Mai Vice-Rector for Academic Affairs goat cutter. The main aviation university of the country received a new head. Recommended list of dissertations

At this stage in the development of military aviation equipment in all developed countries of the world, considerable attention is paid to combat unmanned aerial vehicles (UAVs), which are increasingly used to solve military aviation tasks. This is determined by the advantages provided by the use of UAVs for solving such tasks as reconnaissance, jamming, delivery of payloads, including the delivery of means of influencing the enemy, namely: the relative cheapness of UAVs, high survivability and stealth.

These qualities of combat UAVs are most clearly manifested when they are used in the low-altitude flight mode (LAF), i.e. when flying around the terrain.

Low-altitude flight is usually called a flight at an extremely low altitude, provided that the necessary safety is ensured. In the MVP mode, the aircraft is a so-called low-flying target (NLT). From the point of view of detection and tracking, the NLC is a complex object, which is associated with various features of the operation of ground-based radar stations (RLS), in particular:

The line-of-sight range of the NLC is much less than when flying at high altitudes, since the aircraft spends a considerable time in the so-called radar shadow - a region of space where the radar signal cannot propagate, due to the curvature of the earth and the presence of obstacles in the path of the radar signal propagation;

Due to the reduction in the detection range of the NLC, the time for preparing and implementing the interception of the target is reduced;

Target tracking is periodically interrupted when the aircraft enters the area of ​​the radar shadow;

The probability of correct detection of the NLC is reduced due to the so-called antipode effect, the manifestation of which consists in the “blurring” of the target image or the appearance of two or more target marks due to multiple re-reflections of the LA signal from the earth's surface.

One of the most popular types of UAVs that are able to operate in the MVP mode is a helicopter-type UAV, considered as a reconnaissance, jammer or carrier of high-precision aviation weapons.

Indeed, tactical UAVs and UAVs of the battlefield are tasked with detecting and defeating hidden and camouflaged targets, issuing target designations for interacting manned aircraft. At the same time, it is necessary to ensure the secrecy of the approach to the target flight area, the use in any weather conditions, regardless of the time of day from unprepared sites or directly from the carrier vehicle, the modularity of UAV information systems, the ability to operate at ultra-low altitudes, and the complete autonomy of the UAV. The latter allows the effective use of electronic warfare, hitting enemy information networks and assets, while maintaining its own low vulnerability to air defense systems.

In addition, it should be noted that, from an economic point of view, reusable UAVs using non-aerodrome start with a point landing are preferable.

The requirements listed above are most fully met by helicopter-type UAVs operating in low-altitude flight mode.

At the same time, it is obvious that for the implementation of such a mode of an unmanned helicopter, there are a number of difficulties associated, on the one hand, with the features of the MVP listed above and, on the other hand, with the features of the helicopter as a control object. It is also necessary to take into account the fact that the use of a UAV as a tactical UAV or a battlefield UAV will inevitably lead to the problem of ensuring its functioning in conditions of interference.

When performing the MVP, it is necessary to carry out the rounding of the terrain, which is implemented with the help of maneuvers of "bypass", "fly" and their combination - "bypass-fly" of obstacles rising above the average level of the relief.

Bypass" is commonly called an aircraft maneuver associated with a change in course and roll at a constant flight altitude. "Fly" is a maneuver in a vertical plane that allows you to overcome an obstacle with a given relative height without changing course.

The possibility of performing these maneuvers in automatic mode is associated with a number of technical problems, in particular, when performing the MVP, there is a significant decrease in the maneuverability of the aircraft as a result of the proximity of the underlying surface and the presence of obstacles, which require significant evolution of the aircraft to overcome. This fact tightens the requirements for the accuracy of solving the navigation problem and automatic control of the UAV up to 30-60 m in position, 5-10 meters in height and 5-10 m/s in speed, with a navigation solution generation frequency of at least 10 Hz.

An analysis of typical tasks performed in the MVP mode, taking into account the dynamic properties of promising unmanned helicopters and the safety requirements for their flight, allows us to formulate the following requirements for the onboard navigation system (NC) in the MVP mode:

The NC must ensure the solution of the navigation problem in the MVP process with the necessary reliability, accuracy and frequency;

The accuracy of determining the 3D position of the center of mass of the aircraft should be characterized by a value of the order of units of meters, by the components of the velocity - by a value of the order of units of m/s, by the angles of orientation - by values ​​of the order of 1°;

The refresh rate of information should be about 100 Hz;

The solution must be formed in topographic coordinate systems.

The above requirements for the NDT of a helicopter capable of performing the MVP determine the choice of a strapdown inertial navigation system (SINS) as the main subsystem of the NDT. An extensive literature, both domestic and foreign authors, is devoted to the construction of these devices.

Note that SINS, which do not use such complex and expensive technical devices as gyro-stabilized platforms for stabilization of their inertial sensors, have been developing especially intensively in recent years. Potential advantages of SINS over platform ANNs include:

Smaller size, weight and power consumption;

Significant simplification of the mechanical part of the system and its layout and, as a result, an increase in the reliability of the system;

No restrictions on turning angles;

Reducing the time of the initial exhibition;

Universality of the system, since the transition to the determination of certain navigation parameters is carried out algorithmically;

Simplification of the solution of the problem of redundancy and control of the system and its elements.

The main disadvantage of SINS is its relatively low accuracy, which is determined by the rate of drift or "departure" of the navigation solution generated by SINS from the "true" values ​​of position and speed. In particular, in relation to the accuracy of the sensitive elements used in SINS, the following data can be taken:

Type of inertial sensor Accuracy of navigation solution, not less than

Laser gyroscope 0.003 deg/h

Fiber optic gyroscope 0.05 deg/h

Wave solid state gyroscope 0.005 deg/h Micromechanical gyroscope 30 deg/h Micromechanical accelerometer 5x10"5 g Pendulum accelerometers 2x10"6 g Vibration accelerometers 1x10"6 g

It should be noted here that the use of traditional (laser, fiber-optic and solid-state gyroscopes, pendulum and vibration accelerometers) for installation on UAVs is not economically feasible due to their high cost, and relatively cheap micromechanical sensing elements have high drift rates and low measurement accuracy. . Thus, with regard to UAVs in the MVP mode, SINS is not able to provide an acceptable accuracy of navigation determinations to ensure safe flight for any length of time. The way out of this situation is to use additional sources of navigation information, which will allow you to periodically adjust the navigation solution supplied by the SINS.

Currently, GNSS receivers are widely used as an additional tool that corrects the SINS navigation solution. This fact is determined by the fact that SINS and GNSS use navigation signals that are different in their physical nature and spectrum of errors. The joint use of navigation solutions supplied by inertial and satellite navigation systems makes it possible, on the one hand, to limit the growth of SINS errors, and on the other hand, to level the main disadvantages of GNSS - a low update rate of navigation information and poor noise immunity. It should be noted here that the task of ensuring the operation of a GNSS receiver under conditions of natural and artificial interference is an independent task, the solution of which requires significant changes in the consumer's navigation equipment and the algorithm for processing the data of the received navigation measurements.

Combining SINS and GNSS receiver into a single navigation system (data integration of SINS and GNSS receiver) can be done in various ways. Currently, there are 4 main options for data integration: separate schema, loosely coupled schema, tightly coupled and deeply integrated system. Each of these schemes has its own advantages and disadvantages. However, as the analysis shows, in the absence of interference, it is advisable to use a loosely coupled scheme for combining the inertial and satellite navigation systems, since such an option, on the one hand, due to the inertial component, will ensure the continuity of the navigation solution, and, on the other hand, the solution of the navigation problem supplied by the GNSS receiver , eliminates the main drawback of the inertial system - the accumulation of errors. At the same time, both the SINS and the GNSS receiver remain independent devices, which will make it easy to adapt such a navigation system to a specific UAV, in accordance with mass-dimensional, accuracy and cost requirements.

However, such a composition of onboard equipment is not sufficient for the navigation support of the MVP. This is due to the fact that the navigation solution generated by the SINS is unstable in the altitude channel, which is extremely important in the implementation of the MVP. A necessary addition to the NC to ensure the possibility of performing the MVP is a radio baro-altimeter (RBV), which is a complex device that combines radio and baro-altimeters. Efficiency of using RBM is based on the difference in the physical principles of operation of meters (i.e., baroaltimeter and radio altimeter), as well as the fact that baroaltimeter errors are concentrated in the low-frequency part of the spectrum, and radio altimeter errors in the high-frequency part. In this regard, in the complex EWM there is an algorithm for the primary processing of measurements, which allows taking into account information from other navigation subsystems and eliminating height offset errors, as well as part of the errors caused by the helicopter dynamics. In addition, the standard (typical) RBM contains a secondary processing algorithm, which is the simplest Kalman filter that estimates the measured height and the parameters of the methodological errors of radio and baro altimeters.

It is known that in the presence of interference to GNSS signals, it is necessary to use a deeply integrated data integration architecture and the use of special navigation equipment for the consumer of the SNS, which would provide detection and filtering of interference from the navigation signal. Thus, it is necessary to consider not only loosely coupled, but also deeply integrated data integration architectures.

As a result, the choice of types of data integration architectures and the minimum required composition of the NC of a promising helicopter to provide the MVP was determined and justified.

The data of the navigation complex are used in the future to solve the problem of controlling the center of mass in the MVP mode, i.e. to implement the maneuvers described above bypass, flyby and their combination bypass-fly. We will assume that the helicopter is equipped with a standard stabilization system (autopilot) for single-rotor helicopters. In this case, the task is to form an algorithm for controlling the center of mass of the UAV, which operates on the basis of data from the navigation complex and a digital map of the underlying surface stored on board, under the assumption that the stabilization system works perfectly. The control algorithm must provide for the choice of the type of maneuver, the determination of the start point of the maneuver, and the calculation of the required control action. We will form the so-called rational algorithms that ensure the choice of the type of helicopter maneuver based on the so-called "decision rule" (i.e., the trajectory control criterion), from the condition of the available dynamic resource for control and is determined from the condition of minimizing the used resource .

As mentioned above, the use of a UAV as a tactical UAV and a battlefield UAV implies the presence of a millimeter-wave radar station (RLS) on board, whose tasks include, in particular, ensuring the high-precision use of equipment. In the light of the foregoing and in connection with the presence of a digital map of the underlying surface on board the UAV, it becomes possible to highly accurately bind the UAV to the topographic coordinates of the area by using the data of the onboard radar and the digital map of the underlying surface in the correlation-extreme navigation algorithm (CEAN). The obtained navigation solution of CEAN for planned coordinates can be used in NC, in case of possible degradation of OC, in particular, in the absence of GNSS signals due to various reasons.

It should be noted here that the main problem of using the CEAN solution in an integrated navigation system is the lack of information about the reliability and accuracy of the estimates of navigation parameters obtained using the CEAN, therefore, it is necessary to develop a criterion for evaluating the navigation solution obtained by the CEAN.

Thus, the implementation of the MVP of a helicopter-type UAV under the influence of interference and possible degradation (lack of GNSS signals) of the NC leads to the need to solve two problems: navigation, taking into account all the above difficulties, and controlling the movement of the center of mass according to the solution of the navigation problem, taking into account the above restrictions .

Both of these tasks can be interpreted as the task of forming the appearance of an onboard integrated navigation and control system for a helicopter. Here, under the appearance of the system we mean its architecture, its hardware composition, as well as navigation and control algorithms that ensure the fulfillment of the tasks listed above.

Thus, taking into account the foregoing, the aim of the work was to increase the efficiency of using helicopter-type unmanned JIAs by implementing a safe MVP in the terrain avoidance mode, including in the presence of active interference.

The subject of the study is a set of hardware and software tools that ensure the achievement of the set goal, and the object of the study is the on-board integrated navigation and automatic control system of the MVP of a promising helicopter.

In accordance with the purpose of the work, a technical task was set: to determine the appearance, i.e. the architecture and the required composition of hardware and software, as well as the properties of the onboard integrated navigation and control system of an automatic helicopter-type unmanned aerial vehicle.

Ultimately, to achieve the goal of the work, the following subtasks must be solved:

Definition of the airborne integrated system architecture,

Formation of mathematical models of the object and on-board equipment,

Solving the problem of navigation, including in conditions of interference,

Solution of the control problem in the MVP mode,

Creation of a functional and software prototype of an integrated system,

Creation of a software package for process simulation

Implementation of simulation modeling of profit centers,

Analysis of the results and development of recommendations on the composition and structure of the means of navigation and control of an automatic UAV of a helicopter type

MVP, including in conditions of interference.

The first chapter of the dissertation presents mathematical models and algorithms used in the formation of integrated navigation and control systems. The main attention is paid to taking into account uncontrollable factors that affect the operation of the navigation system components. Particular attention is paid to the architecture of the GNSS receiver operating in conditions of active white-noise interference, as well as the modification of the correlation-extremal navigation algorithm, supplemented by a probabilistic criterion for the reliability of the obtained navigation solution.

The second chapter discusses the developed navigation data integration algorithms using loosely coupled and deeply integrated architectures.

The third chapter of the dissertation presents the main results of the simulation modeling of the functioning of the created functional software prototypes of onboard integrated systems, demonstrating the capabilities and advantages of loosely coupled and deeply integrated data integration architectures. Here are the results proving the possibility of carrying out a safe low-altitude flight of a helicopter-type UAV using the proposed architectures of on-board systems and the developed automatic control system "ideal pilot". It is shown that in the absence of interference, a weakly coupled navigation data integration architecture is sufficient for safe low-altitude flight. It is shown that when exposed to active white-noise narrow-band interference, the use of a special GNSS receiver together with a deeply integrated navigation data integration architecture provides the accuracy of the navigation solution sufficient to perform a safe low-altitude flight of a helicopter-type UAV.

Conclusions on chapter 3.

1. Software and mathematical software was created in the form of object-oriented complexes with an open architecture in the Borland Delphi 7.0 and Microsoft C++ development environments, which provide imitation of the process of functioning of functional software prototypes of integrated systems. The complexes include a model of the external environment, taking into account uncontrolled factors and a model of an unmanned helicopter interacting as a control object with a functional and software prototype of an integrated onboard system.

2. Functional and software prototypes of the integrated onboard navigation and control system have been developed in the form of two architectures - loosely coupled and deeply integrated. Functional software prototypes are software systems in Borland Delphi 7.0 and Microsoft C++ environments that combine navigation and navigation data integration algorithms, as well as stabilization and control algorithms, within the framework of the corresponding architectures.

3. Simulation modeling of the MVP process has been carried out in relation to loosely coupled and deeply integrated architectures.

4. Based on the results of simulation modeling, we can state the following:

In the absence of interference, a loosely coupled architecture of data integration, hardware composition (SINS, RBV, GNSS receiver), algorithms (integration of SINS, GNSS, RBV data), an "ideal pilot", the accuracy of the solution of navigation in this case, the task is 30 m in position, 0.5 m / s in speed;

Under the conditions of narrow-band interference (0.1 MHz), with a power of up to 300 W, at a distance of 80 km, in order to implement a safe MVP in the terrain envelope mode, it is necessary to use a deeply integrated architecture, hardware composition (SINS, RBV, GNSS receiver, HEADLIGHTS, interference direction finder, radar), algorithms (data integration of SINS, GNSS, RBV, radar, antenna directional control, adaptive filtering), the accuracy of solving the navigation problem is 15 m in position, 0.3 m/s in speed;

Under conditions of broadband interference (1 MHz), power up to 300 W, at a distance of 80 km, the use of a GNSS receiver as part of a deeply integrated architecture as a supplier of navigation information is impossible;

In the absence of GNSS signals, as well as under conditions of broadband interference, on-board systems with loosely coupled and deeply integrated architectures, hardware composition (SINS, RBV, radar), algorithms (data integration of SINS, RBV, radar), "ideal pilot", correlation the extreme navigation algorithm, in the presence of characteristic (informative) sections on the underlying surface, makes it possible to obtain the accuracy of solving the navigation problem by position - 50 m, by velocities 0.8 m/s;

Conclusion

In the presented work, an urgent technical problem is formulated and solved for the formation of the appearance of an onboard integrated system of a promising unmanned helicopter in low-altitude flight.

The scientific novelty of the work is determined by the following results:

1) the image of the onboard integrated navigation and control system of a promising unmanned helicopter has been formed, which ensures a safe MVP in the mode of enveloping the terrain, including in the presence of active interference;

2) the architecture of the integrated system, the hardware composition and algorithms for navigation and control are proposed, which ensure the safe MVP of the UAV in the absence of interference with the accuracy of navigation determinations (3 cg): in position - 30 m, in speed - 0.5 m/s, in height - 3 m , including the degradation of the navigation system (lack of GPS/GLONASS signals);

3) the architecture of the integrated system, the hardware composition and algorithms for navigation and control are proposed, which ensure the safe MVP of the UAV in the presence of active white-noise interference with a power of up to 300 W, with a band of 0.1 MHz and a distance to the source of interference of the order of 80 km.

4) navigation data integration algorithms have been developed within the framework of a loosely coupled and deeply integrated architecture of the onboard complex, providing the accuracy of tying the center of mass of the UAV to geographic coordinates required for a safe MVP;

5) a modified correlation-extreme navigation algorithm (CEAN) for UAVs has been created. The modification of the algorithm consists in taking into account the evolution of the UAV in the formation of a reference image, as well as in using a probabilistic assessment of the reliability and accuracy of the resulting navigation solution. The modified KEAN ensures, in the absence of GPS/GLONASS signals, the accuracy of solving the navigation problem, is characterized by the parameters of the onboard digital map of the underlying surface;

6) an algorithm for controlling the center of mass of the UAV has been developed, which, with the above-mentioned accuracy of tying the center of mass to geographic coordinates, provides a safe MVP by performing “bypass”, “fly” and “bypass-fly” maneuvers;

7) a mathematical model of the influence of active interference on the functioning of the GNSS receiver has been developed;

8) the architecture of the GNSS receiver and the algorithm for adaptive filtering of the received navigation signal are proposed, which ensure the operability of the receiver in conditions of active interference;

9) Mathematical models have been developed for: a standard GNSS receiver, taking into account the errors of the onboard equipment of the SV, the error caused by the ionospheric signal delay, the error caused by the tropospheric signal delay, the error caused by the multipath effect, the error introduced by the internal noise of the receiver, the systematic error of the velocity vector, introduced by the high-frequency part of the receiver, random additive components of estimation errors.

A GNSS receiver operating under active interference conditions, which includes an interference source direction finder, a phased antenna array with a beam control system, and an adaptive filtering unit. This receiver model takes into account the effect of interference by determining the equivalent pseudorange error;

10) a functional and software prototype of an integrated onboard system was developed in two versions, implemented as open architecture software systems in the Delphi and C ++ environments;

11) A software package has been created that provides simulation of the process of functioning of the onboard integrated complex in the external environment, taking into account the nature of the underlying surface, the influence of interference, wind and variations in atmospheric density;

12) simulation modeling of the process of operation of the functional software prototype was carried out under various integration conditions and various levels of degradation of the complex, proving the satisfactory accuracy of the resulting navigation solution for the implementation of automatic MVP, including under active interference.

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