Thrust control method and system in flight height layer change mode

Abstract

The present application relates to a thrust control system in an FLCH mode, comprising: an upper branch comprising: a height difference calculation module configured to calculate a height difference between a target height and a current height of an aircraft; the latching module is configured to be used for latching the numerical value of the height difference according to the manual operation response time delay and the industry requirement; the vertical speed calculator is configured to be used for calculating a corresponding expected vertical speed according to the latched height difference output by the latch module; a thrust calculator configured to calculate a corresponding thrust from the desired vertical velocity; the lower branch comprises a selector which is configured to be used for selecting an integration rate according to an integration rate judgment condition; an integrator configured to perform integration by time according to the selected integration rate to output a compensation thrust; and an adder configured to add the thrust from the upper branch and the compensation thrust from the lower branch to output a thrust command.

Description

Technical Field

[0001] The present application relates to the field of design of automatic flight control systems for civil aircraft, and more specifically, to a thrust control scheme in a flight level change mode (FLCH mode) of an automatic flight control system for civil aircraft. Background Art

[0002] FLCH, short for "Flight Level Change," is one of the most commonly used modes in civil aircraft automatic flight control systems. FLCH's control features: When engaged, the autothrottle and vertical axis coordinate simultaneously to rapidly climb or descend the aircraft to a specified flight level.

[0003] Typically, FLCH mode is activated by selecting the FLCH button on the flight mode control panel. This mode is a commonly used climb / descent mode by civil aircraft pilots due to its ease of operation and ability to control rapid climbs / descents while maintaining the target speed, preventing the aircraft from entering the critical speed zone.

[0004] The control characteristics of FLCH mode are as follows: when this mode is engaged, the autothrottle controls the engine to maintain a fixed thrust, providing the energy required for flight climb / descent. The vertical axis autopilot controls the flight attitude through the elevator to achieve target speed control.

[0005] Due to the control characteristics of the FLCH mode, existing FLCH mode control methods face a core challenge: how to control engine thrust to provide the energy required to meet the necessary climb rate and acceleration / deceleration for flight, while preventing excess engine energy. Excess energy refers to the situation where the engine's energy is greater than the energy required for flight climb / descent and acceleration / deceleration. Excessive excess energy can lead to excessive aircraft maneuverability, excessive load, reduced comfort, and engine damage.

[0006] For thrust control in FLCH mode, the common control methods are:

[0007] (1) It does not distinguish between the altitude difference of climbing and descending. When climbing, the throttle lever is in the TOGA position, providing maximum continuous thrust; when descending, it is in the IDLE position, providing idle thrust. This control method will result in a large amount of residual engine energy during the climbing and descending process. Especially in the climbing and descending scenarios with small altitude differences, using this control method, the aircraft will maneuver quickly, quickly capture the target altitude, and then maintain the target altitude. The load during the entire climbing process is too large, affecting passenger comfort.

[0008] (2) In a small altitude difference FLCH climb / descent scenario, the vertical axis controls the fixed vertical speed, and the throttle only controls the speed. However, if the target speed is lowered during the climb, this mechanism may result in the disadvantage of reducing the throttle to control the speed.

[0009] For example, reference document D1 (CN 113778116 B) discloses a flight level change control device and method for a civil airliner, which proposes an engine throttle controller based on energy management. The difference between the desired energy and the expected energy is subjected to PID control to obtain the throttle thrust. However, this control method cannot guarantee the aircraft's vertical speed. In particular, in the FLCH mode deceleration climb / acceleration descent scenario, the vertical speed may be too low, resulting in an unfavorable time to reach the target altitude. Furthermore, the control method requires accurate aircraft mass during calculations, otherwise it directly affects the control effect. However, accurate mass measurements are difficult to obtain.

[0010] Reference D2 (CN105912006 B) discloses a method for controlling an aircraft go-around, which proposes a thrust control method during the go-around process, including three steps: S1. Utilizing the flight control system to obtain the go-around thrust, go-around target vertical speed, and go-around target airspeed of the aircraft in the current state; S2. Pressing the go-around button causes the autothrottle to push the throttle lever to the aircraft's go-around thrust position, maintaining the target thrust, causing the aircraft to tilt its head upward and increase the current vertical speed to the target vertical speed; S3. When the aircraft's vertical speed reaches the target vertical speed, the aircraft climbs toward the target airspeed at the current airspeed.

[0011] Reference D3 (US5386954 A) discloses the process of maintaining flight speed while using an elevator. It proposes a control method in FLCH mode, which consists of two phases. For example, in the first phase, the elevator generates a pitch-up command, while the throttle command is calculated using the expected speed and real-time speed feedback to prevent the aircraft from losing speed. In the second phase, the throttle is set to maximum thrust and maintained at a constant level, with the elevator controlling the aircraft's speed.

[0012] Reference D4 (US5031102 A) discloses a method and apparatus for controlling the pitch and thrust axes of an aircraft, which proposes an automatic or semi-automatic vertical track control system for an aircraft, wherein when climbing in FLCH mode, the thrust is controlled to the upper thrust limit; when descending in FLCH mode, the thrust is controlled to the IDLE thrust.

[0013] However, in the solutions of references D3 and D4, the thrust limit thrust is still used for climbing, and the IDLE thrust is still used for descent. Therefore, the solutions still have the technical problem mentioned in the first point.

[0014] Therefore, there is a need to provide a thrust control solution that can ensure that the desired vertical speed is maintained during the climb / descent process, while ensuring the kinetic energy required for the aircraft to perform acceleration and deceleration operations. Summary of the Invention

[0015] In this application, the algorithm core of the thrust control scheme in FLCH mode is to control the thrust size based on the desired vertical speed and the kinetic energy required for acceleration and deceleration of the aircraft during the climb process. That is, the calculated thrust should be able to ensure both maintaining the desired vertical speed during the climb / descent process and ensuring the kinetic energy required for the aircraft to perform acceleration and deceleration operations.

[0016] According to a first aspect of the present application, a thrust control system in FLCH mode is provided, comprising:

[0017] Upper branch, including:

[0018] an altitude difference calculation module configured to calculate an altitude difference between a target altitude and a current altitude of the aircraft;

[0019] a latch module configured to latch a value of the height difference according to a manual operation reaction time delay and industry requirements;

[0020] a vertical speed calculator configured to calculate a corresponding expected vertical speed according to the latched height difference output by the latch module;

[0021] a thrust calculator configured to calculate a corresponding thrust according to the desired vertical speed;

[0022] The lower branch includes:

[0023] a selector configured to select an integration rate according to an integration rate determination condition;

[0024] an integrator configured to integrate over time according to a selected integration rate to output a compensated thrust; and

[0025] An adder is configured to add the thrust from the upper branch and the compensation thrust from the lower branch to output a thrust command.

[0026] According to a second aspect of the present application, a thrust control method in FLCH mode is provided, comprising:

[0027] Thrust calculation sub-process:

[0028] Calculate the altitude difference between the target altitude and the current altitude of the aircraft;

[0029] The value of the height difference is locked according to the delay of manual operation reaction time and industry demand;

[0030] Calculating the corresponding expected vertical speed based on the latched height difference;

[0031] Calculating a corresponding thrust according to the desired vertical velocity;

[0032] Compensation thrust sub-process:

[0033] Select the integration rate according to the integration rate judgment condition;

[0034] integrating over time according to a selected integration rate to output a compensated thrust; and

[0035] The thrust from the thrust calculation subroutine is added to the compensation thrust from the compensation thrust subroutine to output a thrust command.

[0036] This Summary is provided to introduce some concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] To illustrate the manner in which the above-recited and other advantages and features of the present invention can be obtained, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments of the invention that are illustrated in the accompanying drawings. Understanding that these drawings depict only typical embodiments of the invention and are not therefore to be considered limiting of its scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings, in which:

[0038] Figure 1 An example logical structure diagram of a thrust control system in a flight level change (FLCH) mode according to an embodiment of the present application is shown.

[0039] Figure 2 An exemplary structural diagram of a latch module in a thrust control system according to an embodiment of the present application is shown.

[0040] Figure 3 An exemplary flow chart of a thrust control method in a flight level change (FLCH) mode according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0041] In this application, generally speaking, the algorithm core of the thrust control scheme in FLCH mode is to control the thrust size based on the desired vertical speed and the kinetic energy required for acceleration and deceleration of the aircraft during the climb process. That is, the calculated thrust should be able to ensure that the desired vertical speed is maintained during the climb / descent process, while ensuring the kinetic energy required for acceleration and deceleration operations of the aircraft.

[0042] Reference below Figure 1 An example logical structure diagram of a thrust control system in a flight level change (FLCH) mode according to an embodiment of the present application is described below.

[0043] As shown in the figure, the thrust control system is implemented by a combination of upper and lower branches.

[0044] The upper branch is the thrust calculation branch to achieve thrust control that is adaptive to the desired vertical speed.

[0045] In summary, the thrust calculation branch includes the following operations:

[0046] After activating FLCH mode, the aircraft's altitude difference between the current and target altitudes is first calculated. The desired vertical speed is then interpolated from this altitude difference. The thrust required to achieve this desired vertical speed is then calculated using the aircraft's steady climb formula.

[0047] Civil aircraft design standards generally stipulate that in FLCH mode, the target altitude must be reached within a specified time, T seconds. Therefore, the principle for selecting the desired vertical speed is as follows: if the aircraft's capabilities are not limited, the target altitude must be reached within the specified time, T; if the aircraft's capabilities are limited, the aircraft must climb / descent according to its maximum climb / descent performance.

[0048] Therefore, the greater the altitude difference between climbing and descending, the higher the expected vertical speed. When climbing or descending with a small altitude difference, the interpolated vertical speed will not be too high to avoid the problem of rapid maneuvering and excessive payload. When climbing or descending with a large altitude difference, the interpolated vertical speed will be slightly higher to meet the requirement of reaching the specified target layer within the specified time.

[0049] To achieve the above operations, the upper branch circuit accordingly provides an altitude difference calculation module, a latch module, a vertical velocity calculator, and a thrust calculator coupled via a communication medium, including wired media such as A664 and A429 buses, and wireless networks.

[0050] First, the altitude difference calculation module is configured to calculate the altitude difference ALT between the target altitude and the current altitude of the aircraft. error The current real-time altitude of the aircraft may be derived from the aircraft's atmospheric system, and the target altitude of the aircraft may be derived from the flight mode control panel, such as manually input by the pilot.

[0051] The latch module is configured to latch the value of the height difference according to the manual operation reaction time delay and industry requirements.

[0052] Specifically, the latch module uses two latches. The example logical structure of the latch module is as follows: Figure 2 shown.

[0053] The function of the first latch is to give the pilot time to confirm the altitude. That is, after the pilot has selected the target altitude and maintained it for a period of time, the first latch will latch the target altitude and output the altitude difference ALT. error_unchanged For example, if the aircraft is at an altitude of 500 ft and the target altitude is 2000 ft, the ideal situation is for the pilot to directly adjust the altitude to 2000 ft. However, in reality, the pilot may pause for 0.1 seconds when adjusting to 1000 ft, hesitate for a moment at 1800 ft, and then continue to adjust to 2000 ft. Without the first latch, the system may calculate the desired vertical speed and thrust three times using 1000 ft, 1800 ft, and 2000 ft as the target altitudes. The presence of the first latch allows a reaction confirmation period (e.g., Y seconds) after the pilot sets the target altitude before the formal calculation begins, thus avoiding the problem caused by the delayed reaction time of manual operation. It should be understood that if the pilot is sufficiently familiar with the system and has sufficient operation skills, the confirmation time in the first latch can be set to a smaller value for such an experienced pilot. Conversely, if the pilot is a novice with inexperienced operation and a slower reaction speed, the time can be set to a larger value.

[0054] The second latch specifies when to re-enable the latch to calculate the desired vertical speed and thrust and output the latched altitude difference when the target altitude is modified during a climb / descent in FLCH mode.

[0055] Specifically, if the original target altitude is greater than the actual aircraft altitude, and the pilot continues to increase the target altitude during a FLCH climb, the second latch is reactivated to recalculate the desired vertical speed and increase thrust. However, if the pilot continues to decrease the target altitude during a FLCH climb (but the newly set target altitude is still greater than the actual aircraft altitude), the second latch is not activated and thrust remains unchanged, not reduced. This meets the industry requirement that thrust cannot be reduced during a FLCH climb.

[0056] Similarly, if the original target altitude is lower than the aircraft's actual altitude, while descending in FLCH mode, if the pilot continues to lower the target altitude, the second latch will be reactivated to recalculate the desired vertical speed and reduce thrust. However, if the pilot raises the target altitude during a FLCH descent (but the newly set target altitude is still lower than the aircraft's actual altitude), the second latch will not be activated and thrust will remain unchanged, not increased. This meets the industry requirement that thrust cannot be increased during a FLCH descent.

[0057] From the perspective of logical judgment, the second latch performs the following latch judgment logic:

[0058] Among them, the output of the first latch ALT error_unchanged As an input of the second latch, if any of the following conditions is detected, the second latch starts latching and outputs the latched ALT error_latch :

[0059] (a) If the height difference between the target height and the current height is greater than 0, and the height difference output by the first latch increases, that is, when ALT error Greater than 0, and ALT error_unchanged The scenario described is: during a climb in FLCH mode, the target altitude is greater than the actual aircraft altitude, and the pilot continues to increase the target altitude. At this time, the latch needs to be restarted to calculate the target altitude difference and increase thrust.

[0060] (b) If the height difference between the target height and the current height is less than 0, and the height difference output by the first latch decreases, that is, when ALT error Less than 0, and ALT error_unchanged The scenario described is: during a descent in FLCH mode, the target altitude is lower than the actual aircraft altitude, and the pilot continues to lower the target altitude. At this time, the latch needs to be restarted to calculate the target altitude difference and reduce thrust.

[0061] (c) When the FLCH mode is initially activated, it is necessary to start latching and calculating the height target difference.

[0062] In other cases, the second latch does not start latching, that is, there is no need to change the vertical speed and thrust.

[0063] Without the second latch, if the pilot lowers the target altitude during a FLCH climb or raises the target altitude during a FLCH descent, the aircraft may throttle back to reduce thrust, violating industry requirements and causing unnecessary interference to the pilot.

[0064] It should be understood that the above “first” and “second” are only used to facilitate the distinction between the two latches, and are not a specific limitation.

[0065] The vertical speed calculator is configured to calculate a corresponding expected vertical speed according to the latched height difference output by the latch module.

[0066] When calculating the desired vertical speed, it is necessary to consider how to meet industry standards for quickly reaching the target altitude in FLCH mode while also taking into account passenger comfort and energy-saving functional designs.

[0067] Specifically, civil aircraft design standards generally stipulate that in FLCH mode, the target altitude must be reached within a specified time, T seconds. Therefore, the calculated desired vertical speed must meet this requirement. This, in turn, determines the lower limit for the desired vertical speed. Whenever the aircraft is climbing, it should exceed this climb rate. A desired vertical speed exceeding this lower limit theoretically meets these requirements. However, while a faster vertical speed allows for faster arrival at the target altitude, it may also result in reduced passenger comfort and greater thrust (energy) waste. Furthermore, industry requirements also include a default minimum vertical speed. For example, during a FLCH climb, the autoflight system cannot command the aircraft to descend. Therefore, a small vertical speed target, such as 250 ft / min, is set as the lower limit for the desired vertical speed to ensure that the aircraft does not descend during a FLCH climb.

[0068] Based on this, the vertical velocity calculator can be implemented in several modes:

[0069] 1) Calculate the desired vertical speed in real time based on the locked altitude difference and the specified time T to reach the target altitude layer. For example, if the FLCH mode requires reaching an altitude of 8000ft within 1 minute, and the current altitude of the aircraft is 5000ft, then the desired vertical speed VS exp =(8000-5000) / 1=3000ft / min.

[0070] While vertical speeds exceeding this limit can meet regulatory requirements, passenger comfort and energy efficiency must also be considered. High vertical speeds can cause passenger discomfort. For example, in FLCH mode climb / descent scenarios with small altitude differences, excessive vertical speeds can cause the aircraft to immediately acquire the target altitude, resulting in significant overload and negatively impacting both economy and passenger comfort.

[0071] In addition, as mentioned above, the industry standard vertical speed should be no less than 250 ft / min. If the calculated vertical speed is lower than 250 ft / min, 250 ft / min can be directly used as the vertical speed.

[0072] However, this real-time calculation actually consumes a lot of system resources and has a long response time. Therefore, the following interpolation table method is commonly used in the industry for quick calculation.

[0073] 2) Calculating the desired vertical speed using an interpolation table. That is, the desired vertical speed is obtained by interpolating the altitude difference output by the latch module based on the interpolation table. Different climbing / descending altitude differences will result in different interpolated desired vertical speeds.

[0074] Specifically, since a large number of pilots and aircraft are performing climb / descent operations at various altitude differences every day in the world, there is a large amount of flight experience available to follow regarding which vertical speed should be adopted for different altitude differences to both meet industry standards for quickly reaching the target altitude layer while also taking into account passenger comfort and energy conservation. Therefore, an interpolation table can be designed based on this accumulated industry flight experience. The interpolation table includes multiple records. Each record includes a specific locked altitude difference and the preferred expected vertical speed for that altitude difference, which is set based on experience. An example of the interpolation table is as follows:

[0075] Breakpoints ALT_error_latch(ft) <![CDATA[VS exp (ft / min)]]> (1) -2000 -7700 (2) -1000 -1400 (3) -0.1 -250 (4) 0 0 (5) 0.1 250 (6) 1000 1400 (7) 2000 7700

[0076] Based on these specific records in the interpolation table, for the latched height differences that are not recorded in the interpolation table, the corresponding expected vertical speed can be derived by interpolation, that is, the formula:

[0077] VS exp =f(ALT error_latch ) (1)

[0078] VS exp represents the desired vertical velocity, and f represents the interpolation based on the interpolation table.

[0079] The thrust calculator is configured to calculate a corresponding thrust according to the desired vertical speed, under which the aircraft can maintain a steady-state desired vertical speed to reach a target altitude.

[0080] Specifically, the required thrust can be calculated based on the desired vertical speed using the formula for steady climb of an aircraft. The formula for steady climb of an example aircraft is as follows:

[0081] γ exp =VS exp / GS (2)

[0082] F=D+Wsinγ exp (3)

[0083] Among them, γ exp represents the desired flight track angle; GS represents the ground speed, which comes from the aircraft's inertial navigation system; F is the thrust; D is the flight resistance, which can be calculated through the aircraft's aerodynamic drag coefficient, flight speed, etc.; W is the aircraft's weight, which comes from the aircraft's flight control system.

[0084] From the above formula, we can understand that, first, according to the desired vertical speed VS exp The ratio of this to ground speed GS allows the desired flight path angle to be calculated.

[0085] The thrust is then calculated by adding the product of the aircraft's flight drag and the aircraft's weight and the sine of the desired flight path angle, and output to one input of a subsequent adder.

[0086] By utilizing the upper branch, the desired vertical speed and corresponding thrust can be adaptively changed. That is, when the altitude difference changes, the system automatically recalculates the corresponding desired vertical speed and thrust as needed.

[0087] However, the thrust calculated using the upper branch cannot meet actual needs. The reasons are:

[0088] 1) In the above thrust calculation process, parameters such as flight resistance and aircraft gravity are required, but these parameters are often not accurately obtained;

[0089] 2) The flight (horizontal) speed of an aircraft may change during its motion, such as accelerating or decelerating, and these changes will also affect the thrust.

[0090] Therefore, in order to make the calculated thrust more accurate, a thrust compensation mechanism is designed in the lower branch.

[0091] In other words, the upper branch alone cannot accurately control the aircraft to achieve the desired vertical speed. Therefore, the lower branch's integral control based on vertical speed feedback is required to provide thrust compensation. Therefore, the command output by the lower branch supplements the thrust output by the upper branch.

[0092] Specifically, if Figure 1 As shown, the lower branch includes a selector and an integrator, and its working principle is as follows:

[0093] Taking FLCH mode climbing as an example, the integrator starts when all the following conditions are met:

[0094] ①Activate FLCH mode;

[0095] ②Climbing stage;

[0096] Condition 1 indicates that the FLCH mode is activated; Condition 2 indicates that the aircraft is in the climbing phase;

[0097] The integration rate is set by the following integration rate judgment conditions:

[0098] ① If the actual vertical speed is not less than the desired vertical speed, the integral rate is 0. This situation indicates that the actual vertical speed is greater than or equal to the desired vertical speed, indicating that the current thrust is sufficient to maintain the desired vertical speed and no further thrust increase is required.

[0099] ② The actual vertical velocity is less than the desired vertical velocity, and the actual flight speed is less than the target flight speed. The integral rate is K1. This situation indicates that the actual vertical velocity is less than the desired vertical velocity, and the actual flight speed is also less than the target flight speed. A rapid increase in thrust is required. The increased thrust is used to increase vertical velocity and provide kinetic energy. Therefore, the integral rate value provided is large.

[0100] ③ The actual vertical velocity is less than the desired vertical velocity, but the actual flight speed is not less than the target flight speed. The integration rate is K2. This situation indicates that the actual vertical velocity is less than the desired vertical velocity, and the thrust needs to be increased to increase the vertical velocity. However, since the actual flight speed is greater than the target flight speed, this excess kinetic energy can be converted into vertical velocity, so an excessively large integration rate is not required.

[0101] It can be seen from this that the relationship between the integral rates should satisfy: K1>K2>0.

[0102] It should be understood that the purpose of the above operation is to: if the aircraft's actual vertical speed does not reach the desired vertical speed due to the thrust of the upper branch, the lower branch can be used to slowly compensate for the thrust to achieve the desired vertical speed. Therefore, the values ​​of K1 and K2 should not be too large. The specific range of these values ​​is generally selected based on the results of simulation tests.

[0103] Specifically, if, in the simulation tests for the three scenarios described above, the value of K is too large, potentially causing the compensated current aircraft's vertical velocity to be large and deviate significantly from the desired vertical velocity, the value of K is adjusted downward. Conversely, if the value of K is too small, potentially causing the compensated current aircraft's vertical velocity to be small and still deviate significantly from the desired vertical velocity, the value of K is adjusted upward. This process is repeated until the value of K that results in the compensated vertical velocity falling within the acceptable range of the desired vertical velocity is determined as the value of K. Generally speaking, a value of around 0-0.5 is appropriate for K1 and K2.

[0104] After the selector selects the corresponding value (0, K1, or K2) based on the aforementioned integration rate determination conditions and outputs it to the integrator, the integrator integrates the selected integration rate over time to output the compensated thrust as another input to the adder. It will be appreciated that when the integration rate is 0, the integrator effectively performs no integration, and therefore the outputted compensated thrust is also effectively 0, meaning no thrust compensation is required.

[0105] Finally, the adder is configured to add the calculated thrust from the upper branch and the compensated thrust from the lower branch to output a final thrust command.

[0106] Therefore, based on the final thrust command output, the throttle lever is not necessarily limited to the TOGA or IDLE position.

[0107] When climbing or descending in FLCH mode with a small altitude difference, the throttle lever is generally in the neutral position, and the necessary thrust is sufficient for climbing or descending. This not only provides better passenger comfort but also saves energy. Therefore, in this scenario, the solution proposed in this application is superior to conventional FLCH mode thrust control methods.

[0108] If the altitude difference is large, the throttle lever may reach the TOGA / IDLE position under thrust control. In this scenario, the throttle lever maintains the TOGA / IDLE position. At this time, the thrust control method of this application is the same as the conventional FLCH mode thrust control method.

[0109] After describing the example logical structure diagram of the thrust control system. Figure 3 An example flow chart of a thrust control method in a flight level change (FLCH) mode according to an embodiment of the present application is described.

[0110] As shown in the figure, when the pilot activates the FLCH mode, the thrust control method begins. As previously mentioned, the method can be divided into two branches: the left branch of the method executes the processing in the upper branch of the thrust control system, namely the thrust calculation sub-process; while the right branch of the method executes the processing in the lower branch of the thrust control system, namely the compensatory thrust sub-process.

[0111] First, in the thrust calculation subprocess:

[0112] In step 302 , the altitude difference calculation module calculates the altitude difference between the target altitude and the current altitude of the aircraft.

[0113] Then, in step 304 , the latch module latches the value of the height difference according to the manual operation reaction time delay and industry requirements.

[0114] As mentioned above, the latch module may include two latches.

[0115] The function of the first latch is to give the pilot time to confirm the altitude. That is, after the pilot has selected the target altitude and maintained it for a period of time, the first latch will latch the target altitude and output the altitude difference ALT. error_unchanged to the second latch.

[0116] The second latch specifies when to restart the latch to calculate the desired vertical speed and thrust and output the latched altitude difference ALT when the target altitude is modified during FLCH mode climb / descent.error_latch to meet industry needs.

[0117] Then, in step 306 , the vertical speed calculator calculates the corresponding expected vertical speed according to the latched height difference output by the latch module.

[0118] As previously mentioned, the desired vertical speed can meet the industry standard of quickly reaching the target altitude in the FLCH mode while taking into account the functional design of passenger comfort and energy saving.

[0119] The calculation can calculate the desired vertical speed in real time based on the latched altitude difference and the specified time T to reach the target altitude layer.

[0120] It is more convenient and quick to calculate the desired vertical velocity using an interpolation table (see Table 1, Formula 1 and its related contents).

[0121] Next, in step 308, the thrust calculator calculates the corresponding thrust according to the desired vertical speed. The specific calculation process can be found in formulas 2 and 3 and their related contents.

[0122] At the same time, another thrust compensation sub-process can also be executed synchronously, which mainly includes: selecting an integration rate according to the integration rate judgment condition; integrating according to time according to the selected integration rate to output the thrust compensation. Specifically:

[0123] In step 303, first, it is determined whether the current actual vertical speed is less than the expected vertical speed.

[0124] If not, the flow proceeds to step 305 , the selector selects an integration rate of 0, and the flow then proceeds to step 313 .

[0125] If yes, the process proceeds to step 307 to determine again whether the actual flight speed is less than the target flight speed.

[0126] If yes, the process proceeds to step 309 , the selector selects the integration rate as K1 , and the process then enters step 313 .

[0127] If not, the process proceeds to step 311 , the selector selects the integration rate to be K2 , and the process then proceeds to step 313 .

[0128] In step 313 , the integrator integrates over time according to the integration rate received from the selector to output compensated thrust.

[0129] Finally, in step 320 , a final thrust command is generated by summing the thrust output from step 308 and the thrust output from step 313 .

[0130] In this way, according to the thrust command, the throttle lever can be placed in an appropriate position to generate the corresponding thrust.

[0131] Compared to conventional FLCH mode techniques, if the altitude difference is large, the throttle lever may still reach the TOGA / IDLE position under thrust control in this solution. In this scenario, the throttle lever maintains the TOGA / IDLE position, which is the same as conventional FLCH mode thrust control.

[0132] However, when climbing or descending with a small altitude difference, the thrust lever under this solution can be placed in the middle position to meet the necessary thrust for climbing or descending. This not only provides better passenger comfort but also saves energy. Therefore, in this scenario, the solution proposed in this application is superior to the conventional FLCH mode thrust control method.

[0133] Although various embodiments have been described above, it should be understood that they are intended to be illustrative only and not limiting. Persons skilled in the relevant art(s) will appreciate that various modifications in form and detail may be made without departing from the spirit and scope of the present invention as defined by the appended claims. Therefore, the breadth and scope of the present invention disclosed herein should not be limited by the exemplary embodiments disclosed above, but should be defined only in accordance with the appended claims and their equivalents.

Claims

1. A thrust control system in FLCH mode, comprising: Upper branch, including: an altitude difference calculation module configured to calculate an altitude difference between a target altitude and a current altitude of the aircraft; a latch module configured to latch a value of the height difference according to a manual operation reaction time delay and industry requirements; a vertical speed calculator configured to calculate a corresponding expected vertical speed according to the latched height difference output by the latch module; a thrust calculator configured to calculate a corresponding thrust according to the desired vertical speed; The lower branch includes: a selector configured to select an integration rate according to an integration rate determination condition; an integrator configured to integrate over time according to a selected integration rate to output a compensated thrust; and An adder is configured to add the thrust from the upper branch and the compensation thrust from the lower branch to output a thrust command.

2. The thrust control system according to claim 1, wherein: The latch module includes: a first latch configured to latch the target height after detecting that the selected target height is maintained for a period of time and output the height difference to an input of a second latch; The second latch is configured to start latching according to a latch judgment logic to output the latched height difference.

3. The thrust control system according to claim 2, wherein: The latch judgment logic includes: (a) if the height difference between the target height and the current height is greater than 0, and the height difference output by the first latch increases, activating the second latch; (b) if the height difference between the target height and the current height is less than 0, and the height difference output by the first latch decreases, activating the second latch; (c) When the FLCH mode is initially activated, the second latch is enabled.

4. The thrust control system according to claim 1, wherein: The vertical velocity calculator calculates the desired vertical velocity using an interpolation table according to the following formula: VS exp =f(ALL error_latch ) (1) Among them, VS exp represents the desired vertical speed, f represents interpolation based on the interpolation table, ALT error_latch Represents the height difference of the latch output by the latch module.

5. The thrust control system according to claim 1, wherein: The thrust calculator calculates the thrust according to the following formula for steady climb of the aircraft: γ exp =VS exp / GS (2) F=D+W sinγ exp (3) Among them, γ exp represents the desired flight path angle; GS represents ground speed; F represents thrust; D represents flight drag; and W represents aircraft weight.

6. The thrust control system according to claim 1, wherein: The selector selects the integration rate according to the following integration rate judgment conditions: During the climb phase in the FLCH mode: 1) If the actual vertical velocity is not less than the expected vertical velocity, the integral rate is 0; 2) If the actual vertical speed is less than the desired vertical speed and the actual flight speed is less than the target flight speed, the integral rate is K1; 3) If the actual vertical speed is less than the desired vertical speed and the actual flight speed is not less than the target flight speed, the integral rate is K2; The relationship between the integral rates satisfies: K1>K2>0.

7. A thrust control method in FLCH mode, comprising: Thrust calculation sub-process: Calculate the altitude difference between the aircraft's target altitude and current altitude; The value of the height difference is locked according to the delay of manual operation reaction time and industry demand; Calculating the corresponding expected vertical speed based on the latched height difference; Calculating a corresponding thrust according to the desired vertical velocity; Compensation thrust sub-process: Select the integration rate according to the integration rate judgment condition; integrating over time according to a selected integration rate to output a compensated thrust; and The thrust from the thrust calculation subroutine is added to the compensation thrust from the compensation thrust subroutine to output a thrust command.

8. The thrust control method according to claim 7, wherein: The step of locking the value of the height difference according to the manual operation reaction time delay and industry demand includes: The first latch latches the target height after detecting that the selected target height is maintained for a period of time and outputs the height difference to the input of the second latch; The second latch starts latching according to the latch judgment logic to output the latched height difference; Wherein, the latch judgment logic includes: (a) if the height difference between the target height and the current height is greater than 0, and the height difference output by the first latch increases, activating the second latch; (b) if the height difference between the target height and the current height is less than 0, and the height difference output by the first latch decreases, activating the second latch; (c) When the FLCH mode is initially activated, the second latch is enabled.

9. The thrust control method according to claim 7, wherein: The step of calculating the corresponding expected vertical speed according to the latched height difference comprises: The desired vertical velocity is calculated using the following formula using an interpolation table: VS exp =f(ALL error_latch ) (1) Among them, VS exp represents the desired vertical speed, f represents interpolation based on the interpolation table, ALT error_latch represents the height difference of the latch; and The step of calculating the corresponding thrust according to the desired vertical speed includes: calculating the thrust according to the following formula for steady climb of the aircraft: γ exp =VS exp / GS (2) F=D+W sinγ exp (3) Among them, γ exp represents the desired flight path angle; GS represents ground speed; F represents thrust; D represents flight drag; and W represents aircraft weight.

10. The thrust control method according to claim 7, wherein: Select the integration rate based on the following integration rate judgment criteria: During the climb phase in the FLCH mode: Determine whether the current actual vertical speed is less than the expected vertical speed: If not, the integration rate is 0; If yes, then determine whether the actual flight speed is less than the target flight speed: If yes, select the integration rate as K1; If not, select the integration rate as K2; The relationship between the integral rates satisfies: K1>K2>0.

Images