Method for compensating and correcting total static pressure based on flight state of helicopter

Abstract

The invention provides a total static pressure compensation correction method based on the flight state of a helicopter, and belongs to the technical field of helicopter control, and the method specifically comprises the steps: carrying out the comparative analysis based on actual flight data and collected data, and obtaining a total static pressure correction value comparison table of an atmospheric engine under different airspeed drop rates; the indicated total pressure and the indicated static pressure of the current product are collected, and the indicated airspeed is calculated; based on the indicated airspeed calculated in the current period and the lifting speed calculated in the previous period, the total pressure correction and the static pressure correction in the current period are calculated through a comparison table; real static pressure and real total pressure are obtained based on the correction; calculating a real indicated airspeed according to the real static pressure and the real total pressure; and according to the real static pressure, the lifting speed of the period is obtained based on a lifting speed calculation formula. According to the scheme, an accurate data source can be obtained, the air speed error correction is avoided, the air speed is closer to the real air speed, flight control is facilitated, and the flight quality is improved.

Description

Technical Field

[0001] The present application relates to the technical field of helicopter control, and in particular to a method for performing total static pressure compensation correction based on the flight status of a helicopter. Background Art

[0002] Compared with the three-axis atmospheric data system, the most significant feature of the distributed atmospheric data system is that the measurement angle of the airspeed tube head of the distributed atmospheric data system is fixed, and it can only measure the speed within a certain angle of attack directly in front of the helicopter nose. Therefore, when the incoming flow angle of attack exceeds the insensitive range of the pitot tube measurement, the total pressure measurement loss increases exponentially. At the same time, due to the influence of the helicopter nose profile, the static pressure measurement of the distributed atmospheric data system is in the negative pressure area, and the measured static pressure is less than the actual static pressure, which ultimately leads to abnormal airspeed signal solution. When the airspeed is abnormal, the simple processing measure is to directly correct the airspeed so that it can smoothly pass through the abnormal interval. This method can improve the output airspeed quality, but it does not fundamentally solve the source of the airspeed abnormality. With the increasing number of different helicopters in different flight states, the airspeed abnormality must be fundamentally solved, that is, the original measured total static pressure must be corrected. Summary of the invention

[0003] In view of this, the embodiment of the present application provides a method for total static pressure compensation correction based on the flight status of the helicopter, which at least partially solves the problems existing in the prior art: when the helicopter is climbing or descending while flying forward, when the angle of the velocity vector and exceeds the pitot tube measurement angle, as the excess angle increases, the total pressure loss increases in an indicated level, and at the same time, different forward flight speeds will cause the negative pressure area near the atmospheric data system to change, which will lead to inaccurate static pressure measurement. The indicated airspeed finally calculated is different from the actual airspeed of the aircraft, and this phenomenon is more obvious in the low-speed section. Inaccurate airspeed will cause abnormal judgment of the aircraft attitude by the flight control, affecting flight control and flight experience.

[0004] The embodiment of the present application provides a method for performing total static pressure compensation correction based on the flight state of a helicopter, the method comprising:

[0005] Based on the comparison and analysis between the actual flight data and the collected data, a static pressure correction comparison table and a total pressure correction comparison table of the atmospheric aircraft at different airspeed descent rates are obtained, wherein an array of the static pressure correction comparison table is a static pressure correction corresponding to an ascending speed and an indicated airspeed, and an array of the total pressure correction comparison table is a total pressure correction corresponding to an ascending speed and an indicated airspeed;

[0006] Collect the indicated total pressure and indicated static pressure of the current product;

[0007] Calculating the indicated airspeed according to the indicated total pressure and the indicated static pressure based on an indicated airspeed calculation formula;

[0008] Based on the indicated airspeed calculated in the current cycle and the vertical speed calculated in the previous cycle, the static pressure correction amount of the current cycle is calculated by the static pressure correction amount comparison table, and the total pressure correction amount of the current cycle is calculated by the total pressure correction amount comparison table;

[0009] Based on the indicated static pressure and the static pressure correction amount of this cycle, the real static pressure is obtained; based on the indicated total pressure and the total pressure correction amount of this cycle, the real total pressure is obtained;

[0010] Calculate the true indicated airspeed according to the true static pressure and the true total pressure based on the indicated airspeed calculation formula;

[0011] According to the real static pressure, based on the lifting speed calculation formula, the lifting speed of this cycle is obtained.

[0012] According to a specific implementation of the embodiment of the present application, collecting the indicated total pressure and indicated static pressure of the current product includes:

[0013] The indicated total pressure and indicated static pressure are collected respectively by the total pressure sensor and static pressure sensor inside the product.

[0014] According to a specific implementation of the embodiment of the present application, the indicated airspeed calculation formula is:

[0015] When M≤1,

[0016] When M>1,

[0017] Where M is the Mach number, q c is the dynamic pressure, which is the difference between the indicated total pressure and the indicated static pressure, in kPa; V i is the indicated airspeed, unit: km / h; P n is the standard atmospheric pressure at sea level 101.325 kPa, unit kPa; k is the adiabatic index, c n is the standard speed of sound at sea level, in m / s.

[0018] According to a specific implementation of an embodiment of the present application, the indicated airspeed calculated in the current cycle and the vertical speed calculated in the previous cycle, the static pressure correction amount of the current cycle is calculated through the static pressure correction amount comparison table, and the total pressure correction amount of the current cycle is calculated through the total pressure correction amount comparison table, including:

[0019] The indicated airspeed calculated in the current cycle and the vertical speed calculated in the previous cycle are used as the data elements to be checked;

[0020] When the data element to be checked is within the data range of the static pressure correction value comparison table and the total pressure correction value comparison table, the position of the data element to be checked in the array is found using the bisection table lookup method to obtain the static pressure correction value and the total pressure correction value of this cycle.

[0021] According to a specific implementation of the embodiment of the present application, the use of the bisection table lookup method to find the position of the data element to be queried in the array to obtain the static pressure correction value and the total pressure correction value of the current cycle includes:

[0022] According to the data element to be checked, in the static pressure correction value comparison table or the total pressure correction value comparison table, the indicated airspeed calculated in the current cycle is interpolated between two adjacent indicated airspeeds that may include the indicated airspeed calculated in the current cycle, and the vertical speed calculated in the previous cycle is interpolated between two adjacent vertical speeds that may include the vertical speed calculated in the previous cycle;

[0023] According to the pressure correction calculation formula, the static pressure correction amount of this cycle and the total pressure correction amount of this cycle are calculated respectively. The pressure correction calculation formula is:

[0024] de lta1=(Pb1-Pa1)*(vi-via) / (vib-via)+Pa1

[0025] de lta2=(Pb2-Pa2)*(vi-via) / (vib-via)+Pa2

[0026] de lta=(de lta2-de lta1)*(hr-hra) / (hrb-hra)+de lta1

[0027] Wherein, delta is the pressure correction value, delta1 and delta2 are the interpolation ranges of the current vertical speed under the current indicated airspeed vi, vi a and vib are respectively two adjacent indicated airspeeds that may include the indicated airspeed calculated in the current cycle, hr and hb are respectively two adjacent vertical speeds that may include the vertical speed calculated in the previous cycle, Pa1, Pb1, Pa2, Pb2 correspond to the pressure correction values ​​of the positions of (via, hra), (vi b, hra), (via, hrb), (vib, hrb), respectively, vi is the indicated airspeed calculated in the current cycle, and hr is the vertical speed calculated in the previous cycle.

[0028] According to a specific implementation of the embodiment of the present application, the lifting speed calculation formula is:

[0029] Hrate = dhp*(Ps0avg-Ps1avg) / (static pressure sampling time*half of the static pressure filter array length);

[0030] Where: Hrate is the ascent and dhp is the inverse of the atmospheric pressure gradient; Ps0avg is the average value of the first half of the static pressure filter array after removing the maximum and minimum values; Ps1avg is the average value of the second half of the static pressure filter array after removing the maximum and minimum values.

[0031] Beneficial effects:

[0032] The method for compensating and correcting the total static pressure based on the flight state of the helicopter in the embodiment of the present application establishes a corresponding relationship between the total static pressure measured by the atmospheric data system and the actual total static pressure of the aircraft at different airspeeds and different lifting speeds. When the aircraft is in a certain state, the loss of the measured pressure is compensated accordingly to obtain the actual pressure and other atmospheric parameters of the aircraft. By introducing the airspeed and lifting speed that can reflect the state of the helicopter, the idea of ​​directly compensating and correcting the airspeed is abandoned, and the abnormal pressure at the source is directly compensated and corrected, an accurate data source can be obtained, the airspeed is avoided from being incorrectly corrected, and it can be closer to the actual airspeed, which is beneficial to flight control and improves flight quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0034] Figure 1 The figure is a schematic diagram of airspeed line results calculated by a method for total static pressure compensation correction based on helicopter flight status according to an embodiment of the present invention. DETAILED DESCRIPTION

[0035] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0036] The following describes the implementation methods of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The present application can also be implemented or applied through other different specific implementation methods, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that, in the absence of conflict, the following embodiments and the features in the embodiments can be combined with each other. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work belong to the scope of protection of the present application.

[0037] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on the present application, it should be understood by those skilled in the art that an 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 described herein can be used to implement the device and / or practice the method. In addition, other structures and / or functionalities other than one or more of the aspects described herein can be used to implement this device and / or practice this method.

[0038] It should also be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present application. The illustrations only show the components related to the present application rather than being drawn according to the number, shape and size of the components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed at will, and the component layout may also be more complicated.

[0039] Additionally, in the following description, specific details are provided to facilitate a thorough understanding of the examples. However, it will be understood by those skilled in the art that the aspects described may be practiced without these specific details.

[0040] The present application embodiment provides a method for total static pressure compensation correction based on the flight state of a helicopter. Figure 1 Describe in detail.

[0041] The embodiment of the present application provides a method for performing total static pressure compensation correction based on the flight state of a helicopter, the method comprising:

[0042] Step 1: Based on the actual flight data and the collected data, a comparison table of static pressure corrections and a comparison table of total pressure corrections of atmospheric aircraft at different airspeed descent rates are obtained, wherein an array of the static pressure correction comparison table is a static pressure correction corresponding to an ascending speed and an indicated airspeed, and an array of the total pressure correction comparison table is a total pressure correction corresponding to an ascending speed and an indicated airspeed;

[0043] Step 2: Collect the indicated total pressure and indicated static pressure of the current product;

[0044] Step 3, calculating the indicated airspeed according to the indicated total pressure and the indicated static pressure based on the indicated airspeed calculation formula;

[0045] Step 4, based on the indicated airspeed calculated in this cycle and the vertical speed calculated in the previous cycle, the static pressure correction amount of this cycle is calculated by the static pressure correction amount comparison table, and the total pressure correction amount of this cycle is calculated by the total pressure correction amount comparison table;

[0046] Step 5: Based on the indicated static pressure and the static pressure correction amount of this cycle, the real static pressure is obtained; based on the indicated total pressure and the total pressure correction amount of this cycle, the real total pressure is obtained;

[0047] Step 6, calculating the true indicated airspeed according to the true static pressure and the true total pressure based on the indicated airspeed calculation formula;

[0048] Step 7: According to the actual static pressure and based on the lifting speed calculation formula, the lifting speed of this cycle is obtained.

[0049] As the forward flight speed increases, the impact on static pressure gradually decreases; under the condition of a certain forward flight speed, the greater the absolute value of the vertical speed and the larger the local angle of attack, the greater the error in measuring the total pressure. When the angle of attack exceeds the critical angle, the total pressure error increases exponentially.

[0050] This embodiment establishes a corresponding relationship (comparison table) between the total static pressure measured by the atmospheric data system and the actual total static pressure of the aircraft at different airspeeds and different lifting speeds, and compensates for the loss of measured pressure when the aircraft is in a certain state to obtain the actual pressure and other atmospheric parameters of the aircraft. Therefore, by introducing the airspeed and lifting speed that can reflect the state of the helicopter, the loss of total static pressure is compensated and corrected, and the accuracy of the airspeed is improved, which has important practical significance for improving the flight quality.

[0051] Furthermore, the indicated total pressure and indicated static pressure of the current product are collected, including:

[0052] The indicated total pressure and indicated static pressure are collected respectively by the total pressure sensor and static pressure sensor inside the product.

[0053] Furthermore, the calculation formulas for indicated airspeed in subsonic and supersonic conditions are different, and the indicated airspeed is calculated segment by segment using a formula, and the indicated airspeed calculation formula is:

[0054] When M≤1,

[0055] When M>1,

[0056] Where M is the Mach number, q c is the dynamic pressure, which is the difference between the indicated total pressure and the indicated static pressure, in kPa; V i is the indicated airspeed, unit: km / h; P n is the standard atmospheric pressure at sea level, 101.325 kPa, in kPa; k is the adiabatic index, with a value of 1.4; c n It is the standard speed of sound at sea level, in m / s, and its value is 340.294 m / s.

[0057] Further, the static pressure correction amount of the current cycle is calculated based on the indicated airspeed calculated in the current cycle and the vertical speed calculated in the previous cycle through the static pressure correction amount comparison table, and the total pressure correction amount of the current cycle is calculated through the total pressure correction amount comparison table, including:

[0058] The indicated airspeed calculated in the current cycle and the vertical speed calculated in the previous cycle are used as the data elements to be checked;

[0059] When the data element to be checked is within the data range of the static pressure correction value comparison table and the total pressure correction value comparison table, the position of the data element to be checked in the array is found using the bisection table lookup method to obtain the static pressure correction value and the total pressure correction value of this cycle.

[0060] In specific implementation, the static pressure correction comparison table includes the static pressure correction comparison table of the left atmospheric engine at different airspeed descent rates as shown in Table 1 and the static pressure correction comparison table of the right atmospheric engine at different airspeed descent rates as shown in Table 3, and the total pressure correction comparison table includes the total pressure correction comparison table of the left atmospheric engine at different airspeed descent rates as shown in Table 2 and the total pressure correction comparison table of the right atmospheric engine at different airspeed descent rates as shown in Table 4. In the table, ΔPsL is the static pressure correction of the left atmospheric engine, PtL is the total pressure correction of the left atmospheric engine, PsR is the static pressure correction of the right atmospheric engine, and PtR is the total pressure correction of the right atmospheric engine. The pressure correction data in the table are obtained by comparing and analyzing the actual flight data with the collected data, and adjusting them in combination with experience.

[0061] Table 1 Left-hand engine static pressure correction for different airspeed descent rates

[0062]

[0063]

[0064] Table 2 Total pressure correction of the left atmospheric engine at different airspeed descent rates

[0065]

[0066] Table 3 Right-hand engine static pressure correction for different airspeed descent rates

[0067]

[0068] Table 4 Correction of total pressure of right atmospheric engine at different airspeed descent rates

[0069]

[0070]

[0071] Furthermore, the method of using the bisection table lookup method to find the position of the data element to be searched in the array to obtain the static pressure correction value and the total pressure correction value of the current cycle includes:

[0072] According to the data element to be checked, in the static pressure correction value comparison table or the total pressure correction value comparison table, the indicated airspeed calculated in the current cycle is interpolated between two adjacent indicated airspeeds that may include the indicated airspeed calculated in the current cycle, and the vertical speed calculated in the previous cycle is interpolated between two adjacent vertical speeds that may include the vertical speed calculated in the previous cycle;

[0073] According to the pressure correction calculation formula, the static pressure correction amount of this cycle and the total pressure correction amount of this cycle are calculated respectively. The pressure correction calculation formula is:

[0074] de l ta1=(Pb1-Pa1)*(vi-vi a) / (vi b-vi a)+Pa1

[0075] de l ta2=(Pb2-Pa2)*(vi-vi a) / (vi b-vi a)+Pa2

[0076] de l ta=(de l ta2-de l ta1)*(hr-hra) / (hrb-hra)+de l ta1

[0077] Wherein, de l ta is the pressure correction value, de l ta1 and de l ta2 are the interpolation ranges of the current vertical speed under the current indicated airspeed vi, vi a and vi b are respectively two adjacent indicated airspeeds that may include the indicated airspeed calculated in the current cycle, hr and hb are respectively two adjacent vertical speeds that may include the vertical speed calculated in the previous cycle, Pa1, Pb1, Pa2, Pb2 correspond to the pressure correction values ​​of the positions of (vi a, hra), (vi b, hra), (vi a, hrb), (vib, hrb), respectively, vi is the indicated airspeed calculated in the current cycle, and hr is the vertical speed calculated in the previous cycle.

[0078] In specific implementation, according to the indicated airspeed calculated in this cycle and the ascending and descending speed calculated in the previous cycle, the total pressure correction amount and the static pressure correction amount of this cycle are calculated by looking up Tables 1 to 4 respectively through the pressure correction calculation formula, and the true total pressure and true static pressure are calculated. The ascending and descending speed is set to 0 during the first calculation.

[0079] The bisection table lookup method specifically includes the following contents:

[0080] When the data element to be queried is less than the first element of the array, the result is 0;

[0081] When the data element to be checked is greater than the last element of the array, the result (array length - 2) is returned;

[0082] If the first two conditions are not met, the bisection table lookup method is used to find the left position of the data element to be queried in the array and return the corresponding result. The calculation formula for the true total pressure and true static pressure is:

[0083] True total pressure = indicated total pressure + total pressure correction;

[0084] True static pressure = indicated static pressure + static pressure correction.

[0085] According to a specific implementation of the embodiment of the present application, the lifting speed calculation formula is:

[0086] Hrate = dhp*(Ps0avg-Ps1avg) / (static pressure sampling time*half of static pressure filter array length);

[0087] Among them: Hrate is the lifting speed, dhp is the inverse of the atmospheric pressure gradient; Ps0avg is the average value of the first half of the static pressure filter array after removing the maximum and minimum values; Ps1avg is the average value of the second half of the static pressure filter array after removing the maximum and minimum values. According to experience, the filter array length is 40.

[0088] The airspeed line results calculated based on the method of this application are as follows Figure 1 shown.

[0089] The embodiment provided by the present invention, the airspeed correction method for pressure compensation of total static pressure based on the aircraft status, abandons the idea of ​​directly compensating and correcting the airspeed, and directly compensates and corrects the abnormal pressure at the source, compared with the existing airspeed correction method, can obtain an accurate data source, avoid erroneous correction of airspeed, can be closer to the actual airspeed, is beneficial to flight control, and improves flight quality.

[0090] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A method for total static pressure compensation correction based on helicopter flight status, characterized in that: The method comprises: Based on the comparison and analysis between the actual flight data and the collected data, a static pressure correction comparison table and a total pressure correction comparison table of the atmospheric aircraft at different airspeed descent rates are obtained, wherein an array of the static pressure correction comparison table is a static pressure correction corresponding to an ascending speed and an indicated airspeed, and an array of the total pressure correction comparison table is a total pressure correction corresponding to an ascending speed and an indicated airspeed; Collect the indicated total pressure and indicated static pressure of the current product; Calculating the indicated airspeed according to the indicated total pressure and the indicated static pressure based on an indicated airspeed calculation formula; Based on the indicated airspeed calculated in the current cycle and the vertical speed calculated in the previous cycle, the static pressure correction amount of the current cycle is calculated by the static pressure correction amount comparison table, and the total pressure correction amount of the current cycle is calculated by the total pressure correction amount comparison table; Based on the indicated static pressure and the static pressure correction amount of this cycle, the real static pressure is obtained; based on the indicated total pressure and the total pressure correction amount of this cycle, the real total pressure is obtained; Calculate the true indicated airspeed according to the true static pressure and the true total pressure based on the indicated airspeed calculation formula; According to the real static pressure, based on the lifting speed calculation formula, the lifting speed of this cycle is obtained.

2. The method for total static pressure compensation correction based on helicopter flight status according to claim 1, characterized in that: Collect the indicated total pressure and indicated static pressure of the current product, including: The indicated total pressure and indicated static pressure are collected respectively by the total pressure sensor and static pressure sensor inside the product.

3. The method for total static pressure compensation correction based on helicopter flight status according to claim 1, characterized in that: The indicated airspeed calculation formula is: When M≤1, When M>1, Where M is the Mach number, q c is the dynamic pressure, which is the difference between the indicated total pressure and the indicated static pressure, in kPa; V i is the indicated airspeed, unit: km / h; P n is the standard atmospheric pressure at sea level 101.325 kPa, unit kPa; k is the adiabatic index, c n is the standard speed of sound at sea level, in m / s.

4. The method for total static pressure compensation correction based on helicopter flight status according to claim 1, characterized in that: The step of calculating the static pressure correction amount of the current cycle based on the indicated airspeed calculated in the current cycle and the vertical speed calculated in the previous cycle through the static pressure correction amount comparison table and calculating the total pressure correction amount of the current cycle through the total pressure correction amount comparison table includes: The indicated airspeed calculated in the current cycle and the vertical speed calculated in the previous cycle are used as the data elements to be checked; When the data element to be checked is within the data range of the static pressure correction value comparison table and the total pressure correction value comparison table, the position of the data element to be checked in the array is found using the bisection table lookup method to obtain the static pressure correction value and the total pressure correction value of this cycle.

5. The method for total static pressure compensation correction based on helicopter flight status according to claim 4, characterized in that: The method of using the bisection table lookup method to find the position of the data element to be looked up in the array to obtain the static pressure correction value and the total pressure correction value of the current cycle includes: According to the data element to be checked, in the static pressure correction value comparison table or the total pressure correction value comparison table, the indicated airspeed calculated in the current cycle is interpolated between two adjacent indicated airspeeds that may include the indicated airspeed calculated in the current cycle, and the vertical speed calculated in the previous cycle is interpolated between two adjacent vertical speeds that may include the vertical speed calculated in the previous cycle; According to the pressure correction calculation formula, the static pressure correction amount of this cycle and the total pressure correction amount of this cycle are calculated respectively. The pressure correction calculation formula is: delta1=(Pb1-Pa1)*(vi-via) / (vib-via)+Pa1 delta2=(Pb2-Pa2)*(vi-via) / (vib-via)+Pa2 delta=(delta2-delta1)*(hr-hra) / (hrb-hra)+delta1 Wherein, delta is the pressure correction value, delta1 and delta2 are the interpolation ranges of the current vertical speed under the current indicated airspeed vi, via and vib are respectively two adjacent indicated airspeeds that may include the indicated airspeed calculated in the current cycle, hr and hb are respectively two adjacent vertical speeds that may include the vertical speed calculated in the previous cycle, Pa1, Pb1, Pa2, Pb2 correspond to the pressure correction values ​​of the positions of (via, hra), (vib, hra), (via, hrb), (vib, hrb), respectively, vi is the indicated airspeed calculated in the current cycle, and hr is the vertical speed calculated in the previous cycle.

6. The method for total static pressure compensation correction based on helicopter flight status according to claim 1, characterized in that: The lifting speed calculation formula is: Hrate = dhp*(Ps0avg-Ps1avg) / (static pressure sampling time*half of static pressure filter array length); Where: Hrate is the ascent and dhp is the inverse of the atmospheric pressure gradient; Ps0avg is the average value of the first half of the static pressure filter array after removing the maximum and minimum values; Ps1avg is the average value of the second half of the static pressure filter array after removing the maximum and minimum values.

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