A method for judging the rationality of the helicopter gravity center based on hovering attitude

Abstract

The present application belongs to the technical field of helicopter overall, and relates to a method for judging the rationality of the center of gravity of a helicopter based on a hovering attitude. The method comprises: collecting multi-dimensional airborne sensor data of the helicopter in a hovering state; identifying key factors that will cause the center of gravity to deviate from the multi-dimensional airborne sensor data; calculating a linear regression model of the take-off weight point and the pitch angle in the hovering state according to the key factors; and judging the rationality of the center of gravity according to the linear regression model. The present application is suitable for the test flight and delivery stage of the helicopter, and can quickly judge whether the center of gravity of the helicopter is within a safe range, thereby reducing the test flight and use cost and risk of the helicopter.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of helicopters, and relates to a method for judging rationality of a center of gravity of a helicopter based on a hovering attitude. BACKGROUND

[0002] Flight safety and quality of a helicopter are significantly affected by the position of the center of gravity. When the helicopter is flying, exceeding the limit range of the center of gravity will cause problems such as larger rotor load, flight load, attitude of the fuselage, and poor control stability, and even loss of control. Therefore, it is crucial to evaluate the rationality of the center of gravity of the helicopter before flight.

[0003] At present, the center of gravity of the helicopter is mainly evaluated before flight by manual calculation, such as calculating the center of gravity of the whole machine according to the theoretical or actual weight center of gravity data of the empty machine, crew, load, fuel and the like, and then further judging whether the center of gravity will exceed the limit range of the center of gravity during use.

[0004] The prior art has the following disadvantages: the calculation is complex, and the rationality of the center of gravity cannot be quickly judged; human errors cannot be completely avoided, resulting in calculation errors. SUMMARY

[0005] The application aims to evaluate and judge whether the center of gravity of a helicopter meets the limit requirements during use by collecting the attitude of the helicopter during takeoff hovering at different weights. The application is suitable for the test flight and delivery of the helicopter to the user, and can quickly judge whether the center of gravity of the helicopter is within a safe range, thereby reducing the cost and risk of the test flight and use of the helicopter.

[0006] TECHNICAL SCHEME

[0007] A method for judging rationality of a center of gravity of a helicopter based on a hovering attitude is provided, comprising:

[0008] Collecting multi-dimensional airborne sensor data of the helicopter in a hovering state;

[0009] Identifying key factors that will cause the center of gravity to deviate from the multi-dimensional airborne sensor data;

[0010] According to the key factors, a linear regression model of the takeoff weight point and the pitch angle in the hovering state is calculated;

[0011] According to the linear regression model, the rationality of the center of gravity is judged.

[0012] Further, the key factors that will cause the center of gravity to deviate are identified from the multi-dimensional airborne sensor data, comprising:

[0013] Identifying the center of gravity characteristics of the model, and identifying the risk points of the center of gravity;

[0014] According to the design characteristics, the use environment and the risk point of the center of gravity of the helicopter, key factors causing the center of gravity deviation are identified.

[0015] Further, according to the key factors, a linear regression model of the take-off weight center of gravity point and the pitch angle in the hovering state is calculated, including:

[0016] According to the maximum allowable take-off weight and the center of gravity limit range of the helicopter, weight center of gravity data of a series of key take-off weight points are calculated; the weight center of gravity data includes the take-off weight and the position of the center of gravity of the whole machine; these take-off weight points represent that the position of the center of gravity of the whole machine in the full fuel state and the empty fuel state is within the center of gravity envelope range; wherein, the position of the center of gravity of the whole machine in the full fuel state is the rear limit of the center of gravity of the helicopter, and the position of the center of gravity of the whole machine in the empty fuel state is the front limit of the center of gravity of the helicopter;

[0017] Using a high-precision helicopter flight mechanics model based on flight test data correction, the hovering attitude of the aircraft at each take-off weight point is calculated.

[0018] Further, using a high-precision helicopter flight mechanics model based on flight test data correction, the hovering attitude of the aircraft at each take-off weight point is calculated, including:

[0019] A high-precision helicopter flight mechanics model is established, and the whole machine is trimmed;

[0020] According to the take-off weight of each take-off weight point, the pitch angle of the helicopter in the hovering state is calculated through the trimmed flight model.

[0021] Further, the linear regression model is:

[0022] θi=aWi+b;

[0023] a and b are regression coefficients; Wi is the take-off weight of the take-off weight point; θi is the corresponding pitch angle in the hovering state.

[0024] Further, according to the linear regression model, the center of gravity rationality is judged, including:

[0025] The actual take-off weight of the helicopter is read by the airborne weight sensor;

[0026] According to the linear regression model, the theoretical pitch angle corresponding to the actual take-off weight is calculated;

[0027] The actual pitch angle of the helicopter in the hovering state is obtained;

[0028] The actual take-off weight corresponding to the theoretical pitch angle and the actual pitch angle are compared, and the center of gravity rationality is judged.

[0029] Further, for the case of forward movement of the center of gravity with fuel consumption, the actual pitch angle corresponding to the actual take-off weight is compared with the theoretical pitch angle, and the rationality of the center of gravity is judged, including:

[0030] If the actual pitch angle > the theoretical pitch angle, it indicates that the current center of gravity of the helicopter is further than the preset center of gravity, and the center of gravity of the whole machine will not exceed the front limit of the center of gravity with fuel consumption, the center of gravity of the whole machine is reasonable, and the center of gravity limit will not be exceeded in use.

[0031] If the actual pitch angle = the theoretical pitch angle, it indicates that the current center of gravity of the helicopter is consistent with the preset center of gravity, and the center of gravity of the whole machine will not exceed the front limit of the center of gravity with fuel consumption, the center of gravity of the whole machine is reasonable, and the center of gravity limit will not be exceeded in use.

[0032] If the actual pitch angle < the theoretical pitch angle, it indicates that the current center of gravity of the helicopter is further than the preset center of gravity, and the center of gravity of the whole machine has the risk of exceeding the front limit of the center of gravity with fuel consumption, the center of gravity of the whole machine is unreasonable, and the center of gravity of the whole machine needs to be adjusted.

[0033] Further, for the case of forward movement of the center of gravity with fuel consumption, the actual pitch angle corresponding to the actual take-off weight is compared with the theoretical pitch angle, and the rationality of the center of gravity is judged, including:

[0034] If the actual pitch angle > the theoretical pitch angle, it indicates that the current center of gravity of the helicopter is further than the preset center of gravity, and the center of gravity of the whole machine will not exceed the front limit of the center of gravity with fuel consumption, the center of gravity of the whole machine is reasonable, and the center of gravity limit will not be exceeded in use.

[0035] If the actual pitch angle = the theoretical pitch angle, it indicates that the current center of gravity of the helicopter is consistent with the preset center of gravity, and the center of gravity of the whole machine will not exceed the front limit of the center of gravity with fuel consumption, the center of gravity of the whole machine is reasonable, and the center of gravity limit will not be exceeded in use.

[0036] If the actual pitch angle < the theoretical pitch angle, it indicates that the current center of gravity of the helicopter is further than the preset center of gravity, and the center of gravity of the whole machine will not exceed the front limit of the center of gravity with fuel consumption, the center of gravity of the whole machine is reasonable, and the center of gravity limit will not be exceeded in use.

[0037] Beneficial effects:

[0038] The application provides a method for evaluating the rationality of the center of gravity of a helicopter based on hovering attitude, which realizes rapid and accurate evaluation of the center of gravity of the helicopter by combining airborne sensor data with a pre-established attitude-weight relationship model. The method first collects multi-dimensional airborne sensor data of the helicopter in a hovering state, including but not limited to real-time parameters measured by devices such as accelerometers, gyroscopes, altimeters, etc.; then inputs these sensor data into a weight analysis system based on hovering attitude for processing and calculation. The system internally integrates an attitude-weight relationship model established through a large number of experiments and flight tests, which can quickly calculate the position of the overall center of gravity of the helicopter according to the current attitude parameters (such as pitch angle) of the helicopter and the total weight information, and evaluate its rationality. Compared with traditional manual measurement or ground weighing methods, this technology has the characteristics of strong real-time performance, simple operation, wide application range, etc., and is particularly suitable for helicopter operation scenarios in complex environments, which can effectively improve flight safety and control efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 Figure 1 is a diagram showing the change of helicopter weight and longitudinal center of gravity position with fuel consumption.

[0040] Figure 2 Figure 4 is a weight and attitude relationship curve diagram under the reasonable center of gravity boundary at different weights. DETAILED DESCRIPTION

[0041] To make the purposes, technical solutions and advantages of the application clearer, the technical solutions in the embodiments of the application will be described in more detail below with reference to the drawings in the embodiments of the application. In the drawings, the same or similar reference signs represent the same or similar elements or elements with the same or similar functions throughout. The described embodiments are part of the embodiments of the application, not all embodiments. The embodiments described below by reference to the drawings are exemplary and are intended to explain the application, and cannot be understood as limiting the application. Based on the embodiments in the application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the application. The embodiments of the application will be described in detail below with reference to the drawings.

[0042] The application provides a method for judging the rationality of the center of gravity of a helicopter based on hovering attitude, comprising:

[0043] Step one: key factor identification

[0044] The position of the center of gravity of the helicopter is mainly affected by the empty center of gravity, the loaded center of gravity and the fuel center of gravity. The center of gravity characteristics of different helicopter platforms are inconsistent, so the model center of gravity characteristics need to be identified first to identify the center of gravity risk points. According to the design characteristics and use environment of the helicopter, the key factors that will cause the center of gravity to deviate are identified.

[0045] For example:

[0046] like Figure 1 As shown, if the fuel tank is located behind the aircraft's center of gravity, the center of gravity will gradually shift forward during flight as fuel is consumed, posing a risk of exceeding the forward limit.

[0047] Uneven payload distribution: The distribution of payloads in different missions may cause changes in the center of gravity. For example, if the payload is loaded behind the center of gravity of the entire aircraft, and there is unloading during flight (such as personnel parachuting), the center of gravity may exceed the forward limit.

[0048] Equipment installation or removal: The addition or removal of certain equipment during helicopter use may affect the overall center of gravity of the helicopter, and changes in the overall center of gravity of the helicopter must be monitored at all times.

[0049] Taking the Type A helicopter as an example, the fuel tank is located behind the rotor shaft at a considerable distance. After fuel is loaded, the aircraft's center of gravity is within its center of gravity envelope. However, during flight, as fuel is consumed, the aircraft's center of gravity will continuously shift forward, posing a risk of exceeding the forward limit of the center of gravity in the later stages of flight. Therefore, fuel consumption needs to be given special attention when designing evaluation methods.

[0050] Step 2: Calculate the appropriate takeoff weight and center of gravity.

[0051] Based on the maximum permissible takeoff weight and center of gravity limit range of helicopter A, the takeoff weight Wi and corresponding longitudinal center of gravity positions Xi (i=1, 2, 3...) at a series of key takeoff weight points are calculated. These takeoff weight points represent the center of gravity positions of helicopter A in both fully fueled and empty-fueled states, and all of these weight points are within the center of gravity envelope. The specific calculation method is as follows:

[0052] 1. Based on the helicopter's design parameters (such as maximum takeoff weight, fuel capacity, etc.), determine a series of reasonable landing weight points. 着陆 (Generally, equal gradient weights are used, covering the range from the minimum weight to the maximum weight, such as 6t, 7t, 8t, 9t, etc.).

[0053] 2. Based on the helicopter's center of gravity limitations, determine Wi 着陆 The corresponding longitudinal center of gravity position Xi 着陆 Here, the vertical center of gravity position indicates the center of gravity of the entire aircraft.

[0054] 3. According to Wi 着陆 Xi 着陆 And the Wi-Fi calculated based on fuel weight and center of gravity during takeoff. 起飞 and Xi 起飞 .

[0055] For example:

[0056] A type helicopter parameters:

[0057] The allowable flight weight is between 5.5t to 10t;

[0058] The longitudinal center of gravity limit range is 8.1m to 8.7m;

[0059] The helicopter fuel weight is 1t, and the longitudinal center of gravity position is 9.8m.

[0060] A type helicopter with fuel consumption, the center of gravity of the whole machine gradually moves forward, the risk point is that the center of gravity of the whole machine may exceed the front boundary 8.1m after the fuel is consumed. Therefore, the landing weight front center of gravity boundary point (6t, 8.1m), (7t, 8.1m), (8t, 8.1m), (9t, 8.1m), (10t, 8.1m) are taken.

[0061] Then according to the landing weight point, the take-off weight center of gravity point is calculated, for example, the landing weight is 6000kg, see table 1.

[0062] Table 1

[0063] Item Weight Weight (t) Longitudinal Center of Gravity Position (m) Remarks Landing 6 8.100 Fuel 1 9.800 Takeoff 7 8.343 When the longitudinal center of gravity at the time of landing is greater than 8.100, the longitudinal center of gravity at the time of takeoff must be greater than 8.343

[0064] The sum of the weight of each item is the take-off weight:

[0065] 6+1=7(t);

[0066] According to the moment method, the center of gravity under the take-off state is obtained:

[0067] (6x8.1+1x9.8) ÷7=8.343;

[0068] The longitudinal center of gravity position corresponding to the take-off weight of 7t is 8.343m.

[0069] Similarly, the following is calculated:

[0070] (8t, 8.313m), (9t, 8.289m), (10t, 8.270m).

[0071] Step three: hover attitude calculation and establishment of linear regression model

[0072] Based on the helicopter flight mechanics model, the hover attitude θi(i=1, 2, 3...) of each take-off weight point is calculated. The specific steps are as follows:

[0073] 1. According to the weight and center of gravity data of each weight point Wi, the pitch angle θi of the helicopter in hover state is calculated.

[0074] 2. Based on the calculated Wi and θi results, establish a linear regression model: θi = aWi + b; where a and b are regression coefficients. The optimal a and b values are fitted by least squares method or other methods.

[0075] For example:

[0076] According to the full machine trim calculation, Table 2 is obtained, and the calculation method refers to the content of Section 12-3 of "Helicopter Aerodynamics" for the balance of the helicopter in hover.

[0077] Table 2

[0078] Weight (t) Longitudinal Center of Gravity Position (m) Pitch Angle (°) Takeoff Weight 1 7t 8.343 4.2 Takeoff Weight 2 8t 8.313 3.7 Takeoff Weight 3 9t 8.289 3.23 Takeoff Weight 4 10t 8.27 2.75

[0079] Linear regression analysis based on Table 2 is shown in Figure 2 :

[0080] The regression calculation model is obtained: θi = -0.482Wi + 7.567.

[0081] Step four: theoretical pitch angle calculation

[0082] Read the takeoff weight W of the helicopter through the airborne weight sensor, and calculate the theoretical pitch angle θ according to the W value and the linear equation θi = aWi + b.

[0083] For example:

[0084] The takeoff weight is 8.6t, and the corresponding pitch angle calculated according to θi = -0.482Wi + 7.567 is 3.42°.

[0085] Step five: actual attitude measurement

[0086] Read the pitch angle β of the helicopter in hover attitude according to the airborne attitude sensor. It should be noted that the sensor data needs to be calibrated and filtered to improve accuracy.

[0087] For example:

[0088] The takeoff weight is 8.6t, and the actual measured hover attitude angle of the helicopter according to the airborne sensor is 3.8°.

[0089] Step six: center of gravity rationality judgment

[0090] (1) With the consumption of fuel, the center of gravity of the whole machine moves forward, and the calculation of the preset center of gravity considers the front boundary of the center of gravity:

[0091] If the actual pitch angle > theoretical pitch angle, it means that the current center of gravity of the helicopter is behind the preset center of gravity, and with the consumption of fuel, the center of gravity of the whole machine will not exceed the front limit of the center of gravity, and the center of gravity of the whole machine is reasonable, and will not exceed the center of gravity limit during use;

[0092] If the actual pitch angle = the theoretical pitch angle, it means that the current center of gravity of the helicopter is consistent with the preset center of gravity, and as the fuel is consumed, the center of gravity of the helicopter will not exceed the front limit of the center of gravity, and the center of gravity of the helicopter is reasonably distributed, and the center of gravity limit will not be exceeded in the use process.

[0093] If the actual pitch angle < the theoretical pitch angle, it means that the current center of gravity of the helicopter is forward of the preset center of gravity, and as the fuel is consumed, the center of gravity of the helicopter will exceed the front limit of the center of gravity, and the center of gravity of the helicopter is not reasonably distributed, and the center of gravity of the helicopter needs to be adjusted again.

[0094] (2) As the fuel is consumed, the center of gravity of the helicopter moves backward, and the calculation of the preset center of gravity considers the rear boundary of the center of gravity:

[0095] If the actual pitch angle > the theoretical pitch angle, it means that the current center of gravity of the helicopter is rearward of the preset center of gravity, and as the fuel is consumed, the center of gravity of the helicopter will exceed the rear limit of the center of gravity, and the center of gravity of the helicopter is not reasonably distributed, and the center of gravity of the helicopter needs to be adjusted again.

[0096] If the actual pitch angle = the theoretical pitch angle, it means that the current center of gravity of the helicopter is consistent with the preset center of gravity, and as the fuel is consumed, the center of gravity of the helicopter will not exceed the rear limit of the center of gravity, and the center of gravity of the helicopter is reasonably distributed, and the center of gravity limit will not be exceeded in the use process.

[0097] If the actual pitch angle < the theoretical pitch angle, it means that the current center of gravity of the helicopter is forward of the preset center of gravity, and as the fuel is consumed, the center of gravity of the helicopter will not exceed the rear limit of the center of gravity, and the center of gravity of the helicopter is reasonably distributed, and the center of gravity limit will not be exceeded in the use process.

[0098] Taking helicopter A as an example, the center of gravity risk point is in the front center of gravity, and the β value and the θ value are compared:

[0099] If β > θ, it means that the current center of gravity of the helicopter is rearward of the preset center of gravity, and as the fuel is consumed, the center of gravity of the helicopter will not exceed the front limit of the center of gravity, and the center of gravity of the helicopter is reasonably distributed, and the center of gravity limit will not be exceeded in the use process.

[0100] If β = θ, it means that the current center of gravity of the helicopter is consistent with the preset center of gravity, and as the fuel is consumed, the center of gravity of the helicopter will not exceed the front limit of the center of gravity, and the center of gravity of the helicopter is reasonably distributed, and the center of gravity limit will not be exceeded in the use process.

[0101] If β < θ, it means that the current center of gravity of the helicopter is forward of the preset center of gravity, and as the fuel is consumed, the center of gravity of the helicopter has the risk of exceeding the front limit of the center of gravity, and the center of gravity of the helicopter is not reasonably distributed, and the center of gravity of the helicopter needs to be adjusted again (such as adjusting the position of the task load).

[0102] For example:

[0103] The takeoff weight is 8.6t, and the helicopter hovering attitude angle actually measured by the on-board sensor is 3.8°, which is greater than 3.42°.

[0104] It can be judged that the helicopter take-off weight is 8.6t, the hovering attitude is 3.8 degrees, the helicopter take-off center of gravity is more rear than the preset center of gravity, and the center of gravity moves forward after the fuel consumption, and still will not exceed the center of gravity limit, meets the task requirement, and can take off.

[0105] Other embodiments of the disclosure will be apparent to those of ordinary skill in the art from a consideration of the specification and practice of the disclosure disclosed herein. This application is intended to cover any variations, uses or adaptations of the disclosure other than those expressly indicated by the claims. The specification and examples are to be regarded as illustrative only, and the true scope and spirit of the disclosure are indicated by the following claims.

[0106] It should be understood that the present disclosure is not limited to the precise structures herein described and illustrated in the drawings, and that various modifications and changes can be made without departing from its scope. The scope of the present disclosure is limited only by the claims that follow.

Claims

1. A method for determining the rationality of the center of gravity of a helicopter based on hovering attitude, characterized in that, The method comprises the following steps: collecting multi-dimensional airborne sensor data of the helicopter in a hovering state; identifying key factors that cause the center of gravity to deviate from the multi-dimensional airborne sensor data; calculating a linear regression model of the take-off weight point and the pitch angle in the hovering state according to the key factors; judging the rationality of the center of gravity according to the linear regression model; judging the rationality of the center of gravity according to the linear regression model, comprising: reading the actual take-off weight of the helicopter through the airborne weight sensor; calculating the theoretical pitch angle corresponding to the actual take-off weight according to the linear regression model; obtaining the actual pitch angle of the helicopter in the hovering state; comparing the theoretical pitch angle corresponding to the actual take-off weight with the actual pitch angle to judge the rationality of the center of gravity.

2. The method of claim 1, wherein, Identifying key factors that cause the center of gravity to deviate from the multi-dimensional airborne sensor data, comprising: identifying the type of the center of gravity, identifying the center of gravity risk point; identifying key factors that cause the center of gravity to deviate according to the design characteristics, use environment and center of gravity risk point of the helicopter.

3. The method of claim 2, wherein, According to the key factors, the linear regression model of the take-off weight center of gravity point and the pitch angle in the hovering state is calculated, comprising: According to the maximum allowable take-off weight of the helicopter and the center of gravity limit range, the weight center of gravity data of a series of key take-off weight points is calculated; the weight center of gravity data includes the take-off weight and the position of the center of gravity of the whole machine; these take-off weight points represent that the position of the center of gravity of the whole machine is within the center of gravity envelope in the full fuel state and the empty fuel state; wherein, the position of the center of gravity of the whole machine in the full fuel state is the rear limit of the center of gravity of the helicopter, and the position of the center of gravity of the whole machine in the empty fuel state is the front limit of the center of gravity of the helicopter; Using the high-precision helicopter flight mechanics model corrected based on flight test data, the helicopter hovering attitude under each take-off weight point is calculated.

4. The method of claim 3, wherein, Using the high-precision helicopter flight mechanics model corrected based on flight test data, the helicopter hovering attitude under each take-off weight point is calculated, comprising: establishing a high-precision helicopter flight mechanics model for the whole machine trim; According to the take-off weight of each take-off weight point, the pitch angle of the helicopter in the hovering state is calculated through the trimmed flight model.

5. The method of claim 4, wherein, The linear regression model is: θi=aWi+b; a and b are regression coefficients; Wi is the take-off weight of the take-off weight point; θi is the corresponding pitch angle in the hovering state.

6. The method of claim 5, wherein, For the case that the center of gravity of the whole machine moves forward with fuel consumption, comparing the theoretical pitch angle corresponding to the actual take-off weight with the actual pitch angle to judge the rationality of the center of gravity, comprising: If the actual pitch angle > the theoretical pitch angle, it indicates that the current center of gravity of the helicopter is behind the preset center of gravity, the center of gravity of the whole machine will not exceed the front limit of the center of gravity with the consumption of fuel, the center of gravity of the whole machine is reasonable, and the center of gravity will not exceed the center of gravity limit in the use process; If the actual pitch angle = the theoretical pitch angle, it indicates that the current center of gravity of the helicopter is consistent with the preset center of gravity, the center of gravity of the whole machine will not exceed the front limit of the center of gravity with the consumption of fuel, the center of gravity of the whole machine is reasonable, and the center of gravity will not exceed the center of gravity limit in the use process; If the actual pitch angle < the theoretical pitch angle, it indicates that the current center of gravity of the helicopter is in front of the preset center of gravity, the center of gravity of the whole machine has the risk of exceeding the front limit of the center of gravity with the consumption of fuel, the center of gravity of the whole machine is unreasonable, and the center of gravity of the whole machine needs to be adjusted.

7. The method of claim 5, wherein, For the case of the whole machine center of gravity moving backward with fuel consumption, the actual take-off weight corresponding to the theoretical pitch angle and the actual pitch angle are compared to make a reasonable judgment of the center of gravity, including: If the actual pitch angle > theoretical pitch angle, it means that the current center of gravity of the helicopter is further back than the preset center of gravity, and the whole machine center of gravity will exceed the rear limit of the center of gravity with the consumption of fuel, and the whole machine center of gravity is not reasonable, and the whole machine center of gravity needs to be adjusted; If the actual pitch angle = theoretical pitch angle, it means that the current center of gravity of the helicopter is consistent with the preset center of gravity, and the whole machine center of gravity will not exceed the rear limit of the center of gravity with the consumption of fuel, and the whole machine center of gravity is reasonable, and the whole machine center of gravity will not exceed the center of gravity limit in the use process; If the actual pitch angle < theoretical pitch angle, it means that the current center of gravity of the helicopter is further forward than the preset center of gravity, and the whole machine center of gravity will not exceed the rear limit of the center of gravity with the consumption of fuel, and the whole machine center of gravity is reasonable, and the whole machine center of gravity will not exceed the center of gravity limit in the use process.

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