Abstract:
A method and a system for automatic identification of ammunition type simultaneously with the performance of loading is based on optical reading of the ammunition&#39;s silhouette, and emits a signal concerning ammunition type to a computer for calculation of parameters for firing of the ammunition or to a display panel which indicates the ballistic data for the ammunition. The system is specially, but not exclusively, intended for use in armored vehicles. The system may include a selector switch for selecting between AUTOMATIC and MANUAL modes. The method and the system may also be employed for automatic correction of firing data as a result of wear caused by the use of different ammunition types.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This is the 35 USC 371 national stage of international application PCT/NO97/00012 filed on Jan. 15, 1997, which designated the United States of America. 
    
    
     FIELD OF THE INVENTION 
     The invention concerns a method and a system for automatic identification of ammunition type in connection with guns both with and without firing computers. The method and the system are particularly, but not exclusively, intended for firing shells from armoured vehicles. The invention also concerns an application of the system for calculation of firing data. 
     BACKGROUND OF THE INVENTION 
     Many types of ammunition are often used today, where the different ammunition types have different departure speeds and weights. The result of this is that the different ammunition types have differing ballistic characteristics. At present the ammunition type is normally manually fed by the person who loads the gun. As a rule this process is implemented by the person pressing a key or operating a switch on a control panel associated thereto. Ballistic data concerning the ammunition are then retrieved from the control panel, which data are either presented to the person who has to calculate the firing parameters or are transmitted directly to a firing computer which performs these calculations and controls the firing. When firing takes place with a gun employing this kind of manual feeding of ammunition type, it is a common occurrence for the person loading the gun and feeding in the ammunition type to place one type of ammunition in the gun and key in another type of ammunition or perhaps forget to key in the ammunition type. One result of this is that the target is not hit since the ballistic data which form the basis of the firing parameters, and the actual ballistic data for ammunition deviate from each other. This kind of faulty feeding in of information occurs relatively frequently, and up to 10% of the entries are assumed to be wrong. An example of a control panel currently in use is illustrated in FIG. 1. 
     U.S. Pat. No. 5,233,125 discloses a system for automatic loading, and comprises a device for identification of ammunition type and selection of the correct ballistic data which are transmitted to a computer for control of the firing. This identification device is based on the bar code principle, which implies that all ammunition must be provided with bar codes to enable the identification device to work. If bar codes are not applied to the ammunition which has to be used, an operator must manually feed in the necessary data concerning ammunition type. The device also requires the ammunition to be located in a specific position, and thus cannot be used independently of the automatic loading system. 
     U.S. Pat. No. 5,157,486 describes a camera sensor having an array of charge-coupled device (CCD) units that are used in connection with the real-time creation of a high resolution silhouette image of an object on a moving conveyor. The sensor is used in relation to automatic inspection or assembly of objects. The objects pass between a camera sensor and a light source after which they move downstream to a conventional detector and diverter which enables reorientation and/or rejection of improperly oriented or sized articles. The sensor is not meant for use in combination with a weapon firing system and is thus not adapted to this purpose. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is therefore to avoid the drawbacks mentioned in connection with the purely manual feeding in of the ammunition type, as well as the flaws and defects of the system according to the above-mentioned U.S. patent. Further objects of the invention are to simplify the loader&#39;s tasks and reduce the time taken to prepare the gun for firing. Provided the gunner carries out his job correctly, in all probability the target will thereby always be hit. 
     The above-mentioned advantages and objects are achieved with a method and a system which are characterized by features which are presented in the claims. Further features and advantages are presented in the attached dependent claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be explained in more detail in the form of an embodiment with reference to the attached figures, in which: 
     FIG. 1 illustrates a known control panel for manual feeding in of ammunition type, 
     FIG. 2 illustrates silhouettes of some ammunition types currently in use, 
     FIG. 3 is a principle drawing of a first embodiment of the invention, 
     FIG. 4 is a principle drawing of a second embodiment of the invention, 
     FIG. 5 is a principle drawing of a further development of the invention, 
     FIG. 6 illustrates the invention mounted inside the turret of an armoured vehicle, and 
     FIG. 7 illustrates the invention mounted inside the turret of an armoured vehicle viewed from another angle. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In FIG. 1 the reference numeral 1 indicates the keys between which the loader must choose in order to specify the correct ammunition type, while reference numeral 20 designates the control panel which the loader has to operate before firing shots. 
     FIG. 3 illustrates a linear sensor 31 for optical reading of the ammunition&#39;s silhouettes. The sensor is placed in the roof in the vicinity of the gun&#39;s breech block and is thereby not dependent on the ammunition being placed in a specific position. It is sufficient to pass the ammunition through a zone which extends over a relatively large area. It can also be envisaged that the ammunition is stationary while the sensor(s) are moved in relation to the ammunition, or that by means of, e.g., optical systems with movable mirrors or lenses, an apparent movement is created between ammunition and sensor. 
     The sensor may be of different types, one type being a sensor which performs a number of one-dimensional readings of the ammunition&#39;s contour (curtain sensor). When the readings are assembled a two-dimensional image of the contour will be obtained. Another type of sensor which can be employed is a video camera or, e.g., a CCD chip which takes one or more two-dimensional images of the ammunition. The use of such sensors enables the entire system to be stationary, with no relative movement being required between sensor and ammunition. In practice, more than one image will be employed to enable noise to be removed from the images by comparing several images taken at almost the same time. By means of devices in the microprocessor 33 the two-dimensional image(s) are analysed or the series of one-dimensional images from the first sensor type. The analysis determines the ammunition&#39;s silhouette, and on this basis it can be established what kind of ammunition is recorded by the sensor(s). Identification systems of this kind work rapidly and with great reliability. The ammunition type can thereby be determined with a high degree of accuracy by the microprocessor 33, despite interference in the form of, e.g., smoke or empty shell cases. 
     In connection with the sensor, the system can include an infrared radiation source 32. This source emits infrared radiation at least within the zone in which the sensor(s) perform the measurement(s). The infrared radiation source can either be mounted in the vicinity of the sensor 31 (not shown) or directly incorporated with the sensor 31 as illustrated in FIGS. 3 and 4. 
     The sensor 31 possibly with the infrared radiation source 32 together form a read unit 30, which together with the microprocessor 33 constitute an identification device. The reference numeral 20 designates the control panel from FIG. 1, while the reference numeral 21 designates the firing computer. 
     In FIG. 4 the microprocessor 33 is incorporated with the sensor 31 and possibly the infrared radiation source 32 to form a complete identification device 40. The identification device according to one of the FIGS. 3 or 4 reduces the fault rate to 0.1%. 
     The signals from the microprocessor 33 are identical to the signals which are generated when the loader presses the correct key 1 on the control panel 20 in the known system for manual determination of ammunition type. By means of the present invention the possibility of error is avoided in connection with a manual specification of ammunition type. The firing computer 21 will thereby receive the correct ballistic data for calculation of the firing parameters when the identification device according to the invention is employed. 
     Between the control panel 20 and the firing computer 21 a selector switch 22 can be mounted for selecting between AUTOMATIC and MANUAL feeding of ammunition type. Even though the switch is positioned in AUTOMATIC mode, the functions which are not concerned with feeding of ammunition type will be connected to the firing computer. In a second variant (not shown in the figures) the selector switch can be built into the control panel, in which case the sensor(s) will be connected to this panel via the microprocessor which performs the actual analysis/identification of the ammunition and via the built-in selector switch. 
     In the embodiment according to FIG. 5 the read unit 30 together with the microprocessor 33, or the identification device 40, are extended with an additional optical sensor 41, e.g. of the CCD type. This additional sensor is preferably equipped with its own microprocessor for processing the image from the actual sensor. The assembly is generally designated by reference numeral 50. This variant further reduces the fault rate in identification of ammunition type. 
     FIGS. 6 and 7 illustrate the system mounted in the turret of an armoured vehicle. Reference numeral 61 designates one of the devices 30, 40 or 50 together with the cable to the control panel. The reference numerals 20 and 21 are the same as before, referring to the control panel and firing computer respectively. 
     It is possible to connect a display panel to the identification system. e.g. if a firing computer is not used. When the identification system has identified the ammunition type, data concerning the ammunition type are employed to obtain ballistic data from a memory dedicated thereto. This memory may either be of a non-volatile or a volatile type. 
     The optical sensor(s) may be of other types than that specified above, e.g. the use may be envisaged of laser systems instead of the sensor types indicated. Other optical sensors may also be used, and as such lie within the scope of the invention. Many possibilities exist, the most important according to this invention being that it is not necessary to provide the ammunition with a special marking, e.g. in the form of bar codes, magnetic or electronic tags, etc. 
     It is also possible to incorporate several functions together with this system, e.g. the gun can be provided with an automatic safety device. This may be implemented, e.g. in such a manner that the system secures the gun for a predetermined period after the ammunition type has been established. 
     A special application of the system according to the invention is for automatically correcting the firing data for the tube wear resulting from the firing of a shot with a special ammunition type. Tube wear from the use of a specific ammunition type (HEAT-T M456 A1) for armoured vehicles is illustrated in table 1, which indicates the chances in tube diameter and muzzle velocity for a 105 mm gun, with consequent adjustment of the elevation for a given firing distance. 
     Other ammunition types give other wear values. When firing it will be necessary to correct the firing data for an existing tube wear which will be determined by the number of previously fired shots and ammunition types employed. When the ammunition type is recorded with the system according to the present invention and the shot fired, the tube wear for this shot can thereby be immediately specified and the firing data corrected for the next shot. When a firing computer is used the wear compensation can be performed entirely automatically in a particularly expedient fashion. This has obvious advantages when different ammunition types are used in turn. The standard conditions for wear correction for different ammunition types can then be stored in the firing computer&#39;s memory or in a memory connected with the microprocessor. 
     
                       TABLE 1______________________________________HEAT-T M456 A11.6 NON-STANDARD CONDITIONSCHANCE OF ELEVATION ANGLE ANDDEPARTURE SPEED AS A RESULT OF TUBE WEARNo. ofstandard Tube           %shells dia.           change                      Change of elevation angleleft  mm      V.sub.0                of V.sub.0                      1000 m                            1500 m                                  2000 m                                        2500 m______________________________________186   104,496 1180   +0,511                      -0,042                            -0,070                                  -0,106                                        -0,152171   104,750 1177   +0,256                      -0,021                            -0,035                                  -0,053                                        -0,076155   105,004 1174   0      4,322                             7,137                                  10,557                                        14,778139   105,258 1171   -0,256                      +0,024                            +0,041                                  +0,062                                        +0,070124   105,512 1168   -0,511                      +0,048                            +0,081                                  +0,124                                        +0,180109   105,766 1165   -0,767                      +0,072                            +0,122                                  +0,186                                        +0,21793    106,020 1162   -1,022                      +0,096                            +0,162                                  +0,247                                        +0,36178    106,274 1159   -1,278                      +0,121                            +0,203                                  +0,309                                        +0,45162    106,528 1156   -1,533                      +0,145                            +0,244                                  +0,371                                        +0,54147    106,782 1153   -1,789                      +0,169                            +0,284                                  +0,433                                        +0,63231    107,036 1150   -2,044                      +0,193                            +0,325                                  +0,495                                        +0,72116    107,290 1147   -2,300                      +0,217                            +0,366                                  +0,557                                        +0,8120     107,544 1144   -2,555                      +0,241                            +0,406                                  +0,618                                        +0,902______________________________________