Control method of flight height layer change mode and automatic flight system

Abstract

The invention discloses a control method of a flight height layer change mode and an automatic flight system, which can ideally change a set value of a vertical speed threshold value in the flight height layer change mode according to the requirements of the vertical speed threshold value in different scenes. The control method includes selectively setting respective different vertical speed thresholds during climbing and descending in a flight altitude level change mode according to a double-shot or single-shot signal acquired from the engine.

Description

Technical Field

[0001] The present invention relates to the field of automatic flight technology for civil aircraft, and more specifically, to a control method for changing a flight altitude layer mode and an automatic flight system, which can not only complete the aircraft climbing and descending under normal dual-engine conditions (both engines are working), but also support drifting and descending in the event of a single engine failure. Background Art

[0002] The automatic flight system of civil aircraft generally has a flight level change (FLC) mode, which is also called Open Climb (Open CLB) and Open Descent (Open Descent) mode. When this mode is activated, the automatic flight system will control the aircraft to maneuver in the pitch direction to ensure that the aircraft speed can reach the target speed selected by the pilot. At the same time, this mode will also take into account the target altitude selected by the pilot, allowing the aircraft to climb or descend towards the target altitude selected by the pilot while maintaining the target speed. In addition, the pilot can set the target altitude and target speed through the human-machine interface device of the automatic flight system, namely the flight control panel.

[0003] In a normal dual-engine situation (both engines are working), the pilot will use the FLC mode of the autoflight system to achieve a climb or descent at the target speed. The rate of climb or descent cannot be too slow, otherwise it will affect the pilot's flying experience. In addition, in the case of a single-engine failure, the pilot also needs to use the FLC mode to complete a single-engine drift descent, so that the aircraft's altitude can be lowered as slowly as possible to meet the aircraft's obstacle clearance requirements.

[0004] Therefore, the FLC mode control algorithm of the automatic flight system must be designed to meet the usage requirements of both normal dual-engine and single-engine failure situations.

[0005] In the prior art, the FLC mode control law takes the target speed as the control target, but also takes into account the vertical speed (Vertical Speed, "VS") of the aircraft. When the aircraft is climbing, VS is required to be a positive number, while when the aircraft is descending, VS is required to be a negative number. In addition, when the absolute value of the aircraft's VS is greater than a certain threshold, the FLC mode of the automatic flight system will issue a "pitch maneuver command" to allow the aircraft to track the target speed, and when the absolute value of the aircraft's VS is less than a certain threshold, the automatic flight FLC mode will issue a "pitch command" to give priority to the aircraft to generate the required VS, thereby ensuring that the aircraft can climb or descend toward the target altitude.

[0006] In the prior art, there are mainly two ways to set the vertical speed threshold.

[0007] (1) Set the vertical speed threshold to 0

[0008] When the target altitude is greater than the current altitude of the aircraft, the FLC mode prioritizes ensuring that VS is a positive number. To ensure that the aircraft climbs, and when the target altitude is less than the current altitude of the aircraft, the FLC mode prioritizes ensuring that VS is a negative number to ensure that the aircraft descends.

[0009] However, if the vertical speed threshold is set to 0, in a normal twin-engine flight scenario, There may be situations where the automatic flight system controls the aircraft to pitch and maneuver to maintain the target speed, but the aircraft climbs or descends very slowly (due to a small VS), which does not meet the flight operation requirements of civil aircraft. For example, when the target speed is greater than the current speed of the aircraft and the target altitude is greater than the current altitude of the aircraft, that is, when the aircraft needs to increase the speed to climb, the automatic flight system may keep the aircraft at a very small VS, making the climb very slow, which does not meet the actual flight requirements.

[0010] (2) Set the vertical speed threshold to a certain value (e.g. 200 ft / m)

[0011] When the target altitude is greater than the current altitude of the aircraft, the FLC mode prioritizes ensuring that VS is greater than 200ft / m, and when the target altitude is less than the current altitude of the aircraft, the FLC mode prioritizes ensuring that VS is less than -200ft / m.

[0012] If the vertical speed threshold is set to a certain value (for example, 200ft / m), in most normal dual-engine climbing or descending scenarios, the aircraft's VS absolute value will be greater than the threshold, and there may not be any special problems. However, in the scenario of a single-engine failure and drifting down, the aircraft needs to maintain a given single-engine drifting target speed to allow the aircraft's flight altitude to drop at the slowest possible rate of descent. At this time, the FLC mode of the autoflight system will still prioritize ensuring that the aircraft's VS absolute value is greater than the threshold, resulting in the aircraft descending too quickly when drifting down with a single-engine failure, and failing to maintain the target speed, thereby failing to fully utilize the aircraft's single-engine drifting performance.

[0013] Therefore, how to design a control method for a flight altitude layer change mode that can ideally change the set value of the vertical speed threshold in the flight altitude layer change mode according to the requirements of the vertical speed threshold in different scenarios has become a technical problem that needs to be solved urgently. Summary of the invention

[0014] The present invention is made to solve the above-mentioned existing problems, and its purpose is to provide a control method for a flight altitude layer change mode that can ideally change the setting value of the vertical speed threshold in the flight altitude layer change mode according to the requirements of the vertical speed threshold in different scenarios.

[0015] Another object of the present invention is to provide an automatic flight system for implementing a control method of a flight altitude layer change module.

[0016] In order to achieve the above-mentioned purpose, the present invention provides a control method for a flight altitude layer change mode, characterized in that the control method includes: selectively setting different vertical speed thresholds for the climbing and descending processes in the flight altitude layer change mode according to the dual-engine or single-engine signal obtained from the engine.

[0017] Preferably, when the engine status is judged to be dual-engine, that is, both engines are operating normally, the vertical speed threshold of the aircraft is set according to the relationship between the current altitude of the aircraft and the target altitude obtained from the flight control panel and two preset altitude thresholds.

[0018] Preferably, if the current altitude of the aircraft is less than the target altitude, the vertical speed threshold set for the aircraft at this time is a first climbing vertical speed threshold, and the vertical speed of the aircraft should be greater than the first climbing vertical speed threshold; if the current altitude of the aircraft is greater than the target altitude, the vertical speed threshold set for the aircraft at this time is a first descending vertical speed threshold, and the vertical speed of the aircraft should be less than the first descending vertical speed threshold.

[0019] Preferably, the first climbing vertical speed threshold is set to be a constant value when the current altitude of the aircraft is less than a first altitude threshold, and is linearly reduced from the constant value to 0 ft / mm within the range from the first altitude threshold to the second altitude threshold.

[0020] As an example, the first altitude threshold is 20,000 ft, the second altitude threshold is 40,000 ft, the constant value of the first climbing vertical speed threshold is 250 ft / m, and the first descending vertical speed threshold is -250 ft / m.

[0021] Preferably, when the engine status is determined to be single engine, that is, when a single engine fails, the vertical speed threshold of the aircraft is set according to the current altitude of the aircraft and the target altitude obtained from the flight control panel.

[0022] Preferably, if the current altitude of the aircraft is less than the target altitude, the vertical speed threshold set for the aircraft at this time is a second climbing vertical speed threshold that is less than the first climbing vertical speed threshold; if the current altitude of the aircraft is greater than the target altitude, the vertical speed threshold set for the aircraft at this time is a second descending vertical speed threshold that is greater than the first descending vertical speed threshold.

[0023] As an example, the second climbing vertical speed threshold is 0 ft / m, and the second descending vertical speed threshold is 0 ft / m.

[0024] Preferably, based on the vertical velocity signal obtained from the atmospheric system and the normal acceleration signal obtained from the inertial navigation system, a compensation value of the vertical velocity is calculated and complementary filtering is performed, and the vertical velocity after complementary filtering and the vertical velocity threshold are input into the flight altitude layer change control law, which then issues a pitch maneuver command to an external action unit.

[0025] Preferably, the complementary filtering method of the vertical velocity signal and the normal acceleration signal is as shown in formula (1):

[0026] Another aspect of the present invention provides an automatic flight system for implementing the control method of the aforementioned flight altitude layer change mode, characterized in that the automatic flight system has: a threshold setting unit that selectively sets the vertical speed threshold of the aircraft according to different engine states obtained from the engine; a compensation calculation unit that calculates the compensation value of the vertical speed according to the vertical speed signal obtained from the atmospheric system and the normal acceleration signal obtained from the inertial navigation system; and a flight altitude layer change control law that receives the vertical speed and the vertical speed threshold after complementary filtering and issues a pitch maneuver command to an external action unit.

[0027] According to the above-described construction, the control method for the flight level change mode of the present invention and the automatic flight system for implementing the control method can distinguish between the dual-engine and single-engine situations according to the different states of the relevant engines. The automatic flight system adopts different vertical speed thresholds during the climbing and descending processes in the flight level change mode, thereby ensuring that the flight level change mode can complete the aircraft climbing and descending under normal circumstances (both engines are working) and can also support drifting and descending in the event of a single engine failure.

[0028] In addition, according to the structure as described above, since the air at high altitudes is thin, the climbing ability of the aircraft is lower than that at low altitudes. Therefore, the first climb vertical speed threshold is set to different climb vertical speed thresholds for climbing at flight altitude layers of different altitudes, and the higher the current flight altitude, the smaller the first climb vertical speed threshold. Therefore, it can be avoided that the automatic flight system controls the aircraft to have too large a pitch angle at high altitudes due to the use of an excessively large climb speed threshold, thereby causing an unexpected aircraft response.

[0029] In addition, according to the above-described configuration, by comparing the vertical speed VS after complementary filtering with the vertical speed threshold value set in the aforementioned manner, it is possible to avoid the inaccuracy of the vertical speed output by the atmosphere due to lateral disturbances when a single engine fails, thereby avoiding the impact on the control performance of the flight altitude layer change. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a schematic block diagram of an autoflight system for implementing the control method of the flight level change mode of the present invention.

[0031] Figure 2 Yes means Figure 1 A graph showing the setting of the vertical speed threshold in the twin-engine climb case in the control method of the flight altitude layer change mode is shown. DETAILED DESCRIPTION

[0032] Below, refer to Figure 1 and Figure 2 , the control method of the flight altitude layer change mode of the present invention is described in detail, wherein, Figure 1 is a schematic block diagram showing an implementation of a control method for a flight level change mode of the present invention, Figure 2 Yes means Figure 1 A graph showing the setting of the vertical speed threshold in a climbing situation in the control method of the flight level change mode is shown.

[0033] The control method of the flight level change mode of the present invention can adaptively design the flight level change mode in each scenario into different vertical speed thresholds VSth in response to different requirements in the two scenarios of twin-engine climbing / descending and single-engine drifting. Considering that the aircraft is susceptible to lateral disturbances in the single-engine case, the vertical speed VS after complementary filtering is used for comparison with the vertical speed threshold VSth.

[0034] More specifically, if Figure 1 As shown, the autoflight system 100 for implementing the control method of the flight level change mode of the present invention can obtain signals related to the state of the engine from the engine 10, can obtain signals related to the vertical speed VS, airspeed and altitude from the atmosphere system 20, and can obtain signals related to the normal acceleration Nz from the inertial navigation system 30. In addition, the autoflight system 100 also obtains set values ​​related to the target speed and target altitude from the flight control board 40.

[0035] The autoflight system 100 for implementing the control method of the flight level change mode of the present invention includes a threshold setting unit 110 for selectively setting the vertical speed threshold VSth of the aircraft according to the status of the relevant engine.

[0036] When the engine status is determined to be that both engines are operating normally, the vertical speed threshold VSth of the aircraft is set according to the relationship between the current altitude of the aircraft and the target altitude and the two altitude thresholds.

[0037] That is, when the flight altitude layer change mode is activated, the size of the current altitude of the aircraft and the target altitude is judged. If the current altitude of the aircraft is less than the target altitude, the vertical speed threshold VSth set for the aircraft at this time is the first climbing vertical speed threshold VScth1, and the vertical speed of the aircraft should be greater than the first climbing vertical speed threshold VScth1. Conversely, if the current altitude of the aircraft is greater than the target altitude, the vertical speed threshold VSth set for the aircraft at this time is the first descending vertical speed threshold VSdth1, and the vertical speed of the aircraft should be less than the first descending vertical speed threshold VSdth1.

[0038] In addition, the first climbing vertical speed threshold VScth1 is set as follows: Figure 2 As shown, when the current altitude of the aircraft is less than the first altitude threshold Hth1, it is a constant value (eg, 250 ft / m), and within the range from the first altitude threshold Hth1 to the second altitude threshold Hth2, it decreases linearly from the constant value (eg, 250 ft / m) to 0 ft / m.

[0039] On the other hand, when the engine status is judged as a single engine failure, Set the aircraft's vertical speed threshold based on the aircraft's current altitude and target altitude.

[0040] That is, when the flight altitude layer change mode is activated, the size of the current altitude of the aircraft and the target altitude is judged. If the current altitude of the aircraft is less than the target altitude, the vertical speed threshold VSth set for the aircraft at this time is the second climbing vertical speed threshold VScth2. Conversely, if the current altitude of the aircraft is greater than the target altitude, the vertical speed threshold VSth set for the aircraft at this time is the second descending vertical speed threshold VSdth2.

[0041] As an example, the first altitude threshold Hth1 is 20000 ft, and the second altitude threshold Hth2 is 40000 ft. In addition, the first descent vertical speed threshold VSdth1 is -250 ft / m, and the second climb vertical speed threshold VScth2 and the second descent vertical speed threshold VSdth2 are both 0 ft / m.

[0042] In addition, since the vertical speed signal from the onboard atmospheric system 20 indirectly measures the altitude change by measuring the atmospheric pressure (static pressure), and when a single engine of the aircraft fails, the lateral direction is easily disturbed, resulting in the value and phase of the vertical speed output by the atmospheric system 20 being abnormal. At this time, if only the value of the vertical speed output by the atmospheric system 20 is compared with the set vertical speed threshold VS, it will have an adverse effect on the control of the flight altitude layer change mode. Therefore, in the automatic flight system 100 for implementing the control method of the flight altitude layer change mode of the present invention, if Figure 1As shown, there is also a compensation calculation unit 120 for calculating a compensation value of the vertical velocity VS based on the signal related to the vertical velocity VS and the signal related to the normal acceleration Nz.

[0043] Since the inertial navigation system 30 is not easily affected by the external environment, the vertical velocity VS signal output by the atmospheric system 20 and the normal acceleration Nz signal output by the inertial navigation system 30 are complementary filtered to reduce the impact of a single engine failure.

[0044] The complementary filtering method is shown in formula (1):

[0045] In addition, in the automatic flight system 100, if Figure 1 As shown, the vertical speed VS and the vertical speed threshold VSth after complementary filtering are input into the flight altitude layer change control law 130, and the control law 130 issues a pitch maneuver instruction to the external main flight control / elevator and other action parts 50.

[0046] According to the above-described construction, the control method for the flight level change mode of the present invention and the automatic flight system for implementing the control method can distinguish between the dual-engine and single-engine situations according to the different states of the relevant engines. The automatic flight system adopts different vertical speed thresholds VSth during the climbing and descending processes in the flight level change mode, thereby ensuring that the flight level change mode can complete the aircraft climbing and descending under normal conditions (both engines are working) and can also support drifting and descending in the event of a single engine failure.

[0047] In addition, according to the structure as described above, since the air at high altitudes is thin, the climbing ability of the aircraft is lower than that at low altitudes. Therefore, the first climbing vertical speed threshold value VScth1 is set to different climbing vertical speed threshold values ​​for climbing at flight altitude layers of different altitudes, and the higher the current flight altitude, the smaller the first climbing vertical speed threshold value VScth1. Therefore, it can avoid the automatic flight system controlling the aircraft to have too large a pitch angle at high altitudes due to the use of an excessively large climbing speed threshold, thereby causing unexpected aircraft response.

[0048] Furthermore, according to the configuration as described above, by comparing the vertical speed VS after complementary filtering with the vertical speed threshold VSth set in the aforementioned manner, it is possible to avoid the inaccuracy of the vertical speed output by the atmosphere due to lateral disturbances when a single engine fails, thereby preventing the control performance of the flight altitude layer change from being affected.

[0049] Other advantages and modifications will readily occur to those skilled in the art. Therefore, in its broader sense, the present invention is not limited to the specific details and representative embodiments shown and described herein. Therefore, modifications may be made without departing from the spirit or scope of the overall inventive concept as defined by the appended claims and their equivalents.

Claims

1. A control method for changing a flight altitude layer mode, characterized in that: The control method comprises: According to the signal obtained from the engine (10) regarding the dual engine or single engine of the engine (10), different vertical speed thresholds (VSth) are selectively set during the climbing and descending processes in the flight altitude layer change mode.

2. The control method for changing the flight altitude layer mode as claimed in claim 1, characterized in that: When the engine status is determined to be dual-engine, that is, both engines are operating normally, the vertical speed threshold (VSth) of the aircraft is set according to the relationship between the current altitude of the aircraft and the target altitude obtained from the flight control panel (40) and two preset altitude thresholds.

3. The control method for changing the flight altitude layer mode as claimed in claim 2, characterized in that: If the current altitude of the aircraft is less than the target altitude, the vertical speed threshold (VSth) set by the aircraft at this time is the first climbing vertical speed threshold (VScth1), and the vertical speed (VS) of the aircraft should be greater than the first climbing vertical speed threshold (VScth1). If the current altitude of the aircraft is greater than the target altitude, the vertical speed threshold (VSth) set by the aircraft at this time is the first descent vertical speed threshold (VSdth1), and the vertical speed (VS) of the aircraft should be less than the first descent vertical speed threshold (VSdth1).

4. The control method for changing the flight altitude layer mode as claimed in claim 3, characterized in that: The first climb vertical speed threshold (VScth1) is set to be a constant value when the current altitude of the aircraft is less than the first altitude threshold (Hth1), and is linearly reduced from the constant value to 0 ft / mm within the range from the first altitude threshold (Hth1) to the second altitude threshold (Hth2).

5. The control method for changing the flight altitude layer mode as claimed in claim 4, characterized in that: The first height threshold (Hth1) is 20000ft, The second altitude threshold (Hth2) is 40000ft, The constant value of the first climb vertical speed threshold (VScth1) is 250 ft / m, The first descent vertical speed threshold (VSdth1) is -250 ft / m.

6. The control method for changing the flight altitude layer mode as claimed in claim 3, characterized in that: When the engine status is judged to be single engine, that is, a single engine failure, the vertical speed threshold (VSth) of the aircraft is set according to the current altitude of the aircraft and the target altitude obtained from the flight control panel (40).

7. The control method for changing the flight altitude layer mode as claimed in claim 6, characterized in that: If the current altitude of the aircraft is less than the target altitude, the vertical speed threshold (VSth) set by the aircraft at this time is a second climbing vertical speed threshold (VScth2) that is less than the first climbing vertical speed threshold (VScth1). If the current altitude of the aircraft is greater than the target altitude, the vertical speed threshold (VSth) set by the aircraft at this time is the second descent vertical speed threshold (VSdth2) greater than the first descent vertical speed threshold (VSdth1).

8. The control method for changing the flight level mode as claimed in claim 7, characterized in that: The second climbing vertical speed threshold (VScth2) is 0 ft / m, The second descent vertical speed threshold (VSdth2) is 0 ft / m.

9. The control method for flight level change mode according to any one of claims 1 to 8, characterized in that: According to a signal related to the vertical speed (VS) obtained from the atmospheric system (20) and a signal related to the normal acceleration (Nz) obtained from the inertial navigation system (30), a compensation value of the vertical speed (VS) is calculated and complementary filtering is performed, The vertical speed (VS) after complementary filtering and the vertical speed threshold (VSth) are input into a flight level change control law (130), which then issues a pitch maneuver instruction to an external action unit (50).

10. The control method for changing the flight level mode as claimed in claim 9, characterized in that: The complementary filtering method of the vertical velocity (VS) signal and the normal acceleration (Nz) signal is shown in formula (1):

11. An automatic flight system, used to implement the control method of the flight level change mode according to any one of claims 1 to 10, characterized in that: The automatic flight system has: A threshold setting unit (110) for selectively setting a vertical speed threshold (VSth) of the aircraft according to different engine states obtained from the engine (10); a compensation calculation unit (120) for calculating a compensation value of the vertical speed (VS) based on a signal related to the vertical speed (VS) obtained from an atmospheric system (20) and a signal related to the normal acceleration (Nz) obtained from an inertial navigation system (30); and A flight level change control law (130) receives the vertical speed (VS) and the vertical speed threshold (VSth) after complementary filtering and issues a pitch maneuver instruction to an external action unit (50).

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