Tilting rotorcraft transition boundary protection method

Abstract

The invention belongs to the technical field of tilt rotorcraft flight control, and relates to a tilt rotorcraft transition boundary protection method. According to the transition corridor upper boundary and the transition corridor lower boundary of the tilt rotorcraft, the transition corridor maximum tilt speed rate upper boundary and the transition corridor maximum tilt speed rate lower boundary are calculated; according to the current flight speed, the upper boundary of the transition corridor, the lower boundary of the transition corridor, the upper boundary of the maximum tilting speed rate and the lower boundary of the maximum tilting speed rate, calculating a proportionality coefficient of approaching the upper boundary of the transition corridor and a proportionality coefficient of approaching the lower boundary of the transition corridor in the current flight state; calculating an amplitude limiting upper limit proportionality coefficient and an amplitude limiting lower limit proportionality coefficient according to the current given nacelle tilting speed rate instruction and the current nacelle angle; according to the nacelle tilting maximum rate, the nacelle tilting minimum rate, the proportionality coefficient, the proportionality coefficient, the amplitude limiting upper limit proportionality coefficient and the amplitude limiting lower limit proportionality coefficient, the amplitude limiting upper limit and the amplitude limiting lower limit of the nacelle tilting rate are calculated; and calculating a nacelle tilting speed rate instruction with a boundary protection function according to the current given nacelle tilting speed rate instruction, the nacelle tilting maximum speed, the nacelle tilting minimum speed, the proportionality coefficient, the amplitude limiting upper limit and the amplitude limiting lower limit.

Description

Technical Field

[0001] The invention belongs to the technical field of tiltrotor aircraft flight control and relates to a tiltrotor aircraft transition boundary protection method. Background Art

[0002] Tilt-rotor transition flight is the transition stage for tilt-rotor aircraft to achieve the conversion between helicopter mode and fixed-wing mode. It is a unique flying mode for tilt-rotor aircraft. Due to the restrictions such as stall limit, load limit, blade flapping limit, power limit, etc. in the tilting process, the tilt-rotor aircraft must transition within a certain range of flight speed and nacelle tilt angle combination to ensure flight safety. This safe transition range forms a unique transition corridor for tilt-rotor aircraft. In the process of tilt-rotor transition flight, in addition to operating the four conventional control channels, the pilot also needs to control the nacelle tilt rate to match the nacelle tilt angle with the flight speed, ensuring that the flight state in the tilt-rotor transition flight is always within the transition corridor. Therefore, the load on the pilot to operate the tilt-rotor aircraft is greater than that of conventional aircraft. Summary of the invention

[0003] Technical problem solved by the invention: The purpose of the invention is to provide a transition boundary protection method for tilt-rotor aircraft tilt transition flight control, which can improve flight safety and reduce the pilot's control load.

[0004] The technical solution of the present invention:

[0005] A tiltrotor aircraft transition boundary protection method, the method comprising the following steps:

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

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

[0008] Step 3: Calculate the upper limit proportional coefficient KUL and the lower limit proportional coefficient KDL according to the current given nacelle tilt rate instruction NacRate_cmd and the current nacelle angle Nat;

[0009] Step 4: Calculate the nacelle tilt rate limit upper limit NacRate_UL and limit lower limit NacRate_DL according to the nacelle tilt maximum rate NacRsteMax, the nacelle tilt minimum rate NacRateMin, the proportional coefficient x1, the proportional coefficient x2, the upper limit proportional coefficient KUL and the lower limit proportional coefficient KDL;

[0010] Step 5: Calculate the nacelle tilt rate command NacRate_law with boundary protection function according to the current given nacelle tilt rate command NacRate_cmd, the maximum nacelle tilt rate NacRateMax, the minimum nacelle tilt rate NacRateMin, the proportional coefficient x1, the proportional coefficient x2, the upper limit NacRate_UL and the lower limit NaeRate_DL.

[0011] Furthermore, in step 1, the maximum tilt rate upper limit NACR_Vmax is calculated as follows:

[0012]

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

[0014] Furthermore, in step 1, the maximum tilt rate lower limit NACR_Vmin is calculated as follows:

[0015] NACR_Vmin=NAC_Vmin+(NAC_Vmax-NAC_Vmin)*(1-a) / 2, Nac<Nac0.

[0016] Furthermore, in step 2, the calculation formula of the proportional coefficient x1 close to the upper boundary of the transition corridor is as follows:

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

[0018] Furthermore, in step 2, the calculation formula of the proportional coefficient x2 close to the lower boundary of the transition corridor is as follows:

[0019]

[0020] Furthermore, in step 3, the calculation formula of the upper limit ratio coefficient KUL is as follows:

[0021]

[0022] Furthermore, in step 3, the calculation formula of the lower limit proportional coefficient KDL is as follows:

[0023]

[0024] Furthermore, in step 4, the calculation formula of the clipping upper limit NacRate_UL is as follows:

[0025] NacRate_UL=x1*NacRateMax*KUL.

[0026] Furthermore, in step 4, the calculation formula of the clipping lower limit NacRate_DL is as follows:

[0027] NacRate_DL=x2*NacRateMin*KDL.

[0028] Furthermore, in step 5, the calculation formula of the nacelle tilt rate instruction NacRate_law is as follows:

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

[0030] Compared with the prior art, the present invention adopts the above technical solution and has the following technical effects:

[0031] 1) When the present invention makes the tilt-rotor aircraft transition from the fixed-wing mode to the helicopter mode, when the relative speed change of the pilot's nacelle tilt instruction is small, the tilt instruction can be automatically increased so that the transition trajectory does not exceed the lower boundary of the transition corridor; when the relative speed change of the pilot's nacelle tilt instruction is large, the tilt instruction can be automatically reduced so that the transition trajectory does not exceed the upper boundary of the transition corridor;

[0032] 2) When the tilt-rotor aircraft transitions from helicopter mode to fixed-wing mode, the present invention can automatically increase the tilt command when the relative speed change of the pilot's nacelle tilt command is small, so that the transition trajectory does not exceed the upper boundary of the transition corridor; when the relative speed change of the pilot's nacelle tilt command is large, the tilt command can be automatically reduced, so that the transition trajectory does not exceed the lower boundary of the transition corridor. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a block diagram of the tilt-rotor aircraft tilt transition boundary protection control;

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

[0035] Figure 3is the curve of proportional coefficients x1 and x2 changing with speed;

[0036] Figure 4 The limiting proportional coefficients KUL and KDL are changing with speed;

[0037] Figure 5 The upper limit NacRate_UL and the lower limit NacRate_DL are changing with speed;

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

[0039] Figure 7 The flight trajectory for the transition from helicopter mode to fixed-wing mode (given a large tilt command);

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

[0041] Fig. 9 The flight trajectory for the transition from helicopter mode to fixed-wing mode (given a small tilt command);

[0042] Fig.10 is the time variation curve of the nacelle tilt rate command NacRate_law (deceleration tilt, given tilt command is large);

[0043] Fig.11 The flight trajectory for the transition from fixed-wing mode to helicopter mode (given a large tilt command);

[0044] Fig.12 is the time variation curve of the nacelle tilt rate command NacRate_law (accelerated tilt, small given tilt command);

[0045] Fig.13 This is the flight trajectory for the transition from fixed-wing mode to helicopter mode (given a small tilt command). DETAILED DESCRIPTION

[0046] The technical solution of the present invention is described in detail below in conjunction with the accompanying drawings.

[0047] The present invention protects the transition corridor boundary of the tilt-rotor transition flight by dynamically adjusting and limiting the nacelle tilt rate instruction of the tilt-rotor aircraft, ensuring that the flight state never exceeds the transition corridor, thereby improving flight safety and reducing the pilot's control load.

[0048] The overall description of the scheme is as follows: during the tilt-rotor aircraft's tilt transition flight, in the case where the pilot gives a large nacelle tilt rate instruction, the instruction is dynamically limited according to the flight state; in the case where the pilot gives a small nacelle tilt rate instruction, the instruction is dynamically corrected according to the flight state, so that the tilt-rotor aircraft's flight state does not exceed the transition corridor boundary, such as Figure 1 shown.

[0049] Specific implementation steps:

[0050] Step 1): According to the upper boundary NAC_Vmax and the lower boundary NAC_Vmin of the transition corridor of the tiltrotor aircraft, the upper boundary nACR_Vmax and the lower boundary NACR_Vmin of the maximum tilt rate of the transition corridor are calculated by formulas (1) and (2), respectively, where a is the proportion coefficient of the maximum tilt rate area in the transition corridor, Nac is the nacelle tilt angle, and Nac0 is the minimum nacelle angle in the hovering 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 of the transition corridor NAC_Vmax, the lower boundary of the transition corridor NAC_Vmin, the upper boundary of the maximum tilt rate NACR_Vmax and the lower boundary of the maximum tilt rate NACR_Vmin, the proportional coefficient x1 of the current flight state close to the upper boundary of the transition corridor and the proportional coefficient x2 of the current flight state 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 nacelle tilt rate instruction NacRate_cmd and the current nacelle angle Nac, the upper limit proportional coefficient KUL and the lower limit proportional coefficient KDL are calculated by formulas (5) and (6) respectively:

[0057]

[0058]

[0059] Step 4): According to the maximum nacelle tilting rate NaeRateMax, the minimum nacelle tilting rate NacRateMin, the proportional coefficient x1, the proportional coefficient x2, the upper limit proportional coefficient KUL and the lower limit proportional coefficient KDL, the nacelle tilting rate upper limit NacRate_UL and the lower limit NacRate_DL are calculated by formulas (7) and (8) respectively;

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

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

[0062] Step 5): According to the current given nacelle tilt rate instruction NacRate_cmd, the maximum nacelle tilt rate NacRateMax, the minimum nacelle tilt rate NacRateMin, the proportional coefficient x1, the proportional coefficient x2, the upper limit NacRate_UL and the lower limit NacRate_DL, the nacelle tilt rate instruction NacRate_law with boundary protection function is calculated by formula (9);

[0063]

[0064] Implementation Cases:

[0065] Step 1): Given the upper boundary speed NAC_Vmax and lower boundary speed NAC_Ymin corresponding to different nacelle angles, and 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 shown.

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

[0067] Step 3): With the initial state of nacelle angle 90° and speed 40°, during the tilting process to the fixed-wing mode with acceleration 2 and nacelle tilt rate instruction -6° / s, calculate the limit proportional coefficients KUL and KDL, as follows: Figure 4 shown.

[0068] Step 4): Given NacRateMax=8, NacRateMin=-8, calculate the upper limit NacRate_UL and lower limit NacRate_DL of the nacelle tilt rate according to the calculated x1, x2, KUL and KDL, as follows: Figure 5 shown.

[0069] Step 5): According to the current given nacelle tilt rate instruction NacRate_end=-6, the nacelle tilt rate instruction NacRate_law with boundary protection function is calculated, such as Figure 6 shown.

[0070] During the tilt transition, the flight trajectory is located in the transition corridor as follows: Figure 7 shown.

[0071] In other working conditions, the nacelle tilt rate command and flight trajectory during the tilt transition process are as follows: Figures 8 to 13 shown.

[0072] Compared with the prior art, the present invention adopts the above technical solution and has the following technical effects:

[0073] 1) When the present invention makes the tilt-rotor aircraft transition from the fixed-wing mode to the helicopter mode, when the relative speed change of the pilot's nacelle tilt instruction is small, the tilt instruction can be automatically increased so that the transition trajectory does not exceed the lower boundary of the transition corridor; when the relative speed change of the pilot's nacelle tilt instruction is large, the tilt instruction can be automatically reduced so that the transition trajectory does not exceed the upper boundary of the transition corridor;

[0074] 2) When the tilt-rotor aircraft transitions from helicopter mode to fixed-wing mode, the present invention can automatically increase the tilt command when the relative speed change of the pilot's nacelle tilt command is small, so that the transition trajectory does not exceed the upper boundary of the transition corridor; when the relative speed change of the pilot's nacelle tilt command 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 tiltrotor aircraft transition boundary protection method, characterized in that: The method comprises the following steps: Step 1: Calculate the upper boundary NACR_Vmax of the transition corridor maximum tilt rate and the lower boundary NACR_Vmin of the transition corridor maximum tilt rate according to the upper boundary NAC_Vmax and the lower boundary NAC_Vmin of the transition corridor of the tiltrotor aircraft; Step 2: Calculate the proportional coefficient x1 of the current flight state approaching the upper boundary of the transition corridor and the proportional coefficient x2 of the current flight state approaching the lower boundary of the transition corridor according to the current flight speed Vx, the upper boundary of the transition corridor NAC_Vmax, the lower boundary of the transition corridor NAC_Vmin, the upper boundary of the maximum tilt rate NACR_Vmax and the lower boundary of the maximum tilt rate NACR_Vmin; Step 3: Calculate the upper limit proportional coefficient KUL and the lower limit proportional coefficient KDL according to the current given nacelle tilt rate instruction NacRate_cmd and the current nacelle angle Nat; Step 4: Calculate the nacelle tilt rate upper limit NacRate_UL and the lower limit NacRate_DL according to the nacelle tilt rate maximum NaoRatoMax, the nacelle tilt rate minimum NaoRatoMin, the proportional coefficient x1, the proportional coefficient x2, the upper limit proportional coefficient KUL and the lower limit proportional coefficient KDL; Step 5: Calculate the nacelle tilt rate command NacRate_law with boundary protection function according to the current given nacelle tilt rate command NacRate_cmd, the maximum nacelle tilt rate NacRateMax, the minimum nacelle tilt rate NacRateMin, the proportional coefficient x1, the proportional coefficient x2, the upper limit NacRate_UL and the lower limit NacRate_DL.

2. The tiltrotor aircraft transition boundary protection method according to claim 1, characterized in that: In step 1, the maximum tilt rate upper limit NACR_Vmax is calculated as follows: Wherein, a is the proportion coefficient of the maximum tilt rate area in the transition corridor, Nac is the nacelle tilt angle, and Nac0 is the minimum nacelle angle in the hovering state.

3. The tiltrotor aircraft transition boundary protection method according to claim 2, characterized in that: In step 1, the calculation formula of the lower limit of the maximum tilt rate NACR_Vmin is as follows: NACR_Vmin=NAC_Vmin+(NAC_Vmax-NAC_Vmin)*(1-a) / 2, Nac<Nac0.

4. The tiltrotor aircraft transition boundary protection method according to claim 3, characterized in that: In the step 2, the calculation formula of the proportional coefficient x1 close to the upper boundary of the transition corridor is as follows: x1=max(min((NAC_Vmax-Vx) / (NAC_Vmax-NACR_Vmax), 1), 0).

5. The tiltrotor aircraft transition boundary protection method according to claim 4, characterized in that: In step 2, the calculation formula of the proportional coefficient x2 close to the lower boundary of the transition corridor is as follows:

6. The tiltrotor aircraft transition boundary protection method according to claim 5, characterized in that: In step 3, the calculation formula of the upper limit ratio coefficient KUL is as follows:

7. The tiltrotor aircraft transition boundary protection method according to claim 6, characterized in that: In step 3, the calculation formula of the lower limit proportional coefficient KDL is as follows:

8. The tiltrotor aircraft transition boundary protection method according to claim 7, characterized in that: In the step 4, the calculation formula of the clipping upper limit NacRate_UL is as follows: NacRaio_U1=x1*NacRatoMax*KUL.

9. The tiltrotor aircraft transition boundary protection method according to claim 8, characterized in that: In step 4, the calculation formula of the lower limit NacRate_DL is as follows: NacRate_DL=x2*NacRateMin*KDL.

10. The tiltrotor aircraft transition boundary protection method according to claim 9, characterized in that: In step 5, the calculation formula of the nacelle tilt rate instruction NacRate_law is as follows: NacRate law =max(min((NacRate_cmd-(1-x1)*NacRateMax-(1-x2)*NacRateMin),NacRate_UL),NacRate_DL)。

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