High-altitude long-endurance target aircraft combined navigation method and system suitable for satellite denial conditions

Abstract

The application discloses a high-altitude long-endurance target aircraft combined navigation method and system applicable to satellite denial conditions, relates to the high-altitude target aircraft, general unmanned aerial vehicle and navigation guidance field of cruise missile, and the high-altitude long-endurance target aircraft combined navigation method applicable to satellite denial conditions comprises the following steps: in a take-off preparation stage, a combined navigation unit receives navigation basic information set through a data link; in a take-off stage, the combined navigation unit completes self-alignment based on a current attitude angle of the target aircraft, a current speed of the target aircraft and current position coordinate information of the target aircraft, and then the target aircraft is launched; in a target aircraft flight stage, the combined navigation unit analyzes a PDOP value by using a preset threshold value, determines a current navigation mode, calculates target aircraft navigation state information and transmits the target aircraft navigation state information to a flight control unit, and the flight control unit generates flight control instructions based on the target aircraft navigation state information. The application can realize accurate positioning and navigation of a flight vehicle (such as a target aircraft) in a normal satellite signal environment and a satellite denial environment.

Description

Technical Field

[0001] This application relates to the fields of navigation and guidance for high-altitude target drones, general-purpose unmanned aerial vehicles, and loitering munitions, and in particular to a combined navigation method and system for high-altitude long-endurance target drones that is suitable for satellite denial conditions. Background Technology

[0002] With the rapid development of science and technology and the increasing frequency of realistic military exercises, target drones, as a core means of testing the effectiveness of air defense weapons and combat systems, have been widely used in various military training scenarios. However, recent local wars have shown that both sides often use electromagnetic countermeasures to interfere with each other's satellites and communication signals in the early stages of combat, creating a battlefield area denial environment. This directly leads to a significant decrease in the combat effectiveness of low-cost unmanned equipment.

[0003] Currently, the navigation method of low-cost high-altitude long-endurance target drones mainly relies on a combination of MEMS (microelectromechanical systems) inertial components and satellite positioning. However, this solution is highly dependent on satellite signals. Once the satellite signals are interfered with, the target drone's attitude, speed, position and other key navigation information will drift significantly in a short period of time, making it difficult to meet the accuracy requirements of equipment exercises under strong electromagnetic backgrounds.

[0004] To address the navigation and positioning challenges in satellite-denied environments, existing technologies have proposed various improvement schemes. For example, patent application CN120178286A discloses an autonomous navigation and positioning method for UAVs in satellite-denied environments. This method collects multi-dimensional data using devices such as an optoelectronic pod, dual-light cameras, and frequency analyzers. After preprocessing, a monitoring model is constructed using a random forest algorithm. This model combines inertial navigation, visual SLAM (Simultaneous Localization and Mapping), and GNSS (Global Navigation Satellite System) positioning to establish a combined navigation mode, thus solving the problem of single navigation methods being susceptible to interference. Another example is patent application CN114184194A, which discloses an autonomous navigation and positioning method for UAVs in denied environments. This method fuses multi-source data from accelerometers, magnetometers, optical flow sensors, barometers, and gyroscopes based on the UAV's motion state, and uses extended Kalman filtering to calculate attitude, position, and velocity information to achieve autonomous navigation in denied environments.

[0005] However, both of the above-mentioned combined navigation schemes rely on multi-source data fusion technology and generally incorporate visual positioning data to improve navigation accuracy. They have obvious application limitations: when UAVs / target drones are in high-altitude flight for a long time, ground visual image features are scarce or they are blocked by clouds and cannot obtain effective visual image information. This will cause the data fusion accuracy to drift significantly over time, eventually causing the navigation and positioning error to exceed the allowable range. They still cannot meet the accurate navigation needs of high-altitude long-endurance target drones in complex battlefield environments. Summary of the Invention

[0006] The purpose of this application is to provide a high-altitude long-endurance target drone integrated navigation method and system applicable to satellite denial conditions, which can achieve accurate positioning and navigation of aircraft (such as target drones) under both normal satellite signal and satellite denial environments.

[0007] To achieve the above objectives, this application provides a high-altitude long-endurance target drone integrated navigation method applicable to satellite denial conditions, comprising the following steps: S1: During takeoff preparation, the integrated navigation unit receives navigation basic information configured via a data link, wherein the navigation basic information includes at least: heading, waypoints, and geomagnetic parameters; S2: During takeoff, the integrated navigation unit acquires the target drone's current attitude angle, current speed, and current position coordinates, and completes self-alignment based on the target drone's current attitude angle, current speed, and current position coordinates, subsequently performing a booster takeoff; S3: During target drone flight, the integrated navigation unit acquires real-time... The PDOP value is obtained and analyzed using a preset threshold to determine the current navigation mode. The target drone navigation status information is then calculated from the current navigation mode. If the PDOP value is not lower than the set threshold, it indicates that the satellite signal is normal, and the integrated navigation unit adopts the conventional integrated navigation mode as the current navigation mode. If the PDOP value is lower than the set threshold, it indicates that the target drone is in a satellite denial environment, and the integrated navigation unit automatically switches to the satellite denial integrated navigation mode as the current navigation mode. S4: The integrated navigation unit transmits the calculated target drone navigation status information to the flight control unit, which generates flight control commands based on the target drone navigation status information.

[0008] As mentioned above, the conventional integrated navigation mode is a satellite and IMU integrated navigation mode. By using the conventional solution method of satellite and IMU integrated navigation, the dynamic real-time acquisition and solution data of the target drone during the flight phase are integrated for navigation solution, and finally the target drone navigation status information is obtained.

[0009] As described above, the sub-steps for calculating the target drone's navigation status information using the satellite denial integrated navigation mode as the current navigation mode are as follows: S31: In the satellite denial integrated navigation mode, the integrated navigation unit collects the target drone's real-time attitude angular velocity and real-time three-axis geomagnetic components within a preset time interval, performs data fusion on the target drone's real-time attitude angular velocity and real-time three-axis geomagnetic components, and calculates the target drone's real-time attitude angle information; S32: The integrated navigation unit collects the target drone's accelerometer three-axis specific force within a preset time interval, and calculates the target drone's real-time axial velocity and real-time angle of attack based on the target drone's accelerometer three-axis specific force, and then... The target drone's real-time axial velocity, real-time angle of attack, and real-time attitude angle information are fused to calculate the target drone's real-time velocity information in the navigation coordinates; S33: The integrated navigation unit performs integral calculation on the target drone's real-time velocity information in the navigation coordinates according to a preset time interval to obtain the target drone's relative displacement. Combined with the target drone's real-time velocity information in the navigation coordinates system within the previous preset time interval, the target drone's position information in the navigation coordinates system at the current moment is calculated; The target drone's position information in the navigation coordinates system at the current moment, the target drone's real-time attitude angle information, and the target drone's real-time velocity information in the navigation coordinates system are used as the target drone's navigation status information.

[0010] As described above, the integrated navigation unit uses a preset attitude angle calculation method to fuse the real-time attitude angular velocity and real-time three-axis geomagnetic components of the target drone to calculate the real-time attitude angle information of the target drone; the preset calculation method is the EKF filtering algorithm based on the target drone attitude angle filtering model.

[0011] As mentioned above, the integrated navigation unit uses a preset speed calculation method to fuse the target drone's real-time axial velocity, real-time angle of attack, and real-time attitude angle information to calculate the target drone's real-time speed information under navigation coordinates; the preset speed calculation method is the EKF filtering algorithm based on the target drone speed filtering model.

[0012] As shown above, the integrated navigation unit transmits the calculated target drone navigation status information to the flight control unit via the SPI bus.

[0013] This application also provides a high-altitude long-endurance target drone integrated navigation system applicable to satellite denial conditions, comprising: an integrated navigation unit, an information setting / debugging and upgrade interface, a flight control unit, and a power management module; wherein, the integrated navigation unit is used to execute the aforementioned high-altitude long-endurance target drone integrated navigation method applicable to satellite denial conditions; the information setting / debugging and upgrade interface is communicatively connected to the integrated navigation unit and is used to set navigation basic information to the integrated navigation unit, wherein the navigation basic information includes at least: heading, waypoints, and geomagnetic parameters; the flight control unit is communicatively connected to the integrated navigation unit via an SPI bus and is used to receive target drone navigation status information calculated by the integrated navigation unit under normal satellite signal or satellite denial conditions, and generate flight control commands based on the target drone navigation status information; wherein the target drone navigation status information includes at least: target drone attitude angles, velocity, and position coordinates; the power management module is electrically connected to the integrated navigation unit and the flight control unit respectively, and is used to supply power to the integrated navigation unit and the flight control unit after completing power conversion.

[0014] As described above, the integrated navigation unit includes: a DSP information processing board, a satellite receiving module, a MEMS IMU module, a pitot tube, and a geomagnetic sensor. The DSP information processing board establishes bidirectional / unidirectional data communication connections with the satellite receiving module, the MEMS IMU module, the pitot tube, and the geomagnetic sensor. The DSP information processing board receives the target drone's current attitude angle, current velocity, and current position coordinates, and performs self-alignment of the integrated navigation unit based on these information and a self-alignment algorithm. The satellite receiving module integrates a GNSS antenna and a satellite processing unit. The GNSS antenna is used to acquire current and real-time satellite navigation signals. The satellite processing unit is used to calculate the current satellite navigation signals to obtain the target drone's current velocity and current position coordinates, and to calculate the real-time satellite navigation signals to obtain the target drone's real-time position and velocity. The MEMS IMU module receives the target drone's current attitude angle, current velocity, and current position coordinates, and performs self-alignment based on the real-time satellite navigation signals. The IMU module includes a gyroscope, an accelerometer, and an inertial measurement unit. The gyroscope is used to collect the target drone's current attitude angular velocity information. The accelerometer is used to collect the target drone's current triaxial specific force information and to collect the target drone's triaxial specific force within a preset time interval in real time. The inertial measurement unit is used to fuse and calculate the target drone's current attitude angular velocity information and current triaxial specific force information to obtain the target drone's current attitude angle, and to calculate the target drone's real-time attitude angular velocity and real-time velocity increment information. The airspeed tube integrates an information processing board. The information processing board is used to calculate the target drone's real-time axial velocity and real-time angle of attack in real time based on the target drone's triaxial specific force and flight status. The geomagnetic sensor is used to collect the target drone's real-time triaxial geomagnetic components.

[0015] As mentioned above, the power management module is connected to the airborne DC power supply to provide a stable DC power supply for the DSP information processing board of the integrated navigation unit, and at the same time, to provide DC power supply for the airborne computer of the flight control unit.

[0016] As shown above, the input supply voltage of the power management module is 36~58VDC. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings.

[0018] Figure 1 A schematic diagram of the structure of an embodiment of a high-altitude long-endurance target drone integrated navigation system applicable to satellite denial conditions; Figure 2 A flowchart of an embodiment of a high-altitude long-endurance target drone integrated navigation method applicable to satellite denial conditions; Figure 3 Simulation diagram of target drone attitude angle filtering under satellite denial conditions; Figure 4 This is a simulation diagram of target drone velocity filtering under satellite denial conditions. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] like Figure 1 As shown, this application provides a high-altitude long-endurance target drone integrated navigation system applicable to satellite denial conditions, including: an integrated navigation unit, an information setting / debugging and upgrade interface, a flight control unit, and a power management module.

[0021] Among them, the integrated navigation unit is used to perform the high-altitude long-endurance target drone integrated navigation method under the applicable satellite denial conditions described below.

[0022] The information loading / debugging upgrade interface communicates with the integrated navigation unit and is used to load basic navigation information into the integrated navigation unit. The basic navigation information includes at least: heading, waypoints, and geomagnetic parameters.

[0023] The flight control unit communicates with the integrated navigation unit via the SPI bus (serial peripheral interface bus) to receive the target drone navigation status information calculated by the integrated navigation unit under normal satellite signal or satellite rejection conditions, and generates flight control commands based on the target drone navigation status information; wherein, the target drone navigation status information includes at least: target drone attitude angle, speed and position coordinate information.

[0024] The power management module is electrically connected to both the integrated navigation unit and the flight control unit, and is used to supply power to the integrated navigation unit and the flight control unit after the power conversion is completed.

[0025] Furthermore, the power management module is connected to the airborne DC power supply to provide a stable DC power supply for the DSP (Digital Signal Processor) information processing board of the integrated navigation unit, and at the same time to provide DC power supply for the airborne computer of the flight control unit, ensuring the continuous and reliable operation of the navigation calculation work of the DSP information processing board and the instruction processing work of the airborne computer.

[0026] Furthermore, the specific value of the input power supply voltage of the power management module is set according to actual needs. In this application, it is preferred that the input power supply voltage of the power management module is 36~58VDC (direct current voltage), which can complete voltage conversion, voltage regulation and power distribution control according to the working voltage requirements of each module such as the integrated navigation unit, the airspeed tube integrated information processing board, and the sensor module, so as to ensure that each module works continuously and reliably during the flight of the target drone.

[0027] Furthermore, the integrated navigation unit includes: a DSP information processing board, a satellite receiving module, a MEMS IMU module (microelectromechanical system inertial measurement unit module), a pitot tube, and a geomagnetic sensor; the DSP information processing board establishes bidirectional / unidirectional data communication connections with the satellite receiving module, the MEMS IMU module, the pitot tube, and the geomagnetic sensor, respectively.

[0028] The DSP information processing board receives the target drone's current attitude angle, current speed, and current position coordinates. Based on these parameters and a self-alignment algorithm, it completes the self-alignment of the integrated navigation unit.

[0029] The satellite receiving module integrates a GNSS antenna (Global Navigation Satellite System antenna) and a satellite processing unit. The GNSS antenna is used to acquire current and real-time satellite navigation signals. The satellite processing unit is used to calculate the current satellite navigation signal to obtain the target drone's current velocity and current position coordinates, and to calculate the real-time satellite navigation signal to obtain the target drone's real-time position and velocity information. The MEMS IMU module includes a gyroscope, an accelerometer, and an inertial measurement processing unit. The gyroscope is used to acquire the target drone's current attitude angular velocity information. The accelerometer is used to acquire the target drone's current three-axis specific force information and to acquire the target drone's accelerometer three-axis specific force within a preset time interval in real time.

[0030] The inertial measurement processing unit is used to fuse and calculate the current attitude angular velocity information and the current triaxial force information of the target drone to obtain the current attitude angle of the target drone, as well as to calculate the real-time attitude angular velocity and real-time velocity increment information of the target drone.

[0031] The airspeed tube integrates an information processing board; the information processing board is used to calculate the real-time axial velocity and real-time angle of attack of the target drone based on the triaxial specific force of the target drone's accelerometer and the target drone's flight status.

[0032] The geomagnetic sensor is used to acquire the real-time triaxial geomagnetic components of the target drone.

[0033] Furthermore, a data communication connection is established between the satellite receiving module and the DSP information processing board through the 1PPS / RS232 interface for transmitting satellite navigation and positioning data to the DSP information processing board, but it is not limited to the 1PPS / RS232 interface.

[0034] Furthermore, the MEMS IMU module and the DSP information processing board establish a data communication connection through the RS422 interface to transmit inertial sensing data such as the target drone's real-time attitude angular velocity and three-axis specific force to the DSP information processing board, but it is not limited to the RS422 interface.

[0035] Furthermore, the airspeed tube information processing board and the DSP information processing board establish a data communication connection through an RS422 interface to transmit the calculated aerodynamic parameters of the target drone, such as real-time axial velocity and real-time angle of attack, to the DSP information processing board, but this is not limited to the RS422 interface.

[0036] Furthermore, a data communication connection is established between the geomagnetic sensor and the DSP information processing board via an I2C interface to transmit real-time triaxial geomagnetic component data of the target drone to the DSP information processing board, but it is not limited to the I2C interface.

[0037] like Figure 2 As shown, this application provides a high-altitude long-endurance target drone integrated navigation method applicable to satellite denial conditions, comprising the following steps:

[0038] S1: During the takeoff preparation phase, the integrated navigation unit receives basic navigation information via the data link, which includes at least: heading, waypoints, and geomagnetic parameters.

[0039] Specifically, the integrated navigation unit receives basic navigation information configured via the data link through the information configuration / debugging and upgrade interface.

[0040] Furthermore, geomagnetic parameters are used in magnetic maps, but are not limited to magnetic maps.

[0041] S2: During takeoff, the integrated navigation unit acquires the target drone's current attitude angle, current speed, and current position coordinates. Based on these information, the target drone completes its self-alignment and then takes off with a boost.

[0042] Specifically, the integrated navigation unit acquires the current satellite navigation signal through the GNSS antenna of the satellite receiving module; and the satellite processing unit of the satellite receiving module processes the current satellite navigation signal to obtain the target drone's current speed and current position coordinates.

[0043] The integrated navigation unit acquires the target drone's current attitude angular velocity information through the gyroscope of the MEMS IMU module; acquires the target drone's current three-axis specific force information through the accelerometer of the MEMS IMU module; and performs fusion calculation on the target drone's current attitude angular velocity information and the target drone's current three-axis specific force information through the inertial measurement processing unit of the MEMS IMU module to obtain the target drone's current attitude angle.

[0044] The DSP information processing board receives the target drone's current attitude angle, current speed, and current position coordinates, and completes the self-alignment of the integrated navigation unit based on the target drone's current attitude angle, current speed, current position coordinates, and self-alignment algorithm.

[0045] Specifically, the preferred self-alignment algorithm is a satellite-assisted self-alignment algorithm. This algorithm uses the target drone's current velocity and current position coordinates calculated by the satellite receiving module as a reference to calibrate and compensate for the error of the target drone's current attitude angle calculated by the MEMS IMU module, thus completing the self-alignment of the integrated navigation unit. However, it is not limited to using a satellite-assisted self-alignment algorithm; existing inertial navigation self-alignment algorithms in the field of airborne integrated navigation, such as static base self-alignment algorithms and geomagnetic-assisted self-alignment algorithms, can also be used, as long as they can achieve the self-alignment technical effect of this application.

[0046] S3: During the target drone's flight phase, the integrated navigation unit acquires the PDOP value in real time, analyzes the PDOP value using a preset threshold, determines the current navigation mode, and calculates the target drone's navigation status information from the current navigation mode. If the PDOP value is not lower than the set threshold, it indicates that the satellite signal is normal, and the integrated navigation unit adopts the conventional integrated navigation mode as the current navigation mode. If the PDOP value is lower than the set threshold, it indicates that the target drone is in a satellite denial environment, and the integrated navigation unit automatically switches to the satellite denial integrated navigation mode as the current navigation mode.

[0047] Specifically, the integrated navigation unit acquires the PDOP (Position Precision Factor) value in real time through the satellite receiving module. The specific value of the threshold is set according to actual needs.

[0048] Furthermore, conventional integrated navigation modes can be achieved using existing technologies in the field of airborne integrated navigation. This application preferably adopts a satellite and IMU (Inertial Measurement Unit) integrated navigation mode. By using conventional calculation methods for satellite and IMU integrated navigation, the dynamic real-time acquisition and calculation data during the flight phase of the target drone are integrated for navigation calculation, and the target drone navigation status information is finally obtained. Among them, the dynamic real-time acquisition and calculation data includes at least: the target drone's real-time position, real-time velocity information, real-time attitude angular velocity, and real-time velocity increment information.

[0049] Specifically, the satellite receiving module of the integrated navigation unit calculates the real-time position and velocity information of the target drone, and the MEMS IMU module of the integrated navigation unit calculates the real-time attitude angular velocity and real-time velocity increment information of the target drone.

[0050] This application does not limit the specific implementation method of conventional integrated navigation mode. In addition to satellite and IMU integrated navigation mode, other satellite-assisted integrated navigation modes such as satellite and fiber optic IMU integrated navigation, satellite and Beidou / GPS dual-mode and IMU integrated navigation can also be adopted. All integrated navigation modes that rely on satellite navigation signals fall within the protection scope of conventional integrated navigation mode of this application.

[0051] Furthermore, the sub-steps for calculating the target drone's navigation status information using the satellite denial combined navigation mode as the current navigation mode are as follows:

[0052] S31: In satellite denial combined navigation mode, the combined navigation unit collects the real-time attitude angular velocity and real-time three-axis geomagnetic components of the target drone within a preset time interval, performs data fusion on the real-time attitude angular velocity and real-time three-axis geomagnetic components of the target drone, and calculates the real-time attitude angle information of the target drone.

[0053] Specifically, the gyroscope of the integrated navigation unit collects the real-time attitude angular velocity of the target drone within a preset time interval, and the geomagnetic sensor of the integrated navigation unit collects the real-time three-axis geomagnetic components of the target drone. The specific value of the preset time interval can be flexibly set according to the actual application requirements.

[0054] Furthermore, the integrated navigation unit uses a preset attitude angle calculation method to fuse the real-time attitude angular velocity and real-time three-axis geomagnetic components of the target drone to calculate the real-time attitude angle information of the target drone; wherein, the preset calculation method is the EKF (Extended Kalman Filter) filtering algorithm based on the target drone attitude angle filtering model.

[0055] Specifically, the specific type of the preset attitude angle calculation method can be flexibly set according to the actual application requirements. For example, the preset attitude angle calculation method can also use unscented Kalman filtering (UKF) to adapt to the nonlinear scenario of highly maneuverable target drones, use complementary filtering (CF) to adapt to the low computing power hardware scenario of small target drones, or use particle filtering (PF) to adapt to the satellite denial scenario with complex electromagnetic interference.

[0056] Furthermore, the state equation of the target drone attitude angle filtering model is: ; in, For the first The target drone attitude quaternion within a preset time interval is used to describe the real-time attitude of the target drone. For the first 4-ary values ​​of the target drone's attitude within a preset time interval , For the first The real part of the target attitude quaternion within a preset time interval; , and For the first The imaginary components of the target drone attitude quaternion within a preset time interval correspond to the attitude rotation components of the X-axis, Y-axis and Z-axis in the navigation coordinate system, respectively. For transpose; This is the preset time interval (i.e., the data acquisition period). For the first System process noise within a preset time interval; , and These are the angle changes of the target machine along the X, Y, and Z axes, measured by the gyroscope within a preset time interval. For the first The magnitudes of the angle changes of the target drone's X, Y, and Z axes within a preset time interval. .

[0057] Specifically, The main sources of error are gyroscope drift and measurement noise, which are estimated in real time using the EKF (Extended Kalman Filter) algorithm. And compensation is performed to improve the accuracy of attitude angle calculation.

[0058] Furthermore, the measurement equation for the target drone attitude angle filtering model is: ; in, For the first Geomagnetic observation vector in the body coordinate system within a preset time interval; , and These are the components of the geomagnetic vector of the current geographical location on the X, Y, and Z axes in the navigation coordinates; For the first quaternions of target attitude within a preset time interval; For the first The real part of the target attitude quaternion within a preset time interval; , and For the first The imaginary components of the target drone attitude quaternion within a preset time interval correspond to the attitude rotation components of the X-axis, Y-axis and Z-axis in the navigation coordinate system, respectively. For the first Measurement of white noise within a preset time interval.

[0059] Specifically, This is the observation value obtained by transforming the geomagnetic components in the navigation coordinate system to the target drone's own body coordinate system using a four-element transformation. , and It provides an absolute reference to the Earth's magnetic field for attitude angle calculation and can correct for the cumulative drift of the gyroscope. The main sources are electromagnetic interference and measurement errors from the geomagnetic sensor, which are estimated in real time using the EKF (Extended Kalman Filter) algorithm. This is to optimize the weighting of observations and improve the stability of attitude angles.

[0060] The target drone's real-time attitude angle information includes at least: roll angle, pitch angle, and yaw angle. The roll angle, pitch angle, and yaw angle are determined by... It can be directly calculated through coordinate transformation.

[0061] S32: The integrated navigation unit collects the three-axis specific force of the target drone's accelerometer in real time within a preset time interval, and calculates the real-time axial velocity and real-time angle of attack of the target drone based on the three-axis specific force of the target drone's accelerometer. Then, it fuses the real-time axial velocity, real-time angle of attack and the real-time attitude angle information of the target drone to calculate the real-time velocity information of the target drone under the navigation coordinates.

[0062] Specifically, the accelerometer of the integrated navigation unit collects the three-axis specific force of the target drone's accelerometer in real time within a preset time interval. The airspeed tube of the integrated navigation unit calculates the real-time axial velocity and real-time angle of attack of the target drone based on the three-axis specific force of the target drone's accelerometer and the target drone's flight status. Then, the real-time axial velocity, real-time angle of attack and real-time attitude angle information of the target drone are fused together to calculate the real-time velocity information of the target drone under the navigation coordinates.

[0063] Furthermore, the integrated navigation unit uses a preset speed calculation method to fuse the target drone's real-time axial velocity, real-time angle of attack, and real-time attitude angle information to calculate the target drone's real-time speed information under navigation coordinates; among which, the preset speed calculation method is the EKF (Extended Kalman Filter) filtering algorithm based on the target drone speed filtering model.

[0064] Specifically, the type of preset velocity calculation method can be flexibly selected according to the target drone's computing resources, the degree of nonlinearity of the flight scenario, and the actual requirements for accuracy and real-time performance. For example, the preset velocity calculation method can also use the unscented Kalman filter (UKF) algorithm, the particle filter (PF) algorithm, or the complementary filter algorithm.

[0065] Furthermore, the state equation of the target drone velocity filtering model is: ; ; in, , The first The components of the target drone's velocity vector in the navigation coordinate system along the X, Y, and Z axes within a preset time interval; , The first Within a preset time interval, the accelerometer measures the relative forces along the X, Y, and Z axes of the target drone. , For transpose; This is a preset time interval; , , The first The components of the target drone's velocity vector along the X, Y, and Z axes in the navigation coordinate system within a preset time interval. ; The geographic dimensions of the target drone's current location; This is the radius of curvature of the Earth's circumpolar coordinates at its current latitude; This represents the radius of curvature of the Earth's meridian at its current latitude. This represents the amplitude of the Earth's rotational angular velocity; This refers to the local gravitational acceleration. This is the target drone's current flight altitude; , , The first Within a preset time interval, the system process white noise introduced by the accelerometer in the X-axis, Y-axis and Z-axis of the navigation coordinate system; , , All are trigonometric function symbols.

[0066] Furthermore, the measurement equation for the target drone velocity filtering model is: ; in, These are the X-axis and Z-axis velocities in the airspeed tube solver system, respectively. , For transpose; The target drone's heading angle; The pitch angle of the target drone; The roll angle of the target drone; For the first Measurement of white noise within a preset time interval.

[0067] S33: The integrated navigation unit performs integral calculation on the real-time velocity information of the target drone under the navigation coordinates according to a preset time interval to obtain the relative displacement of the target drone. Combined with the real-time velocity information of the target drone under the navigation coordinates in the previous preset time interval, the unit calculates the position information of the target drone under the navigation coordinates at the current moment. The position information of the target drone under the navigation coordinates at the current moment, the real-time attitude angle information of the target drone, and the real-time velocity information of the target drone under the navigation coordinates are used as the navigation status information of the target drone.

[0068] To achieve high-precision positioning and navigation of the target drone under both normal and denied satellite signal conditions, the core technical solution adopted in this application is as follows: Adaptive switching between dual combined navigation modes is achieved based on the PDOP value of the satellite positioning module. Before takeoff, the target drone completes the setting of heading, waypoints, geomagnetic parameters (magnetic map), and self-alignment of the combined navigation unit. When the satellite signal is normal (PDOP value not lower than a set threshold), the conventional combined navigation mode is adopted, using the satellite second pulse signal as the timing reference, and fusing satellite positioning information with attitude angle and velocity information measured by the MEMS IMU to complete combined navigation. When satellite rejection occurs (PDOP value lower than a set threshold), the satellite rejection combined navigation mode is adopted, using the crystal oscillator inside the combined navigation unit as the timing reference, fusing multi-source sensor data from the MEMS IMU, geomagnetic sensor, and pitot tube to calculate the target drone's attitude angle, flight speed, and relative displacement under the navigation system, and combining the previous moment's navigation system coordinates to calculate the current position. The flight control unit generates flight control commands for the target drone based on the deviation between the actual positioning coordinates and the set coordinates.

[0069] S4: The integrated navigation unit transmits the calculated target drone navigation status information to the flight control unit, which then generates flight control commands based on the target drone navigation status information.

[0070] Furthermore, the integrated navigation unit transmits the calculated target drone navigation status information to the flight control unit via the SPI bus, but is not limited to the SPI bus.

[0071] Figure 3 This image shows the simulation results of the target drone's attitude angle filtering under the satellite rejection integrated navigation mode of this application. Based on the target drone's motion conditions and selected hardware parameters set in this application, the EKF (Extended Kalman Filter) filtering algorithm based on the target drone's attitude angle filtering model of this application is used to fuse the target drone's real-time attitude angular velocity and real-time three-axis geomagnetic components to obtain the target drone's real-time attitude angle information. The root mean square error of the calculated pitch angle is 0.0008°, the root mean square error of the yaw angle is 0.001°, and the root mean square error of the roll angle is 0.0007°. While the EKF (Extended Kalman Filter) filtering algorithm based on the target drone's attitude angle filtering model of this application achieves high-precision calculation, it will cause a fixed deviation in the calculated real-time attitude angle information of the target drone. Therefore, this application uses the real-time attitude angle information of the target drone calculated by the EKF (Extended Kalman Filter) filtering algorithm based on the target drone's attitude angle filtering model as the core basis, performs targeted angle compensation processing on it, and then uses the compensated attitude angle information for subsequent velocity calculation and position estimation.

[0072] Figure 4This image shows the simulation results of the target drone velocity filtering under the satellite rejection combined navigation mode of this application. Based on the target drone motion conditions and selected hardware parameters set in this application, the EKF (Extended Kalman Filter) filtering algorithm based on the target drone velocity filtering model of this application is used to calculate the real-time velocity information of the target drone in the navigation coordinate system by fusing the three-axis specific force of the target drone accelerometer, real-time axial velocity, real-time angle of attack and real-time attitude angle information before compensation. The root mean square error of the eastward velocity is 0.047 m / s, the root mean square error of the northward velocity is 0.189 m / s, and the root mean square error of the upward velocity is 2.5 m / s. While the EKF (Extended Kalman Filter) filtering algorithm based on the target drone velocity filtering model of this application achieves high-precision calculation, it will cause a fixed deviation in the calculated real-time velocity information of the target drone. Therefore, this application uses the real-time velocity information of the target drone calculated by the EKF (Extended Kalman Filter) filtering algorithm based on the target drone velocity filtering model as the core basis, performs targeted velocity compensation processing on it, and then uses the compensated velocity information for subsequent position estimation.

[0073] The beneficial effects achieved by this application are as follows: (1) In view of the technical defects of existing target drone navigation technology in positioning failure and insufficient positioning accuracy under satellite denial conditions, this application designs a high-altitude long-endurance target drone integrated navigation method and system applicable to satellite denial conditions. It covers the integrated navigation hardware composition, multi-mode navigation control process and special filtering model, which can realize adaptive high-precision positioning and navigation of target drone under both normal and denied satellite signal conditions, and meet the full-condition navigation needs of target drone in complex battlefield environment.

[0074] (2) The high-altitude long-endurance target drone integrated navigation method and system applicable to satellite denial conditions of this application, in the satellite denial integrated navigation mode, only uses a low-cost sensing module of MEMS IMU module, geomagnetic sensor and airspeed tube to complete the fusion of multi-source data, without the need for additional high-precision navigation hardware, effectively controlling hardware costs while ensuring navigation accuracy, and has engineering application value.

[0075] (3) The high-altitude long-endurance target drone integrated navigation method and system applicable to satellite denial conditions of this application are designed with a dedicated target drone attitude angle filtering model and target drone velocity filtering model. The filtering model is adapted to the flight characteristics of the target drone and can complete high-precision filtering calculation under the condition of limited measurement information due to satellite denial. The calculation efficiency is high and the error is small, providing algorithmic support for accurate navigation under satellite denial conditions.

[0076] (4) The high-altitude long-endurance target drone integrated navigation method and system applicable to satellite denial conditions of this application adopts a time reference adaptive switching strategy. When the satellite signal is normal, the integrated navigation unit uses the satellite second pulse signal as the calculation reference; when the satellite is denied, the integrated navigation unit uses its internal crystal oscillator as the calculation reference, which ensures the time synchronization of data calculation under different navigation modes, improves the accuracy of multi-source data fusion, and further ensures navigation accuracy.

[0077] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the scope of protection of this application is intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application. Obviously, those skilled in the art can make various alterations and variations to this application without departing from the spirit and scope of this application. Thus, if these modifications and variations of this application fall within the scope of protection of this application and its equivalents, this application also intends to include these modifications and variations.

Claims

1. A high-altitude, long-endurance target drone integrated navigation method applicable to satellite denial conditions, characterized in that, Includes the following steps: S1: During the takeoff preparation phase, the integrated navigation unit receives basic navigation information via the data link, which includes at least: heading, waypoints, and geomagnetic parameters. S2: During the takeoff phase, the integrated navigation unit acquires the target drone's current attitude angle, current speed, and current position coordinates, and completes its self-alignment based on these information. The target drone then takes off with a boost. S3: During the target drone's flight phase, the integrated navigation unit acquires the PDOP value in real time, analyzes the PDOP value using a preset threshold, determines the current navigation mode, and calculates the target drone's navigation status information from the current navigation mode. If the PDOP value is not lower than the set threshold, it indicates that the satellite signal is normal, and the integrated navigation unit adopts the conventional integrated navigation mode as the current navigation mode. If the PDOP value is lower than the set threshold, it indicates that the target drone is in a satellite denial environment, and the integrated navigation unit automatically switches to the satellite denial integrated navigation mode as the current navigation mode. S4: The integrated navigation unit transmits the calculated target drone navigation status information to the flight control unit, which then generates flight control commands based on the target drone navigation status information.

2. The high-altitude long-endurance target drone integrated navigation method applicable to satellite denial conditions according to claim 1, characterized in that, The conventional integrated navigation mode is a satellite and IMU integrated navigation mode. It uses the conventional solution method of satellite and IMU integrated navigation, and integrates the dynamic real-time acquisition and solution data of the target drone during the flight phase to perform integrated navigation solution, and finally obtains the target drone navigation status information.

3. The high-altitude long-endurance target drone integrated navigation method applicable to satellite denial conditions according to claim 1, characterized in that, The sub-steps for calculating the target drone's navigation status information using satellite denial combined navigation mode as the current navigation mode are as follows: S31: In satellite denial integrated navigation mode, the integrated navigation unit collects the real-time attitude angular velocity and real-time three-axis geomagnetic components of the target drone within a preset time interval, performs data fusion on the real-time attitude angular velocity and real-time three-axis geomagnetic components of the target drone, and calculates the real-time attitude angle information of the target drone. S32: The integrated navigation unit collects the three-axis specific force of the target drone's accelerometer in real time within a preset time interval, and calculates the real-time axial velocity and real-time angle of attack of the target drone based on the three-axis specific force of the target drone's accelerometer. Then, it fuses the real-time axial velocity, real-time angle of attack and the real-time attitude angle information of the target drone to calculate the real-time velocity information of the target drone under the navigation coordinates. S33: The integrated navigation unit performs integral calculation on the real-time velocity information of the target drone under the navigation coordinates according to a preset time interval to obtain the relative displacement of the target drone. Combined with the real-time velocity information of the target drone under the navigation coordinates in the previous preset time interval, the unit calculates the position information of the target drone under the navigation coordinates at the current moment. The position information of the target drone under the navigation coordinates at the current moment, the real-time attitude angle information of the target drone, and the real-time velocity information of the target drone under the navigation coordinates are used as the navigation status information of the target drone.

4. The high-altitude long-endurance target drone integrated navigation method applicable to satellite denial conditions according to claim 3, characterized in that, The integrated navigation unit uses a preset attitude angle calculation method to fuse the real-time attitude angular velocity and real-time three-axis geomagnetic components of the target drone to calculate the real-time attitude angle information of the target drone; the preset calculation method is the EKF filtering algorithm based on the target drone attitude angle filtering model.

5. The high-altitude long-endurance target drone integrated navigation method applicable to satellite denial conditions according to claim 3, characterized in that, The integrated navigation unit uses a preset speed calculation method to fuse the target drone's real-time axial velocity, real-time angle of attack, and real-time attitude angle information to calculate the target drone's real-time speed information in navigation coordinates; the preset speed calculation method is the EKF filtering algorithm based on the target drone speed filtering model.

6. The high-altitude long-endurance target drone integrated navigation method applicable to satellite denial conditions according to claim 1, characterized in that, The integrated navigation unit transmits the calculated target drone navigation status information to the flight control unit via the SPI bus.

7. A high-altitude, long-endurance target drone integrated navigation system suitable for satellite denial conditions, characterized in that, include: Integrated navigation unit, information setting / debugging and upgrade interface, flight control unit and power management module; The integrated navigation unit is used to execute the high-altitude long-endurance target drone integrated navigation method applicable to satellite denial conditions as described in any one of claims 1-6. The information loading / debugging upgrade interface is connected to the integrated navigation unit and is used to load basic navigation information into the integrated navigation unit. The basic navigation information includes at least: heading, waypoints, and geomagnetic parameters. The flight control unit communicates with the integrated navigation unit via the SPI bus. It receives the target drone navigation status information calculated by the integrated navigation unit under normal satellite signal or satellite rejection conditions, and generates flight control commands based on the target drone navigation status information. The target drone navigation status information includes at least the target drone attitude angle, velocity, and position coordinate information. The power management module is electrically connected to both the integrated navigation unit and the flight control unit, and is used to supply power to the integrated navigation unit and the flight control unit after the power conversion is completed.

8. The high-altitude long-endurance target drone integrated navigation system applicable to satellite denial conditions according to claim 7, characterized in that, The integrated navigation unit includes: a DSP information processing board, a satellite receiving module, a MEMS IMU module, a pitot tube, and a geomagnetic sensor; the DSP information processing board establishes bidirectional / unidirectional data communication connections with the satellite receiving module, the MEMS IMU module, the pitot tube, and the geomagnetic sensor, respectively; Among them, the DSP information processing board receives the target drone's current attitude angle, current speed, and current position coordinates, and completes the self-alignment of the integrated navigation unit based on the target drone's current attitude angle, current speed, current position coordinates, and self-alignment algorithm. The satellite receiving module integrates a GNSS antenna and a satellite processing unit. The GNSS antenna is used to acquire current and real-time satellite navigation signals. The satellite processing unit is used to calculate the current satellite navigation signal to obtain the target drone's current velocity and current position coordinates, and to calculate the real-time satellite navigation signal to obtain the target drone's real-time position and velocity information. The MEMS IMU module includes a gyroscope, an accelerometer, and an inertial measurement processing unit. The gyroscope is used to acquire the target drone's current attitude angular velocity information. The accelerometer is used to acquire the target drone's current three-axis specific force information and to acquire the target drone's accelerometer three-axis specific force within a preset time interval in real time. The inertial measurement processing unit is used to fuse and calculate the current attitude angular velocity information and the current triaxial force information of the target drone to obtain the current attitude angle of the target drone, as well as to calculate the real-time attitude angular velocity and real-time velocity increment information of the target drone. The airspeed tube integrates an information processing board; the information processing board is used to calculate the real-time axial velocity and real-time angle of attack of the target drone based on the triaxial specific force of the target drone's accelerometer and the target drone's flight status. The geomagnetic sensor is used to acquire the real-time triaxial geomagnetic components of the target drone.

9. The high-altitude long-endurance target drone integrated navigation system applicable to satellite denial conditions according to claim 8, characterized in that, The power management module is connected to the airborne DC power supply to provide a stable DC power supply for the DSP information processing board of the integrated navigation unit, and at the same time to provide DC power supply for the airborne computer of the flight control unit.

10. The high-altitude long-endurance target drone integrated navigation system applicable to satellite denial conditions according to claim 9, characterized in that, The power management module has an input supply voltage of 36~58VDC.

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