Method of monitoring an aircraft landing gear and aircraft implementing the method

Abstract

A method for monitoring the landing gear (100) of an aircraft includes the step of using information from at least one accelerometer (108), the accelerometer being securely attached to a landing gear wheel (103) mounted to rotate on a landing gear wheel axle (102), to estimate the deflection angle of the wheel axle at least when the wheel is in contact with the ground. An aircraft implementing this method.

Description

Technical Field

[0001] This invention relates to the field of aviation, and more specifically, to the monitoring of aircraft landing gear. Background Technology

[0002] The aircraft landing gear is constantly monitored. Landing gear is rarely equipped with hard-landing sensors capable of emitting signals for a specific hard landing, which could cause deformation of certain landing gear components, particularly the axles that support the landing gear wheels. This sensor constitutes additional onboard equipment and is a source of extra weight and maintenance.

[0003] Furthermore, there is no requirement to monitor landing gear axle deflection in real time to check whether these deflections meet expected values ​​during service, or conversely, whether they reach values ​​indicating plastic deformation of a portion of the landing gear. In practice, these plastic deformations can only be detected during major maintenance operations, when the landing gear is removed from the aircraft and returned to the maintenance workshop. Summary of the Invention

[0004] The purpose of this invention is to provide a device for real-time monitoring of aircraft landing gear, which does not require the landing gear to be equipped with temporary devices or to be removed.

[0005] To achieve this objective, a method for monitoring aircraft landing gear is proposed, which includes the step of using information from at least one accelerometer, which is securely attached to a landing gear wheel mounted to rotate on a landing gear wheel axle, to estimate at least the deflection angle of the wheel axle when the wheel is in contact with the ground.

[0006] In this way, the presence of accelerometers on the landing gear wheels is used to evaluate the signal to generate information that is not directly related to the wheels but is useful for monitoring the landing gear itself and its deformation during use.

[0007] Specifically, the landing gear wheels are equipped with tire pressure monitoring systems (TPMS). The latest devices of this type to be developed are energy-sufficient, transmit their information remotely, and are equipped with at least one triaxial accelerometer. Some even have two accelerometers, one for identifying the flight phase (especially by detecting the acceleration caused by the wheels hitting the ground during landing), and the other for identifying the angular position of the device when the aircraft is stationary.

[0008] Therefore, according to an advantageous embodiment of the invention, signals from one or more accelerometers integrated into a device for monitoring the pressure of a tire fixed to the wheel are used. In this way, the presence of the accelerometers in the tire pressure monitoring device can be utilized to use the signals. The signals from these accelerometers are always available and can therefore be used to generate the desired information about the landing gear.

[0009] The present invention also relates to an aircraft equipped to implement the method. Attached Figure Description

[0010] The invention can be better understood from the following description of specific embodiments of the invention given with reference to the accompanying drawings, in which:

[0011] [ Figure 1 ] Figure 1 This is a schematic diagram of an aircraft landing gear, with wheels shown in dashed lines to indicate the axles that support them;

[0012] [ Figure 2 ] Figure 2 yes Figure 1 A three-dimensional diagram of one half-rim of the landing gear wheel, equipped with a tire pressure monitoring device;

[0013] [ Figure 3 ] Figure 3 This is a schematic diagram of various reference points used to utilize accelerometer signals, showing the wheel from the side;

[0014] [ Figure 4 ] Figure 4 Looking at it from the front Figure 1 A partial schematic diagram of the landing gear in the figure, showing in an exaggerated manner the wheel axle deflection to be estimated by the method of the present invention. Detailed Implementation

[0015] This invention relates to the monitoring of aircraft landing gear 100, such as... Figure 1 As shown. The landing gear 100 includes a strut 101 fixed to the aircraft structure, the strut 101 carrying an axle 102, and wheels 103 mounted on the axle 102 for rotation. Each wheel 103 includes a rim 104 that carries a tire 105. In a manner known per se, each rim includes two half-rims bolted together. Figure 2 The outer half-rim 106 is shown, equipped with a tire pressure monitoring device 107. This device incorporates at least one accelerometer 108, in this example a triaxial accelerometer, whose signal is used according to the invention. The following direct reference points are used to indicate the evaluation of the accelerometer signal:

[0016]

[0017] like Figure 3 and Figure 4 As shown, the reference structure is as follows:

[0018] - Reference point G: A direct orthogonal reference point related to the wheel under consideration, which is not tilted and mounted on a perfectly non-bent axle, with its origin at point O, where the axis Z... g Vertical, axis Xg Horizontal and following the direction of forward movement, axis Y g Horizontal and complete the direct orthogonal trihedron;

[0019] - Reference point A: A direct orthogonal reference point related to the wheel axle, whose origin is located at point O on the geometric axis of the wheel axle, approximately at the center of wheel 103. For example... Figure 4 More specifically, the reference point G passes through the axis X. g The rotation angle α is converted into a reference point A, where α is the estimated deflection angle of the wheel axle. a The shaft extends along the axis of rotation of the wheel. The origin of this reference point is along the X-axis with velocity V0. g Axis motion. The transformation matrix from reference point G to reference point A is as follows:

[0020]

[0021] - Reference point M: A direct orthogonal reference point related to the wheel, with its origin located on the Y-axis. a Point M is located at a distance R. Reference point M essentially corresponds to the center of the accelerometer 108 carried by the pressure monitoring device 107. Reference point M is located around the axis Y. a Rotation angle This angle is derived from reference point A. This is the rotation angle of the wheels when the aircraft is moving. Therefore, the rotational speed of the wheels is... Y m axis along Y a Movement in the same direction as the axis. Z m The axis extends radially, while X m The axis extends along an orthogonal radial direction. The transformation matrix from reference point A to reference point M is as follows:

[0022]

[0023] - Reference point C: A direct reference point (not necessarily orthogonal) associated with the accelerometer 108 carried by the pressure monitoring device 107. The three axes of reference point C correspond to the three input axes of the three basic accelerometers forming accelerometer 108. It should be noted that, theoretically, reference points C and M coincide. In practice, due to assembly defects, they are slightly offset from each other. The alignment error (or misalignment) of the accelerometer is limited by a movement from reference point M to reference point C through six small rotations. , , , , , It defines the transformation matrix used to obtain the acceleration measured from reference point M and sensed by accelerometer 108 at reference point C:

[0024]

[0025] With all calculations completed and only first-order terms retained, the acceleration values ​​measured by the basic accelerometer of the triaxial accelerometer 108 along the three axes of reference point C are... (basically orthogonal radial) (Along the direction that is substantially parallel to the central axis of the wheel axle) and (Basically radial):

[0026]

[0027] In this expression, It is the acceleration due to Earth's gravity. It is the distance R and the wheel's rolling radius. d The ratio between them, and the quantity , , This is the offset (commonly referred to as bias) that affects the acceleration measurements on each axis of the accelerometer 108. Lateral acceleration It appears to include various items, including:

[0028] 1- Item This parameter remains essentially constant during the ground rolling phase and therefore depends directly on the deflection angle of the wheel axle 102. ;

[0029] 2- Offset Item This term is essentially constant;

[0030] 3- Wheels in , The periodic variable term at the point of rotation;

[0031] 4- Finally, with the rotational speed of the wheel The variable.

[0032] According to the present invention, by utilizing lateral acceleration This allows us to estimate the deflection angle of the axle 102. .

[0033] According to a first specific type of embodiment of the method of the present invention, based on orthogonal radial acceleration and / or radial acceleration To estimate the rotation angle of wheel 103 And based on this estimate, the rotational speed is estimated. These two estimates enable the estimation of variables 3 / and 4 / , in order to separate them from lateral acceleration. Eliminate the middle part, thus retaining only what will be processed to extract the deflection angle. Quantity .

[0034] A second specific type of embodiment of the invention includes using a low-pass filter to adjust the rotation angle of the wheel 103. The periodic variable term is filtered, and the cutoff frequency of this low-pass filter is lower than the rotation frequency of the wheel (equal to...). Thus, the filtered acceleration is obtained:

[0035]

[0036] At sufficiently high speeds, the offset term can... Neglecting the effect, the filtered acceleration This item A good estimate. By using the expression... The replacement will yield the following items:

[0037]

[0038] Therefore, the same quantity can be estimated again. This allows for monitoring of the wheel axle's deflection angle. The last type of relationship can be modeled as:

[0039]

[0040] Where v is the measurement noise, and:

[0041]

[0042] Then, the two components of the state vector X can be estimated by accumulating the y and h measurements over the effective time period of the filter, just after the initial transient of wheel 103 hitting the ground and before the wheel speed is too slow (i.e., when the wheel frequency is below the filter cutoff frequency), and then by any suitable method such as the pseudo-inverse method.

[0043] A first algorithm for implementing a second specific type of embodiment of the method of the present invention is now described. It comprises the following five steps:

[0044] A- Acceleration Measurement and It begins at a fixed frequency (e.g., 100 Hz) and is then filtered using a low-pass filter with a cutoff frequency of a few hertz. Sampling starts from landing, when... It can be detected when a certain threshold or saturation is exceeded. Filtering can start from the saturation value, allowing the transition period to pass more quickly and enabling the filter to be built up faster;

[0045] B- Once the saturation phase has passed, the following data will be collected at the same or lower frequency:

[0046] .

[0047] in, It is the sampling time;

[0048] C- Sampling stops when the wheel speed falls below a given threshold. The threshold is used for detection.

[0049] D- The sampled data is placed in the following matrix form:

[0050]

[0051] Estimated state vector X It is achieved by using pseudo-inverse calculate And obtained.

[0052] E- Finally, through (Ignore offset) The estimated deflection angle α is obtained by... Obtain the estimated misalignment .

[0053] The first algorithm can be activated as soon as the landing gear wheels touch the ground. This moment can be detected by monitoring tire pressure and detecting a sudden increase in tire pressure mounted on the rims. This triggers the acquisition of measurement values. If the measurement values ​​saturate, the start of processing may be delayed. Specifically, acceleration and... The centripetal acceleration integral can reach tens of g at the start of rotation. However, in this case, a low-pass filter can be activated, allowing for a faster attainment of a steady state (eliminating transients). Measurements are taken after a pre-defined time to calculate quantities Y and H. Sampling is performed after a pre-defined time or when acceleration... The process ends when the value drops below a predetermined threshold. Below this threshold, the low-pass filter is no longer effective in eliminating the sinusoidal variable term. Then, calculations can be performed. .

[0054] Calculations can be performed in real time in one of the aircraft's computers (e.g., onboard computing devices on the wheels or landing gear), or remotely by transmitting data to a data collection device during each flight or when the aircraft is being inspected at a maintenance center.

[0055] The pseudo-inverse computation can be replaced by recursive least squares. This can be used to smooth the computational load during the acquisition process. For example, when using a large number of points for the least squares estimation of the state vector, the previously performed low-pass filtering step A / can be omitted, and then the least squares estimation achieves the filtering effect.

[0056] A second simplified algorithm is now proposed. In fact, the previous algorithm was better suited for misalignment. Very sensitive. If misaligned... It is roughly known at least before flight (e.g., obtained using a first algorithm, assuming it remains sufficiently constant over a period of time, which is usually the case), and at a sufficiently low speed, the term... and Compared to the smaller assumptions, the filtered lateral acceleration The following corrections have been made:

[0057]

[0058] The estimated deflection angle α can then be obtained directly using the following formula:

[0059]

[0060] An alternative embodiment of the method of the present invention is applied to a wheel, wherein the pressure monitoring device 107 of the wheel includes a second accelerometer 109, which is also triaxial and arranged radially relative to the first accelerometer 108. The acceleration measured by the first accelerometer 108 is invoked. , , and acceleration measured by the second accelerometer 109 , , radial acceleration and Values:

[0061]

[0062] The average of these two accelerations is:

[0063]

[0064] Within this average value, The variable terms in the original text have disappeared. There is a sinusoidal variable term, but its amplitude is low, making it easier to filter. Then, this average acceleration is used to implement the method of this invention.

[0065] Because of the method of the present invention, the deflection angle of the wheel axle can be estimated using only signals from one or more accelerometers carried by the relevant wheel. This estimation can be used to monitor wheel axle deformation in various ways, such as:

[0066] - When the aircraft is in operation, monitor any deflection of the wheel axle and check at each landing whether the deflection of the wheel axle remains within a value compatible with normal elastic deformation;

[0067] - Record any deflection estimated in this way to build a trend curve and detect any drift of that deflection over time;

[0068] - Detecting significant deflection after landing, potentially indicating plastic deformation of the wheel axle, is the result of one of the accelerations measured by one or more accelerometers exceeding a predetermined threshold.

[0069] The present invention is not limited to the above description; rather, it covers any variations within the scope defined by the appended claims.

[0070] Specifically, although this example uses a signal from a triaxial accelerometer integrated into the tire pressure monitoring unit, it is more general to use an accelerometer that is not necessarily triaxial, since the deflection angle can even be estimated using a single filtered lateral acceleration:

[0071]

[0072] If the rotational speed of the axle can also be estimated (e.g., by using speed information provided by a tachometer) to eliminate the term. .

[0073] Reference point G can be located at the landing zone.

[0074] This invention can be applied to aircraft carrying an electronic control unit (e.g., including a processor and memory), which is connected to an accelerometer and executes a computer program including instructions arranged to implement the method. The electronic control unit is, for example, an Aircraft Condition Monitoring System (ACMS). Alternatively, the electronic control unit is housed in a landing gear bay and can be inspected via radio or wired link using a maintenance terminal.

Claims

1. A method for monitoring an aircraft landing gear (100), the aircraft landing gear being provided with a pressure monitoring device (107) for monitoring the pressure of a tire (105), the tire (105) being carried by a wheel (103) of the landing gear, the wheel (103) being mounted to rotate on a landing gear axle (102), the method comprising the step of estimating a deflection angle α of the axle at least when the wheel is in contact with the ground, characterized in that, The estimation uses information from at least one accelerometer (108) integrated into the pressure monitoring device (107).

2. The method according to claim 1, characterized in that, The lateral acceleration measured by the accelerometer (108) in a direction substantially parallel to the central axis of the wheel axle (102) and dependent on the deflection angle α of the wheel axle. Used to estimate the deflection angle α.

3. The method according to claim 2, characterized in that, Based on the orthogonal radial acceleration measured by the accelerometer (108) and / or radial acceleration To estimate the rotation angle of the wheel (103) Then estimate the rotational speed. These two estimates are used to extract the lateral acceleration term that varies with rotational angle and rotational speed. Eliminate from the middle, and then adjust the lateral acceleration according to the reprocessed lateral acceleration. To estimate the deflection angle of the wheel axle.

4. The method according to claim 2, characterized in that, By eliminating the rotation angle of the wheel The periodically changing terms affect the lateral acceleration measured by the accelerometer (108). and radial acceleration Filtering is performed to obtain the filtered lateral acceleration. and filtered radial acceleration .

5. The method according to claim 4, characterized in that, Filtering begins at the moment of landing, when the radial acceleration... absolute value Landing is detected when a certain threshold is exceeded or saturation occurs.

6. The method according to claim 4, characterized in that, After the filter has been established: - Collect data in, It is the sampling time. It is the filtered lateral acceleration. It is the filtered radial acceleration; - The collected data is presented in the following matrix format: - Perform pseudo-inverse calculation, by using pseudo-inverse calculate To estimate the state vector ; - By calculation Estimate the deflection angle of the wheel axle, where g is the acceleration due to gravity.

7. The method according to claim 6, characterized in that, The pseudo-inverse calculation is replaced by recursive least squares.

8. The method according to claim 4, characterized in that, Based on the filtered acceleration and Calculate the corrected acceleration : in, The deflection angle of the axle is predetermined or estimated, and is estimated through the following calculations. in, It is gravitational acceleration.

9. The method according to claim 4, characterized in that, Two accelerometers (108, 109) are arranged radially opposite each other on the wheel (103) and measure their respective radial accelerations. and And within it, the average radial acceleration is formed. It is then used as the radial acceleration for estimating the deflection angle of the wheel axle.

10. An aircraft comprising at least one landing gear having wheels, at least one accelerometer attached to the wheels, the accelerometer being connected to an electronic control unit, the electronic control unit executing a computer program comprising instructions arranged to implement the method according to any one of the preceding claims.

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