate gyros are adapted for measuring the sight line angular velocities in azimuth ω_As and in elevation ω_Es, and means being adapted for measuring the angular velocities between the sight line and the barrel direction in azimuth Δ ψ and in elevation ΔΘ.
Device according to anyone of claims 1-3, characte rized in that the servomotors mentioned in said phase II are activated and are correcting the angles ψ_e and Θ_e with an accelerated movement.
Device according to claim 4, characterized in that the acceleration of the movement is limited to the difference between the barrel directions and the sight line directions angles in azimuth and in elevation, Δ ψ and ΔΘ.
Device according to anyone of claims 1-5, characte rized in that the servomotors are aligning the barrel directions in azimuth and in elevation with a feed back, i.e. in closed loop control circuits.
Device according to anyone of claims 1-6, with for pivoting of the aiming unit (8) in azimuth and in elevation in relation to said support (2, 5) two handles being incorporated to be gripped by the right and the left hand, respectively, characte rized in that the initiating of said three phases I-III is meant to be achieved by activating a series of switches (28, 29, 30, 31) to be kept activated in series.
Device according to claim 7, characterized in that the initiating of phase II can be achieved by activating another switch (29) first when the initiating of phase I has been achieved by sustained activation of a first switch (28).