Transition boundary protection method for tiltrotor aircraft

Abstract

The present application belongs to the technical field of tilt-rotor aircraft flight control, and relates to a transition boundary protection method for tilt-rotor aircraft. According to the upper boundary of the transition corridor and the lower boundary of the transition corridor of the tilt-rotor aircraft, the maximum tilt rate upper boundary of the transition corridor and the maximum tilt rate lower boundary of the transition corridor are calculated. According to the current flight speed, the upper boundary of the transition corridor, the lower boundary of the transition corridor, the maximum tilt rate upper boundary and the maximum tilt rate lower boundary, the proportional coefficient of the current flight state approaching the upper boundary of the transition corridor and the proportional coefficient of the current flight state approaching the lower boundary of the transition corridor are calculated. According to the current given nacelle tilt rate instruction and the current nacelle angle, the upper limit proportional coefficient of the amplitude limiting and the lower limit proportional coefficient of the amplitude limiting are calculated. According to the maximum nacelle tilt rate, the minimum nacelle tilt rate, the proportional coefficient, the proportional coefficient, the upper limit proportional coefficient of the amplitude limiting and the lower limit proportional coefficient of the amplitude limiting, the upper limit of the nacelle tilt rate amplitude limiting and the lower limit of the nacelle tilt rate amplitude limiting are calculated. According to the current given nacelle tilt rate instruction, the maximum nacelle tilt rate, the minimum nacelle tilt rate, the proportional coefficient, the proportional coefficient, the upper limit and the lower limit of the amplitude limiting, the nacelle tilt rate instruction with the boundary protection function is calculated.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of tilt-rotor aircraft flight control, and relates to a tilt-rotor aircraft transition boundary protection method. BACKGROUND

[0002] Tilt transition flight is a transition stage for a tilt-rotor aircraft to realize conversion between a helicopter mode and a fixed-wing mode, and is a unique flight mode of the tilt-rotor aircraft. Due to the existence of stall limit, load limit, blade flapping limit and power limit during tilting, the tilt-rotor aircraft must transition and convert within a certain flight speed and nacelle tilting angle combination range to ensure flight safety, and the safe transition range forms a unique transition corridor of the tilt-rotor aircraft. During the tilt transition flight, the pilot needs to control the nacelle tilting rate in addition to controlling the four conventional control channels, so as to match the nacelle tilting angle and the flight speed, and ensure that the flight state in the tilt transition flight is always within the transition corridor, and therefore the pilot's manipulation load of the tilt-rotor aircraft is greater than that of a conventional aircraft. SUMMARY

[0003] The application solves the technical problem: The purpose of the application is to provide a transition boundary protection method for tilt-rotor aircraft tilt transition flight control, which can improve flight safety and reduce pilot manipulation load.

[0004] The technical scheme of the application is as follows:

[0005] A tilt-rotor aircraft transition boundary protection method, the method comprising the following steps:

[0006] Step 1: calculating the upper boundary NACR_Vmax of the maximum tilting rate of the transition corridor and the lower boundary NACR_Vmin of the maximum tilting rate of the transition corridor according to the upper boundary NAC_Vmax of the transition corridor and the lower boundary NAC_Vmin of the transition corridor of the tilt-rotor aircraft;

[0007] Step 2: calculating the proportion coefficient x1 of the current flight state close to the upper boundary of the transition corridor and the proportion coefficient x2 of the current flight state close to the lower boundary of the transition corridor according to the current flight speed Vx, the upper boundary NAC_ymax of the transition corridor, the lower boundary NAC_Vmin of the transition corridor, the upper boundary NACR_Vmax of the maximum tilting rate and the lower boundary NACR_Vmin of the maximum tilting rate;

[0008] Step 3: calculating the upper limit proportion coefficient KUL and the lower limit proportion coefficient KDL according to the current given nacelle tilting rate command NacRate_cmd and the current nacelle angle Nat;

[0009] Step four: according to the nacelle tilting maximum rate NacRsteMax, the nacelle tilting minimum rate NacRateMin, the proportional coefficient x1, the proportional coefficient x2, the upper limit clipping coefficient KUL and the lower limit clipping coefficient KDL, the nacelle tilting rate upper limit clipping NacRate_UL and the lower limit clipping NacRate_DL are calculated;

[0010] Step five: according to the current given nacelle tilting rate instruction NacRate_cmd, the nacelle tilting maximum rate NacRateMax, the nacelle tilting minimum rate NacRateMin, the proportional coefficient x1, the proportional coefficient x2, the upper limit clipping NacRate_UL and the lower limit clipping NaeRate_DL, the nacelle tilting rate instruction NacRate_law with boundary protection function is calculated.

[0011] Further, in the step one, the maximum tilting rate upper boundary NACR_Vmax is calculated according to the following formula:

[0012]

[0013] Wherein, a is the proportion coefficient of the maximum tilting rate region in the transition corridor, Nac is the nacelle tilting angle, Nac0 is the minimum nacelle angle in the hovering state.

[0014] Further, in the step one, the maximum tilting rate lower boundary NACR_Vmin is calculated according to the following formula:

[0015] NACR_Vmin=NAC_Vmin+(NAC_Vmax-NAC_Vmin)*(1-a) / 2, Nac

[0016] Further, in the step two, the proportional coefficient x1 approaching the upper boundary of the transition corridor is calculated according to the following formula:

[0017] x1=max(min((NAC_Vmax-Vx) / (NAC_Vmax-NACR_Vmax),1),0).

[0018] Further, in the step two, the proportional coefficient x2 approaching the lower boundary of the transition corridor is calculated according to the following formula:

[0019]

[0020] Further, in the step three, the upper limit clipping coefficient KUL is calculated according to the following formula:

[0021]

[0022] Further, in the step three, the lower limit amplitude ratio coefficient KDL is calculated according to the following formula:

[0023]

[0024] Further, in the step four, the upper limit amplitude NacRate_UL is calculated according to the following formula:

[0025] NacRate_UL=x1*NacRateMax*KUL.

[0026] Further, in the step four, the lower limit amplitude NacRate_DL is calculated according to the following formula:

[0027] NacRate_DL=x2*NacRateMin*KDL.

[0028] Further, in the step five, the nacelle tilting rate instruction NacRate_law is calculated according to the following formula:

[0029] NacRate law =max(min((NacRate_cmd-(1-x1)*NacRateMax-(1-x2)*NacRateMin),NacRate_UL),NacRate_DL).

[0030] Compared with the prior art, the technical scheme has the following technical effects:

[0031] 1) The present application can automatically increase the tilting instruction when the pilot's nacelle tilting instruction relative speed change is small, so that the transition trajectory does not exceed the lower boundary of the transition corridor; when the pilot's nacelle tilting instruction relative speed change is large, the tilting instruction can be automatically reduced, so that the transition trajectory does not exceed the upper boundary of the transition corridor.

[0032] 2) The present application can automatically increase the tilting instruction when the pilot's nacelle tilting instruction relative speed change is small, so that the transition trajectory does not exceed the lower boundary of the transition corridor; when the pilot's nacelle tilting instruction relative speed change is large, the tilting instruction can be automatically reduced, so that the transition trajectory does not exceed the upper boundary of the transition corridor. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 The tilting transition boundary protection control block diagram for tilt rotor aircraft;

[0034] Figure 2 The transition corridor for tilt rotor aircraft;

[0035] Figure 3is a speed variation curve of the proportional coefficient x1, x2;

[0036] Figure 4 is a speed variation curve of the amplitude limiting proportional coefficient KUL and KDL;

[0037] Figure 5 is a speed variation curve of the amplitude limiting upper limit NacRate_UL and the amplitude limiting lower limit NacRate_DL;

[0038] Figure 6 is a time variation curve of the nacelle tilting rate command NacRate_law (accelerating tilting, given large tilting command);

[0039] Figure 7 is a flight trajectory of the transition from the helicopter mode to the fixed-wing mode (given large tilting command);

[0040] Figure 8 is a time variation curve of the nacelle tilting rate command NacRate_law (accelerating tilting, given small tilting command);

[0041] Figure 9 is a flight trajectory of the transition from the helicopter mode to the fixed-wing mode (given small tilting command);

[0042] Figure 10 is a time variation curve of the nacelle tilting rate command NacRate_law (decelerating tilting, given large tilting command);

[0043] Figure 11 is a flight trajectory of the transition from the fixed-wing mode to the helicopter mode (given large tilting command);

[0044] Figure 12 is a time variation curve of the nacelle tilting rate command NacRate_law (accelerating tilting, given small tilting command);

[0045] Figure 13 is a flight trajectory of the transition from the fixed-wing mode to the helicopter mode (given small tilting command). DETAILED DESCRIPTION

[0046] The technical solutions of the present application are described in detail below with reference to the accompanying drawings.

[0047] The present application protects the transition corridor boundary of the tilting transition flight by dynamically adjusting and limiting the nacelle tilting rate command of the tilt-rotor aircraft, ensures that the flight state does not exceed the transition corridor at all times, and improves flight safety and reduces the pilot's control load.

[0048] The scheme is generally described as follows: in the process of tilting transition flight of the tilt-rotor aircraft, for the case that the pilot gives a short nacelle tilting rate instruction larger, the instruction is dynamically limited according to the flight state, for the case that the pilot gives a short nacelle tilting rate instruction smaller, the instruction is dynamically corrected according to the flight state, so as to realize that the flight state of the tilt-rotor aircraft does not exceed the boundary of the transition corridor, such as shown in FIG. 1. Figure 1

[0049] The specific implementation steps are as follows:

[0050] Step 1): according to the upper boundary NAC_Vmax and the lower boundary NAC_Vmin of the transition corridor of the tilt-rotor aircraft, the maximum tilting rate upper boundary NACR_Vmax and the maximum tilting rate lower boundary NACR_Vmin of the transition corridor are calculated by formulas (1) and (2) respectively, wherein a is the proportion coefficient of the maximum tilting rate region in the transition corridor, Nac is the short nacelle tilting angle, and Nac0 is the minimum short nacelle angle in the hover state;

[0051]

[0052] NACR_Vmin=NAC_Vmin+(NAC_Vmax-NAC_Vmin)*(1-a) / 2, Nac<Nac0 (2)

[0053] Step 2): according to the current flight speed Vx, the upper boundary NAC_Vmax and the lower boundary NAC_Vmin of the transition corridor, the maximum tilting rate upper boundary NACR_Vmax and the maximum tilting rate lower boundary NACR_Vmin, the proportion coefficient x1 of the current flight state close to the upper boundary of the transition corridor and the proportion coefficient x2 close to the lower boundary of the transition corridor are calculated by formulas (3) and (4) respectively;

[0054] x1=max(min((NAC_Vmax-Vx) / (NAC_Vmax-NACR_Vmax),1),0) (3)

[0055]

[0056] Step 3): according to the current given short nacelle tilting rate instruction NacRate_cmd and the current short nacelle angle Nac, the upper limit limiting coefficient KUL and the lower limit limiting coefficient KDL are calculated by formulas (5) and (6) respectively:

[0057]

[0058]

[0059] ​Step 4): Based on the maximum nacelle roll rate NaeRateMax, the minimum nacelle roll rate NacRateMin, the proportional coefficient x1, the proportional coefficient x2, the upper limit proportional coefficient KUL, and the lower limit proportional coefficient KDL, calculate the upper limit NacRate_UL and the lower limit NacRate_DL of the nacelle roll rate using formulas (7) and (8), respectively.

[0060] NacRate_UL=x1*NacRateMax*KUL (7)

[0061] NacRate_DL=x2*NacRateMin*KDL (8)

[0062] Step 5): Based on the given nacelle roll rate command NacRate_cmd, nacelle roll maximum rate NacRateMax, nacelle roll minimum rate NacRateMin, proportional coefficient x1, proportional coefficient x2, upper limit limit NacRate_UL, and lower limit limit NacRate_DL, calculate the nacelle roll rate command NacRate_law with boundary protection function using formula (9);

[0063]

[0064] Implementation Case:

[0065] Step 1): Given the upper boundary velocity NAC_Vmax and lower boundary velocity NAC_Ymin corresponding to different nacelle angles, and given the proportion coefficient 'a' corresponding to different nacelle angles, calculate the upper boundary NACR_Vmax and lower boundary NACR_Vmin of the maximum tilt rate corresponding to different nacelle angles, such as... Figure 2 As shown.

[0066] Step 2): With the initial state as nacelle angle 90° and velocity 40, during the tilting process towards fixed-wing mode with acceleration 2 and nacelle tilt rate command -6° / s, calculate the proportional coefficient x1 for approaching the upper boundary of the transition corridor and the proportional coefficient x2 for approaching the lower boundary of the transition corridor. Figure 3 As shown.

[0067] Step 3): With the initial state as nacelle angle 90° and velocity 40, during the tilting process towards fixed-wing mode with acceleration 2 and nacelle tilt rate command -6° / s, calculate the flapping ratio coefficients KUL and KDL, such as... Figure 4 As shown.

[0068] Step 4): Given NacRateMax = 8, NacRateMin = -8, NacRate_UL and NacRate_DL are calculated according to x1, x2, KUL and KDL, as shown in Figure 5

[0069] Step 5): Given NacRate_end = -6, NacRate_law with boundary protection is calculated, as shown in Figure 6

[0070] The flight trajectory in the transition corridor during the transition process is shown in Figure 7

[0071] The short nacelle tilt rate command and flight trajectory during the transition process under other working conditions are shown in Figures 8 to 13

[0072] Compared with the prior art, the present application has the following technical effects:

[0073] 1) The present application can automatically increase the tilt command when the pilot's short nacelle tilt command relative speed change is small, so that the transition trajectory does not exceed the lower boundary of the transition corridor; when the pilot's short nacelle tilt command relative speed change is large, the tilt command can be automatically reduced, so that the transition trajectory does not exceed the upper boundary of the transition corridor.

[0074] 2) The present application can automatically increase the tilt command when the pilot's short nacelle tilt command relative speed change is small, so that the transition trajectory does not exceed the upper boundary of the transition corridor; when the pilot's short nacelle tilt command relative speed change is large, the tilt command can be automatically reduced, so that the transition trajectory does not exceed the lower boundary of the transition corridor.​​​​

Claims

1. A method for protecting the transition boundary of a tiltrotor aircraft, characterized in that, The method includes the following steps: Step 1: Based on the upper boundary of the transition corridor of the tiltrotor aircraft and the lower boundary of the transition corridor Calculate the upper boundary of the maximum tilt rate of the transition corridor. and the lower boundary of the maximum tilt rate of the transition corridor ; Step Two: Based on the current flight speed Upper boundary of the transition corridor Lower boundary of the transition corridor Upper boundary of maximum tilt rate and the lower boundary of the maximum tilt rate Calculate the proportionality coefficient of the current flight state as it approaches the upper boundary of the transition corridor. and the proportional coefficient near the lower boundary of the transition corridor ; Step 3: Based on the currently given nacelle tilt rate command and current nacelle angle Calculate the upper limit ratio coefficient. and the lower limit ratio coefficient ; Step 4: Based on the maximum tilt rate of the nacelle Minimum rate of nacelle tilt proportionality coefficient proportionality coefficient Limiting upper limit ratio coefficient and the lower limit ratio coefficient Calculate the upper limit of the nacelle tilt rate. and lower limit of amplitude ; Step 5: Based on the currently given nacelle tilt rate command Maximum rate of nacelle tilt Minimum rate of nacelle tilt proportionality coefficient proportionality coefficient , limiting upper limit and lower limit of amplitude Calculate the tilt rate command for the nacelle with boundary protection function. .

2. The method for protecting the transition boundary of a tiltrotor aircraft according to claim 1, characterized in that, In step one, the upper boundary of the maximum tilt rate The calculation formula is as follows: in, This represents the proportion of the region with the highest tilt rate in the transition corridor. The tilt angle of the nacelle. This is the minimum nacelle angle for hovering.

3. The method for protecting the transition boundary of a tiltrotor aircraft according to claim 2, characterized in that, In step one, the lower boundary of the maximum tilt rate The calculation formula is as follows: 。 4. The method for protecting the transition boundary of a tiltrotor aircraft according to claim 3, characterized in that, In step two, the scaling factor near the upper boundary of the transition corridor The calculation formula is as follows: 。 5. The method for protecting the transition boundary of a tiltrotor aircraft according to claim 4, characterized in that, In step two, the scaling factor near the lower boundary of the transition corridor The calculation formula is as follows: 。 6. The method for protecting the transition boundary of a tiltrotor aircraft according to claim 5, characterized in that, In step three, the upper limit ratio coefficient of the amplitude limit The calculation formula is as follows: 。 7. The method for protecting the transition boundary of a tiltrotor aircraft according to claim 6, characterized in that, In step three, the lower limit ratio coefficient of the amplitude limit The calculation formula is as follows: 。 8. The method for protecting the transition boundary of a tiltrotor aircraft according to claim 7, characterized in that, In step four, the upper limit of the amplitude limit The calculation formula is as follows: 。 9. The method for protecting the transition boundary of a tiltrotor aircraft according to claim 8, characterized in that, In step four, the lower limit of the amplitude limit The calculation formula is as follows: 。 10. The method for protecting the transition boundary of a tiltrotor aircraft according to claim 9, characterized in that, In step five, the nacelle tilt rate command The calculation formula is as follows: 。

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