Method, device and system for measuring scalar geomagnetic self-ground-finding and transient roll angle of high-rotation flying body

Abstract

The invention provides a scalar geomagnetic self-ground-finding and transient roll angle measuring method, device and system for a high-rotation flying body. The method comprises the following steps: measuring orthogonal biaxial geomagnetic intensity data by adopting a biaxial magnetoresistive sensor; performing self-compensation on the measured orthogonal biaxial geomagnetic intensity data based on the geomagnetic data internal constraint and the flight body rolling motion characteristic constraint; carrying out self-calibration on the self-compensated orthogonal biaxial geomagnetic intensity data; based on the self-calibrated orthogonal biaxial geomagnetic intensity data, calculating a roll angle of the magnetoresistive sensor relative to the geomagnetic direction, namely the roll angle of the magnetoresistive sensor; and finally, correcting the roll angle of the magnetoresistive sensor according to the installation bias of the magnetoresistive sensor and the local magnetic inclination angle to obtain the roll angle of the aircraft relative to the ground direction. By using the method, the navigation calculation precision of the large-span transient roll angle of the flight body can be improved.

Description

Technical Field

[0001] This invention relates to the field of high dynamic navigation technology, and in particular to a method, apparatus and system for measuring the scalar geomagnetic self-homing and transient roll angle of a high-rotational flying body. Background Technology

[0002] Because artillery propels projectiles through the explosion of propellant within the barrel, and the projectiles simultaneously spin at high speed along the rifling to maintain stable flight, artillery projectiles face a harsh firing environment of high temperature and high pressure, as well as a high-speed, high-spin, and high-dynamic flight environment. Overcoming this highly dynamic environment is both the key and the challenge in achieving guided artillery. Achieving guided artillery first requires precise navigation calculation of the projectile's flight attitude to enable precise control of the control mechanisms. Due to the highly dynamic characteristics of projectile flight attitude, especially roll attitude, which features high roll speed and large range of change, there are currently few navigation devices capable of accurately measuring the roll attitude of projectiles in the highly dynamic environment of artillery. Furthermore, navigation methods such as satellite navigation, inertial navigation, and radar all have certain shortcomings for artillery, such as susceptibility to interference, low calculation frequency, and incomplete navigation information calculation.

[0003] To address the shortcomings of the aforementioned navigation methods, existing technologies propose calculating the roll attitude of a flight vehicle by measuring stable geophysical fields, such as measuring the Earth's magnetic field and calculating the roll attitude based on the measurement data. This method relies solely on geomagnetic information for navigation calculations, resulting in a high calculation frequency and preventing error accumulation.

[0004] However, existing navigation calculation technologies for aircraft based on geomagnetic information are usually based on single-axis magnetoresistive sensor measurements, which do not fully explore the inherent constraints of geomagnetic information, nor do they fully consider the constraints of the large-span transient motion characteristics of the aircraft. The measurement signals are difficult to improve the measurement and navigation calculation accuracy through these constraints, and can only rely on high-precision measurement devices to ensure the accuracy of navigation calculation.

[0005] In addition, geomagnetic measurements can be affected by electromagnetic interference from other equipment on the aircraft. At the same time, the outer shell of the navigation and guidance device is usually made of metal material that is resistant to high overload, which may cause electromagnetic shielding effect, causing the internal electromagnetic signals to resonate and greatly interfere with the measurement of geomagnetic information. Summary of the Invention

[0006] In view of this, the present invention provides a method, device and system for measuring scalar geomagnetic self-homing and transient roll angle of a high-spinning aircraft. It uses a dual-axis magnetoresistive sensor to measure the geomagnetic intensity, and combines the inherent constraints of scalar geomagnetic information and the constraints of the large-span transient roll motion characteristics of the aircraft to compensate for the geomagnetic measurement data, thereby improving the navigation calculation accuracy of the large-span transient roll angle of the aircraft.

[0007] One method for measuring the scalar geomagnetic self-locating and transient roll angle of a high-rotational flying body includes:

[0008] Step 1: Use a biaxial magnetoresistive sensor to measure the orthogonal biaxial geomagnetic intensity data;

[0009] Step 2: Based on the inherent constraints of geomagnetic data, namely that the orthogonal composite vector of the orthogonal biaxial geomagnetic intensity data during the roll motion period of the flight body is a geomagnetic vector and the magnitude of the orthogonal composite vector is constant, and the constraints of the flight body's roll motion characteristics, namely that the waveforms of the orthogonal biaxial geomagnetic intensity data are approximately consistent and there is a constant 90° phase difference, self-compensation is performed on the measured orthogonal biaxial geomagnetic intensity data.

[0010] Step 3: Perform self-calibration on the self-compensated orthogonal biaxial geomagnetic intensity data;

[0011] Step 4: Based on the self-calibrated orthogonal biaxial geomagnetic intensity data, calculate the roll angle of the magnetoresistive sensor relative to the geomagnetic direction, i.e., the magnetoresistive sensor roll angle γ.

[0012] Step 5: Based on the installation bias of the magnetoresistive sensor and the local magnetic tilt angle, correct the roll angle γ of the magnetoresistive sensor to obtain the roll angle γ of the aircraft relative to the ground. g .

[0013] Preferably, the inherent constraints of geomagnetic data and the constraints of the roll motion characteristics of the flight body used for self-compensation in step 2 are expressed as follows:

[0014]

[0015] Where, m X and m Y These are the X-axis and Y-axis geomagnetic intensity data from the orthogonal biaxial geomagnetic intensity data obtained in step 1; m Xmax and m Ymax These represent the maximum values ​​of the X-axis and Y-axis geomagnetic intensity data within one roll cycle of the flight body, respectively. α is the angle between the Y-axis sensitive axis and the geomagnetic direction, and m... g The data represents local geomagnetic data; (1) to (3) represent constraints on the rolling motion characteristics of the flying body; and (4) represents the inherent constraints of the geomagnetic data.

[0016] Preferably, in step 2, the self-compensation of the measured orthogonal biaxial geomagnetic intensity data includes:

[0017] Correction of orthogonal biaxial geomagnetic intensity data: Modify or even remove data that does not meet the inherent constraints of geomagnetic data and the constraints of the rolling motion characteristics of the flying body, so that it conforms to the two constraint relationships.

[0018] Preferably, in step 2, the self-compensation of the measured orthogonal biaxial geomagnetic intensity data includes:

[0019] The corrected orthogonal biaxial geomagnetic intensity data is expanded: the data points of the orthogonal biaxial geomagnetic intensity data are expanded by cubic spline interpolation, thereby increasing the data frequency. The expanded geomagnetic intensity data are then stitched into a smooth curve by piecewise cubic polynomials.

[0020] Preferably, in step 3, the self-calibration of the self-compensated orthogonal biaxial geomagnetic intensity data adopts a piecewise normalization method, including:

[0021] Orthogonal biaxial geomagnetic intensity data are segmented using a sliding time window, and the segmented geomagnetic intensity data are normalized. The length of the sliding time window is set to N times the length of half a sine cycle of geomagnetic intensity data, where N < 10, and the boundary of the sliding time window is selected at the extreme point of the sine cycle of the geomagnetic intensity data.

[0022] Preferably, the sliding time window is a dynamically changing sliding time window:

[0023] The length of the initial sliding time window is set based on the estimated value of the initial roll speed of the flight vehicle;

[0024] The length of the subsequent sliding time window is set according to the length of the last half of the sine cycle within the previous sliding time window.

[0025] Preferably, in step 4, the roll angle γ of the magnetoresistive sensor is calculated in quadrants, and the calculation formula is as follows:

[0026]

[0027] Among them, the axis lagging behind by 90 degrees during clockwise rotation is the roll angle, and the roll angle γ of the magnetoresistive sensor is calculated using formula (5); m NX and m NY These are the geomagnetic intensity data for the X and Y axes after self-calibration.

[0028] Preferably, step 5 is as follows:

[0029] Step 51: Based on the installation offset angle φ between the sensitive axis of the magnetoresistive sensor and the 0° axis of the flight body's roll attitude. b The roll angle γ of the magnetoresistive sensor is corrected by installation offset to obtain the roll angle γ of the aircraft relative to the geomagnetic direction. m :

[0030] γ m =mod(γ+φ) b ,2π)

[0031] Step 52: Based on the local magnetic inclination angle φ m The roll angle γ of the flying body relative to the geomagnetic direction mPerform ground-finding correction to obtain the roll angle γ of the aircraft relative to the ground. g ;

[0032]

[0033] Here, mod(·) is the modulo operation.

[0034] The present invention also provides a scalar geomagnetic self-seeking and transient roll angle measurement device for high-rotation flying bodies, used to perform the above-mentioned roll angle measurement method. The device includes: a main control module, a geomagnetic measurement module, a storage module, a communication bus and a power supply module.

[0035] The geomagnetic measurement module includes a dual-axis magnetoresistive sensor and an analog-to-digital converter circuit. The dual-axis magnetoresistive sensor is installed parallel to the cross-section of the flight body to measure orthogonal dual-axis geomagnetic intensity data, which is converted into digital signals by the analog-to-digital converter circuit and sent to the main control module and the storage module.

[0036] The main control module is used to run the roll angle measurement method and calculate the roll angle γ of the flight body relative to the ground. g ;

[0037] Storage module for saving the mounting bias angle φ of the magnetoresistive sensor. b Local magnetic inclination φ m The initial binding data, including the original measurement data from the geomagnetic measurement module, and the roll angle data of the flight body calculated by the main control module;

[0038] The communication bus is used to enable data communication between the main control module, the geomagnetic measurement module, and the storage module.

[0039] The power module is used to supply power to the various modules in the device.

[0040] The present invention further provides a scalar geomagnetic self-locating and transient roll angle measurement system for high-speed rotating aircraft, including a titanium alloy protective device and the aforementioned roll angle measuring device; the titanium alloy protective device is installed at the tail of the aircraft; the roll angle measuring device is installed inside the titanium alloy protective device and encapsulated by a potting process.

[0041] Beneficial effects:

[0042] (1) This invention uses a magnetoresistive sensor to measure geomagnetic intensity data and then calculates the roll angle of the aircraft. This avoids the problems of low calculation frequency and error accumulation caused by using inertial navigation, and is suitable for calculating the roll angle of high-rotation aircraft. Moreover, this invention uses a dual-axis magnetoresistive sensor and combines the inherent constraints of geomagnetic data and the constraints of the aircraft's roll motion characteristics to perform self-compensation on the geomagnetic data, ensuring the availability of geomagnetic data and improving the accuracy of subsequent roll angle calculations, thus laying the foundation for achieving precision strikes by high-rotation aircraft.

[0043] (2) In a preferred embodiment, a geomagnetic data normalization method based on an adaptive sliding time window is proposed. This method segments geomagnetic data based on the projectile's roll motion characteristics and designs the length of the time window to avoid excessive amplitude variations in geomagnetic data amplitudes across different sine cycles within a single time window, which could lead to inaccurate normalization. The time window boundary is selected at the extreme points of the sine cycle to ensure the continuity and accuracy of normalization processing across different time windows. Furthermore, the sliding time window length is adaptively adjusted to ensure that the length changes adaptively with the projectile's roll speed, guaranteeing that each time window can capture a stable number of half-sine cycles of geomagnetic data, thereby ensuring the accuracy and continuity of the normalization process. Therefore, the multi-angle design of the sliding time window in this invention achieves the effect of ensuring the continuity and smoothness of the normalization process while maintaining accurate geomagnetic data normalization.

[0044] (3) This invention proposes a scalar geomagnetic self-location method for high-spinning flying bodies that combines the inherent constraints of scalar geomagnetic information with the constraints of the large-span transient roll motion characteristics of flying bodies. This method can realize the location solution based on orthogonal biaxial scalar geomagnetic data.

[0045] (4) In a preferred embodiment, the present invention proposes a high overload protection device made of non-magnetic titanium alloy, which will not be magnetized by the geomagnetic field and electromagnetic noise of other electronic components, and can provide a stable geomagnetic measurement environment for magnetoresistive sensors. Attached Figure Description

[0046] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0047] Figure 1 This is a flowchart of the method for measuring the scalar geomagnetic self-locating and transient roll angle of a high-rotation flying body according to Embodiment 1 of the present invention;

[0048] Figure 2 A diagram illustrating the working process of the scalar geomagnetic self-location method for high-rotational flying bodies;

[0049] Figure 3 This is a diagram showing the calculation results of the roll angle of a flight body according to an embodiment of the present invention;

[0050] Figure 4 This is a schematic diagram of the structure of the scalar geomagnetic self-locating and transient roll angle measuring device and system for high-rotation flying bodies in Embodiments 2 and 3 of the present invention. Detailed Implementation

[0051] This invention provides a scalar geomagnetic self-homing and transient roll angle measurement scheme for high-rotation aircraft. The core idea is to use a biaxial magnetoresistive sensor to measure orthogonal biaxial geomagnetic intensity data; fully exploit the inherent constraints of the geomagnetic data and the constraints of the aircraft's roll motion characteristics, and perform self-compensation on the measured orthogonal biaxial geomagnetic intensity data based on these two constraints to ensure data availability; then calculate the roll angle of the magnetoresistive sensor relative to the geomagnetic direction, and use the magnetoresistive sensor installation bias and the geomagnetic inclination for correction to obtain the roll angle γ of the aircraft relative to the Earth's direction. g .

[0052] As can be seen, this invention uses a magnetoresistive sensor to measure geomagnetic intensity data and then calculates the roll angle of the aircraft, avoiding the problems of low calculation frequency and error accumulation associated with inertial navigation systems. This makes it suitable for calculating the roll angle of high-speed rotating aircraft. Furthermore, this invention employs a dual-axis magnetoresistive sensor and combines the inherent constraints of geomagnetic data with the constraints of the aircraft's roll motion characteristics to perform self-compensation on the geomagnetic data, ensuring its availability and improving the accuracy of subsequent roll angle calculations. This invention's roll angle measurement method based on a dual-axis magnetoresistive sensor can achieve large-span transient roll attitude calculations for high-speed rotating aircraft, laying the foundation for precision strikes against such aircraft.

[0053] Furthermore, this invention utilizes titanium alloy to manufacture a high-overload protection device. A potting process is used to embed the measuring devices, composed of various functional modules, into the protection device, constructing a scalar geomagnetic self-homing and transient roll angle measurement system for high-rotation flying bodies. During flight, geomagnetic data is measured using a magnetoresistive sensor. This data is then augmented, and an adaptive sliding time window is constructed to self-calibrate the self-compensated geomagnetic data (i.e., segmented normalization). Finally, through self-homing correction, the roll angle of the flying body relative to the Earth's direction (gravity direction) is calculated. These technological improvements collectively enhance the accuracy of calculating the large-span transient roll attitude of high-rotation flying bodies.

[0054] To achieve the above solution, the following describes in detail the scalar geomagnetic self-locating and transient roll angle measurement scheme for high-rotation flying bodies of the present invention, with reference to the accompanying drawings and examples.

[0055] Example 1

[0056] This embodiment provides a method for measuring the scalar geomagnetic self-locating and transient roll angle of a high-rotational flying body, such as... Figure 1 As shown, the method includes the following steps:

[0057] Step 1: Set up a dual-axis magnetoresistive sensor. The dual-axis magnetoresistive sensor is installed parallel to the cross-section of the flight body to measure the orthogonal dual-axis geomagnetic intensity data.

[0058] (1) Selection and installation of biaxial magnetoresistive sensors

[0059] This embodiment constructs a biaxial magnetoresistive sensor based on the anisotropic magnetoresistive effect to measure orthogonal biaxial geomagnetic data. The resistance value of the anisotropic magnetoresistive material changes with the direction and intensity of the external magnetic field. Within a certain range of external magnetic field intensity, its resistance change is linearly related to the external magnetic field intensity. The external magnetic field intensity can be converted into a resistance value, and then the external magnetic field intensity can be converted into an electrical signal through the measurement circuit.

[0060] Therefore, this embodiment employs a biaxial magnetoresistive sensor made of anisotropic magnetoresistive material, which includes a pair of orthogonal sensing axes and can measure geomagnetic intensity data in two orthogonal directions. Based on the constraint that the vector synthesis direction of the orthogonal biaxial geomagnetic intensity data is the geomagnetic direction, the geomagnetic direction can be calculated from the two sets of orthogonal geomagnetic data.

[0061] When a current is applied to the sensitive shaft, the angle between its internal magnetization direction and the current direction changes the resistance value of the sensitive shaft. In this embodiment, when there is no external magnetic field, the internal magnetization direction of the sensitive shaft is along a fixed easy-magnetize axis direction, and the current direction and the easy-magnetize axis direction of the sensitive shaft are forcibly set to θ = 45°; after applying an external magnetic field H, the external magnetic field will change the magnetization direction of the sensitive shaft, causing it to deflect in the direction of the external magnetic field, with a deflection angle φ:

[0062]

[0063] In the formula, H k This is the saturation threshold for the magnetization direction of the sensitive axis. Once this threshold is exceeded, the region enters the saturation region, and the magnetization direction of the sensitive axis will not change.

[0064] Since the angle between the direction of the sensitive shaft current and the magnetization direction is θ = 45° when there is no external magnetic field, the relationship between it and the deflection angle of the magnetization direction is:

[0065] θ = φ + 45°

[0066] By combining the relationship between the resistance of the sensitive shaft and the angle between the current direction and the internal magnetization direction, we can obtain:

[0067]

[0068] In the formula, R0 is the resistance value when there is no external magnetic field, and ΔR m This represents the maximum change in resistance that can be caused by an external magnetic field.

[0069] From the above equation, we can see that when |H| < H kWithin a certain range, the resistance value of the sensitive axis is linearly related to the external magnetic field strength; the stronger the external magnetic field, the greater the change in the resistance value of the sensitive axis. In the geomagnetic field environment, the direction and strength of the magnetic field can be considered constant within one roll cycle of the aircraft. Therefore, the resistance value of the sensitive axis is determined only by the degree of deviation between the direction of the sensitive axis current and the direction of the magnetic field. The change in resistance is greatest when the sensitive axis is in the same or opposite direction to the geomagnetic field, and remains unchanged when the sensitive axis is perpendicular to the geomagnetic field.

[0070] Based on the above formula, geomagnetic data can be converted into changes in the resistance of the sensitive axis, thus realizing the conversion of geomagnetic data into electrical signals.

[0071] (2) Conversion of sensitive geomagnetic intensity data

[0072] The Wheatstone bridge and other sensors can detect changes in the resistance of the sensitive axis and convert the external magnetic field strength into a voltage value output proportionally, so as to facilitate subsequent calculation of the geomagnetic intensity.

[0073] This embodiment uses a Wheatstone bridge with a full-bridge configuration to detect the change in resistance along the sensitive axis. The bridge arms consist of four essentially identical sensitive axes, differing only in the direction of their easily magnetized axes. The easily magnetized axes of connected bridge arms face opposite directions, ensuring that under the influence of an external magnetic field, the resistance changes in opposite directions while maintaining the same magnitude. The geomagnetic data can then be further converted into voltage data, specifically expressed as:

[0074]

[0075] In the formula, V o V is the output voltage of the bridge circuit. s R is the excitation voltage of the bridge circuit. b =R0+ΔR m / 2 represents the base resistance of the sensitive axis.

[0076] Combining the expressions for the bridge output voltage and the sensitive axis resistance, the relationship between the geomagnetic intensity measured by the sensitive axis and the bridge output voltage can be obtained:

[0077]

[0078] In the formula, H g This refers to the geomagnetic intensity measured by the sensitive axis.

[0079] This allows the geomagnetic field strength to be converted into a voltage signal, and the geomagnetic field strength can be calculated based on the bridge output voltage. From the above equation, it can be seen that |H| < H k Within the specified range, the external magnetic field strength is directly proportional to the bridge output voltage. The magnitude of the bridge output voltage reflects the magnitude of the external magnetic field strength, and the polarity of the bridge output voltage reflects the direction of the external magnetic field.

[0080] During flight, the position of the aircraft changes very little within one roll cycle, typically a few meters to tens of meters. Within this distance, the geomagnetic intensity and direction can be considered constant. Therefore, the measurement data of the magnetoresistive sensor is determined only by its angular relationship with the geomagnetic direction. From a vector perspective, the measurement data is determined only by the component of the geomagnetic vector along its easily magnetized axis. When its easily magnetized axis is the same as the geomagnetic direction, the measurement data is at its maximum; when it is perpendicular to the geomagnetic direction, the measurement data is an intermediate value; and when it is opposite to the geomagnetic direction, the measurement data is at its minimum.

[0081] Through the sensor sensitivity and Wheatstone bridge conversion in step 1, voltage values ​​characterizing orthogonal biaxial geomagnetic intensity data were obtained.

[0082] Step 2: Self-compensation of raw geomagnetic measurement data based on the inherent constraints of geomagnetic information and the constraints of the rolling motion characteristics of the flight body.

[0083] Self-compensation is a preliminary processing of the raw geomagnetic data measured by a magnetoresistive sensor. Its purpose is to eliminate the influence of various disturbances and interferences, as well as the zero bias error and drift error of the magnetoresistive sensor itself, on the geomagnetic data.

[0084] The self-compensation in this invention includes the correction and expansion of geomagnetic data. The correction is mainly based on the inherent constraints of orthogonal geomagnetic data and the constraints of the roll motion characteristics of the flying body.

[0085] Specifically, the constraints used for correction are as follows: the geomagnetic vector remains constant within one rolling cycle of the aircraft; the orthogonal composite vector of the two sets of scalar geomagnetic data is the geomagnetic vector, and the magnitude of the orthogonal composite vector is constant; simultaneously, since the sensitive axis of the magnetoresistive sensor is placed parallel to the axial section of the aircraft, the waveforms of the two sets of geomagnetic data should be approximately identical, and there should be a constant 90° phase difference; within one rolling cycle of the aircraft, the angle between the axial direction of the two geomagnetic sensor's sensitive axis and the geomagnetic direction will vary within the range of -180° to +180°; combining the aforementioned relationship between the external magnetic field strength and the output voltage of the magnetoresistive sensor, both sets of geomagnetic data should be a complete sine wave. The aforementioned constraint relationship formula is expressed as follows:

[0086]

[0087] In the formula, (1) to (3) represent the constraints on the rolling motion characteristics of the flight body, and (4) represents the inherent constraints on the geomagnetic data. X and m Y The original geomagnetic data for the X and Y axes are shown below, in m. Xmax and m YmaxThese represent the maximum values ​​of the raw geomagnetic data along the X and Y axes within one flight body roll cycle, respectively. α is the angle between the Y-axis sensitive axis and the geomagnetic direction, and m... g The local geomagnetic data can be initially stored in the storage module.

[0088] The original geomagnetic data is corrected based on the above constraints: During actual measurements, external disturbances may generate some abnormal data, such as abrupt changes or data that does not conform to the sinusoidal signal trend. Geomagnetic data correction involves modifying or even removing data in the original geomagnetic data that does not meet the above constraints, so that it conforms to them. For example, if abnormal data deviates too far from the waveform, it is removed; if the deviation is not significant and is within the allowable range, the abnormal data points can be corrected based on adjacent data points to conform to the sinusoidal wave trend.

[0089] The self-compensation step in this process includes geomagnetic data augmentation to increase the data frequency. Because geomagnetic data exhibits a sinusoidal waveform, its frequency can be increased through augmentation. Specifically, after geomagnetic data correction, the geomagnetic intensity data needs to be augmented to a certain extent. Due to the conversion frequency limitations of geomagnetic data analog-to-digital conversion, a completely continuous digital signal conversion of geomagnetic information cannot be achieved, and the conversion frequency of geomagnetic information affects the accuracy of subsequent calculations of the aircraft's roll angle. This embodiment augments the geomagnetic intensity data using cubic spline interpolation, stitching the geomagnetic data into a smooth curve using piecewise cubic polynomials to ensure the continuity and smoothness of the augmented geomagnetic intensity data.

[0090] Step 3: Self-calibration of geomagnetic data based on adaptive sliding time window.

[0091] The self-calibration in this embodiment adopts a segmented normalization method.

[0092] Specifically, this step involves self-calibrating the self-compensated geomagnetic data based on an adaptive sliding time window. This means segmenting the geomagnetic data using a sliding time window of adaptive length, and then normalizing the segmented data. The self-compensated geomagnetic data is a sinusoidal waveform whose amplitude varies with the position of the flying object. To facilitate the extraction of the sinusoidal waveform period information and the phase relationship between the two sets of geomagnetic data, and to calculate the rolling attitude of the flying object based on the geomagnetic data, the two sets of geomagnetic data whose amplitude varies with the flying object's position are normalized. This means that the geomagnetic data within one or half a sinusoidal period is equivalently converted to the range of -1 to +1.

[0093] The adaptive sliding time window in this embodiment extracts geomagnetic data from a finite number of half-sine cycles, avoiding excessive amplitude variations in geomagnetic data from different sine cycles within a single time window, which could lead to inaccurate normalization. At the same time, the time window boundary is selected at the extreme points of the sine cycle to ensure the continuity and accuracy of normalization processing across different time windows.

[0094] In this embodiment, the adaptive sliding time window is set to have a length of N half-sine cycles of geomagnetic data (N < 10), ensuring that the boundaries of the geomagnetic data intercepted by the time window are all extreme points, and ensuring that the normalization processing is performed between the extreme points of the geomagnetic data. As for the selection of half-sine cycles, the last half-sine cycle in the previous sliding time window is selected.

[0095] Specifically, the time window division is initially based on the sinusoidal period of the geomagnetic data in the previous time window, and then further divided by calculating extreme points. The initial time window length is set based on the estimated initial roll speed of the aircraft, and the subsequent time window lengths are set based on the length of the last half of the sinusoidal period of the previous time window. Specifically, as shown in the following formula:

[0096]

[0097] In the formula, i is the time window number, ToW i Let be the length of the i-th time window. ToE is the initial roll speed of the flight body estimated from the launch parameters. i-1 It is the sequence of extreme points of the sinusoidal period within the (i-1)th time window, with the serial numbers endR and endL representing the right extreme point and left extreme point of the last half of the sinusoidal period, respectively.

[0098] The above method can ensure that the sliding time window length is adaptively adjusted, that the time window length changes adaptively with the roll speed of the flight body, and that each time window can capture a stable number of geomagnetic data half-sine cycles, thereby ensuring the accuracy and continuity of normalization processing.

[0099] Furthermore, after completing the initial division of the sliding time window, the time window is further divided by calculating the extreme points of the geomagnetic data within the time window, ensuring that the boundaries of the geomagnetic data intercepted by the time window are at the extreme points. Based on the property that the slope at the extreme points of the self-compensated continuous geomagnetic data is 0, and the slope changes sign at both ends of the extreme point, the calculation is as follows:

[0100]

[0101] In the formula, sign(·) is the sign function.

[0102] According to the above formula, the time that satisfies the formula is the extreme point of the geomagnetic data, as shown above, and the extreme point time sequence is denoted as ToE. To ensure that the boundary of the geomagnetic data intercepted by the time window is at the extreme point, the end time of the time window is modified to the last extreme point time, that is, the last value of the extreme point time sequence ToE. At the same time, the end time of the previous time window is the start time of the next time window, thus ensuring that the left and right boundaries of each time window are extreme points of the geomagnetic data.

[0103] Furthermore, the geomagnetic data within the time window is normalized, segmented between every two extreme points, i.e., normalization is performed within each extreme value interval. As mentioned earlier, the geomagnetic data is sinusoidal waveform data, and it changes monotonically within each extreme value interval. Therefore, the geomagnetic data within each extreme value interval can be equivalently transformed to the range of -1 to +1. Specifically, normalization is performed according to the following formula:

[0104]

[0105] In the formula, m represents the geomagnetic intensity data after the aforementioned steps. N To normalize the geomagnetic intensity data, m mL The data represents the geomagnetic intensity at the left extreme point within the extreme value interval, m. mR This represents the geomagnetic intensity data at the right extreme point within the extreme value range.

[0106] Step 4: Preliminary calculation of the large-span transient roll angle of the flight body: Based on the self-calibrated orthogonal biaxial geomagnetic intensity data, calculate the roll angle of the magnetoresistive sensor relative to the geomagnetic direction, that is, the roll angle γ of the magnetoresistive sensor.

[0107] Based on the principle of geomagnetic vector synthesis using scalar geomagnetic measurement data from two orthogonally positioned sensing axes, the local geomagnetic direction can be calculated from the normalized geomagnetic data. Simultaneously, the roll angle of the magnetoresistive sensor's sensing axis relative to the geomagnetic direction can be calculated, enabling a preliminary calculation of the aircraft's roll angle. The geomagnetic data measured by the two sensing axes of the magnetoresistive sensor exhibit a constant 90° phase difference. The sensing axis with the leading phase is denoted as the X-axis, and the one with the lagging phase as the Y-axis. The measurement data is at an extreme value when the sensing axis is parallel to the geomagnetic direction. Therefore, the tangent ratio of the dual-axis geomagnetic data can reflect the angle by which the sensing axis deviates from the geomagnetic direction.

[0108] Define a biaxial magnetometer with two perpendicular axes. When rotating clockwise, the axis lagging 90 degrees in phase is designated as the Y-axis, and the other axis as the X-axis. Taking the Y-axis as the roll angle sensing axis as an example:

[0109]

[0110] In the formula, γ reflects the degree to which the roll angle sensing axis (Y-axis) deviates from the geomagnetic direction, and mNX and m NY These are the normalized X-axis and Y-axis geomagnetic data, respectively. If the X-axis is to be used as the roll angle sensing axis, simply negative the data obtained from the Y-axis.

[0111] Furthermore, to obtain the deflection angle of the magnetoresistive sensor's sensitive axis roll attitude relative to the geomagnetic direction, the direction of the 0° roll angle relative to the geomagnetic direction is defined as the geomagnetic direction, and clockwise from the tail of the aircraft is defined as the positive roll direction. Therefore, it is necessary to perform quadrant-based calculations on the X-axis and Y-axis geomagnetic data to ensure that the calculated roll angle is within the range [0, 2π). Taking the Y-axis as an example, the specific calculation method is shown in the following formula:

[0112]

[0113] This allows us to calculate the roll angle of the magnetoresistive sensor relative to the geomagnetic direction, thus completing the preliminary calculation of the large-span transient roll angle of the flight body.

[0114] Step 5: Based on the installation bias of the magnetoresistive sensor and the local magnetic tilt angle, correct the roll angle γ of the magnetoresistive sensor to obtain the roll angle γ of the aircraft relative to the ground. g .

[0115] The roll angle obtained in step 4 is the roll angle of the magnetoresistive sensor relative to the geomagnetic direction, and it still needs to be converted into the roll angle of the aircraft relative to the earth direction through the self-grounding method.

[0116] The working process of the scalar geomagnetic self-seeking method for high-rotation flying bodies proposed in this invention is as follows: Figure 2 As shown. During one roll cycle of the flying body, the geomagnetic field can be considered constant. Therefore, the composite vector of the orthogonal biaxial scalar geomagnetic data also remains constant, which is the geomagnetic direction. Based on this, the geomagnetic field direction can be calculated. Then, by looking up tables or the international geomagnetic reference field model, the local magnetic inclination can be calculated. The direction of the earth (gravity direction) can be calculated from the geomagnetic field direction and the magnetic inclination, thus completing the self-location.

[0117] This embodiment calculates the geodetic direction based on the above principles and corrects the initially calculated roll angle of the flight body relative to the geodetic direction to obtain the roll angle of the flight body relative to the reference direction, which is used in subsequent navigation, guidance and control stages. This is called self-homing correction, which mainly includes two parts: installation offset angle correction and self-homing correction. The specific steps are as follows:

[0118] Step 51: Install and offset calibration of the geomagnetic measurement module.

[0119] In this embodiment, the magnetoresistive sensor is placed parallel to the axial section of the flight body, but there is an offset angle φ between the Y-axis of the magnetoresistive sensor and the axial direction of the flight body's roll angle of 0°. bThe positive direction is clockwise rotation from the tail of the aircraft. This offset angle is obtained by measuring the angular relationship between the installation axis of the geomagnetic measurement module in the protective device and the axial direction of the aircraft's roll angle 0°, and is loaded into the storage module before the aircraft is launched.

[0120] Correct the offset angle φ b Then, the roll angle of the magnetoresistive sensor can be converted into the roll angle of the flight body relative to the geomagnetic direction, that is:

[0121] γ m =mod(γ) Y0 +φ b ,2π)

[0122] In the formula, γ m is the roll angle of the flying object relative to the geomagnetic direction, and mod(·) is the modulo operation.

[0123] Step 52: Ground-finding correction of the aircraft's roll angle.

[0124] This step corrects the roll angle of the flight body to the roll angle relative to the earth direction based on the ground direction calculated by the self-grounding method. This makes it easier for subsequent navigation, guidance and control systems to use the roll angle data of the flight body in the reference direction / reference coordinate system.

[0125] To determine the geodetic orientation, the magnetic inclination angle is required. The magnetic inclination angle is the angle by which the direction of the magnetic field deviates from the horizontal plane; therefore, the geodetic orientation can be determined based on the magnetic inclination angle and the direction of the magnetic field, i.e., geodetic location. In this embodiment, the launch position of the spacecraft and the magnetic inclination angles at different positions during flight are calculated using the International Geomagnetic Reference Field Model and stored in the storage module before launch.

[0126] By reading the magnetic inclination binding data, the geodetic direction can be obtained. Then, the roll angle of the flight body is corrected for ground-seeking. The specific calculation formula for ground-seeking correction is as follows:

[0127]

[0128] In the formula, γ g φ is the roll angle of the flying body relative to the Earth (in the direction of gravity). m This is the local magnetic inclination.

[0129] This completes the self-grounding correction of the aircraft's roll angle, and calculates the large-span transient roll angle of the aircraft relative to the ground. Figure 3 This is a diagram showing the calculation results of the roll angle of a flight vehicle according to an embodiment of the present invention.

[0130] Example 2

[0131] This embodiment provides a scalar geomagnetic self-locating and transient roll angle measurement device for high-rotation flying bodies, used to perform the roll angle measurement method of Embodiment 1. For example... Figure 4 As shown, the device includes: a main control module, a geomagnetic measurement module, a storage module, a communication bus, and a power supply module.

[0132] The geomagnetic measurement module includes a dual-axis magnetoresistive sensor and an analog-to-digital converter circuit. The dual-axis magnetoresistive sensor is installed parallel to the cross-section of the flight body and measures orthogonal dual-axis geomagnetic intensity data based on the anisotropic magnetoresistive effect. The data is converted into digital signals by the analog-to-digital converter circuit and sent to the main control module and the storage module.

[0133] The main control module is used to run the roll angle measurement method, read the measurement data from the geomagnetic measurement module, and calculate the roll angle γ of the aircraft relative to the Earth's direction using both the roll angle measurement method and the self-grounding method. g This also includes initialization operations for the geomagnetic measurement module and storage module. Specifically, after the measuring device is powered on, it reads the initialization parameters stored in the storage module to initialize the measuring device. Then, it cyclically reads the raw geomagnetic data, performs self-compensation and self-calibration processing on the raw geomagnetic data to obtain normalized orthogonal dual-axis geomagnetic data. Finally, it calculates the roll angle based on constraint relationships and performs self-ground-finding correction on the roll angle to obtain the aircraft roll angle with the Earth's direction as the reference direction. To achieve the above functions, the main control module should be composed of an MPU to perform the above calculations, and can be built using a microcontroller, FPGA, etc.

[0134] Storage module for saving the mounting bias angle φ of the magnetoresistive sensor. b Local magnetic inclination φ m The data includes initial binding data, raw measurement data from the geomagnetic measurement module, and roll angle data of the flight body calculated by the main control module. FLASH, ROM, and other memory types can be selected.

[0135] The communication bus is used to enable data communication between the main control module, the geomagnetic measurement module, and the storage module. For bidirectional transmission, a parallel interface chip can be selected.

[0136] The power module supplies power to the various modules within the device. Options include high-overload resistant lithium batteries.

[0137] The aforementioned functional modules constitute the transient roll angle measurement device, which operates after the launch of the aircraft. First, the main control module initializes each functional module in the measurement device. Then, the geomagnetic measurement module measures geomagnetic data in real time and converts it into digital signals. After that, the main control module reads the orthogonal dual-axis geomagnetic data in a loop and calculates the large-span transient roll angle of the aircraft using the high-spinning aircraft transient roll angle measurement method and the high-spinning aircraft scalar geomagnetic self-finding method. The original orthogonal dual-axis geomagnetic measurement data and the aircraft roll angle calculation data are then saved to the storage module.

[0138] Example 3

[0139] This embodiment provides a scalar geomagnetic self-locating and transient roll angle measurement system for high-rotation flying bodies. (See also...) Figure 4 The system includes a titanium alloy protective device and the roll angle measuring device described in Example 2.

[0140] The titanium alloy protective device is installed at the tail of the aircraft; the roll angle measuring device is installed inside the titanium alloy protective device and encapsulated through a potting process.

[0141] The high-overload resistant titanium alloy protective device is made of non-magnetic titanium alloy material with extremely low magnetic susceptibility. It is almost unmagnetized in the Earth's magnetic field and therefore will not interfere with the geomagnetic measurement module. Internally, it integrates a high-speed rotating aircraft transient roll angle measurement device, mounted on the tail of the aircraft via bearings, etc. This device possesses characteristics such as high temperature resistance, high pressure resistance, and high overload resistance, ensuring the normal operation of the internal measurement circuitry.

[0142] The protective device is a bell-shaped shell with the same maximum bottom radius as the axial section radius of the aircraft, thus avoiding affecting the aerodynamic shape of the aircraft.

[0143] After the aforementioned functional modules are installed inside a high-overload resistant housing, they are encapsulated using a potting process to ensure normal operation under high temperature, high pressure, and high overload conditions. Simultaneously, the geomagnetic measurement module is positioned far from other functional modules to prevent electromagnetic noise from other modules from affecting its measurement data.

[0144] It should be noted that, in the absence of conflict, the above embodiments and features can be combined with each other; and, 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.

[0145] It should be noted that the foregoing description covers various aspects of embodiments within the scope of the appended claims. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this invention, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using structures and / or functionalities other than one or more of the aspects set forth herein.

Claims

1. A method for measuring the scalar geomagnetic self-homing and transient roll angle of a high-rotation flying body, characterized in that, include: Step 1: Use a biaxial magnetoresistive sensor to measure the orthogonal biaxial geomagnetic intensity data; Step 2: Based on the inherent constraints of geomagnetic data, namely that the orthogonal composite vector of the orthogonal biaxial geomagnetic intensity data during the roll motion period of the flight body is a geomagnetic vector and the magnitude of the orthogonal composite vector is constant, and the constraints of the flight body's roll motion characteristics, namely that the waveforms of the orthogonal biaxial geomagnetic intensity data are approximately consistent and there is a constant 90° phase difference, self-compensation is performed on the measured orthogonal biaxial geomagnetic intensity data. Step 3: Perform self-calibration on the self-compensated orthogonal biaxial geomagnetic intensity data; Step 4: Based on the self-calibrated orthogonal biaxial geomagnetic intensity data, calculate the roll angle of the magnetoresistive sensor relative to the geomagnetic direction, i.e., the magnetoresistive sensor roll angle γ. Step 5: Based on the installation bias of the magnetoresistive sensor and the local magnetic tilt angle, correct the roll angle γ of the magnetoresistive sensor to obtain the roll angle γ of the aircraft relative to the ground. g .

2. The method as described in claim 1, characterized in that, The inherent constraints of geomagnetic data and the constraints of the roll motion characteristics of the flight body used for self-compensation in step 2 are expressed as follows: Where, m X and m Y These are the X-axis and Y-axis geomagnetic intensity data from the orthogonal biaxial geomagnetic intensity data obtained in step 1; m Xmax and m Ymax These represent the maximum values ​​of the X-axis and Y-axis geomagnetic intensity data within one roll cycle of the flight body, respectively. α is the angle between the Y-axis sensitive axis and the geomagnetic direction, and m... g The data represents local geomagnetic data; (1) to (3) represent constraints on the rolling motion characteristics of the flying body; and (4) represents the inherent constraints of the geomagnetic data.

3. The method as described in claim 1 or 2, characterized in that, Step 2, the self-compensation of the measured orthogonal biaxial geomagnetic intensity data, includes: Correction of orthogonal biaxial geomagnetic intensity data: Modify or even remove data that does not meet the inherent constraints of geomagnetic data and the constraints of the rolling motion characteristics of the flying body, so that it conforms to the two constraint relationships.

4. The method as described in claim 3, characterized in that, Step 2, the self-compensation of the measured orthogonal biaxial geomagnetic intensity data, includes: The corrected orthogonal biaxial geomagnetic intensity data is expanded: the data points of the orthogonal biaxial geomagnetic intensity data are expanded by cubic spline interpolation, thereby increasing the data frequency. The expanded geomagnetic intensity data are then stitched into a smooth curve by piecewise cubic polynomials.

5. The method as described in claim 1, characterized in that, In step 3, the self-calibration of the self-compensated orthogonal biaxial geomagnetic intensity data adopts a piecewise normalization method, including: Orthogonal biaxial geomagnetic intensity data are segmented using a sliding time window, and the segmented geomagnetic intensity data are normalized. The length of the sliding time window is set to N times the length of half a sine cycle of geomagnetic intensity data, where N < 10, and the boundary of the sliding time window is selected at the extreme point of the sine cycle of the geomagnetic intensity data.

6. The method as described in claim 5, characterized in that, The sliding time window is dynamically changing. The length of the initial sliding time window is set based on the estimated value of the initial roll speed of the flight vehicle; The length of the subsequent sliding time window is set according to the length of the last half of the sine cycle within the previous sliding time window.

7. The method as described in claim 1, characterized in that, In step 4, the roll angle γ of the magnetoresistive sensor is calculated in quadrants, and the calculation formula is as follows: Among them, the axis lagging behind by 90 degrees during clockwise rotation is the roll angle, and the roll angle γ of the magnetoresistive sensor is calculated using formula (5); m NX and m NY These are the geomagnetic intensity data for the X and Y axes after self-calibration.

8. The method as described in claim 1, characterized in that, Step 5 is as follows: Step 51: Based on the installation offset angle φ between the sensitive axis of the magnetoresistive sensor and the 0° axis of the flight body's roll attitude. b The roll angle γ of the magnetoresistive sensor is corrected by installation offset to obtain the roll angle γ of the aircraft relative to the geomagnetic direction. m : c m =mod(γ+φ b ,2π) Step 52: Based on the local magnetic inclination angle φ m The roll angle γ of the flying body relative to the geomagnetic direction m Perform ground-finding correction to obtain the roll angle γ of the aircraft relative to the ground. g ; Here, mod(·) is the modulo operation.

9. A scalar geomagnetic self-homing and transient roll angle measuring device for high-rotation flying bodies, used to perform the roll angle measurement method according to claims 1-8, characterized in that, The device includes: a main control module, a geomagnetic measurement module, a storage module, a communication bus, and a power supply module; The geomagnetic measurement module includes a dual-axis magnetoresistive sensor and an analog-to-digital converter circuit. The dual-axis magnetoresistive sensor is installed parallel to the cross-section of the flight body to measure orthogonal dual-axis geomagnetic intensity data, which is converted into digital signals by the analog-to-digital converter circuit and sent to the main control module and the storage module. The main control module is used to run the roll angle measurement method and calculate the roll angle γ of the flight body relative to the ground. g ; Storage module for saving the mounting bias angle φ of the magnetoresistive sensor. b Local magnetic inclination φ m The initial binding data, including the original measurement data from the geomagnetic measurement module, and the roll angle data of the flight body calculated by the main control module; The communication bus is used to enable data communication between the main control module, the geomagnetic measurement module, and the storage module. The power module is used to supply power to the various modules in the device.

10. A scalar geomagnetic self-homing and transient roll angle measurement system for high-speed rotating aircraft, comprising a titanium alloy protective device and a roll angle measurement device as described in claim 9, characterized in that: The titanium alloy protective device is installed at the tail of the aircraft; the roll angle measuring device is installed inside the titanium alloy protective device and encapsulated through a potting process.

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