Method for adjusting the angular position of a wheel, in particular a wheel of an aircraft landing gear

Abstract

A method for adjusting the angular position of a wheel, in particular a wheel of an aircraft landing gear, which is connected to at least one hydraulic cylinder controlled by a servo valve, the method comprising a step (E1) of determining an angular difference (ε) between a measured value of the angular position (ANGm) and a setpoint angular position (ANGc), a first proportional correction step (R1), a second integral correction step (R2), and a step (E2) of adding a first current (C1) and a second current (C2) in order to determine a control current (COM) of the servo valve, the second integral regulation step (R2) comprising a sub-step of limiting the second current (C2) according to a parametric law (LP) which applies a zero-value second current (C2) when the absolute value of the angular deviation (ε) is less than a determined first angular threshold.

Description

Technical Field

[0001] The present invention relates to the angular orientation of wheels, in particular to the angular orientation of the wheels of the nose landing gear of an aircraft.

[0002] In a known manner, the nose landing gear of an aircraft has wheels that can be maneuvered when the aircraft is on the ground, in particular during the taxiing phase, to allow the pilot to move the aircraft in a desired direction. Various solutions for checking the wheel orientation are known from documents EP2591998A1, US9139295B2, FR2963606A1, and GB813912A.

[0003] As Figure 1 shown, the nose landing gear has a wheel W, the angular position ANG of which is controlled by two hydraulic cylinders, in particular a front hydraulic cylinder V1 and a rear hydraulic cylinder V2. To check the angular position ANG, it is known to use an SC* checking system consisting of a hydraulic module MH, which generally includes a hydraulic pump (not shown) and a servo valve S in order to output a front command COM1* and a rear command COM2* to the front hydraulic cylinder V1 and the rear hydraulic cylinder V2 respectively.

[0004] The checking system SC* includes a calculator CAL*, which is configured to receive a setpoint angular position ANGc and an angular position measurement value ANGm from a control room to derive a COM* control current, which is transmitted to the hydraulic module MH, in particular to the servo valve S, to modify the angular position ANG of the wheel W such that it corresponds to the setpoint angular position ANGc.

[0005] The calculator CAL* is in the form of a computer system that implements the adjustment method as Figure 2 shown. The adjustment method includes:

[0006] a step 11 of determining an angular deviation ε between the measured value ANGm of the angular position and the setpoint angular position ANGc,

[0007] a first proportional correction step B1 in order to determine a first current C1* from the angular deviation ε,

[0008] a second integral correction step B2 in order to determine a second current C2* from the angular deviation ε,

[0009] a step 12 of adding the first current C1* and the second current C2* in order to determine the control current COM* of the servo valve S,

[0010] and a step 13 of limiting the COM* control current in order to limit the value of the sum of the currents C1*, C2* and to provide a suitable control current COM* to the servo valve S.

[0011] This adjustment method is generally effective. However, referring to Figure 3 , when the setpoint angular position ANGc (curve 3A) changes, OSC oscillations of the control current COM* of the servo valve S (curve 3B) are observed, and pressure variations of the hydraulic cylinders V1, V2 during stationary operation are observed. In other words, if the setpoint angular position ANGc does not change, the control current COM* continues to be unnecessarily adjusted.

[0012] In fact, when the angular deviation ε approaches 0, the integral correction B2 is periodically "loaded". In reality, the actual servo valve S does not have perfect characteristics. When receiving a low but non-zero control current COM*, the servo valve S does not start. As a result, the angular deviation ε remains unchanged and the control current COM* will increase. When the control current COM* is strong enough to control the servo valve S, the servo valve S is activated and the angular deviation ε quickly changes its sign and then returns close to 0. This periodic phenomenon leads to OSC oscillations of the control current COM* of the servo valve S and pressure variations of the hydraulic cylinders V1, V2 during stationary operation.

[0013] A direct solution to eliminate this defect is to change the servo valve S in order to obtain a more effective adjustment model when the angular deviation ε approaches 0. In practice, this change has many drawbacks both from a technical (integration, verification, etc.) and economic (cost) perspective.

[0014] Another direct solution is to stop the integral correction to limit the OSC oscillations, but this will reduce the control performance (static error) of the servo valve S and the wear monitoring performance (zero flow drift, etc.).

[0015] Therefore, the present invention aims to eliminate at least some of these defects by proposing a new adjustment method.

[0016] The present invention also relates to an aircraft including the landing gear described previously. Summary of the Invention

[0017] The present invention relates to an adjustment method for the angular position of a wheel, in particular a wheel of an aircraft landing gear, the wheel being connected to at least one hydraulic jack controlled by a servo valve, the method comprising:

[0018] a step of determining the angular deviation between the measured value of the angular position and the setpoint angular position,

[0019] a first proportional correction step for determining a first current from the angular deviation,

[0020] a second integral correction step for determining a second current from the angular deviation; and

[0021] a step of adding the first current and the second current to determine the servo valve control current.

[0022] The remarkable feature of the present invention is that the second integral regulation step includes a sub-step of restricting the second current according to a parametric law, and when the absolute value of the angular deviation is less than a first determined angular threshold, the parametric law applies a second current with a zero value.

[0023] Advantageously, due to the present invention, the integral correction step is only suppressed for small angular deviations (i.e., angular deviations less than the determined first angular threshold). This avoids the correction of the entire branch, which is untimely and causes changes in the cylinder pressure. Therefore, the actual servo valve defect is eliminated without changing the physical structure, thus avoiding the verification step. In addition, since the integral correction is suppressed on a one-time basis, it remains effective in most cases when the angular position of the wheel changes. This ensures optimal control and eliminates side effects.

[0024] According to an aspect of the present invention, when the absolute value of the angular deviation is between a second determined angular threshold and a third determined angular threshold, and the second determined angular threshold and the third determined angular threshold are greater than the first determined angular threshold, the parametric law restricts the second current to the maximum allowable current value. Therefore, when the setpoint angular position changes, the value of the second current is restricted.

[0025] According to an aspect of the present invention, when the absolute value of the angular deviation is between the first determined angular threshold and the second determined angular threshold, the parametric law restricts the second current according to the rising slope between the zero value and the maximum allowable current value.

[0026] According to an aspect of the present invention, when the absolute value of the angular deviation is between the third determined angular threshold and a fourth determined angular threshold greater than the third determined threshold, the parametric law restricts the second current according to the downward slope between the maximum allowable current value and the zero value.

[0027] Therefore, the control transition (rise or fall) is used to restrict the second current.

[0028] The present invention also relates to a system for controlling the angular position of a wheel, which is particularly a wheel of an aircraft landing gear and is connected to at least one hydraulic cylinder controlled by a servo valve. The control system includes a calculator configured to:

[0029] Determine the angular deviation between the measured value of the angular position and the setpoint angular position,

[0030] Perform a first proportional correction to determine a first current from the angular deviation,

[0031] Perform a second integral correction to determine a second current from the angular deviation,

[0032] Add the first current and the second current to determine the servo valve control current, and

[0033] When performing the second integral correction, the second current is limited according to a parametric law, and when the absolute value of the angle difference is less than the determined first angle threshold, the parametric law applies a second current with a zero value.

[0034] The invention also relates to a wheel assembly, the wheel being in particular a wheel of an aircraft landing gear, which is connected to at least one hydraulic cylinder controlled by a servo valve and to the previously described control system for determining the control current of the servo valve.

[0035] Preferably, the wheel is connected to at least one first hydraulic cylinder and a second hydraulic cylinder controlled by a servo valve.

[0036] Preferably, the assembly includes a hydraulic module, the hydraulic module including a servo valve configured to directly control the first hydraulic cylinder and the second hydraulic cylinder.

[0037] The invention also relates to an aircraft landing gear including the previously described assembly. Description of the Drawings

[0038] The present invention will be better understood by reading the following description given by way of example and by referring to the following drawings given as non-limiting examples, in which the same reference numerals denote similar objects.

[0039] Figure 1 is a schematic diagram of a system for adjusting the angular position of a wheel of a front landing gear according to the prior art.

[0040] Figure 2 is a schematic diagram of the steps of a method for adjusting the angular position according to the prior art.

[0041] Figure 3 is a schematic diagram of the time sequence of a setpoint angular position and a servo valve control current according to the prior art.

[0042] Figure 4 is a schematic diagram of a system for controlling the angular position of a wheel of a front landing gear according to an embodiment of the present invention.

[0043] Figure 5 is a schematic diagram of the steps of an angular position adjustment method according to an embodiment.

[0044] Figure 6 is a schematic diagram of a parametric law for limiting the second current of an integral correction.

[0045] Figure 7 is a schematic diagram of the time course of a setpoint angular position, an angle deviation, and a control current of a servo valve according to the present invention.

[0046] It should be noted that for the implementation of the present invention, the accompanying drawings disclose the present invention in detail, and if necessary, the accompanying drawings can of course be used to better define the present invention. Detailed implementation mode

[0047] The present invention relates to a system for controlling the angular position of a wheel, in particular a system for controlling the angular position of the wheels of the nose landing gear of an aircraft. In a known manner, the nose landing gear on an aircraft has wheels that can be maneuvered when the aircraft is on the ground, especially during the taxiing phase, to allow the pilot to move the aircraft in a desired direction.

[0048] Reference Figure 4 , as shown above, the nose landing gear has W wheels, and the angular position ANG of the W wheels is controlled by two hydraulic cylinders, in particular by a front hydraulic cylinder V1 and a rear hydraulic cylinder V2.

[0049] According to the present invention, in order to control the angular position ANG, a control system SC including a hydraulic module MH is used. The hydraulic module MH includes a hydraulic pump (not shown) and a servo valve S to respectively send a front command COM1 and a rear command COM2 to the front hydraulic cylinder V1 and the rear hydraulic cylinder V2.

[0050] The SC control system includes a CAL calculator configured to receive a setpoint angular position ANGc setting and an angular position measurement value ANGm from a control room to derive a control current COM, and the control current COM is transmitted to the MH hydraulic module, in particular to the servo valve S, to modify the angular position ANG of the wheel W so that it corresponds to the setpoint angular position ANGc.

[0051] According to the present invention, the calculator CAL is in the form of a computer system that implements the adjustment method as Figure 5 shown.

[0052] First, the adjustment method includes a step E1 of determining an angular deviation ε between the measured value ANGm of the angular position and the setpoint angular position ANGc.

[0053] Then, the adjustment method includes a first proportional correction step R1 to determine a first current C1 from the angular deviation ε. Reference Figure 5 , during the proportional correction step R1, the angular deviation ε is multiplied by a first constant Kp to subtract the first current C1, and the value of the first current was previously limited by a limiting operator L1. Preferably, the first proportional correction step R1 is similar to the prior art and will not be described in detail.

[0054] The adjustment method includes a second integral correction step R2 to determine a second current C2 from the angular deviation ε.

[0055] Then, in the addition step E2 of the first current C1 and the second current C2, the control current COM of the servo valve S is determined. After the addition of the first current C1 and the second current C2, the value of the COM control current is limited by the limiting operator L2.

[0056] Now, the second integral correction step R2 will be introduced in detail. This includes a sub-step of integrating R2' the angle deviation ε with the second constant Ki to obtain the second current C2. Preferably, during the R2' integration sub-step of the angle deviation ε, if the absolute value of the difference ε is between 0 and a predetermined threshold (2° in this example), the integration is activated / stopped.

[0057] During the integration sub-step R2', the value of the second current C2 is pre-limited by the limiting operator L3 to form the control current COM. The integration sub-step is similar to the prior art and will not be introduced in detail.

[0058] Preferably, according to the present invention, the second integral regulation step R2 includes a sub-step of limiting (R2”) the second current C2 according to the LP parameter law. Contrary to the traditional limitation aimed at limiting extreme values, this parameter law LP is defined to avoid any oscillation phenomenon.

[0059] The parameter law LP determines the value of the second current C2 as a function of the absolute value of the angle deviation ε. Refer to Figure 6 , a plurality of fixed angle thresholds are defined as increasing values of ε1, ε2, ε3, ε4. The angle thresholds are determined according to the needs of adjustment (speed, accuracy, static error, etc.).

[0060] When the absolute value of the angle deviation ε is less than the determined first angle threshold ε1, that is, when the absolute value of the angle deviation ε is between 0 and ε1, the parameter law LP applies a second current C2 with a zero value. This elimination of the second current C2 eliminates all oscillations by preventing the integral correction from intermittently "loading". No current command C2 is sent to the servo valve to control the hydraulic cylinders V1, V2 with unchanged pressure, and only when the difference is zero is the proportional part C1 cancelled. Any oscillation phenomenon is eliminated without replacing the servo valve S or the jacks V1, V2.

[0061] When the angle deviation ε is between the second angle threshold ε2 determined as the absolute value and the third angle threshold ε3 determined as the absolute value, the second current C2 is limited to the maximum allowable current value C2max to limit the value of the second current C2 and protect the servo valve S.

[0062] When the angular deviation ε is between a determined first angular threshold ε1 and a determined second angular threshold ε2, the second current C2 is limited according to the rising slope between the zero value and the maximum authorized current value C2max. Similarly, when the absolute value of the angular difference ε is between a third determined angular threshold ε3 and a fourth determined angular threshold ε4, the second current C2 is limited according to the falling slope between the maximum authorized current value C2max and the zero value. During the check, when the difference ε is below the determined second angular threshold ε2 or above the determined third angular threshold ε3, the slope advantageously allows a "smooth" variation.

[0063] Therefore, the second integral correction R2 remains effective and is only inhibited when the angular deviation ε is too small to be sensed by the servo valve S. Advantageously, the value of the determined first angular threshold ε1 can be adapted to obtain the desired regulation.

[0064] The calculator CAL is configured to implement the steps of the adjustment method, in particular:

[0065] Determine the angular deviation ε between the measured value of the angular position ANGm and the setpoint angular position ANGc,

[0066] Perform a first proportional correction R1 in order to determine a first current C1 from the angular deviation ε,

[0067] Perform a second integral correction R2 in order to determine a second current C2 from the angular deviation ε,

[0068] Add the first current C1 and the second current C2 to determine the control current COM of the servo valve S,

[0069] When performing the second integral correction R2, the second current C2 is limited according to a parametric law which imposes a second current C2 with a zero value when the absolute value of the angular deviation ε is less than the determined first angular threshold ε1.

[0070] Advantageously, one can benefit from the advantages of the present invention simply by modifying the adjustment method implemented by the calculator CAL, without any other physical change.

[0071] Reference Figure 7 , when implementing the adjustment method, when modifying the setpoint angular position ANGc (curve 7A), when the angular deviation ε is below the determined first angular threshold ε1 and there is no oscillation, the angular deviation ε is eliminated (curve 7B). Therefore, the COM control current (curve 7C) also has no OSC oscillation. Therefore, during stationary operation, there are no unnecessary pressure variations in the hydraulic cylinders V1, V2. In other words, if the setpoint angular position ANGc does not change, the control current COM is not subject to unnecessary corrections.

Claims

1. A method for adjusting the angular position (ANG) of a wheel (W), the wheel (W) being connected to at least one hydraulic cylinder controlled by a servo valve (S), the method comprising: a step (E1) of determining an angular deviation (ε) between a measured value of the angular position (ANGm) and a setpoint angular position (ANGc); a first proportional correction step (R1) for determining a first current (C1) from the angular deviation (ε); a second integral correction step (R2) for determining a second current (C2) from the angular deviation (ε); a step (E2) of adding the first current (C1) and the second current (C2) to determine a control current (COM) for the servo valve (S); the method being characterized in that the second integral correction step (R2) includes a sub-step of limiting (R2”) the second current (C2) according to a parametric law (LP), the parametric law (LP) imposing a second current (C2) with a zero value when the absolute value of the angular deviation (ε) is less than a first determined angular threshold (ε1).

2. The adjustment method according to claim 1, wherein When the absolute value of the angular deviation (ε) is between a second determined angular threshold (ε2) and a third determined angular threshold (ε3), the parametric law (LP) limits the second current (C2) to a maximum allowable current value (C2max), where the second determined angular threshold (ε2) and the third determined angular threshold (ε3) are greater than the first determined angular threshold (ε1).

3. The adjustment method according to claim 2, wherein, When the absolute value of the angular deviation (ε) is between the first determined angular threshold (ε1) and the second determined angular threshold (ε2), the parametric law (LP) limits the second current (C2) according to an ascending slope between a zero value and the maximum allowable current value (C2max).

4. The adjustment method according to claim 2, wherein, When the absolute value of the angular deviation (ε) is between the third determined angular threshold (ε3) and a fourth determined angular threshold (ε4) greater than the third determined angular threshold (ε3), the parametric law (LP) limits the second current (C2) according to a descending slope between the maximum allowable current value (C2max) and a zero value.

5. A control system (SC) for the angular position of a wheel (W), which is connected to at least one hydraulic cylinder controlled by a servo valve (S), the control system (SC) comprising a calculator (CAL), the calculator being configured to: determine an angular deviation (ε) between a measured value of the angular position (ANGm) and a setpoint angular position (ANGc); perform a first proportional correction step (R1) for determining a first current (C1) from the angular deviation (ε); execute a second integral correction step (R2) for determining a second current (C2) from the angular deviation (ε); add the first current (C1) and the second current (C2) to determine a control current (COM) for the servo valve (S); when executing the second integral correction step (R2), limit the second current (C2) according to a parametric law (LP), the parametric law (LP) imposing a second current (C2) with a zero value when the absolute value of the angular deviation (ε) is less than a first determined angular threshold (ε1).

6. An assembly of a wheel (W), which is connected to at least one hydraulic cylinder controlled by a servo valve (S) and the control system (SC) according to claim 5, and the assembly is used to determine the control current (COM) of the servo valve (S).

7. The component according to claim 6, wherein, The wheel (W) is connected to at least one first hydraulic cylinder (V1) and a second hydraulic cylinder (V2) controlled by the servo valve (S).

8. The assembly according to claim 6, which includes a hydraulic module (MH), and the hydraulic module includes a servo valve (S), and the servo valve (S) is configured to directly control the first hydraulic cylinder (V1) and the second hydraulic cylinder (V2).

9. An aircraft landing gear including the assembly according to any one of claims 6 to 8.

10. An aircraft including the aircraft landing gear according to claim 9.

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