Automated information system for testing helicopters equipped with night vision systems based on diagnostics of the functional state of the crew

Soldatov Aleksei Sergeevich PhD in Technical Science Deputy Head of the Center for Testing, Methodological and Research Work of the V.P. Chkalov State Flight Test Center 141102, Russia, Chkalovskii oblast', pgt. Chkalovskii, ul. Chkalova, 1, of. 221 gniiivm.s@ya.ru Maslov Sergei Vladimirovich PhD in Technical Science leading test pilot of the M.L.Mil and N.I.Kamov National Helicopter Building Center 115054, Russia, g. Moscow, ul. Bol'shaya Pionerskaya, 1, of. 111 gniiivm-m@yandex.ru

Kukushkin Yurii Aleksandrovich Doctor of Technical Science Leading Scientific Associate Central Scientific Research Institute of Air Force of the Ministry of Defense of Russia 127183, Russia, Moskovskaya oblast', g. Moscow, Petrovsko-Razumovskaya alleya, 12, of. A prof.Kukushkin@yandex.ru Other publications by this author

Introduction

Performing tasks by helicopter at night significantly reduces the pilot's ability to fully use both out-of-cabin and in-cabin information, making it difficult to navigate the terrain ^[1-3]. For the helicopter crew to successfully complete the tasks assigned, the main importance is acquired by the tools for displaying the out-of-cabin space, systems for automating the processes of piloting, navigation and combat use ^[4-6]. Information about flight parameters, composition and characteristics of such means should correspond to the psychophysiological capabilities and limitations of the pilot in perception, processing, timely and competent use of information for decision-making ^[7-9].

Night vision goggles (NWS) provide the ability to pilot a helicopter at extremely low altitudes, search for targets, detect individual objects (buildings, trees, power lines, etc.) at ranges that ensure safe maneuvering to bypass obstacles, site selection from the air and landing at dusk and at night in conditions of natural night illumination (EN) on the ground from 10-4 to 1.0 lux, and in some cases – with reduced transparency of the atmosphere (haze, fog, rain, etc.) (Figure 1).

Figure 1. GEO-ONV-1-01 night vision goggles

When performing flights using the ONV, the pilot needs to take into account a number of features. So, it is necessary to pilot a helicopter more smoothly than without glasses, to prevent vigorous changes in roll, pitch and course, altitude and flight speed ^{[10, 11]}. When piloting, more attention should be paid to viewing the extra-cabin space in order to detect obstacles in a timely manner ^[12]. A look at the instruments for monitoring the flight mode, the operation of the power plant and systems should be short and performed from under the glasses. A helicopter pilot needs to be constantly ready to fly around obstacles that appear along the flight course, as well as to switch to instrument piloting ^[13-15].

The range of visibility of ground objects along the flight course depends on their geometric dimensions, contrast against the background of the underlying surface and the level of natural night illumination (Figure 2).

Figure 2. Observation of the Mi-8 helicopter at night through the ONV

The detection and recognition of objects against the background of the underlying surface at a level of 5?10-3 lux, for the GEO-ONV1-01 type, are shown in Table 1 ^[16].

Table 1 Detection and recognition of objects against the background of the underlying surface in the GEO-ONV1-01 type of ONV

At the same time, if intense light sources (searchlight beam, car headlights, red lanterns, etc.) come into the field of view of the glasses, the performance of the glasses remains, but the detection range of search objects decreases, and the viewing quality of the underlying surface deteriorates ^[10]. To perform flights in mountainous areas with the use of ONV, the flight crew must undergo a special flight training program. Performing flights in mountainous terrain at night with the use of ONV in simple weather conditions is possible and safe with a visibility range of more than 3 km and a level of 5 x 10-3...10-1 lux ^{[1, 10]}. In these conditions, it is also possible and safe to perform approach and landing at night, both on equipped and unequipped, unprepared high-altitude sites.

To determine the values of slopes on the sites, skills acquired during flights in the mountains, including at night, with the use of ONV are required. Observation of the out-of-the-cabin space with the help of the ONV and conducting visual orientation at a DISTANCE of 5 ?10-3 lux is difficult due to the inability to determine the slopes and boundaries of mountain ranges, natural and artificial objects and structures, as well as the possibility of flickering interference in the ONV. Mountain slopes covered with grass and having no changes in relief are found later than slopes with rocky formations and covered with forest and shrubs, because they are perceived as less contrasting in the ONV. The contrast of the underlying surface is sharply reduced when flying towards sunset or sunrise, moonrise. At the same time, structural lines in the form of "honeycombs" may appear in the eyepieces of glasses, which indicates excessive illumination of the backroom space. In this case, the pilot needs to shift his gaze towards a darker part of the horizon.

For the successful use of ONV, the lighting (lighting and light-signaling) equipment of aircraft must be adapted to the use of night vision goggles.

When adapting the in-cabin lighting equipment of the aircraft, the standard light filters and radiation sources are replaced with adapted filters and radiation sources with an additional installation of adapted filters. As a result, there are no unadapted or excessively bright light sources in the cabin, which reduce the visibility range of the cabin space and significantly reduce the resource of the ONV (Figure 3).

Figure 3. An example of adapting the information field of a helicopter cabin

The research materials of the pilot's activity obtained during flight tests of helicopters equipped with ONV indicate that the use of ONV imposes special requirements for the organization of attention distribution, spatial orientation, the construction of control movements by control bodies and is accompanied by an increase in the level of nervous and emotional tension.

The purpose of the study is to develop an automated information system for testing helicopters equipped with night vision systems based on the diagnosis of the functional state of the crew.

Materials and methods

The development of an automated information system for testing helicopters equipped with night vision systems, based on the diagnosis of the functional state of the crew, is based on the experience of organizing and conducting such tests.

Methods of structural system analysis, decision support and circuit engineering were used to substantiate the architecture of the automated system.

Diagnostics of the functional state of the crew was carried out according to the activity indicators of the cardiorespiratory and central nervous systems, the registration of activity indicators of which was carried out during piloting by contactless methods, as well as using special questionnaires before and after piloting ^{[1, 16]}.

The results of experimental studies were processed using mathematical statistics methods: descriptive statistics and analysis of the presence of anomalous values in a number of measurements.

Results and discussion

When performing flights in the ONV, the average values of deviations of flight parameters from the set values in the sections of experimental modes were: roll from +3.00 to – 2.90; pitch – from +2.20 to – 2.30; flight height from 10.4 m in climb and up to -14.9 m in descent, which practically does not differ from the obtained values in visual flight during the day. However, the altitude and flight speed in night conditions were maintained by the flight crew with higher accuracy. This is due to the fact that in visual flight, the pilot has the opportunity to more accurately assess the criticality of changes in flight parameters.

Piloting at night with an ONV is accompanied by an increase in the pilot's motor load. The total number of control movements by the general pitch lever, control knob and pedals increased by 44% compared to daytime flights and reached 70 movements in one minute ^[1]. At the same time, it was found that the pilot in flights with the ONV devotes about 40% of the time to monitoring the readings of the instruments. This structure of attention distribution, in general, corresponds to the data obtained in daytime visual flights. At the same time, the pilot mainly receives information about the flight altitude, which he determines with an error of 10% in comparison with the visual assessment.

An assessment of the structure of the distribution of the pilot's attention depending on the parameters of altitude, flight speed and air level allowed us to establish that with an increase in the flight altitude and, consequently, a decrease in the risk of collision with ground objects, the access to the extra-cabin space through the ONV decreases. So, if at an altitude of 50 m the pilot devotes 84% of the time to the extra-cabin space (which is typical for a visual daytime flight at altitudes less than 15 m), then at altitudes of 100 and 150 m, the observation time of the extra-cabin space is correspondingly reduced to 54.8% and 55,6% ^{[1, 4, 9, 10, 12]}.

A similar relationship is observed with changes in the water level. It is established that the lower the level of illumination and, consequently, the visibility of ground objects, the more time the pilot observes the extra-cabin space.

The analysis of the materials of the study of the functional state of the pilot showed that the level of nervous and emotional tension of the pilot in flights with ONV is determined by the complexity of the performed regime, the nature of the underlying surface and the degree of natural illumination ^{[1, 17]}. However, in the studied modes, the level of the pilot's nervous and emotional tension did not exceed a moderate degree of tension (Table 2).

Table 2 Indicators of the main physiological functions of a helicopter pilot depending on the level of natural night illumination during flights in the ONV ^[1]

The conducted research and many years of experience in the operation of helicopters with ONV indicate a positive effect of the use of ONV, which makes it possible to justify the expediency of their use by the crew of a round-the-clock helicopter to solve the tasks.

The experience of the use of ONV by the flight crew has shown that the psychological comfort of the pilot mainly depends on the quality of recognition of familiar landmarks. Since the pilot sees practically nothing with the naked eye at night, the effect of using the ONV creates the impression that it is possible to pilot almost as during the day. If, at the same time, flights are performed over familiar terrain, then the impression is transformed into psychological confidence, which, on the one hand, reduces the psychophysiological tension of the pilot, and on the other hand, can weaken attention, the reserves of which depend both on the level of training of the pilot for night instrument flights and on the level of complexity of flight modes.

An increase in the visibility range of landmarks on the ground and an improvement in the situational awareness of the crew can be obtained both by improving the characteristics of the ONV and by implementing technical vision systems in the helicopter ^[18-20].

Technical vision systems (STZ) are a promising direction for improving on-board equipment and a means of improving both the safety and efficiency of the use of helicopters.

Various variations of the development of hardware and software complexes of "Enhanced Vision" (Enhanced Vision Systems, EVS) are represented by the developments of Rockwell Collins Inc. (USA), Thales (France), CMC Electronics Inc. (Canada), Max-Viz Inc. (USA), SELEX Galileo (Italy), etc. ^[18-21].

As sources of information in such systems, television, infrared, radar channels, laser locators, terrain databases, databases of airports and runway facilities, navigation parameters and a number of others are used. The operational graphic information generated by the EVS system is then presented to the pilot in real time on the corresponding display device – an indicator on the windshield. (ILS) or a multifunctional indicator (MFI), which is a computer display that is part of the on-board information display system ^{[18, 22]}.

At the same time, two main subsystems are distinguished as part of the EVS: the technical vision system (STZ), which performs the operations of entering and processing video information, and the computer visualization system (CLE), which directly forms and presents to the pilot graphic images of the cabin environment ^[18].

The SLE and STZ systems provide the crew with an increase in the visibility range of landmarks on the ground and an improvement in situational awareness during landing, landing and taxiing along the runway at night and in difficult weather conditions due to the formation by means of technical vision and computer visualization of an enriched graphic image of the cabin space and the output of this image to the crew indicators (Figure 4).

Figure 4. Synthesized vision systems visualize terrain data, use terrain database

An example of a combined vision system is the FalconEye system on the Falcon 8X aircraft of Dassault Aviation. It simultaneously displays both an advanced vision system (EVS) and an artificial vision system (SVS) on the ILS, with a pilot-controlled distribution between EVS and SVS images. At the same time, part of the airport territory surrounding the runway is always displayed by SVS, and the landing lights and part of the airport are shown by EVS (Figure 5).

Figure 5. FalconEye enhanced vision system with information display on Dassault Aviation's ILS ^[19].

The variety of STZ being developed and possible combinations of their integration into the onboard equipment of the helicopter (for example, a flight to the ONV with the implementation of the STZ on one of the IFIs) imposes special requirements both to confirm the correctness of the choice of a particular technical solution and to determine the psychophysiological characteristics of the flight crew when working with the composition of newly installed equipment ^[1].

An example of the structure of a promising information system for testing helicopters equipped with an ONV and a vision system with an assessment of the functional state of the crew is shown in Figure 6.

Figure 6. A promising automated information system for assessing the functional state of the crew in flight tests of a helicopter equipped with night vision systems

In contrast to what was proposed in ^[23], it is proposed to use intelligent sensors (IDs) (galvanic skin reaction, pulse, heart rate, temperature, etc.) ^[24-28] and appropriate software for recording and processing biometrics of crew members ^[29-31].

The ID can give more accurate readings due to the use of numerical calculations to compensate for the nonlinearity of the sensor element or temperature dependence. Such a sensor is capable of working with a larger variety of different types of sensitive elements, as well as combining two or more measurements into one new dimension, for example, combining measurements of physiological parameters into a summary indicator of psychophysiological load ^[32-35]. The ID allows you to adjust to other measurement ranges or semi-automatic calibration, as well as perform internal self-diagnosis functions, which simplifies maintenance. Along with the improvement of operation, additional functionality of intelligent devices reduces the dimensionality of signal processing by the control system and leads to the fact that several different devices are replaced by a device of the same model, which gives an advantage both in the production itself and in the cost of maintenance ^[24].

To register the direction of view, a video camera system is located in the cockpit of the helicopter, which allows, based on a digital image recognition complex, to automatically determine and register the direction of view of each crew member during the entire flight. Modern video processing systems reliably allow us to determine at what point in time the pilot is looking at the dashboard, and at what point in the out-of-cabin space.

The information received through the switching and synchronization unit is supplemented with the current values of flight parameters and the values of control deviations coming from the onboard measurement system, as well as a recording of the video recording system, which contains a record of the current display of the ILS and all MFIs in the helicopter cabin.

Conclusion

Thus, the proposed automated system will allow recording, processing and accumulating flight and psychophysiological information in real test flights during the implementation of the entire flight test program, providing specialists in the field of aviation medicine and ergonomics with accurate quantitative characteristics of the studied parameters when evaluating promising night vision systems.

The introduction of modern information technologies will allow to objectively and accurately analyze and evaluate the content and psychophysiological structure of the pilot's activity based on a comparison of changes in flight parameters, the movement of controls, the direction of the pilot's gaze and his biomedical parameters and recommend specific options for the introduction of night vision systems.