Source: https://patents.justia.com/patent/6216595
Timestamp: 2020-04-02 10:49:05
Document Index: 113037852

Matched Legal Cases: ['art 10', 'art 10', 'art 10', 'art 10', 'art 10', 'art 10', 'art 10', 'art 10', 'art 10', 'art 10', 'art 10']

US Patent for Process for the in-flight programming of a trigger time for a projectile element Patent (Patent # 6,216,595 issued April 17, 2001) - Justia Patents Search
Justia Patents Mode Selecting MeansUS Patent for Process for the in-flight programming of a trigger time for a projectile element Patent (Patent # 6,216,595)
Process for the in-flight programming of a trigger time for a projectile element
Apr 3, 1998 - Giat Industries
A process for the in-flight programming of a trigger time for an element of a projectile by a fire control system of a weapon, wherein the muzzle velocity (Vo) of the projectile is measured and the distancing velocity of the projectile at at least one other point during its trajectory after exiting the weapon barrel it measured. Based on these measured values an optimal trigger time is determined for the element so as to minimize the difference between the actual ground impact point and the desired ground impact point for the projectile or for a payload released during the payload's trajectory, and a programming or corrective programming is transmitted to the projectile which takes this optimal trigger time into account.
The technical scope of the invention is that of processes enabling the in-flight programming of a time to trigger a projectile element form the fire control system of a weapon.
The aim of the invention is to propose a process (and associated fire control system system) enabling the in-flight programming of a trigger time for a projectile element, process and fire control system which are free from the drawbacks characterizing known systems.
The invention will be better understood after reading the following description of the different embodiments, the description made with reference to the appended drawings, in which:
FIGS. 5a and 5b illustrate a particular embodiment of the fuse, respectively in its flight position and in its braking position, and
With reference to FIG. 1, a piece of artillery 1, such as a self-propelled howitzer, is attempting to hit a target 2 by means of a projectile 3. The theoretical ballistic trajectory of the projectile is shown by curve 4. A fire control system (not shown), integrated with the piece of artillery 1, determines the elevation and traverse angles, depending on the coordinates of target 2 and self-propelled howitzer 1, which must be given to barrel 5 as well as the propellant charge which will have to be used in order to obtain theoretical trajectory 4.
Step 18 corresponds to the measurement of the Vo, the measured value is compared to the Voth (theoretical Vo) which is stored (firing table). The computer thereafter determines a &Dgr;Vo which is the measured deviation.
Step 19 corresponds to the measurement of V1. This measured value is compared to a value V1th (theoretical V1) which is stored (another firing table), which enables the deviation with respect to V1 to be determined, noted &Dgr;V1.
A function h has also been stored which links the &Dgr;V1 to the &Dgr;Vo (block 20). The difference between the measured &Dgr;V1 and the expected one given the measured &Dgr;Vo is thus computed (comparator 21). This difference is noted &Dgr;V1D and corresponds to the velocity deviation exclusively due to the actual aerodynamic drag.
The function f has been stored (block 26) in a firing table and gives the forecasted deviation observed in the vicinity of the target for a given variation in velocity due to the muzzle velocity (&Dgr;Vo).
The function g has also been stored (block 22) in another firing table and gives the forecasted deviation observed in the vicinity of the target for a given variation in velocity due to the aerodynamic drag (&Dgr;V1D).
FIG. 3 shows a variant to the preceding algorithm in which the measured deviations &Dgr;Vo and &Dgr;V1 are respectively multiplied by coefficients &mgr;o (block 27) and &mgr;1 (block 28) which are read in the specific firing tables and which depend on the firing conditions (firing angles and muzzle velocities).
The forecasted deviation E is obtained by adding (analog adder 29) &mgr;o×&Dgr;Vo+&mgr;1×&Dgr;V1.
The coefficient tables &mgr;o and &mgr;1 are determined by computation (and/or trials).
FIG. 5a shows by way of example a fuse 10 which incorporates a front part 10a and a rear part 10b. Rear part 10b contains the different electronic circuits and notably computation unit 16 connected to antenna 15.
Front part 10a contains element 17 which, in this case, is formed by a pyrotechnic charge initiated by an electrical primer.
Front part 10a and rear part 10b are separated by a ring-shaped incipient fracture 24. Front part 10a can, for example, be formed by a thin casing made of steel which is clipped into or bonded onto a groove carried in rear part 10b.
At the optimal time, determined by the fire control system and contained in computation unit 16, the latter causes the initiation of pyrotechnic charge 17. The resulting pressure build up inside front part 10a causes it to separate from the rear part 10b.
This ejection of front part 10a causes a sudden change in the profile of fuse 10 which opposes the aerodynamic flow presenting a plan face (FIG. 5b).
1. A process for the in-flight programming of a trigger time for an element of a projectile by a fire control system of a weapon, comprising the steps of:
a muzzle velocity of said projectile is measured,
a distancing velocity of said projectile at at least one other point during its trajectory after exiting the weapon barrel is measured,
based on these measured values an optimal trigger time is determined for said element so as to minimize the difference between the actual ground impact point and the desired ground impact point for said projectile or for a payload released during its trajectory,
a programming or corrective programming is transmitted to said projectile in flight which takes this optimal trigger time into account.
2. A process according to claim 1, to determine the optimal trigger time wherein:
the difference with respect to the predictable ground impact point which can be attributed to the variation measured in the muzzle velocity (Vo) of said projectile is determined,
the predictable deviation with respect to the ground impact point attributable to the variation in aerodynamic drag is calculated by subtracting from a measurement of the distancing velocity the variation in distancing velocity attributable to the variation in muzzle velocity.
the two predictable deviations thus estimated are added together.
3. A process according to claim 1, to determine the optimal trigger time wherein:
the predictable deviation with respect to the ground impact point is determined by carrying out a linear combination of the difference in velocity measured at at least two points.
before firing, a theoretical trigger time is programmed taking into account characteristics of a required theoretical trajectory,
after firing, a correction to the initial programming is transmitted to the projectile.
5. A process according to claim 4, wherein a program is transmitted to said projectile after firing in the form of a trigger time counted from a reference time.
measuring a muzzle velocity of the projectile substantially at a time the projectile leaves the weapon;
measuring a flight velocity of the projectile at at least one point along the trajectory;
computing an optimal trigger time for an element of the projectile to correct an actual trajectory of the projectile to provide projectile detonation substantially at a designated target impact point; and
providing triggering programming to the projectile in flight based on the optimal trigger time.
13. The process according to claim 12, wherein the step of computing an optimal trigger time comprises the steps of:
comparing the muzzle velocity to a theoretical velocity to obtain an initial velocity deviation;
comparing the flight velocity to a theoretical flight velocity to obtain a flight velocity deviation;
calculating an expected flight velocity deviation;
determining a difference between the expected flight velocity deviation and the flight velocity deviation to obtain an air drag factor;
computing an expected target impact point deviation on a basis of the initial velocity deviation;
computing an expected target impact point deviation on a basis of the air drag factor; and
determining an estimated deviation from the target impact point using the expected target impact point deviations based on the initial velocity deviation and the air drag factor.
14. The process according to claim 13, further comprising the step of determining a trigger time for the element on a basis of the estimated deviation from the target impact point.
adjusting the initial velocity deviation and the flight velocity deviation respectively on the basis of predetermined firing conditions; and
combining the adjusted initial velocity deviation and the adjusted flight velocity deviation to obtain an estimated deviation from the target impact point.
16. The process according to claim 15, wherein the step of computing the optimal trigger time comprises applying a correction factor to the estimated deviation from the target impact point.
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Patent number: 6216595
Inventors: Gérard Lamorlette (Trezelles), Thierry Bredy (Asnières les Bourges)
Application Number: 09/054,520
Current U.S. Class: Mode Selecting Means (102/270); Igniting Devices And Systems (102/200); Combined With Projecting, Launching Or Releasing Devices (89/6.5); Automatic Guidance (244/3.15)
International Classification: F41F/100;