An automatic approach control method and system for aircraft

Abstract

This invention pertains to automatic flight control technology, specifically an automatic approach control method and system for aircraft. When an aircraft engages approach mode and executes an approach procedure, it becomes increasingly sensitive to localizer deviation signals as it approaches the localizer beacon. This invention proposes an improved control method and system for automatic approach mode. The glide slope control law and localizer control law employ specially designed algorithms, enabling the aircraft to more accurately guide itself along the localizer and align with the runway during the approach procedure. This reduces the sensitivity to localizer deviation signals and lateral oscillations caused by noise interference, thereby improving the success rate and safety of aircraft approach and landing.

Description

Technical Field

[0001] This invention belongs to the field of automatic flight control technology, and relates to an automatic control method and system for aircraft approach. Background Technology

[0002] Approach mode is a functional mode of the aircraft's automatic flight control system. This mode consists of a glide slope sub-mode and a localizer sub-mode, each with its own control law. Using this mode, the aircraft can automatically approach the airport runway along the predetermined glide slope and localizer, and at a certain altitude, switch to manual control, allowing the pilot to continue the landing.

[0003] Currently, aircraft approach control laws are divided into glide slope control laws and localizer control laws. The glide slope control law is used for controlling the aircraft's longitudinal path, and it introduces the glide slope deviation signal as the main input signal of the control law. The localizer control law is used for controlling the aircraft's lateral path, and it introduces the localizer deviation signal as the main input signal of the control law.

[0004] The disadvantages of the above control method are as follows: When the aircraft engages approach mode and executes the approach procedure, the closer it gets to the localizer, the more sensitive it becomes to the localizer deviation signal. Combined with noise interference from the ground localizer, the localizer deviation signal emitted by the aircraft's multi-mode receiver may be mixed with noise. This causes lateral oscillations during automatic approach, making it impossible to accurately guide the aircraft along the localizer and align it with the runway. This also increases the pilot's workload when switching to manual piloting and negatively impacts flight safety. Summary of the Invention

[0005] The purpose of this invention is to propose an improved control method and system for automatic aircraft approach mode, which enables the aircraft to be guided more accurately along the localizer and aligned with the runway when performing the approach procedure, thereby reducing the lateral oscillation phenomenon caused by the sensitivity of the localizer deviation signal and noise interference.

[0006] The technical solution of this invention is: an automatic control method for aircraft approach, comprising a glide slope control law and a heading control law.

[0007] The glide slope control law is as follows:

[0008]

[0009]

[0010] Where, n zc V is the output signal for the glide slope control law. d η is the ground speed, η is the glide slope deviation, and γ is the flight path inclination angle. The differential signal of the flight path inclination angle. For vertical velocity, η g Let T3 be the glide slope angle, T3 be the time constant, and K be the glide slope angle. γ , K η This is the proportionality coefficient;

[0011] The course control law is as follows:

[0012]

[0013] In the formula, p c The output signal is the heading control law, and ξ is the LOC deviation. The differential signal of LOC deviation, φ is the roll angle, p is the roll rate, T1 and T2 are time constants, and K φ K p K ξ K ξs K ξ Both are proportionality coefficients.

[0014] Advantageously, the glide slope angle η in the glide slope control law g It is determined based on the beam emission angle of the airport glide slope.

[0015] Advantageously, the vertical velocity deviation in the glide slope control law A first-order low-pass filter should be applied.

[0016] Advantageously, the proportional coefficients in the glide slope control law algorithm are rationally selected based on the aircraft's main flight control internal loop control law and aircraft characteristics.

[0017] Advantageously, the differential signal of the LOC deviation in the heading control law algorithm The result is obtained by differential operation based on the LOC deviation, and then subjected to first-order low-pass filtering.

[0018] Advantageously, the LOC deviation signal ξ in the heading control law algorithm is subjected to first-order low-pass filtering.

[0019] Advantageously, the proportional coefficient K in the heading control law algorithm ξs K ξ It is a function of the radio altitude signal.

[0020] Advantageously, this method can be used for automatic control during the approach phase of fixed-wing aircraft.

[0021] This invention also proposes an automatic approach control system for aircraft, which includes a glide slope control module and a heading control module, wherein...

[0022] The glide slope control module performs the following calculations:

[0023]

[0024]

[0025] Where, n zc V is the output signal for the glide slope control law. d η is the ground speed, η is the glide slope deviation, and γ is the flight path inclination angle. The differential signal of the flight path inclination angle. For vertical velocity, η g Let T3 be the glide slope angle, T3 be the time constant, and K be the glide slope angle. γ , K η This is the proportionality coefficient;

[0026] The heading control module performs the following calculations:

[0027]

[0028] In the formula, p c The output signal is the heading control law, and ξ is the LOC deviation. The differential signal of LOC deviation, φ is the roll angle, p is the roll rate, T1 and T2 are time constants, and K φ K p K ξ K ξs K ξ Both are proportionality coefficients.

[0029] Advantageously, the glide slope angle η g The vertical velocity deviation is determined based on the airport glide slope beam emission angle. A first-order low-pass filter should be applied; the differential signal of the LOC deviation. The LOC deviation signal ξ is obtained by differential operation and then subjected to first-order low-pass filtering; the LOC deviation signal ξ is subjected to first-order low-pass filtering.

[0030] The advantages of this invention are: using this method will enable the aircraft to be guided more accurately along the locale and aligned with the runway when performing the approach procedure, reducing the sensitivity of the locale deviation signal and the lateral oscillation caused by noise interference, thereby improving the success rate and safety of the aircraft approach and landing. Attached Figure Description

[0031] Figure 1 This is an automatic control block diagram of the present invention;

[0032] Figure 2 It is a simulation curve of aircraft approach heading control;

[0033] Figure 3 These are simulation curves of aircraft approach glide slope control.

[0034] Figure 4 These are simulation curves of the longitudinal parameters of the aircraft approach;

[0035] Figure 5 These are simulation curves of the aircraft's lateral approach parameters. Detailed Implementation

[0036] The present invention will now be described in further detail with reference to the accompanying drawings.

[0037] Example

[0038] This embodiment uses the following steps to verify the approach control law:

[0039] Step 1) Use mathematical simulation software Matlab / Simulink / Stataflow to build an approach control law model, which includes a heading control law model and a glide slope control law model.

[0040] A discretized control law simulation model was established based on the approach glide slope control law algorithm. The control law model added necessary amplitude limiting to the integral element and necessary softening and filtering to the calculation process. The control law output was also limited. The control law parameters selected in this embodiment are shown in Table 1.

[0041] Table 1. Approach Glide Path Control Law Parameters

[0042]

[0043] Based on the aforementioned approach course control law algorithm, a discretized control law simulation model was established. The model incorporates necessary amplitude limiting for the integral term, as well as necessary softening and filtering stages in the calculation process. Gain adjustment is performed based on altitude, and the control law output is also limited. The differential signal of the course deviation is further optimized. The filter process was performed, and its control law parameters are shown in Table 2.

[0044] Table 2 Approach Course Control Law Parameters

[0045]

[0046] Step 2) Use Matlab / Simulink to build a six-DOF full aircraft equation model, main flight control system model, glide slope beacon model, heading beacon model, and autothrottle model. Figure 1 δ e Indicates the elevator deflection angle, δ a Indicates the aileron deflection angle, δ r Indicates the rudder deflection angle, δ TV represents the throttle lever angle, and V represents airspeed.

[0047] Step 3) Set the entire model execution cycle to 0.02 seconds;

[0048] Step 4) Balance the aircraft equation model so that the aircraft is in a state of equilibrium motion;

[0049] Step 5) Combine the flight track tilt angle signal θ and the flight track tilt angle differential signal. Altitude signal H, vertical velocity signal Ground speed V d The roll angle φ and roll rate p are derived from the six-DOF aircraft equation model and fed to the control law model. Simultaneously, the glide slope deviation signal η output from the glide slope beacon model and the heading beacon deviation signal ξ output from the heading beacon model are introduced into the approach control law model. The signals calculated by the approach control law model are sent to the primary flight control law model, which then sends the signals back to the aircraft equation model, thus forming a signal closed loop. See [link to relevant documentation]. Figure 1 .

[0050] Step 6) The initial flight trajectory coordinates in the geodetic coordinate system are [40000, 10000], and the tower coordinates are [0, 0], in meters; the runway heading is due east at -180 degrees, the glide slope is 2.75 degrees, the aircraft is in flap configuration of 35 degrees, the aircraft airspeed is maintained at 70 m / s, and the aircraft altitude is 500 m;

[0051] Step 7) Simulation begins. At T=0s, the aircraft flies horizontally eastward and yaws 135 degrees to the right, forming a 45-degree angle with the runway direction.

[0052] When the localizer deviation is less than 2 degrees, the aircraft enters localizer acquisition and turns to runway heading; when the localizer deviation is less than 1 degree, the aircraft tracks the localizer beacon.

[0053] When the glide path deviation is less than 0.3 degrees, the aircraft enters glide path capture and begins its descent, following the glide path beacon.

[0054] Step 8) The approach ends when the aircraft's radio altitude is less than 30m above the ground.

[0055] like Figure 2 The pentagram represents the aircraft's initial point. Initially, the aircraft flies eastward. At the initial position, the aircraft begins to turn and approaches the LOC beam radial line, i.e. the runway centerline, at a 45-degree angle to the runway. It begins to intercept the LOC beacon at a position of (35km, 1.7km) with an LOC deviation of 2 degrees. After intercepting the LOC beacon, the aircraft begins to turn to the runway heading. After several slight oscillations, the aircraft gradually tracks the runway centerline normally.

[0056] After intercepting the LOC beacon, the aircraft also intercepted the GS beacon and descended the glide path at a vertical speed of -3.6 m / s until it reached a radio altitude of 30 m. Figure 3 As shown.

[0057] from Figure 4-5 As can be seen, when the aircraft approaches the coordinate origin, i.e., the heading beacon, the control effect is stable, with no oscillation, and it can accurately track the runway centerline. This verifies the effectiveness of the method of the present invention.

Claims

1. An automatic approach control method for aircraft, comprising a glide slope control law and a heading path control law, characterized in that: The glide slope control law is as follows: in, This refers to the vertical velocity deviation in the glide slope control law. Output signal for the glide slope control law. For ground speed, For glide slope deviation, For the inclination angle of the flight path, The differential signal of the flight path inclination angle. Vertical velocity, For the glide slope angle, It is a time constant. , , , , This is the proportionality coefficient; The course control law is as follows: In the formula, Output signal for the heading control law. For LOC deviation, The differential signal of LOC deviation, For roll angle, For the roll rate, , It is a time constant. , , , , Both are proportionality coefficients.

2. The automatic aircraft approach control method according to claim 1, characterized in that: Glide slope angle in glide slope control law It is determined based on the beam emission angle of the airport glide slope.

3. The automatic aircraft approach control method according to claim 1, characterized in that: Vertical velocity deviation in the glide slope control law Perform a first-order low-pass filter.

4. The automatic aircraft approach control method according to claim 1, characterized in that: The proportional coefficients in the glide slope control law algorithm are selected reasonably based on the aircraft's main flight control internal loop control law and aircraft characteristics.

5. The automatic aircraft approach control method according to claim 1, characterized in that: Differential signal of LOC deviation in the heading control law algorithm The result is obtained by differential operation based on the LOC deviation, and then subjected to first-order low-pass filtering.

6. The automatic aircraft approach control method according to claim 1, characterized in that: LOC deviation signal in the heading control law algorithm Perform first-order low-pass filtering.

7. The automatic aircraft approach control method according to claim 1, characterized in that: Proportional coefficient in the course control law algorithm , It is a function of the radio altitude signal.

8. The automatic aircraft approach control method according to claim 1, characterized in that: This method is used for automatic control during the approach phase of fixed-wing aircraft.

9. An automatic approach control system for aircraft, characterized in that: The system includes a glide slope control module and a heading control module, wherein The glide slope control module performs the following calculations: in, This refers to the vertical velocity deviation in the glide slope control law. Output signal for the glide slope control law. For ground speed, For glide slope deviation, For the inclination angle of the flight path, The differential signal of the flight path inclination angle. Vertical velocity, For the glide slope angle, It is a time constant. , , , , This is the proportionality coefficient; The heading control module performs the following calculations: In the formula, Output signal for the heading control law. For LOC deviation, The differential signal of LOC deviation, For roll angle, For the roll rate, , It is a time constant. , , , , Both are proportionality coefficients.

10. The aircraft approach automatic control system according to claim 9, characterized in that: The angle of the glide path The vertical velocity deviation is determined based on the airport glide slope beam emission angle. Perform first-order low-pass filtering; the differential signal of the LOC deviation The LOC deviation signal is obtained by differential processing based on the LOC deviation, followed by first-order low-pass filtering; Perform first-order low-pass filtering.

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