Drone navigation filters

Abstract

The present invention discloses a UAV navigation filter, which includes an inertial navigation unit, a GPS unit, a radar measurement unit, a pressure altitude sensor measurement unit, a signal output unit and a switching unit; wherein the inertial navigation unit is connected to the signal output unit after being connected in parallel with the GPS unit to form a first navigation measurement channel; wherein the inertial navigation unit is connected to the signal output unit after being connected in parallel with the GPS unit, the radar measurement unit and the pressure altitude sensor measurement unit to form a second navigation measurement channel; wherein the switching unit is used to switch the first navigation measurement channel and the second navigation measurement channel. The UAV navigation filter has a wide range of applications and can be simultaneously applied to UAV low-altitude, medium-altitude and high-altitude navigation at sea.

Description

Technical Field

[0001] The present invention relates to the field of aircraft, and in particular to a navigation filter for unmanned aerial vehicles. Background Art

[0002] Existing drones generally use an inertial navigation / GPS combined navigation system, which can meet navigation needs in most cases. However, when the drone is flying at low altitude, the inertial navigation / GPS combined navigation has low accuracy and cannot meet the drone's low-altitude navigation or low-altitude to medium and high-altitude navigation needs.

[0003] Therefore, it is necessary to develop a UAV navigation filter with a wide range of applications that can be used for UAV low-altitude, medium-altitude and high-altitude navigation.

[0004] The information disclosed in the background technology section of the present invention is only intended to deepen the understanding of the general background technology of the present invention, and should not be regarded as acknowledging or suggesting in any form that the information constitutes the prior art already known to those skilled in the art. Summary of the invention

[0005] The purpose of the present invention is to provide a UAV navigation filter, which has a wide application range and can be simultaneously applied to UAV low-altitude, medium-altitude and high-altitude navigation at sea.

[0006] In order to achieve the above-mentioned object, a drone navigation filter is provided according to the present invention, the drone navigation filter comprising: an inertial navigation unit, a GPS unit, a radar measurement unit, a barometric altitude sensor measurement unit, a signal output unit and a switching unit;

[0007] Wherein, the inertial navigation unit and the GPS unit are connected in parallel to the signal output unit to form a first navigation measurement channel;

[0008] The inertial navigation unit is connected in parallel with the GPS unit, the radar measurement unit and the barometric altitude sensor measurement unit and then connected to the signal output unit to form a second navigation measurement channel;

[0009] The switching unit is used for switching between the first navigation measurement channel and the second navigation measurement channel.

[0010] Preferably, the switching unit includes a first switching valve and a second switching valve. The first switching valve is arranged on a channel connecting the GPS unit and the signal transmitter, and the second switching valve is arranged on a channel connected to the signal output unit after the GPS unit, the radar measurement unit and the barometric altitude sensor measurement unit are connected in parallel. When the first switching valve is opened and the second switching valve is closed, it presents a first navigation measurement channel. When the second switching valve is opened and the first switching valve is closed, it presents a second navigation measurement channel.

[0011] Preferably, the UAV navigation filter further includes a combined filter, and the combined filter is arranged on the second navigation measurement channel.

[0012] Preferably, the altitude determination unit is adapted to obtain altitude information of the UAV, and the switching unit controls the switching between the first navigation measurement channel and the second navigation measurement channel based on the altitude information.

[0013] Preferably, the UAV navigation filter also includes: setting a height threshold for the height judgment unit; when the height information is greater than the height threshold, the switching unit switches the UAV navigation filter to the first navigation measurement channel; when the height information is less than or equal to the height threshold, the switching unit switches the UAV navigation filter to the second navigation measurement channel.

[0014] Preferably, the height threshold is 500m.

[0015] Preferably, the drone navigation filter further comprises: a processor, which outputs information based on the measurement result error of the first navigation measurement channel or the second navigation measurement channel, and sends the navigation information to the signal output unit.

[0016] Preferably, the processor outputs information based on the measurement result error of the first navigation measurement channel or the second navigation measurement channel, and the specific steps include:

[0017] The altitude determination unit performs sliding windowing to average the altitude output by the GPS to obtain altitude information;

[0018] When the altitude information is greater than 500m, the difference between the measurement result output by the inertial navigation unit and the average value of the sliding window of the GPS unit is used as output information based on the first navigation measurement channel;

[0019] When the altitude information is less than or equal to 500m, the difference between the measurement result output by the inertial navigation unit and the measurement result after fusion of the GPS unit, the radar measurement unit and the barometric altitude sensor measurement unit is used as output information based on the second navigation measurement channel;

[0020] The specific formula is:

[0021]

[0022] Among them, h I is the measurement result output by the inertial navigation unit, is the sliding window average value of the GPS unit, and y represents the measurement result after the fusion of the GPS unit, the radar measurement unit and the barometric altitude sensor measurement unit.

[0023] Preferably, the measurement results after fusion of the GPS unit, the radar measurement unit and the barometric altitude sensor measurement unit are calculated, and the specific calculation formula is:

[0024]

[0025]

[0026]

[0027]

[0028]

[0029] Where y represents the fused measurement result, W represents the weight coefficient of the measurement values ​​corresponding to the GPS unit, radar measurement unit and barometric altitude sensor measurement unit; X represents the measurement values ​​corresponding to the GPS unit, radar measurement unit and barometric altitude sensor measurement unit, ω R Represents the weight coefficient of the measurement value of the radar measurement unit, ω A Represents the weight coefficient of the measurement value of the barometric altitude sensor measurement unit, ω G Represents the weight coefficient of the measurement value of the GPS unit, h R represents the measurement value of the radar measurement unit, h A Indicates the measured value of the barometric altitude sensor measurement unit, is the average value of the sliding window of GPS units; σ A Represents the standard deviation of the error of the barometric altitude sensor measurement unit; σ R Represents the error standard deviation of the radar measurement unit; σ G Indicates the standard deviation of the GPS unit error; Represents the error variance of the fused measurement results.

[0030] Preferably, the weight coefficient of the height output by the radar measurement unit, the weight coefficient of the height output by the barometric altitude sensor measurement unit, and the weight coefficient of the measurement result output by the GPS unit are specifically formulated as follows:

[0031]

[0032]

[0033]

[0034] Among them, σ R is the standard deviation of the error of the height output by the radar measurement unit, σ A is the standard deviation of the error of the height output by the barometric altitude sensor measurement unit, σ G is the standard deviation of the error in the altitude output by the GPS unit.

[0035] Beneficial effect: The present invention forms a first navigation measurement channel through the arrangement of an inertial navigation unit, a GPS unit, a radar measurement unit and a barometric altitude sensor measurement unit. The inertial navigation unit and the GPS unit form a first navigation measurement channel, so that the UAV navigation filter has two different navigation modes, and the UAV navigation filter has a wide range of applications, and can be simultaneously applicable to UAV low-altitude, medium-altitude and high-altitude navigation at sea. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 Schematic diagram of the structure of a UAV navigation filter according to an embodiment of the present invention.

[0037] Figure 2 It is a three-dimensional flight track diagram of a UAV according to an embodiment of the present invention.

[0038] Figure 3 This is a diagram showing the corresponding relationship between the flight time and altitude of a drone according to an embodiment of the present invention.

[0039] Figure 4 It is a comparison diagram of the local amplification error curves of the prior art navigation filter and the unmanned aerial vehicle navigation filter of the present invention.

[0040] Figure 5 It is a comparison diagram of the height direction R value of the prior art navigation filter and the unmanned aerial vehicle navigation filter of the present invention.

[0041] Figure 6 It is a comparison diagram of the simulation error curves of the anti-interference effects of the prior art navigation filter and the unmanned aerial vehicle navigation filter of the present invention.

[0042] Description of reference numerals:

[0043] 1. First switching valve; 2. Second switching valve. DETAILED DESCRIPTION

[0044] The technical solution of the present invention is described in detail below with reference to the accompanying drawings.

[0045] According to one aspect of the present invention, a drone navigation filter is provided, the drone navigation filter comprising: an inertial navigation unit, a GPS unit, a radar measurement unit, a barometric altitude sensor measurement unit, a signal output unit and a switching unit;

[0046] Wherein, the inertial navigation unit and the GPS unit are connected in parallel to the signal output unit to form a first navigation measurement channel;

[0047] The inertial navigation unit is connected in parallel with the GPS unit, the radar measurement unit and the barometric altitude sensor measurement unit and then connected to the signal output unit to form a second navigation measurement channel;

[0048] The switching unit is used for switching between the first navigation measurement channel and the second navigation measurement channel.

[0049] The unmanned aerial vehicle navigation filter provided by the present invention forms a first navigation measurement channel through the arrangement of an inertial navigation unit, a GPS unit, a radar measurement unit and a barometric altitude sensor measurement unit. The inertial navigation unit and the GPS unit form a first navigation measurement channel, so that the unmanned aerial vehicle navigation filter has two different navigation modes, and the unmanned aerial vehicle navigation filter has a wide range of applications, and can be simultaneously applicable to low-altitude, medium-altitude and high-altitude navigation of unmanned aerial vehicles at sea.

[0050] Specifically, the inertial navigation unit is connected to the GPS unit in parallel and then connected to the signal output unit to form a first navigation measurement channel, which is particularly suitable for navigation of the UAV when operating at medium and high altitudes, and can ensure the navigation accuracy of the UAV when flying at medium and high altitudes; the inertial navigation unit is connected to the GPS unit, the radar measurement unit and the barometric altitude sensor measurement unit in parallel and then connected to the signal output unit to form a second navigation measurement channel, which is particularly suitable for navigation of the UAV when flying at low altitude or flying from low altitude to medium altitude, and can ensure the navigation accuracy of the UAV when flying at low altitude.

[0051] Furthermore, the switching unit includes a first switching valve and a second switching valve. The first switching valve is arranged on a channel connecting the GPS unit and the signal transmitter, and the second switching valve is arranged on a channel connected to the signal output unit after the GPS unit, the radar measurement unit and the barometric altitude sensor measurement unit are connected in parallel. When the first switching valve is opened and the second switching valve is closed, it presents a first navigation measurement channel, and when the second switching valve is opened and the first switching valve is closed, it presents a second navigation measurement channel.

[0052] In this technical solution, the composition of a switching unit is further provided. Through the setting of the first switching valve and the second switching valve, the switching of the first navigation measurement channel and the second navigation measurement channel of the UAV navigation filter is realized, making the use of the UAV navigation filter more convenient and quick, and improving the operability of the UAV navigation filter.

[0053] Furthermore, the UAV navigation filter also includes a combined filter, and the combined filter is arranged on the second navigation measurement channel.

[0054] In this technical solution, by setting up a combined filter, it is possible to eliminate outliers and smooth data, thereby improving the navigation accuracy of the UAV navigation filter.

[0055] Further, the altitude determination unit is adapted to obtain altitude information of the UAV, and the switching unit controls the switching between the first navigation measurement channel and the second navigation measurement channel based on the altitude information.

[0056] In this technical solution, an altitude judgment unit is further included, through which the first navigation measurement channel and the second navigation measurement channel can be automatically switched based on the altitude of the UAV, making the use of the UAV navigation filter more convenient and intelligent.

[0057] Furthermore, the UAV navigation filter also includes: setting a height threshold for the height judgment unit; when the height information is greater than the height threshold, the switching unit switches the UAV navigation filter to the first navigation measurement channel; when the height information is less than or equal to the height threshold, the switching unit switches the UAV navigation filter to the second navigation measurement channel.

[0058] In this technical solution, a working method of the altitude judgment unit is further provided. By setting an altitude threshold for the altitude judgment unit, the altitude judgment unit is compared with the altitude threshold, and the working mode of the drone navigation filter can be further determined based on the comparison result, making the use of the drone navigation filter more convenient and intelligent.

[0059] Furthermore, the height threshold is set to 500m.

[0060] In this technical solution, a value of the height threshold is further provided. By selecting 500m, the actual flight altitude of the UAV is compared with 500m. If the flight altitude exceeds 500m, the first navigation measurement channel is used to navigate the UAV. If the flight altitude is lower than or equal to 500m, the second navigation measurement channel is used to navigate the UAV, thereby improving the navigation accuracy of the UAV when flying at low, medium and high altitudes at sea.

[0061] Furthermore, the UAV navigation filter also includes: a processor, which outputs information based on the measurement result error of the first navigation measurement channel or the second navigation measurement channel, and sends the navigation information to the signal output unit.

[0062] In this technical solution, a processor is further included, and navigation information can be acquired by processing the measurement result of the first navigation measurement channel or the second navigation measurement channel through the processor, and the signal output unit can send out the navigation information.

[0063] Further, the processor outputs information based on the measurement result error of the first navigation measurement channel or the second navigation measurement channel, and the specific steps include:

[0064] The altitude determination unit performs sliding windowing to average the altitude output by the GPS to obtain altitude information;

[0065] When the altitude information is greater than 500m, the difference between the measurement result output by the inertial navigation unit and the average value of the sliding window of the GPS unit is used as output information based on the first navigation measurement channel;

[0066] When the altitude information is less than or equal to 500m, the difference between the measurement result output by the inertial navigation unit and the measurement result after fusion of the GPS unit, the radar measurement unit and the barometric altitude sensor measurement unit is used as output information based on the second navigation measurement channel;

[0067] The specific formula is:

[0068]

[0069] Among them, h I is the measurement result output by the inertial navigation unit, is the sliding window average value of the GPS unit, and y represents the measurement result after the fusion of the GPS unit, the radar measurement unit and the barometric altitude sensor measurement unit.

[0070] In this technical solution, a working method of the processor is further provided, and a specific method for obtaining navigation information is provided. Specifically, when the average value of the sliding window of the GPS unit is used as the actual altitude of the UAV flight, if the altitude value is greater than 500m, the difference between the measurement result output by the inertial navigation unit and the average value of the sliding window of the GPS unit is output as navigation information. If the altitude value is less than or equal to 500m, the difference between the measurement result output by the inertial navigation unit and the weighted average of the sliding window of the GPS unit, the measurement result output by the radar measurement unit, and the measurement result output by the pressure altitude sensor measurement unit is used as navigation information. Based on the different flight altitude airspaces where the UAV is located, a variable structure combined navigation filtering scheme can be proposed to ensure the accuracy of navigation and improve the anti-interference ability.

[0071] Furthermore, the measurement results after fusion of the GPS unit, the radar measurement unit and the barometric altitude sensor measurement unit are calculated, and the specific calculation formula is:

[0072]

[0073]

[0074]

[0075]

[0076]

[0077] Where y represents the fused measurement result, W represents the weight coefficient of the measurement values ​​corresponding to the GPS unit, radar measurement unit and barometric altitude sensor measurement unit; X represents the measurement values ​​corresponding to the GPS unit, radar measurement unit and barometric altitude sensor measurement unit, ω R Represents the weight coefficient of the measurement value of the radar measurement unit, ω A Represents the weight coefficient of the measurement value of the barometric altitude sensor measurement unit, ω G Represents the weight coefficient of the measurement value of the GPS unit, h R represents the measurement value of the radar measurement unit, h A Indicates the measured value of the barometric altitude sensor measurement unit, is the average value of the sliding window of GPS units; σ A Represents the standard deviation of the error of the barometric altitude sensor measurement unit; σ R Represents the error standard deviation of the radar measurement unit; σ G Indicates the standard deviation of the GPS unit error; Represents the error variance of the fused measurement results.

[0078] In this technical solution, further, by obtaining a fused measurement result through weighted averaging of the GPS unit, the radar measurement unit and the radar sensor unit, it has extremely high adaptability to single sensor failure and sudden changes in measurement noise, thereby improving navigation accuracy.

[0079] In this technical solution, a method for obtaining the weight coefficient of each sensor is further provided, so that the measurement results output by the GPS unit, the radar measurement unit and the radar sensor unit are more accurate.

[0080] In this technical solution, the standard deviation of the measurement error output after the fusion of the GPS unit, the radar measurement unit and the radar sensor unit is further provided to provide reference data for calculating the optimal solution of the navigation filter.

[0081] Furthermore, the weight coefficient of the height output by the radar measurement unit, the weight coefficient of the height output by the barometric altitude sensor measurement unit, and the weight coefficient of the measurement result output by the GPS unit are specifically formulated as follows:

[0082]

[0083]

[0084]

[0085] Among them, σ R is the standard deviation of the error of the height output by the radar measurement unit, σ A is the standard deviation of the error of the height output by the barometric altitude sensor measurement unit, σ G is the standard deviation of the error in the altitude output by the GPS unit.

[0086] In this technical solution, the weight coefficient of the output measurement result is further obtained based on the error standard deviation of the measurement results output by the GPS unit, the radar measurement unit and the air pressure sensor unit, so that the weight coefficient of the measurement results output by the GPS unit, the radar measurement unit and the radar air pressure sensor unit can realize dynamic weight allocation, thereby further improving the accuracy of UAV navigation.

[0087] Example 1

[0088] Figure 1 Schematic diagram of the structure of a UAV navigation filter according to an embodiment of the present invention. Figure 2 It is a three-dimensional flight track diagram of a UAV according to an embodiment of the present invention. Figure 3 This is a diagram showing the corresponding relationship between the flight time and altitude of a drone according to an embodiment of the present invention. Figure 4 It is a comparison diagram of the local amplification error curves of the prior art navigation filter and the unmanned aerial vehicle navigation filter of the present invention. Figure 5It is a comparison diagram of the height direction R value of the prior art navigation filter and the unmanned aerial vehicle navigation filter of the present invention. Figure 6 It is a comparison diagram of the simulation error curves of the anti-interference effects of the prior art navigation filter and the unmanned aerial vehicle navigation filter of the present invention.

[0089] like Figure 1 As shown, the UAV navigation filter includes an inertial navigation unit, a GPS unit, a radar measurement unit, an air pressure altitude sensor measurement unit, a signal output unit and a switching unit;

[0090] Wherein, the inertial navigation unit and the GPS unit are connected in parallel to the signal output unit to form a first navigation measurement channel;

[0091] The inertial navigation unit is connected in parallel with the GPS unit, the radar measurement unit and the barometric altitude sensor measurement unit and then connected to the signal output unit to form a second navigation measurement channel;

[0092] The switching unit is used for switching between the first navigation measurement channel and the second navigation measurement channel.

[0093] Furthermore, the switching unit includes a first switching valve 1 and a second switching valve 2. The first switching valve 1 is arranged on a channel connecting the GPS unit and the signal transmitter, and the second switching valve 2 is arranged on a channel connected to the signal output unit after the GPS unit, the radar measurement unit and the barometric altitude sensor measurement unit are connected in parallel. When the first switching valve 1 is opened and the second switching valve 2 is closed, it presents a first navigation measurement channel. When the second switching valve 2 is opened and the first switching valve 1 is closed, it presents a second navigation measurement channel.

[0094] Furthermore, the UAV navigation filter also includes a combined filter, and the combined filter is arranged on the second navigation measurement channel.

[0095] Further, the altitude determination unit is adapted to obtain altitude information of the UAV, and the switching unit controls the switching between the first navigation measurement channel and the second navigation measurement channel based on the altitude information.

[0096] Furthermore, the UAV navigation filter also includes: setting a height threshold for the height judgment unit; when the height information is greater than the height threshold, the switching unit switches the UAV navigation filter to the first navigation measurement channel; when the height information is less than or equal to the height threshold, the switching unit switches the UAV navigation filter to the second navigation measurement channel.

[0097] Furthermore, the height threshold is set to 500m.

[0098] Furthermore, the UAV navigation filter also includes: a processor, which outputs information based on the measurement result error of the first navigation measurement channel or the second navigation measurement channel, and sends the navigation information to the signal output unit.

[0099] Further, the processor outputs information based on the measurement result error of the first navigation measurement channel or the second navigation measurement channel, and the specific steps include:

[0100] The altitude determination unit performs sliding windowing to average the altitude output by the GPS to obtain altitude information;

[0101] When the altitude information is greater than 500m, the difference between the measurement result output by the inertial navigation unit and the average value of the sliding window of the GPS unit is used as output information based on the first navigation measurement channel;

[0102] When the altitude information is less than or equal to 500m, the difference between the measurement result output by the inertial navigation unit and the measurement result after fusion of the GPS unit, the radar measurement unit and the barometric altitude sensor measurement unit is used as output information based on the second navigation measurement channel;

[0103] The specific formula is:

[0104]

[0105] Among them, h I is the measurement result output by the inertial navigation unit, is the sliding window average value of the GPS unit, and y represents the measurement result after the fusion of the GPS unit, the radar measurement unit and the barometric altitude sensor measurement unit.

[0106] In this technical solution, a working method of the processor is further provided, and a specific method for obtaining navigation information is provided. Specifically, when the average value of the sliding window of the GPS unit is used as the actual altitude of the UAV flight, if the altitude value is greater than 500m, the difference between the measurement result output by the inertial navigation unit and the average value of the sliding window of the GPS unit is output as navigation information. If the altitude value is less than or equal to 500m, the difference between the measurement result output by the inertial navigation unit and the weighted average of the sliding window of the GPS unit, the measurement result output by the radar measurement unit, and the measurement result output by the pressure altitude sensor measurement unit is used as navigation information. Based on the different flight altitude airspaces where the UAV is located, a variable structure combined navigation filtering scheme can be proposed to ensure the accuracy of navigation and improve the anti-interference ability.

[0107] Furthermore, the measurement results after fusion of the GPS unit, the radar measurement unit and the barometric altitude sensor measurement unit are calculated, and the specific calculation formula is:

[0108]

[0109]

[0110]

[0111]

[0112]

[0113] Where y represents the fused measurement result, W represents the weight coefficient of the measurement values ​​corresponding to the GPS unit, radar measurement unit and barometric altitude sensor measurement unit; X represents the measurement values ​​corresponding to the GPS unit, radar measurement unit and barometric altitude sensor measurement unit, ω R Represents the weight coefficient of the measurement value of the radar measurement unit, ω A Represents the weight coefficient of the measurement value of the barometric altitude sensor measurement unit, ω G Represents the weight coefficient of the measurement value of the GPS unit, h R represents the measurement value of the radar measurement unit, h A Indicates the measured value of the barometric altitude sensor measurement unit, is the average value of the sliding window of GPS units; σ A Represents the standard deviation of the error of the barometric altitude sensor measurement unit; σ R Represents the error standard deviation of the radar measurement unit; σ G Indicates the standard deviation of the GPS unit error; Represents the error variance of the fused measurement results.

[0114] In this technical solution, further, by obtaining a fused measurement result through weighted averaging of the GPS unit, the radar measurement unit and the radar sensor unit, it has extremely high adaptability to single sensor failures and sudden changes in measurement noise, thereby improving navigation accuracy.

[0115] In this technical solution, a method for obtaining the weight coefficient of each sensor is further provided, so that the measurement results output by the GPS unit, the radar measurement unit and the radar sensor unit are more accurate.

[0116] In this technical solution, the standard deviation of the measurement error output after the fusion of the GPS unit, the radar measurement unit and the radar sensor unit is further provided to provide reference data for calculating the optimal solution of the navigation filter.

[0117] Furthermore, the weight coefficient of the height output by the radar measurement unit, the weight coefficient of the height output by the barometric altitude sensor measurement unit, and the weight coefficient of the measurement result output by the GPS unit are specifically formulated as follows:

[0118]

[0119]

[0120]

[0121] Among them, σ R is the standard deviation of the error of the height output by the radar measurement unit, σ A is the standard deviation of the error of the altitude output by the barometric altitude sensor measurement unit, and σG is the standard deviation of the error of the altitude output by the GPS unit.

[0122] In this technical solution, the weight coefficient of the output measurement result is further obtained based on the error standard deviation of the measurement results output by the GPS unit, the radar measurement unit and the air pressure sensor unit, so that the weight coefficient of the measurement results output by the GPS unit, the radar measurement unit and the radar air pressure sensor unit can realize dynamic weight allocation, thereby further improving the accuracy of UAV navigation.

[0123] In this embodiment, the UAV performs a sliding window (width of 20) on the GPS unit output altitude to calculate the average value in real time while flying in the air. When the altitude average value is greater than or equal to 500m, a combined filtering is performed using the GPS unit and the inertial navigation unit. When the altitude average value is less than 500m, the filter structure is adjusted, and the altitude channel information in the filter is switched to the altitude obtained by weighted fusion of the radar measurement unit, the barometric altitude sensor measurement unit, and the GPS unit.

[0124] Specifically, the simulation duration is set to 1500s, the UAV is launched with a rocket boost at a pitch angle of 14°, and the simulation route is divided into climbing, descending, and low-altitude cruising. The gyroscope constant drift is 1° / h; the white noise mean square error is 0.1° / h; the first-order Markov process mean square error is 0.1° / h; the accelerometer zero bias stability is 2×10 -4 g. The correlation time of the gyro first-order Markov process is 3600s, and the correlation time of the acceleration zero bias first-order Markov process is 1800s. The GPS unit horizontal position measurement error is 20m, the height measurement error is 30m, and the speed measurement error is 0.2m / s. The radar measurement unit measurement error is 0.3+3%H; the pressure altitude sensor measurement unit measurement error is 25m.

[0125] The height measurement error of the radar measurement unit was set to 10m and 8m at 960s-970s and 1000-1005s; the measurement error of the GPS unit was set to 80m at 1050s-1060s to verify the anti-interference ability of the filter.

[0126] in, Figure 2 and Figure 3 It is the flight track and time altitude curve of the UAV.

[0127] Figure 4 Figure 2 is the local amplification error curve of the altitude channel in the constant altitude flight section under the same conditions using the existing standard Kalman filter and the UAV navigation filter proposed by the present invention, where the dotted line represents the existing standard Kalman filter and the solid line represents the improved Kalman filter of the UAV navigation filter of the present invention. Figure 4 It can be seen that the introduction of the radar measurement unit measurement data significantly improves the filtering accuracy of the filter, and the curve has smaller fluctuations and better smoothness.

[0128] Figure 5 The height direction R value comparison of the existing standard Kalman filter and the UAV navigation filter proposed in this invention under the same conditions, where the dotted line represents the existing standard Kalman filter and the solid line represents the improved Kalman filter of the UAV navigation filter. The height measurement noise variance of the standard Kalman filter is always the preset empirical value (900m 2 ), and the improved filter can calculate the standard deviation of the altitude channel fusion error in real time as the UAV flight altitude and sensor measurement accuracy change, and reasonably adjust the R value.

[0129] Figure 6 : is the filter anti-interference effect simulation error curve, where the dotted line represents the existing standard Kalman filter, and the solid line represents the improved standard Kalman filter of the UAV navigation filter proposed by the present invention. Figure 6 It can be seen that when the standard Kalman filter is used, the error increases significantly with the increase of GPS altitude measurement noise at 1050s to 1060s; while the unmanned aerial vehicle navigation filter of the present invention adopts the optimal dynamic weight allocation in the low-altitude constant altitude flight segment, the weight of GPS measurement data is relatively small, and the sudden measurement noise has basically no effect on the filtering result. The radar measurement unit measurement noise at 960 to 970s and 1000 to 1005s causes jitter in the error curve, but the present invention can effectively suppress interference and keep its altitude error within a small range without affecting flight safety.

[0130] The comparison of the navigation information of the unmanned aerial vehicle navigation filter of the present invention and the navigation information of the prior art is shown in Table 1:

[0131] Table 1

[0132]

[0133] It can be seen from Table 1 that the navigation accuracy of the UAV navigation filter of the present invention is significantly improved.

[0134] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A UAV navigation filter, characterized in that: The drone navigation filter includes: an inertial navigation unit, a GPS unit, a radar measurement unit, an air pressure altitude sensor measurement unit, a signal output unit and a switching unit; Wherein, the inertial navigation unit and the GPS unit are connected in parallel to the signal output unit to form a first navigation measurement channel; The inertial navigation unit is connected in parallel with the GPS unit, the radar measurement unit and the barometric altitude sensor measurement unit and then connected to the signal output unit to form a second navigation measurement channel; Wherein, the switching unit is used to switch the first navigation measurement channel and the second navigation measurement channel; an altitude determination unit, the altitude determination unit being adapted to obtain altitude information of the drone, the switching unit controlling the switching between the first navigation measurement channel and the second navigation measurement channel based on the altitude information; Among them, the UAV navigation filter also includes: setting a height threshold for the height judgment unit, when the height information is greater than the height threshold, the switching unit switches the UAV navigation filter to the first navigation measurement channel, when the height information is less than or equal to the height threshold, the switching unit switches the UAV navigation filter to the second navigation measurement channel.

2. The UAV navigation filter according to claim 1, characterized in that: The switching unit includes a first switching valve and a second switching valve. The first switching valve is arranged on a channel connecting the GPS unit and the signal output unit. The second switching valve is arranged on a channel connected to the signal output unit after the GPS unit, the radar measurement unit and the barometric altitude sensor measurement unit are connected in parallel. When the first switching valve is opened and the second switching valve is closed, it presents a first navigation measurement channel. When the second switching valve is opened and the first switching valve is closed, it presents a second navigation measurement channel.

3. The UAV navigation filter according to claim 1, characterized in that: The system also includes a combined filter, which is arranged on the second navigation measurement channel.

4. The UAV navigation filter according to claim 1, characterized in that: The height threshold is 500m.

5. The UAV navigation filter according to claim 4, characterized in that: The system further includes a processor, which outputs information based on a measurement result error of the first navigation measurement channel or the second navigation measurement channel, and sends the information to the signal output unit.

6. The unmanned aerial vehicle navigation filter according to claim 5, characterized in that: The processor outputs information based on the measurement result error of the first navigation measurement channel or the second navigation measurement channel, and the specific steps include: The altitude determination unit performs sliding windowing to average the altitude output by the GPS to obtain altitude information; When the altitude information is greater than 500m, the difference between the measurement result output by the inertial navigation unit and the average value of the sliding window of the GPS unit is used as output information based on the first navigation measurement channel; When the altitude information is less than or equal to 500m, the difference between the measurement result output by the inertial navigation unit and the measurement result after fusion of the GPS unit, the radar measurement unit and the barometric altitude sensor measurement unit is used as output information based on the second navigation measurement channel; The specific formula is: Among them, h I is the measurement result output by the inertial navigation unit, is the sliding window average value of the GPS unit, and y represents the measurement result after the fusion of the GPS unit, the radar measurement unit and the barometric altitude sensor measurement unit.

7. The UAV navigation filter according to claim 6, characterized in that: The measurement results after fusion of the GPS unit, the radar measurement unit and the barometric altitude sensor measurement unit are calculated. The specific calculation formula is: Where y represents the fused measurement result, W represents the weight coefficient of the measurement values ​​corresponding to the GPS unit, radar measurement unit and barometric altitude sensor measurement unit; X represents the measurement values ​​corresponding to the GPS unit, radar measurement unit and barometric altitude sensor measurement unit, ω R Represents the weight coefficient of the measurement value of the radar measurement unit, ω A Represents the weight coefficient of the measurement value of the barometric altitude sensor measurement unit, ω G Represents the weight coefficient of the measurement value of the GPS unit, h R represents the measurement value of the radar measurement unit, h A Indicates the measured value of the barometric altitude sensor measurement unit, is the average value of the sliding window of GPS units; σ A Represents the standard deviation of the error of the barometric altitude sensor measurement unit; σ R Represents the error standard deviation of the radar measurement unit; σ G Indicates the standard deviation of the GPS unit error; Represents the error variance of the fused measurement results.

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