FR2750203A1 - Anti-radiation end-of-flight homing device for missile navigation system e.g. air-to-surface missile - Google Patents

Abstract

The antiradiation homing device guides the vehicle near to a source of radiation and an end-of-flight homing device with its own estimation of measurement quality (90) takes the vehicle to the objective. The goniometer has several antennae (30) along a side wall of the vehicle, freeing the front of vehicle for the end-of-flight homing device. The goniometer has a receiver (31) and the means to determine the direction (34) and the range (33) of the radiation sources from the direction and values held in a memory (35). An identification unit (32) identifies the source from its characteristics and a library of characteristics and a clock (36) provides to the memory the date of information so as to update information to the trajectory processor.

Description

OPTIMIZED NAVIGATION METHOD AND SYSTEM
FOR A VECTOR, ESPECIALLY AERIAL
The invention relates to a method and a navigation system optimized for a vector, in particular air, comprising a self-directing anti-radiation device and possibly a self-directing end-of-travel device.

 The invention can be applied to any guidance vector, propelled (such as a missile) or non-propelled (notably a guideable planing bomb) of the Air-Surface or Surface-Surface type.

 The attack on surface targets is usually carried out using vectors using guidance means such as - navigation to a target with coordinates known in advance - anti-radiation, electromagnetic or other seeker - imagery, radar seeker or electrooptics.

 These guidance means can be used alone, and in the case of a single-mode navigation system, or combined for example for a dual-mode guidance (for example anti-radiation / infrared end-of-travel seeker).

 The effectiveness of these attacks is reduced due, on the one hand, to the progress of Surface-Air defenses, on the other hand, to the technical evolution of the objectives (in particular their protection), which requires more and more precision. higher (blow to the goal sought) to ensure their neutralization, and, finally, advances in methods of countermeasures (for example by intelligent decoy).

 The vulnerability of the vectors to Surface-Air defenses is due in particular - to the direct trajectory of the vectors - to the significant radar equivalent surface of the vector including that of the sensors which is particularly strong if it is a self-directed anti-radiation with a fropltal antenna - the inability to change course to avoid a threat.

 The effectiveness of these vectors is limited by - the low angular resolution of known anti-radiation seeker, in particular at low frequencies due to the limitation of the dimensions of the front antennas - their low capacity to locate in distance the sources of radiation indicative of the presence defenses - their inability to continue their mission when these sources stop emitting while the vector is far from the objective, that is to say their absence of ability to ensure a hit in this case - their inability to choose a lens which is not the source of emission (for example a vehicle next to the antenna); - the aerodynamic discomfort induced by the shapes imposed at the front of the vector necessary to install the sensors of the two systems there in the case of dual mode navigation as will be seen below.

 The object of the present invention is to remedy these drawbacks.

 It therefore relates to a navigation system having very improved performance thanks to greater precision of the measurements on the sources emitting towards the vector, even located in directions very far from the axis of the vector.

 It also relates to an optimized navigation system having many possibilities inaccessible with known systems thanks to a trajectory management based on multi-criteria decision-making responding to a strategy which may vary during the flight.

 According to the invention, there is provided a navigation system optimized for a vector, in particular air, comprising a self-directing anti-radiation device and possibly a self-directing end of travel device> the self-directing anti-radiation including in this case means for guiding the vector up to the proximity of a radiation source so that the homing end-of-travel device can take over to guide the vector towards the final objective, said system being characterized in that said homing anti-radiation device comprises at least one goniometer with wideband distributed antennas and trajectory management means using a multi-criteria strategy, based on the information provided by said goniometer on each radiation source emitting towards the vector.

 According to another aspect of the invention, there is provided an optimized navigation method for a vector, in particular air, in which data characteristic of the position of at least one radiation source are determined and extracted from these. data of the guidance instructions for said vector, characterized in that said method consists in - determining, using at least one goniometer with planar antennas distributed with very wide band, the angular direction, the distance and the identity of each source emitting towards the vector at successive measurement instants - determining the uncertainties in obtaining said characteristic data (8, d, id) of each source - establishing the current situation from data supplied by the vector on its state and characteristic data (e, d, id) on each source at the time considered - determine whether the constraint of accessibility of the vector to the fixed objective is satisfied and in see a maximum turn order to the vector as soon as this constraint is about to be no longer satisfied, taking into account the characteristic data on the various sources at the instant considered and an update of the constraint as a function of the current situation - verify that a plurality of constraints relating to the vector is satisfied in an established order in order to be able to resolve the conflicts and to deduce therefrom a possible domain of the parameters for guiding the vector - determine, as a function of the characteristic data relating to each source and of their uncertainty , to what extent the guidance parameters chosen in said possible field satisfy a series of pre-defined criteria updated according to said current situation - evaluate the different possible actions by merging said criteria and define the best possible action so as to deduce , from said chosen guidance parameters, instructions for e optimized guidance, said merger taking into account priorities established by a choice made according to the current situation and the laws and permanent data related to said vector and its current mission.

The invention will be better understood and other characteristics and advantages will appear with the aid of the description below and of the accompanying drawings in which - FIG. 1 schematically represents a missile of known technique - FIG. 2 is an explanatory diagram of a disadvantage of
known techniques - Figure 3 schematically shows a missile equipped with a
navigation system according to the invention; - Figure 4 is an example of a flat antenna usable in the
system according to the invention; - Figure 5 illustrates one of the possibilities of the navi system
gation according to the invention; - Figure 6 is a block diagram of the navigation system according to the invention with regard to the first mode - Figure 7 is a block diagram of the optimized navigation system according to the invention; and - Figure 8 is the block diagram of a dual-mode navigation system according to the invention.

 Although this is in no way limiting of the invention, we will describe it in the context of a dual-mode missile navigation system, that is to say a system comprising an electromagnetic anti-radiation seeker and a seeker seeker. limit switch, for example with infrared imagery.

 FIG. 1 schematically represents a missile using a known navigation system. The body 1 of the missile is shown with the front warhead 4. Usually the major part of this warhead is occupied by the homing seeker. The antennas 2 of the anti-radiation seeker sensor are also installed towards the front, which implies tormented shapes 3 which constitute aerodynamic discomfort. Furthermore, the antennas 2 being turned towards the front have a very significant radar equivalent surface for the detection systems located towards the front of the missile substantially in the direction of the objective and therefore for the defense systems of the latter.

 As can be seen, the measurement base using the antennas 2 to make angular measurements of direction of the radiation sources is of dimensions reduced substantially to the diameter of the missile, which does not allow an angular resolution of very good quality. In addition, the angular field of measurement around the axis of the missile is limited.

 FIG. 2 illustrates a drawback of such known systems.

 Let Z be the axis on which the missile moves towards a target 7. If we consider a source 5 and its antenna 6 located sufficiently close to the Z axis to be in the angular field of view of the anti-radiation seeker and if l '' dE is the uncertainty on the measurement of the angle O at which the missile sees antenna 6, it is clear that if we combine the angular measurements at points Ml and M2 of the trajectory of the missile to determine the position of this antiphon, it can be located throughout the hatched area. There is therefore a very great imprecision for the localization in distance of the antenna 6.

 FIG. 3 is a diagram of a missile, the anti-radiation seeker of which employs, according to the invention, at least one goniometer with planar antennas 8 with transverse radiation distributed over the external wall of the missile 1. This arrangement of the antennas releases the axial part 4 of the missile at the front to install more conveniently a see-through seeker 9 at the end of the race.

 The planar antennas which can be used in this way must naturally have a relatively wide transverse radiation in order to be able to carry out measurements both in directions very far from the axis of the missile and around this axis.

 Such antennas are described for example in French patent 79 24897 or in French patent applications 84 18053 and 88 12465.

 By way of example, an antenna in accordance with this last patent application is shown in FIG. 4.

This antenna comprises> on the two faces of a substrate S, two identical layers 10, 10 'and 20, 20', symmetrical with respect to a median axis XX 'and each constituting a log-periodic antenna. The two opposite parts, respectively 10, 20 and 10 ', 20' are supplied in phase opposition at points 01, 02 and 0'1, 0'2. The radiation obtained is substantially transverse and the phase centers of the half-antennas 10, 20 and 10 ', 20' deviate from the center of the antenna in proportion to the wavelength, which makes it possible to use this antenna in very broadband interferometric aerial. The angle of arrival of the signals is obtained directly without the need to know the frequency of these signals. A more complete description of such an antenna and its possibilities can be found in the French patent application 88 12465 already cited.

 As seen in connection with FIG. 3, the antennas of the goniometer (s) are distributed over the wall of the body of the missile. We therefore have a larger measurement base which allows us to obtain a much better resolution of the angular direction measurements, particularly if we add the fact that they are practically independent of the frequency and that the radome aberrations are weak, due to the position of the antennas on the missile body and the shape of the antennas.

 It follows from this and from the fact that, thanks to the large field of the antennas, it is possible to make measurements in directions very far from the axis of the vector and from the vector-target line, which can be located in distance emitting sources with good accuracy. This possibility is illustrated schematically in Figure 5 where we find, as in Figure 2, the Z axis of displacement of the missile, the objective 7 and sources 6, 6 ', 6 ". If we take two positions successive M1 and M2 of the missile, we see that, for source 6 for example, the use of angular direction measurements makes it possible to define a much less extensive hatched uncertainty zone. If we add the fact that the resolution of the measurements angular is much better, it can be seen that the use of a goniometer with flat antennas makes it possible to locate the emitting sources at a distance with satisfactory precision.

 The advantage of using such antennas therefore lies in the fact that - such antennas can be used in a very wide frequency range, for example from 2 to 18 GHz; if a wider range is desired, additional antennas of the same technique can be used - the angular reception fields are very wide and orientable, to a certain extent, and therefore make it possible to carry out measurements of the direction of the transmissions in very varied geometric target-vector configurations - their dimensions and their ability to match the external shape of the vector allow the center of the missile to be largely released - the exploitation of all directions of polarization of the reduced signals is possible - if goniometers in two planes are necessary, an appropriate arrangement of antennas allows them to be obtained.

 According to the invention, provision is made to combine the use of one or more goniometers of the type mentioned above with a device for managing the trajectory, which makes it possible to offer many new possibilities and significant advantages over to existing navigation systems, both dual-mode and a fortiori with a single-mode single seeker, as will be seen later.

 FIG. 6 is a block diagram of the system according to the invention relative to the first mode in its application to guiding the missile 1. The control surfaces 11 of the missile are controlled by commands 14 receiving their orders from a pilot 13 which itself receives even guidance instructions for a trajectory management chain 12 according to the invention incorporating the goniometer responsible for providing the angular direction (3, the distance d and possibly the identification (as will be seen below) of each source, such 15.

 The elements 11, 13 and 14 being well known will not be described further.

 FIG. 7 is a diagram of the organization of the trajectory management chain which elaborates and processes the information until the development of the guidance instructions.

This chain includes a goniometer, taken in the broad sense, including all the means 30 to 36 for developing the information of angular direction 0, of distance d and of identity id of the transmitting sources received, and of means for managing the trajectory proper incorporating the other means shown in FIG. 7.

 The planar distributed antennas 30 are connected to a receiver 31 which supplies the signals received, on the one hand, to a device 34 for determining the angular direction O of each transmitting source and, on the other hand, to a device 32 of identification of these sources. The determined angular directions are stored in a memory 35 and, on the other hand, sent to a circuit 33 for calculating the distance d from each source. This circuit 33 performs the calculation from the current value of angular direction and from the previous values of the measurements coming from memory 35.

 During the displacement of the vector, the successive directions of the same emission source make it possible to locate this source with an accuracy all the better as the number of measurements is large, that the individual measurement of direction is precise and that the angular difference between each measurement is high. The characteristics of planar antennas (good precision, wide field), the ability to observe broadcasts and finally the possibility, as we will see, of changing the vector to improve the quality of this localization allow obtaining details unknown so far. The position of the emission sources is stored and updated each time a new measurement is made.

 Furthermore, the identification device 32 studies the signals received to obtain the identity id of the source considered, for example by comparison of various parameters (transmission frequency, repetition, pulse duration, amplitude, etc.). ) with a library written in the memory 35 before the departure of the vector, or by identity with signals received previously. Such a method is well known in the art.

 Finally, a clock 36 provides dating signals to the measurements stored in memory 35 and a clock signal H to the various functions of the trajectory management.

The memory 35 restores the updated measurements 0, d, id for each source detected to the path management means.

 These management means include, for all of the above three items of information, an estimator 51 which encrypts the uncertainties (probability of good identification, probable errors for the direction and the distance).

 The trajectory management means comprise means 38 for establishing the current situation of the vector in the environment it knows, in order to be able to change the data values or reference quantities. This situation is established in particular from the data supplied by a module 37 giving the state of the missile, that is to say for example its position, its speed, its attitude, the mass of fuel remaining, etc.

 That said, the decisions concerning the guidance of the missile first take into account a priority constraint which is the condition of accessibility of the objective by the missile.

Indeed, the missile can validly continue to follow a trajectory only as long as its possibilities allow it to then reach the objective. A module 71 is therefore provided, determining if the accessibility constraint is satisfied as a function of the measurements carried out and of an update taking account of the current situation provided by the means 38 and supplying, towards the pilot 13 of the missile, a turn order at the maximum expected acceleration as soon as this constraint is about to be no longer satisfied, so as to permanently retain the possibility of reaching the objective.

 In addition, a certain number of other constraints must be satisfied in an established logical order in order to be able to resolve conflicts. Thus there are provided means 72 to 7p for taking into account these constraints which are updated as a function of the current situation, a logic of conjunction 70 determining whether these constraints are satisfied in the established order and defining therefrom a possible domain for the missile guidance parameters. As an example of possible constraints, we can cite - check that the direction of the transmitting objective is in the angular domain of the antennas - check that the conditions of observation of the sources to identify them are satisfied (duration, spatial discrimination, - check that the conditions for implementing the second guidance mode are satisfied - stay at a sufficient distance from a danger identified - maintain an orientation to offer a radar equivalent surface or a minimum infrared surface facing a direction - deal with the case extinction of the observed transmitter.

 From the possible parameters, optimization means 52 choose the guidance parameters to be optimized and send them to a series of modules 41 to 4n developing criteria C1 to Cn, which define to what extent, according to the characteristic data relating to each source and their uncertainty, these guidance parameters satisfy predefined criteria updated according to said current situation. As criteria, mention may be made of all the margins relating to compliance with the constraints mentioned above.

The results of the calculation of the criteria are sent to a function 50 of fusion of uncertain criteria, adapted to the problem of this type of guidance and achievable by numerous techniques (for example the theory of evidence of Dempster
Shaffer or Zadéh's fuzzy set theory).

 These means 50 for merging the criteria also receive a command defining the priorities to be taken into account at all times. These priorities are established by a module 40 for choosing priorities, on the basis of the current situation provided by the means 38 and of laws and permanent data recorded in a memory 39. These can be of two types: either specific to the vector and permanently present; either relating to the current mission and introduced before departure.

 The means 50 for merging the criteria provide an evaluation of the various possible actions for the optimization means 52 which develop optimized guidance instructions delivered to the pilot 13 of the missile.

 When the first guidance mode, based on the exploitation of radio emissions, has brought the vector into a position relative to the objective such that the second mode can enter into function, the trajectory management means control the switching of the first mode to second mode after checking the quality of the measurements from the second mode.

 For this, the end-of-travel seeker 9 (FIG. 3 and FIG. 8 described below) includes means 90 for estimating the quality of the measurements of the second mode which supply this information to the means 50 for merging the criteria. so that the optimization means 52 can provide a command 120 which is a mode switching command.

 FIG. 8 illustrates the complete organization of a dual-mode navigation system according to the invention with an objective 60 which is not the emitting source 61 but which is in a known relative position relative to the latter. We find there as in FIG. 6 the pilot 13, the controls of the control surfaces 14, the trajectory management 12 and the antennas 8. In addition, the end-of-travel seeker 9 is represented with its estimator 90 of the quality of the measurements. and switching means 121 controlled by the command 120 coming from the trajectory management 12. The pilot 13 therefore receives his guidance instructions first from the trajectory management chain 12 then, from the switching command of mode 120 switching the means 121, of the end-of-travel seeker. The order 120 is of course only developed on condition that the designated objective 60 is within the angular field of the seeker 9.

 The processing in the trajectory management chain is carried out in real time, that is to say that the operations or calculations to be carried out are simple and compatible with the available computers which can be carried on the vectors considered. Naturally the duration of this treatment is consistent with the reaction times of the vector.

 Thus, the trajectory management chain according to the invention is distinguished by the fact that the guiding principle is based on the search for a guidance instruction defining the trajectory thanks to a multi-criteria evaluation responding to a strategy and by the fact that this strategy is variable during the flight depending on conditions such as flight time from departure, maximum remaining flight time (or fuel available), geometry of the objectives noted in flight, availability or not of distance information, quality of direction measurements or identification of emission sources.

 The main advantageous features of the invention are as follows - better resolution of the angular direction measurements thanks to the large length of the measurement base, their independence from the frequency and the weakness of radome aberrations - the ability to develop in flight and modify the trajectory to avoid known dangers before launch, or discovered in flight, without interrupting the observation of the transmitters (for example possibility of evasive maneuvers without "losing sight of the objective" ) thanks to the large field of antennas - the ability to better separate jammers and lures and to better identify nearby sources thanks to the possibility of evolution, improved angular resolution and localization in distance - the possibility of choosing in flight a radiant target accessible to the vector, not necessarily designated before launch (this can for example be the case of the discovery of 'a higher priority objective whose presence was not known) - possible guidance, in the case where the transmitter constituting the objective, whose position is known, switches off, either in inertial only, or in inertial and with reference to the other issuers located previously and whose observation continues, or only in relative with respect to these emitters - the possibility of choosing a target which is not an emitter, if its position is known with respect to certain emitters - the possibility of bringing the vector into an optimal position (distance, orientation) to designate the objective in the second mode (end of course seeker)> then to choose the instant of passage to the terminal guidance when the quality of the measurements provided by the second mode is sufficient - the possibility of choosing a point of impact on the objective, which can be other than the antenna if it is a transmitter, to seek maximum efficiency, thanks to the quality s specific to the second mode (end-of-travel seeker with imagery for example) - the possibility of presenting a globally weaker radar equivalent surface thanks to less tormented geometric shapes, to the technology of making antennas, to their observation by radars in directions very different from those of the front antennas (lateral antennas shaped instead of front antennas with high specular effect), and finally thanks to the possibility of choosing a vector orientation such that the radar equivalent surface is minimal when facing one or more of dangers - the possibility of presenting a minimum infrared signature in the direction of a danger, thanks to the possibility of choosing the orientation of the vector - finally the possibility of reducing the gain of reception of the antennas in a direction, for example that of '' a crusher, by orientation of the vector and / or angular modification of the antenna diagram.

 Given these characteristics and these advantages, it is clear that the optimized navigation system according to the invention can be applied in particular to vectors (missiles or planing bombs) comprising one or more electromagnetic goniometers and an end-of-travel seeker at imagery (of the millimeter or infrared type) for attacking emitting objectives (for example radars) or non-emitting objectives, but whose position relative to emitters is known.

 The invention also applies to vectors of this type but with a simpler see-through end-of-travel seeker, of the "hot spot" type for example.

 We could also use an end-of-travel seeker obtained from an additional electromagnetic goniometer, whose antiphons, of the same type as those of the goniometer (s) of the first mode, would be placed so as to optimize their angular coverage on the front of the vector, and whose objectives would be issuers only.

 Goniometry towards the front could also be ensured by the goniometers of the first mode, thanks to the possibility of orientation of the diagrams of the planar antennas.

This possibility could be useful in the event that the imaging limit switch is unavailable or if it was not provided for reasons of price reduction.

 The vectors using the invention can be drawn with a very precise designation of objective (position, identity) or not very precise (objective of such type in such portion of ground), with a reference library of the encountered sources, or only with the lens characteristics; in the latter case, the vector will constitute its own library of sources during the flight as a function of the emissions received (learning).

 Although the invention has been more particularly described in the context of an aerial vector, it is clear that it would also apply to any other type of guide vector.

 Of course, the above description and the examples described are in no way limitative of the invention.

Claims (8)

 1. Optimized navigation system for a vector, in particular air, comprising a self-directed anti-radiation device and possibly a self-directed end-of-travel device, the self-directed anti-radiation in this case comprising means for guiding the vector to near a source of radiation so that the homing end-of-travel device can take over to guide the vector towards the finsl objective, said system being characterized in that said homing anti-radiation device comprises at least one goniometer with distributed wideband antennas (8 , 30) and trajectory management means (12) using a multi-criteria strategy, based on the information provided by said goniometer on each radiation source (5, 6) emitting towards the vector.  2. Navigation system according to claim 1, characterized in that said goniometer comprises several wideband planar antennas (8, 30) distributed over the side wall of the vector, thus freeing the front axial part of the vector for the installation of a optional limit switch (9).  3. Navigation system according to claim 2, characterized in that each antenna (8, 30) is a planar antenna with very wide band transverse radiation with wide angular field, allowing measurements in directions distant from the axis (Z ) of said vector.  4. Navigation system according to claim 3, characterized in that said goniometer further comprises a receiver (31) connected to said antennas (30), means (34) for determining the direction (0) of each of the sources received, means (33) for calculating the distance (d) of said sources from the value of the directions O determined by said means (34) and previously determined values stored in a memory (35), means (32) for identification (id) of said sources from the measured characteristics of these sources and of a library of characteristics stored in memory, preferably in said memory (35), and a clock circuit (36) providing in particular to said memory ( 35) the date of the various stored measurements, said memory (35) supplying, at each instant to said trajectory management means, the updated values of direction (o), distance (d) and identity (id) of each so urce detected.  5. Navigation system according to any one of claims 1 to 4, characterized in that said trajectory management means (12) comprise - means (41 to 4n) for developing criteria (C1 to Cn) determining starting from the characteristic values of each source detected to what extent each criterion is satisfied with the means (71 to 7p) for taking into account the various constraints imposed for the navigation of said vector, said means for taking into account the constraints comprising a first means (71 ) taking into account the accessibility constraint of the chosen objective which provides a turn control signal at the maximum acceleration provided for said vector when the latter reaches the limit position of accessibility to said objective - means (37 ) of establishing the state of the vector at each instant - means (38) of establishing the current situation receiving the state of the vector coming from said means (37) of establishing the state of the vector and the characteristic values of each source detected and providing updates of the criteria and constraints according to this situation to said means (41 to 4n) for developing criteria and to said means (71 to 7p) taking into account the various constraints; - a device (39) for storing in memory the laws and permanent data relating to the vector itself and its mission - means (40) for choosing priorities receiving said laws and permanent data from said device (39) and the established current situation by said corresponding means (38) and providing the priorities to be satisfied in multi-criteria decision making - an estimator (51) for calculating the uncertainties on the characteristic values of each detected source, these uncertainties being sent to the various means (41 to 4n ) developing criteria - means (50) for merging the criteria receiving said criteria (C1 to Cn) and said priorities coming from the means (40) for choosing priorities, and providing a multi-criteria evaluation of the various possible actions - a logic of conjunction (70) connected to said means (72 to 7p) for taking into account constraints other than the accessibility constraint, to determine s i said constraints are satisfied in an established logical order and define a possible domain for the vector guidance parameters; and - optimization means (52) which, on the basis of the evaluation provided by the means (50) for merging the criteria and the possible domain for the guidance parameters defined by said conjunction logic (70), determine guidance instructions optimized for said vector, the guidance parameters to be optimized being looped back by said optimization means (52) to the means (41 to 4n) for developing criteria to determine the best action.  6. Navigation system according to claim 5, comprising an end-of-travel seeker intended to be used in a second navigation mode, characterized in that said end-of-travel seeker comprises means (90) for estimating the quality of the second mode measurements which provide this information to said means (50) for merging criteria so that said optimization means can provide a mode switching command (120) to switching means (121) of the first mode anti-radiation seeker in the second mode with end of run seeker (9), when the latter is able to start operating on the finally designated objective.  7. Optimized navigation method for a vector, in particular air, in which data characteristic of the position of at least one radiation source are determined and guidance instructions for said vector are extracted from these data, characterized in what said method consists of - determining, using at least one goniometer with planar antennas distributed with very wide band, the angular direction (O), the distance (d) and the identity (id) of each source transmitting to the vector at successive measurement instants - determining the uncertainties in obtaining said characteristic data (8, d, id) of each source - establishing the current situation from data supplied by the vector on its state and from data characteristics <e> (8, d, id) on each source at the instant considered - determine if the constraint of accessibility of the vector to the fixed objective is satisfied and send a turn order to the maximum acceleration predicted at the vector as soon as this constraint is about to no longer be satisfied, taking into account the characteristic data on the various sources at the instant considered and an update of the constraint according to the current situation - verify that a plurality of constraints relating to the vector is satisfied in an established order in order to be able to resolve the conflicts and to deduce therefrom a possible domain of the parameters for guiding the vector - determine, as a function of the characteristic data relating to each source and of their uncertainty, to what extent selected guidance parameters in said possible field satisfy a series of predefined criteria updated according to said current situation - evaluate the different possible actions by merging said criteria and define the best possible action so as to deduce from of said guidance parameters chosen from optimized guidance, said merger taking into account priorities established by a choice made according to the current situation and the laws and permanent data related to said vector and its current mission.  8. Method according to claim 7, in which one passes from a first guidance mode to a second guidance mode at the end of the race> characterized in that multi-criteria decision-making by merging the criteria also takes account of the quality measurements made in the second mode to possibly decide to switch to this second end-of-travel guidance mode.