RU2202092C2 - Helmet system of target indication and presentation - Google Patents

Abstract

FIELD: military equipment. SUBSTANCE: target indication and presentation channels are optically integrated and spectrally separated. Device forming TV image in presentation channel is optically coupled to pilot's eye with the aid of first objective, first mirror spectrally opaque in visible range of spectrum and second mirror opaque in entire range of spectrum. TV camera in target indication channel is optically coupled to pilot's eye with the help of second objective matched to infrared illumination device, third mirror opaque in infrared range of spectrum and second mirror. Optical axes of both channels are matched in space. EFFECT: increased precision and speed of guidance of weapon. 2 cl, 5 dwg

Description

 The present invention relates to the field of television, and in it to target designation systems.

 There are many modifications of optical and optoelectronic systems designed to perform target designation functions.

 Known target designation system [1]. In this system, adopted as an analogue, a crosshair of the sight is placed in front of the pilot’s eye, which is attached to the pilot’s helmet. The pilot combines the crosshairs of the sight with the target, then the helmet's orientation in the carrier space is automatically determined and the spatial position of the optical axis of the pilot’s eye is calculated.

The closest technical embodiment of the system adopted for the prototype is the helmet-mounted DASH 3 system, currently manufactured by Elbit [3, 4]. It is an optical-electronic system with an angular field of view of 22 ^o , located on the helmet of the pilot, and using a small picture tube, which forms the image of the space observed by the pilot, it is possible to carry out target designation. The accuracy of determining the spatial orientation of the optical axis of the optoelectronic system is 20 angles. min The error of target designation depends on the accuracy of determining the spatial orientation of the optical axis of the target designation system and on the accuracy of alignment of this optical axis with the target.

 The disadvantages of the prototype should include a small accuracy of target designation, determined by the accuracy of pointing the crosshairs of the sight on the target by turning the head. It should also be noted that it is impossible to obtain high accuracy of target designation by determining the orientation of the helmet of the pilot in space, since a person under physiological conditions cannot physiologically control the position of the head with an accuracy of several angular minutes. In addition, the need for simultaneous target designation processes and visual control of the readings of the instrument panel display devices leads to increased fatigue of the pilot.

 The aim of the invention is to increase the accuracy of target designation and reduce fatigue of the pilot in the process of target designation. The goal is achieved by changing the target designation algorithm.

A person in everyday life is used to the following target designation algorithm:
- turning the head toward the target;
- rotation of the eyeball to accurately align the optical axis of the eye with the target.

In addition, it is necessary to note one more characteristic feature of the above algorithm - during vibrations, when a person’s head performs spatial vibrations, the person automatically keeps the optical axis of the eye on the target. It should also be noted that combining the crosshairs of a sight with a target by turning the head for a person is much more difficult than just looking at the target, i.e., combining the optical axis of the eye with the target. All of the above leads to the algorithm of the target designation process, which repeats the process of pointing the optical axis of the eye to the target optimal for a person:
- determination of the coordinates and orientation of the helmet of the pilot in the coordinate system of the aircraft (LA);
- determination of the coordinates and orientation of the optical axis of the pilot’s eye in the coordinate system of the pilot’s helmet;
- recalculation of coordinates and orientation of the optical axis of the pilot’s eye into the coordinate system of the aircraft.

 There is also a method of determining the orientation of the optical axis of the eye in space [2]. This method consists in automatically determining the spatial position of the optical axis of the eye from a television image of the eyeball.

 Based on the foregoing, and also in order to ensure the required accuracy in determining the coordinates and orientation of the optical axis of the eye in space and reduce pilot fatigue, it is advisable to combine the display system and target designation system into one common target designation and indication system (NSCI). The goal is achieved due to the fact that the target designation and indication channels are optically combined and spectrally separated, moreover, in the display channel, the television image forming apparatus is optically connected to the pilot’s eye by means of a first lens, a first mirror, spectrally opaque in the visible range of the spectrum, and a second mirror , opaque in the entire spectrum range, and in the target designation channel, the television camera is optically connected to the pilot’s eye by means of a second lens combined with the device infrared (IR) illumination, a third mirror opaque in the infrared range of the spectrum, and a second mirror, while the optical axes of both channels are aligned in space.

 Thus, the essence of the invention lies in the fact that in the helmet-mounted target designation and indication system comprising a television image forming apparatus, a television camera, an indication channel, a target designation channel, mirrors and lenses, the indication and target designation channels are optically combined and spectrally disconnected, moreover, in the channel The television imaging device is optically coupled to the pilot’s eye by means of a first lens, a first mirror, spectrally opaque in the visible range a spectrum, and a second mirror, opaque in the entire spectrum range, and in the targeting channel, the television camera is optically connected to the pilot’s eye by means of a second lens combined with an infrared (IR) illumination device, a third mirror that is opaque in the infrared range, and a second mirror, the optical axes of both channels are combined in space.

 The specified technical solution allows you to combine a television image of flight information with a television image of the surrounding space. However, to facilitate the equipment located on the pilot’s helmet, it is advisable to place part of the equipment outside the pilot’s helmet, for which an optical fiber and a lens are additionally introduced into each mentioned channel of the proposed system, the lens output of each channel being optically connected to the pilot’s eye through the additional optical fiber and lens, and the corresponding mirrors. To enable turning off the targeting channel and directly observing the surrounding area with the image of the display channel superimposed on it, the second mirror is equipped with a liquid crystal filter with a controlled transmittance to ensure the same visible brightness of external objects and the television image of the display channel.

The system has two working channels:
- target designation channel and
- indication channel.

 In FIG. 1, 4, 5 are sketches of the optical schemes of the NSCI options, and Figs. 2, 3 show the spectral reflection characteristics (ρ%) of the NSCI mirrors.

The device NSCI is shown in Fig.1. It includes: the pilot's eye 1, three mirrors 2, 3, 6, two lenses 4, 7, a source of 8 IR illumination, a television imager 5 (LCD or picture tube) and a television camera 9. Positions 1, 2 enter the display channel , 3, 4, and 5. The target designation channel includes positions 1, 2, 6, 7, 8, and 9. Both channels are optically aligned. For this, the target designation channel and the indication channel are spectrally separated:
- the indication channel works in the visible part of the spectrum (400-650 nm);
- the target designation channel operates in the infrared part of the spectrum (700-1000 nm).

The possibility of alignment is achieved as follows:
- mirror 2 reflects light energy in the wavelength range from 400 to 1000 nm;
- mirror 3 (Fig. 3) reflects light energy in the wavelength range from 400 to 650 nm and is transparent to energy in the wavelength range from 700 to 1000 nm;
- mirror 6 reflects light energy in the wavelength range from 700 to 1000 nm and absorbs energy in the rest of the spectrum.

 The NSC works as follows.

 The pilot’s eye 1 examines the imaginary television image formed by the lens 4, the television imager 5 and transmitted using the mirrors 3 and 2 to the pilot’s eye. The IR source 8 using mirrors 6 and 2 illuminates the eye 1 of the pilot, and the lens 7 forms an image of the eye on the target of the CCD matrix of the television camera 9.

 The device shown in Fig. 1 has one significant drawback: all of these device blocks are located on the pilot's helmet and have significant weight. This parameter significantly increases the pilot's fatigue and, thus, reduces the NSCI's quality indicators. To eliminate this drawback, an optical fiber and a lens are additionally introduced into each channel of the system, the lens output of each channel being optically connected to the pilot's eye through additionally inserted optical fiber and a lens and corresponding mirrors. Figure 4 shows the modification of the NSCI, the weight of which is significantly reduced due to the exclusion from the helmet equipment of the television imager and television camera. For this, an optical fiber and a lens are included in the composition of each channel. In Fig. 4, this is respectively: in the display channel, the lens 10 and the optical fiber 11, and in the targeting channel, the lens 12 and the optical fiber 13. The principle of operation of the NSCI in this case is the same as in the embodiment shown in FIG. 1, except that the display channel lens 4 projects an image of the television imaging unit 5 onto a section of the light guide 11, and the lens 10, together with the pilot's eye 1, creates an imaginary image of the object. The target channel 12 of the target designates the image of the pilot’s eye 1 to the section of the fiber 13, and the lens 7 projects the image from the section of the fiber 13 to the target of the CCD matrix of the television camera 9. Only mirrors 2, 3, 6, lenses are mounted on the pilot’s helmet in this design 10 and 12, as well as sections of the optical fibers 11 and 13. The remaining NSCI units are installed on the body of the pilot's seat.

To provide additional capabilities, the NSCI version shown in FIG. 5 is used. These additional features are:
- the ability to "overlay" the image of the display channel (for example, flight information) on the image of the surrounding space;
- the possibility of electrical shutdown of the operation of the display channel and the transition to a visual analysis of the surrounding space (while maintaining the operation of the target designation channel or with disabling the latter).

 This is achieved by the fact that the mirror 2 is equipped with a liquid crystal filter 14 with a controlled transmittance to ensure the same visible brightness of external objects and the television image of the display channel, and the mirror 2 is translucent in the visible part of the spectrum.

 The spectral reflection characteristic of the mirror 2 is similar to that shown in figure 2. Using the filter 14, it is possible to equalize the brightness of the image created by the imaging unit 5 of the television image, and the brightness of the surrounding space.

The calculation of the effectiveness of the proposed device shows the following:
1. If we assume that four television cameras are used to measure the positioning and orientation parameters of the pilot’s helmet, the helmet’s movement range is 200 mm, the distance between the marks on the helmet is 150 mm, the number of marks is 4, the resolution of the television camera is 500 TV lines and the measurement time is 0 12 s, then we obtain the accuracy of measuring the orientation of the helmet, equal to 1.5 angles. min

 2. When using the targeting channel in the device, taking the range of movement of the pupil of the eye equal to 20 mm, and the parameters of the television camera and the measurement time the same with the option to determine the orientation of the helmet, we obtain the accuracy of determining the orientation of the optical axis of the eye, equal to 0.6 angles. min

 3. The time of aiming the crosshairs of the sight on the target by turning the head is about 1 s, and the time of combining the optical axis of the eye with the object is about 0.1 s.

 Thus, when using the target designation channel and the optical-television sight, we obtain the required accuracy and speed of weapon guidance.

Sources of information
1. EP 0628780 Bl. Aiming system for aircraft.

 2. Enderle. J.D. The Fast Eye Movement Control System. In: The Biomedical Engineering Handbook, ed. J. Bronsino. CRC Press, Inc., Boca Raton, FL, 1995, Chapter 164, p. 2463-2483.

 3. Flug Revue 3, pp. 50-53.

 4. Jane's IDR, Aug. 1997, pp. 41-47.

Claims (3)

 1. A helmet-mounted target designation and indication system, comprising a television image forming apparatus, a television camera, an indication channel, a target designation channel, mirrors and lenses, characterized in that the indication and target designation channels are optically combined and spectrally separated, moreover, a television image forming apparatus is in the indication channel optically connected to the pilot’s eye through the first lens, the first mirror, spectrally opaque in the visible range of the spectrum, and the second mirror, opaque in the entire spectrum range, and in the targeting channel, the television camera is optically connected to the pilot’s eye by means of a second lens combined with an infrared (IR) backlight, a third mirror opaque in the infrared range, and a second mirror, while the optical axes of both channels combined in space.  2. The system according to claim 1, characterized in that an optical fiber and a lens are additionally introduced into each said channel of the system, the lens output of each channel being optically connected to the pilot's eye through additionally inserted optical fiber and the lens and corresponding mirrors.  3. The system according to claim 1, characterized in that the second mirror is equipped with a liquid crystal filter with a controlled transmittance to ensure the same visible brightness of external objects and a television image of the display channel.

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