GB2329778A

GB2329778A - Locating system

Info

Publication number: GB2329778A
Application number: GB9800601A
Authority: GB
Inventors: Peter Gregory Lloyd
Original assignee: Roke Manor Research Ltd
Current assignee: Roke Manor Research Ltd
Priority date: 1997-09-24
Filing date: 1998-01-14
Publication date: 1999-03-31
Anticipated expiration: 2018-01-14
Also published as: GB2329778B; GB9720255D0; GB9800601D0

Abstract

A missile launcher scatters a number of sensors before launching a missile. The sensors emit different spread spectrum chirped radio signals at known times which are received by each other sensor to obtain a time difference between emission and reception and hence the relative range and thus relative position of the sensors. The sensors then receive acoustic radiation from the missile, and measure the difference in time between reception at the various sensors to determine the position of the missile.

Description

VEHICLE GUIDANCE SYSTEM The present invention relates to remote vehicle guidance systems which operate to generate signals which are effective to guide a remotely located vehicle to a target location.

Vehicles which travel in hazardous environments are usually unmanned and so require a remote guidance system to guide the vehicle to a predetermined target location. Known guidance systems have a base unit which is arranged to communicate guidance signals to the remote vehicle.

In some situations the base unit of the remote guidance system must also be located unmanned in the hazardous environment, either because a range at which the vehicle must operate from the base unit prevents effective communication with the vehicle or because a time when the target appears and to which the vehicle is to be guided, is unknown, so requiring the guidance system to act autonomously when the target appears. As such a technical problem exists in providing a vehicle guidance system which operates to guide a vehicle to a target location where the location of the target is unknown at a time when the vehicle guidance system is deployed. This technical problem is addressed by the vehicle guidance system according to the present invention.

According to the present invention, there is provided a guidance system for a vehicle, comprising a plurality of sensors which are arranged to be disposed in a spaced apart relationship, which sensors are provided with a location generator means for generating information appertaining to a relative position of each of the plurality of sensors, which information is communicated to a control processor means with which the vehicle is associated, wherein the control processor means operates to generate guidance signals consequent upon radiation emitted by the target body and detected by the plurality of sensors, which guidance signals serve to guide said vehicle to a location of said target determined by said control processor means from the radiation detected by said plurality of sensors in combination with the relative position of the plurality of sensors.

By arranging for the guidance system to determine a relative position of each of the sensors with respect to one another, and by detecting signals from a target body, a relative position of the target body may be determined with respect to the vehicle. In accordance with the relative position of the target body, the command processor operates to generate guidance signals which have an effect of guiding the vehicle to the target body.

The location generator means may comprise a plurality of communicators each of which is operatively associated with one of the plurality of sensors, and arranged to communicate data to and from any of the others of the plurality of sensors, a plurality of data processors each of which is coupled to one of the communicators and arranged in use to send and receive data via the communicator, and a clock which serves to provide a temporal reference to the data processors, wherein said data processors operate in a first phase in combination with said communicators to communicate a predetermined signal which is detected by the other communicators in the other sensors and in accordance with a temporal difference between a time when said predetermined signal is transmitted and a time when the signal is received a relative distance of said plurality of sensors to the others of the plurality of sensors is determined by the data processors. During a second phase, the data processors may operate to communicate data representative of a set of relative distances of the other sensors with respect to the sensor associated with said data processor via the communicator to at least one other of the data processors and consequent upon receipt of said data, this one other data processor is arranged to determine the relative position of each of the plurality of sensors.

By providing a communicator and data processor within each of the sensors, signals transmitted from each of the plurality of sensors to the others of the plurality of sensors serve to determine a distance of each of the sensors from the others of the plurality of sensors in accordance with the time of flight of said signals. Furthermore, by thereafter arranging for each of the plurality of sensors to transmit the data appertaining to a distance of each of the other sensors with respect to that sensor, to at least one of the data processors, information appertaining to a respective location of each of the sensors may be generated by that data processor. The information corresponding to the respective location of each sensor may be generated by triangulating the location of sensors from the relative distances with respect to each of the other sensors.

According to an aspect of the present invention there is provided a method of guiding a vehicle remotely to a target location, comprising the steps of; deploying a plurality of sensors at spaced apart positions, determining a location of each of said sensors, detecting signals radiated by the target at each of said sensors, determining a relative time difference at which said signals are detected by said sensors, and determining a location of said target from said relative time difference, in combination with the location of each sensor.

One embodiment of the present invention will now be described by way of example only with reference to the accompanying drawings, wherein FIGURE 1 is a representation in aspect view of a missile launcher which includes a remote vehicle guidance system; FIGURE 2 is a schematic block diagram of one of the sensors shown in Figure 1 and a base unit.

FIGURE 3 is a representation in aspect view of the missile launcher shown in Figure 1, with a plurality of deployed detector elements; FIGURE 4 is a representation in aspect view of the missile launcher shown in Figure 1, with the plurality of sensors deployed; FIGURE 5 is a representation in aspect view showing the missile launcher shown in Figure 1 in use detecting a target, and FIGURE 6 is a representation in aspect view of the missile launcher which appears in Figure 1 with the missile deployed.

An example embodiment of the present invention will now be described with reference to a remote vehicle guidance system embodied within a missile launcher.

An illustration of such a missile and missile launcher is shown in Figure 1. In Figure 1 a missile 1 is shown to be disposed within a launching tube 2. Detectably disposed on the outside of the launching tube 2 are a plurality of sensors 4. The launching tube 2 is arranged to stand perpendicularly with respect to the ground which is facilitated by supporting legs 6 which are deployed when the missile and missile launcher are in use. The sensors 4 and a control module within the launching tube 2 is shown in more detail in Figure 2 where parts also appearing in Figure 1 bear identical numerical designations. In Figure 2 one of the sensors 4 is shown to be comprised of an antenna 8 which is coupled to a radio transceiver 10.

The radio transceiver 10 is coupled to a data processor 12. Also coupled to the data processor 12 is a clock 14, a radiation detector 16 and a data store 18. The data processor 12 within the sensor 4 is coupled to a command processor 20 embodied within a base unit 22 forming part of the launching tube. The data processor 12 is connected to the command processor 20 via a conductor 24 which is long enough and strong enough to allow the sensor 4 to be projected away from the base unit 22 to a substantial distance. Also coupled to the command processor 20 within the base unit 22 is a guidance communicator 26. The guidance communicator 26 operates to communicate guidance signals represented by line 28 to the missile 1 between antennas 30 and 32. The guidance radio signals 28 operate to provide guidance signals which are detected and interpreted by a guidance controller 34 embodied within the missile 1.

As mentioned above, in use the missile launcher is deployed so that the supporting legs present the missile launcher in a substantially perpendicular relationship with respect to the ground. Furthermore, as part of the deployment, the sensors which are disposed on the outside of the launching tube 2 are projected away from the launching tube as illustrated in Figure 3 where parts also appearing in Figures 1 and 2 bear identical numerical designations. A result of projecting the sensors 4 is illustrated in Figure 4 where parts also appearing in Figures 1, 2 and 3 bear identical numerical designations. As is shown in Figure 4, the sensors, after being projected from the launching tube, are deployed as far as possible at a substantially uniform displacement with respect to the launching tube and to each other.

In operation, the vehicle guidance system formed from the base unit 22 and sensors 4 and guidance control system 34 operates to autonomously detect a target, determine the location of the target from signals emitted thereby and consequent upon the location of the target, launch the missile and guide the missile to the target. However, in order to determine the location of the target, from signals emitted by the target, it is necessary in a first phase for the command processor 20 to determine the location of each of the deployed sensors 4. This phase of the operation will now be described.

Each of the sensors 4 is provided with a temporal reference through their clocks 14 which may be synchronised by the command processor 20. All of the sensors 4 are connected to the command processor 20 via the conductors 24.

Alternatively, therefore, timing reference may be provided to each of the sensors 4 via a common clock coupled to the command processor 20. The temporal reference provided to the sensors 4 facilitates synchronised transmission of signals between each of the sensors 4 via the radio transceivers 10 and antennas 8, through which a relative distance of each of the sensor elements with respect to each other is determined. To this end, a first of the sensors 4 transmit a predetermined signal at a predetermined time which is detected by each of the other sensors. This signal may be a chirped signal or a spread spectrum signal which has been modulated with a known spreading code. The temporal reference provides all of the sensors with a time at which the predetermined signals are transmitted. Therefore each of the other sensors may determine a relative distance of the sensor 4 which transmitted the predetermined signal in accordance with a temporal difference in the time the signal was transmitted and the time it was received by the other sensors. Correspondingly, each of the other sensors in turn transmits a predetermined signal associated with the sensors, and uniquely identified as associated with the sensor by either the time at which it was transmitted or by the spreading code with which the predetermined signal is modulated. Therefore, each sensor in the array of sensors, will be provided with information appertaining to a relative distance of all the other sensors with respect to it.

In a second phase of the operation, each of the sensors 4 communicates the relative distances of each of the other sensors in the array to the command processor 20. Thereafter command processor 20 operates to determine the relative location of each of the sensors 4 in three dimensional space by triangulating a position of any of the sensors in accordance with the relative distances provided by each of the other sensors. The process of triangulation is known to those skilled in the art as the process of determining a location of an object with respect to a plurality of reference points in accordance with a distance of the object to each of the plurality of reference points.

Once the missile launcher has established the location of each of the sensors 4, a location of a target body may be established from energy radiated by the target body. An example illustration is provided in Figure 5 where parts also appearing in Figures 1, 2, 3 and 4 bear identical numerical designations. In Figure 5 an example target is a tank 40 which is in a process of firing an artillery shell. The presence of the target 40 is determined by the radiation sensor 16 which is provided with a means for detecting acoustic signals. The time at which the acoustic signals are detected by the radiation sensor 16 is communicated via each of the data processors 12 within the sensors 4 to the command processor 20. From a relative difference at which the time when the acoustic signals are detected by each of the sensors, and in combination with the relative location of each of the sensors 4, the command processor operates to determine the location of the target 40. This is achieved in a corresponding manner to the process of triangulation, by solving a set of simultaneous equations provided by the relative distances to each of the sensors from the target 40 in combination with the relative location of those sensors.

Once the target body has been detected and the location of the target body has been determined, the missile 1 is deployed. Typically, a location of a target body will be determined to a sufficient accuracy where the distance to the target is in the order of ten times the diameter of the sensor array. This is illustrated in Figure 6 where parts also appearing in Figures 1 to 5 bear identical numerical designations. As illustrated in Figure 6, the missile 1 is guided to the target location 40 via guidance signals 28 communicated via the guidance communicator 26 and guidance control signal 40 within the missile 1. Furthermore, the command processor further operates to monitor the location of the target body 40 from further signals emitted by the target body as it moves from its originally detected position. Thereafter the command processor 20 operates to adjust the guidance control signals communicated to the missile 1 so that the missile 1, correspondingly adjusts to the movement of the target body 40.

In a further embodiment of the invention, each of the sensors is provided with an apparatus for determining the direction of arrival of radiation emitted by the target body. This direction of arrival information is fed to the data processor and used to facilitate determination of the location of the target. Furthermore, the apparatus can also facilitate determination of the relative position of each sensor in combination with the relative distances between them.

As will be appreciated by those skilled in the art, various modifications may be made to the aforementioned embodiment without departing from the scope of the present invention. For example, as illustrated in Figure 6, communication between the base unit within the missile tube 2, and the missile 1 may be effected by a wire 42 instead of the radio communications link illustrated in Figure 2 through the guidance transmitter 26 and guidance control system 34. Furthermore, the location of the sensors 4 may be determined from various types of signals transmitted by those sensors which may be coded in some way.

Claims

CLAIMS 1. A guidance system for guiding a vehicle (1) to a target location (40), said guidance system comprising a plurality of sensors (4) which in use are disposed in a spaced apart relationship, which sensors (4) are provided with a location generator means which operates to generate a relative location of each of said sensors (4) with respect to each other, and a command processor means (20) coupled to said plurality of sensors (4) which operates to determine the location of said target (40) consequent upon a relative time at which signals radiated by said target body are detected by said sensors in combination with the relative location of said plurality of sensors, said guidance system being thereby provided with the location of the target to which the vehicle is guided.
2. A guidance system as claimed in Claim 1, wherein said location generator means comprises a plurality of data processors (12), and a plurality of communicators (10) coupled to said data processors, one of each of said plurality of data processors (12) and communicators (10) being embodied within one of each of said plurality of sensors (4), and at least one clock (14) for providing a temporal reference to said data processors, from which temporal reference times of flight of signals communicated between said communicators (10) are determined by said data processors, which times of flight are indicative of relative distances between said sensors, from which relative distances said location generator means determines a relative location of said sensors.
3. A guidance system as claimed in Claim 2, wherein at least one of said data processors determines the relative location of said sensors, by triangulating a position of said sensors from said relative distances provided from each of the other sensors.
4. A guidance system as claimed in any preceding claim, wherein said predetermined signals are chirped signals, or spread spectrum signals modulated by a predetermined spreading code.
5. A guidance system as claimed in any preceding claim, wherein said location generator means further includes a plurality of data stores, one of which data stores (18) is disposed within each of said sensors (4) and coupled to the data processor (12), said data processor (12) being arranged to store the relative distance data received from others of said sensors, from which the location of the others of said plurality of sensors is calculated.
6. A method of guiding a vehicle remotely to a target location, comprising the steps of; deploying a plurality of sensors at spaced apart positions, determining a location of each of said sensors, detecting signals radiated by the target at each of said sensors, determining a relative time difference at which said signals are detected by said sensors, and determining a location of said target from said relative time difference, in combination with the location of each sensor.
7. A method of guiding a vehicle remotely as claimed in Claim 6, wherein the step of determining the location of each of said sensors, comprises the steps of transmitting a signal from each of said plurality of sensors to the others of said plurality of sensors, determining relative distances between each of said sensors with respect to said other sensors from a time when said signals were transmitted and a time when said signals were received, communicating said relative distances between said sensors, and determining a relative location of said sensors by triangulating a position of each sensor from said relative distances.
8. A guidance system as hereinbefore described with reference to the accompanying drawings.