Flight control system hydraulic flow demand calculation method based on flight quality requirement

Abstract

The invention relates to the technical field of flight control system hydraulic flow demand calculation, and discloses a flight control system hydraulic flow demand calculation method based on flight quality requirements. According to the method, flight quality related to hydraulic flow is selected, a target airplane model is constructed, a transfer function of a target airplane is given according to an equivalent fitting formula of a short-period pitch angle rate and normal overload, and a control surface instruction required by response parameters is reversely solved according to an inverse function from an airplane body to the response parameters of the airplane. The method comprises the following steps: calculating a rate value required by a control surface and power required by simultaneous movement of all control surface actuators of a flight control system according to rate amplitude limiting of a control surface actuator model, performing control surface combined motion analysis based on actual test flight, analyzing division and control actions of flight stages in the actual test flight, and combining a flight quality test flight project to obtain a control surface combined motion analysis result. And the condition that the control surface combination condition is harsh is selected, the final hydraulic flow demand of the hydraulic source is calculated, and reference is provided for optimization design of the aircraft.

Description

Technical Field

[0001] The present invention relates to the technical field of hydraulic flow demand calculation of a flight control system, and in particular to a method for calculating the hydraulic flow demand of a flight control system based on flight quality requirements. Background Art

[0002] Hydraulic energy is one of the important energy sources on an aircraft. The aircraft uses the hydraulic system to drive the actuators and achieve the required functions. The main users of the hydraulic system include the flight control system and the landing gear system. Among them, the flight control system uses hydraulic energy to drive the control surfaces.

[0003] When designing a hydraulic system, it is necessary to calculate the required hydraulic power or flow based on the user's power or flow requirements, and determine the rated flow of the hydraulic system oil pump based on the working status of the engine. Therefore, the flight control system, as the main user, can propose accurate hydraulic flow requirements, which is the key input for completing the design of the hydraulic system. If the flight control system proposes a demand flow that is too large, it will lead to an increase in the weight and volume of the hydraulic system, and ultimately reduce the aircraft's payload. If the demand flow is too small, it cannot meet the movement requirements of the rudder, thereby affecting the normal operation of the aircraft. Summary of the invention

[0004] 1. Technical issues to be solved

[0005] In view of the deficiencies of the prior art, the present invention provides a method for calculating the hydraulic flow demand of a flight control system based on flight quality requirements, which has the characteristics of selecting a flight quality related to the hydraulic flow, constructing a target aircraft model according to the selected flight quality, giving a transfer function of the target aircraft according to an equivalent fitting formula of a short-period pitch angle rate and a normal overload, inversely solving the rudder instructions required to realize the response parameters according to an inverse function from the aircraft body to the aircraft response parameters, and calculating the required rate value of the rudder according to the rate limit of the rudder actuator model. The power required for all the rudder actuators of the flight control system to move simultaneously is compared with the original rudder combination calculation method for all rudders moving simultaneously. The rudder combination motion analysis based on the actual test flight is carried out. The division of the flight phases and the control actions in the actual test flight are analyzed. In combination with the flight quality test flight project, the situations where the rudder combination is more severe are selected, including tight turns, deceleration turns, maximum roll and pitch combination control, coordinated sideslip, lateral heading control under asymmetric thrust, and takeoff and landing in strong crosswind. The hydraulic flow demand is calculated based on the configuration of the rudder energy, including the hydraulic flow RT_Q required by the j-th rudder for the i-th set of hydraulic sources i[j] and the final hydraulic flow demand of the i-th set of hydraulic sources. Through the control model with hydraulic flow calculation, the control system simulation analysis is carried out to obtain the flow demand at any time, verify the requirements proposed in the scheme demonstration stage and the preliminary design stage, and provide a reference for the optimal design of the aircraft. Through the above method, the flight control system can provide accurate hydraulic flow demand input for the hydraulic system design, without wasting the flow of the hydraulic system under the premise of meeting the requirements of the flight control system, so as to achieve the optimal overall design indicators of the aircraft and solve the above problems.

[0006] (II) Technical solution

[0007] To achieve the above object, the present invention provides the following technical solution: a method for calculating the hydraulic flow demand of a flight control system based on flight quality requirements, comprising the following steps:

[0008] S1. Select the flight quality related to hydraulic flow;

[0009] The target aircraft model is constructed according to the selected flight quality, and the transfer function of the target aircraft is given according to the equivalent matching formula of the aircraft longitudinal short-period pitch angle rate and normal overload;

[0010] According to the inverse function from the aircraft body to the aircraft response parameter, the control surface command required to realize the response parameter is inversely solved;

[0011] Calculate the required movement rate of the rudder according to the rate limit of the rudder actuator model The power required to move all control surface actuators of the flight control system simultaneously;

[0012] S2. Compare the original calculation method of rudder surface combination in which all rudder surfaces move simultaneously, conduct rudder surface combination motion analysis based on actual test flight, analyze the division of flight phases and control actions in actual test flight, and select the more stringent rudder surface combination conditions in combination with the flight quality test flight items, including tight turns, deceleration turns, maximum roll and pitch combination control, coordinated sideslip, lateral heading control under asymmetric thrust, and takeoff and landing in strong crosswind;

[0013] S3. Calculate the hydraulic flow demand based on the configuration of the rudder energy, including the hydraulic flow RT_Q required by the j-th rudder for the i-th set of hydraulic sources i [j] and the final hydraulic flow requirement of the i-th hydraulic source;

[0014] S4. Through the control model with hydraulic flow calculation, the control system simulation analysis is carried out to obtain the flow demand at any time, verify the requirements proposed in the scheme demonstration stage and the preliminary design stage, and provide a reference for the optimal design of the aircraft.

[0015] Preferably, in S1, before selecting the flight quality related to the hydraulic flow, at a specified deflection speed, the maximum power required to overcome the hinge torque to manipulate the control surface is calculated, and the formula is as follows:

[0016]

[0017] In the formula, N max It indicates the maximum power required for a certain control surface of the flight control system to move, K indicates the coefficient of the working characteristics of different control surface actuators, M max represents the maximum hinge moment of the rudder surface, Indicates the required rate of movement of the control surface.

[0018] Preferably, in S1, the short-period pitch rate criterion of the aircraft longitudinal direction has the following characteristics in its flight quality response:

[0019] (1) The effective delay time t1 is within the following range:

[0020] Level 1: t1≤0.12s;

[0021] Level 2: t1≤0.17s;

[0022] Level 3: t1≤0.21s;

[0023] (2) The transient peak ratio Δω2 / Δω1 meets the following requirements:

[0024] Level 1: less than or equal to 0.3;

[0025] Level 2: less than or equal to 0.6;

[0026] Level 3: less than or equal to 0.85;

[0027] (3) The effective rise time Δt is within the following range:

[0028] ① Non-terminal flight phase:

[0029] Level 1: 29.6 / V T ≤t1≤1645 / V T ;

[0030] Level 2: 10.5 / V T ≤t1≤5263 / V T ;

[0031] ②Terminal flight phase:

[0032] Level 1: 29.6 / V T ≤t1≤658 / V T ;

[0033] Level 2: 10.5 / V T≤t1≤2122 / V T ;

[0034] In the formula, V T Indicates true airspeed.

[0035] Preferably, in said S1, the flight quality response of the aircraft longitudinal short-period normal overload criterion has the following characteristics:

[0036] V 表 ≥1.5V 表机动 When the overload value reaches 0.95*n yss The rise time t r Not more than:

[0037] Level 1: 1.5s;

[0038] Level 2: 2.0s;

[0039] Level 3: 2.5s;

[0040] V 表机动 ≤V 表 ≤1.5V 表机动 When the overload value reaches 0.95*n yss The rise time t r Not more than:

[0041] Level 1: 2.0s;

[0042] Level 2: 2.5s;

[0043] Level 3: 3.0s;

[0044] V 表 ≥1.5V 表机动 When overload overshoot (n ymax -n yss ) / n yss Not more than:

[0045] Level 1: 10%;

[0046] Level 2: 20%;

[0047] Level 3: 30%;

[0048] Overload response attenuation to ±5% yss The number of oscillations is no more than 3 times, where V 表 V is the speed indicator; 表机动 It refers to the minimum indicated speed of the aircraft for maneuvering flight, n yss is the steady-state overload, n ymax is the maximum overload.

[0049] Preferably, in S1, a target aircraft model is constructed according to the selected flight quality, and a transfer function of the target aircraft is given according to an equivalent pseudo-matching formula of short-period pitch angle rate and normal overload, wherein the equivalent pseudo-matching formula is a Laplace transform formula, as shown below:

[0050]

[0051]

[0052] In the formula, s is the Laplace operator, represents the transfer function of the pitch rate to the stick force or displacement, is the numerator proportionality coefficient of the pitch rate transfer function, τ ω is the equivalent delay time of the pitch angle rate, ε n1 is the short-period equivalent damping ratio, ω n1 is the short-period equivalent frequency; represents the transfer function of the normal overload with respect to the rod force or displacement, is the numerator proportionality coefficient of the normal overload transfer function, τ n is the overload equivalent delay time, Tθ represents the numerator time constant of the short period, and e is the base of the natural logarithm.

[0053] Preferably, in S1, the velocity value required by the rudder is calculated according to the velocity limit of the rudder actuator model. The calculation process is as follows:

[0054] Taking the response parameters of the aircraft longitudinal short-period pitch rate criterion and the normal overload criterion as input, according to the inverse function of the aircraft body to each response parameter, the control surface instruction δ required to achieve the pitch rate and normal overload response parameters is inversely solved. cmd ; Set the control surface instruction δ cmd Input to the actuator model with rate limit, then simulate through the aircraft body model, output the pitch rate and normal overload response parameters, and compare them with the response parameters of the longitudinal short-period pitch rate criterion and the normal overload criterion. If the flight quality required by the criterion is met, the rate limit value is further reduced until it does not meet the requirements. At this time, the rate limit value is the required motion rate value.

[0055] Preferably, in S1, the power required for all the rudder surface actuators of the flight control system to move simultaneously is calculated according to the rate limit of the rudder surface actuator model, and the calculation formula is as follows:

[0056]

[0057] In the formula, N represents the power required by all actuators of the flight control system, Nmax Indicates the maximum power required for a certain control surface of the flight control system to move. Represents the power loss factor.

[0058] Preferably, the S2 clearly divides the various stages of the test flight according to the different requirements of the flight mission, including take-off, climb, cruise, approach, landing, etc. Each stage will correspond to different control actions and control surface combination requirements, and each stage will be quantified and calibrated through speed, altitude and attitude parameters.

[0059] Preferably, in S3, the hydraulic flow demand is calculated based on the configuration of the rudder energy source, including the hydraulic flow RT_Q required by the j-th rudder for the i-th set of hydraulic sources. i [j], the calculation formula is as follows:

[0060]

[0061] In the formula, RT_Q i [j] represents the hydraulic flow required by the j-th rudder for the i-th hydraulic source, Indicates the movement speed of the j-th rudder surface, SQ[j] indicates the conversion coefficient of the rudder surface movement speed to flow, which is calculated by the connecting rod length and piston area of ​​the actuator. ST[j] indicates the usage status of the j-th rudder surface for the i-th hydraulic source, 0 for not in use and 1 for in use.

[0062] Preferably, in S3, the hydraulic flow demand is calculated based on the configuration of the rudder energy source, and the final hydraulic flow demand calculation formula of the i-th set of hydraulic sources is as follows:

[0063]

[0064] In the formula, H_Q i represents the final hydraulic flow demand of the i-th hydraulic source, RT_Q i [j] represents the hydraulic flow required by the j-th rudder surface for the i-th set of hydraulic sources, and n represents the number of hydraulic sources.

[0065] Compared with the prior art, the present invention provides a method for calculating the hydraulic flow demand of a flight control system based on flight quality requirements, which has the following beneficial effects:

[0066] The present invention selects the flight quality related to the hydraulic flow, constructs the target aircraft model according to the selected flight quality, gives the transfer function of the target aircraft according to the equivalent fitting formula of the short-period pitch angle rate and the normal overload, inversely solves the rudder instructions required to realize the response parameters according to the inverse function from the aircraft body to the aircraft response parameter, and calculates the required rate value of the rudder according to the rate limit of the rudder actuator model. The power required for all the rudder actuators of the flight control system to move simultaneously is compared with the original rudder combination calculation method for all rudders moving simultaneously. The rudder combination motion analysis based on the actual test flight is carried out. The division of the flight phases and the control actions in the actual test flight are analyzed. In combination with the flight quality test flight project, the situations where the rudder combination is more severe are selected, including tight turns, deceleration turns, maximum roll and pitch combination control, coordinated sideslip, lateral heading control under asymmetric thrust, and takeoff and landing in strong crosswind. The hydraulic flow demand is calculated based on the configuration of the rudder energy, including the hydraulic flow RT_Q required by the j-th rudder for the i-th set of hydraulic sources i [j] and the final hydraulic flow demand of the i-th set of hydraulic sources. Through the control model with hydraulic flow calculation, the control system simulation analysis is carried out to obtain the flow demand at any time, verify the requirements proposed in the scheme demonstration stage and the preliminary design stage, and provide a reference for the optimal design of the aircraft. Through the above method, the flight control system can provide accurate hydraulic flow demand input for the hydraulic system design, without wasting the flow of the hydraulic system under the premise of meeting the requirements of the flight control system, so as to achieve the optimal overall design indicators of the aircraft. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] Figure 1 It is a schematic diagram of the steps of the method of the present invention;

[0068] Figure 2 This is the closed-loop control schematic diagram of the flight control system;

[0069] Figure 3 This is a schematic diagram of aircraft pitch rate response evaluation parameters;

[0070] Figure 4 The following is a schematic diagram of the evaluation parameters for the normal overload response of the aircraft;

[0071] Figure 5 The schematic diagram of the flight control system of the present invention is a control model with hydraulic flow calculation. DETAILED DESCRIPTION

[0072] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0073] An aircraft can only fly through the coordinated work of multiple systems. For example, the engine system provides power for the aircraft, the hydraulic system provides energy for the aircraft's moving parts, and the flight control system controls the aircraft by manipulating the control surfaces, allowing the aircraft to move according to the pilot's control intentions, thereby completing various functions and performing various tasks.

[0074] The working principle of the flight control system is as follows Figure 2 As shown: the pilot issues control commands through the cockpit control device. After receiving the control commands, the flight control computer calculates the control commands of the rudder surfaces according to the control law and sends them to the actuators to complete the control of the aircraft rudder surfaces and change the aerodynamic force of the aircraft, so that the aircraft moves according to the pilot's control commands. At the same time, the sensors on the aircraft feed back the aircraft's motion parameters (angular velocity, overload, etc.) to the flight control computer to complete the closed-loop control of the flight control system.

[0075] The flight control system has always been pursuing complete control functions and optimal performance. As the actuator in the flight control system, the rudder actuator is expected to have a higher movement rate, so that the rudder can be quickly deflected to the given command position, so that the aircraft's movement parameters can quickly meet the pilot's requirements. However, this places high demands on the aircraft's energy and structural strength, because the movement of the rudder requires hydraulic energy to drive it, and the movement of the rudder will also produce a hinge torque on the structure.

[0076] From the perspective of the hydraulic energy system, it only needs to provide users with pressure and flow that meet the requirements. The main users on the aircraft are the landing gear system and the flight control system. The landing gear system only works during a period of take-off and landing, while the flight control system works during the entire process of take-off, cruising, and landing. The cruising flight time is much longer than the working time of take-off and landing. Therefore, it can be said that the flight control system is the user with the most demand for it.

[0077] If the required flow rate of the flight control system is too large, the weight and volume of the hydraulic system will increase, and the aircraft payload will be reduced. If the required flow rate is too small, the movement requirements of the control surface cannot be met, which will affect the normal operation of the aircraft. Therefore, a method for calculating the hydraulic flow demand of the flight control system based on the flight quality requirements is proposed. Please refer to Figure 1 , which includes the following steps:

[0078] S1. (a) Select the flight quality associated with the hydraulic flow;

[0079] When studying flight qualities, the longitudinal and lateral directions are usually separated. The following takes the longitudinal direction as an example to introduce the flight quality terms related to hydraulic flow:

[0080] The equivalent fitting method is used to divide the longitudinal motion of the aircraft into two modes: long-period and short-period. When studying the flight quality, more attention is usually paid to the short-period mode. The fitting form of the short-period pitch rate and normal overload is usually:

[0081]

[0082] In the formula, s is the Laplace operator, represents the transfer function of the pitch rate to the stick force or displacement, is the numerator proportionality coefficient of the pitch rate transfer function, τ ω is the equivalent delay time of the pitch angle rate, ε n1 is the short-period equivalent damping ratio, ω n1 is the short-period equivalent frequency; represents the transfer function of the normal overload with respect to the rod force or displacement, is the numerator proportionality coefficient of the normal overload transfer function, τ n is the overload equivalent delay time, T θ Represents the molecular time constant of the short period, and e is the base of the natural logarithm.

[0083] like Figure 3 The figure shows the aircraft pitch rate response evaluation parameters. Taking the aircraft longitudinal short-period pitch rate criterion as an example, the flight quality requires that its response has the following characteristics:

[0084] (1) The effective delay time t1 is within the following range:

[0085] Level 1: t1≤0.12s;

[0086] Level 2: t1≤0.17s;

[0087] Level 3: t1≤0.21s;

[0088] (2) The transient peak ratio Δω2 / Δω1 meets the following requirements:

[0089] Level 1: less than or equal to 0.3;

[0090] Level 2: less than or equal to 0.6;

[0091] Level 3: less than or equal to 0.85;

[0092] (3) The effective rise time Δt is within the following range:

[0093] ① Non-terminal flight phase:

[0094] Level 1: 29.6 / V T ≤t1≤1645 / V T ;

[0095] Level 2: 10.5 / V T ≤t1≤5263 / V T ;

[0096] ②Terminal flight phase:

[0097] Level 1: 29.6 / VT ≤t1≤658 / V T ;

[0098] Level 2: 10.5 / V T ≤t1≤2122 / V T ;

[0099] In the formula, V T Indicates true airspeed;

[0100] like Figure 4 The figure shows the parameters for evaluating the normal overload response of an aircraft. Taking the short-period normal overload criterion of the longitudinal direction of the aircraft as an example, the flight quality requires that its response has the following characteristics:

[0101] V 表 ≥1.5V 表机动 When the overload value reaches 0.95*n yss The rise time t r Not more than:

[0102] Level 1: 1.5s;

[0103] Level 2: 2.0s;

[0104] Level 3: 2.5s;

[0105] V 表机动 ≤V 表 ≤1.5V 表机动 When the overload value reaches 0.95*n yss The rise time t r Not more than:

[0106] Level 1: 2.0s;

[0107] Level 2: 2.5s;

[0108] Level 3: 3.0s;

[0109] V 表 ≥1.5V 表机动 When overload overshoot (n ymax -n yss ) / n yss Not more than:

[0110] Level 1: 10%;

[0111] Level 2: 20%;

[0112] Level 3: 30%;

[0113] Overload response attenuation to ±5% yss The number of oscillations is no more than 3 times, where V 表 V is the speed indicator; 表机动It refers to the minimum indicated speed of the aircraft for maneuvering flight, n yss is the steady-state overload, n ymax is the maximum overload;

[0114] (b) Construct a target aircraft model based on the selected flight qualities and give the transfer function of the target aircraft according to the equivalent fitting formula of short-period pitch rate and normal overload;

[0115] (c) according to the inverse function from the aircraft body to the aircraft response parameter, inversely solving the control surface instructions required to realize the response parameter;

[0116] This step is mainly calculated based on the response characteristics of the aircraft body. Because the normal process is to give the control surface command, and then produce the expected aircraft response through the movement of the aircraft body, here it is necessary to calculate the required control surface command based on the aircraft body response;

[0117] (d) Calculate the required velocity value of the rudder according to the velocity limit of the rudder actuator model

[0118] The power required to move all control surface actuators of the flight control system simultaneously;

[0119] The calculation process of the required speed value of the rudder surface is as follows:

[0120] Taking the response parameters of the aircraft longitudinal short-period pitch rate criterion and the normal overload criterion as input, according to the inverse function of the aircraft body to each response parameter, the control surface instruction δ required to achieve the pitch rate and normal overload response parameters is inversely solved. cmd ; Set the control surface instruction δ cmd Input to the actuator model with rate limit, then simulate through the aircraft body model, output the pitch rate and normal overload response parameters, and compare them with the response parameters of the longitudinal short-period pitch rate criterion and the normal overload criterion. If the flight quality required by the criterion is met, the rate limit value is further reduced until it does not meet the requirements. At this time, the rate limit value is the required motion rate value.

[0121] The power calculation formula for the simultaneous movement of all control surface actuators of the flight control system is as follows:

[0122]

[0123] By calculating the power required for all control surfaces to move simultaneously, it is possible to ensure that the components of the hydraulic system have sufficient capacity to meet the highest power requirements, thereby avoiding system overload and failure. In the formula, N represents the power required by all actuators of the flight control system, N max Indicates the maximum power required for a certain control surface of the flight control system to move. Represents the power loss coefficient. This calculation can help engineers select appropriate hydraulic components during the design phase, ensuring that the entire system can operate efficiently and reliably under different flight conditions, avoiding over-design or waste of resources.

[0124] S2. Compare the original calculation method of rudder surface combination in which all rudder surfaces move simultaneously, conduct rudder surface combination motion analysis based on actual test flight, analyze the division of flight phases and control actions in actual test flight, and select the more stringent rudder surface combination conditions in combination with the flight quality test flight items, including tight turns, deceleration turns, maximum roll and pitch combination control, coordinated sideslip, lateral heading control under asymmetric thrust, and takeoff and landing in strong crosswind;

[0125] The aircraft needs to operate different mechanisms in different flight phases to meet the mission requirements of the current phase. Usually, the flight phase can be divided into: ground phase, before takeoff V1, after takeoff V1, accelerated climb phase, climb phase, cruise phase, mission phase, descent phase, approach phase, landing air phase, landing ground phase, etc. according to a complete flight;

[0126] (1) Ground stage: During the ground stationary stage, the engine is warmed up and ground inspections are performed. During the ground inspections, the pilot will manipulate the control surfaces to check the integrity of the control surfaces. The aircraft taxis from the parking position to the end of the runway. At this time, the landing gear will use the hydraulic system to complete ground braking and turning.

[0127] (2) Before takeoff V1: from releasing the brakes, taking off and rolling to the decision speed V1, the landing gear will use the hydraulic system to complete ground braking and turning, etc.;

[0128] (3) After takeoff V1: From the rollout decision speed V1 to the aircraft pulling up to a safe altitude, the aircraft's elevator and other control surfaces will move;

[0129] (4) Climb phase: Accelerate the climb from a safe altitude, during which the landing gear and flaps and slats will be retracted;

[0130] (5) Cruise phase: During this phase, all control surfaces of the aircraft will move according to the control requirements to achieve control of the aircraft's attitude, route, etc.;

[0131] (6) Mission phase: In addition to the use of hydraulic energy to manipulate the control surfaces to achieve attitude and route control, the mission system also uses hydraulic energy;

[0132] (7) Descent phase: From the end of the cruise altitude to the approach altitude, the control surfaces cooperate to complete the descent attitude establishment and route control;

[0133] (8) Approach phase: from the approach altitude to the landing safety altitude, during which the landing gear and flaps and slats will be lowered;

[0134] (9) Landing air segment: from the landing safety altitude to the landing gear main wheels touching the ground;

[0135] (10) Landing phase: from the main wheel touching the ground and decelerating to taxiing to a stop, during which the spoilers are opened to decelerate, and the landing gear uses the hydraulic system to complete ground braking and turning, etc.

[0136] Through the analysis of the use of the control surfaces at different stages, it can be found that the most commonly used combination of control surfaces is in the cruise stage;

[0137] In order to check the initial response, time delay, short-period modal damping, frequency and other characteristics of the aircraft, the pilot's control actions generally include: single pulse control, double pulse control, step control, sine sweep, deceleration turn, tight turn, somersault, acceleration and deceleration flight, coordinated sideslip, strong crosswind landing, etc. Taking some control actions as an example, the following description is given:

[0138] (1) Single pulse control. Action essentials: Pulse control. The control amplitude increases gradually from 1 / 4, 1 / 2 to full stroke. After the control is completed, it stabilizes for 3 to 7 seconds. The purpose is to check the initial response and equivalent time delay of the aircraft. It can also check the short-period modal frequency and damping of the aircraft. This action only performs single-axis control of longitudinal, lateral and heading each time.

[0139] (2) Sine frequency sweep. Action essentials: Perform equal frequency or variable frequency control on the joystick. The pilot's control frequency is 0.5 to 1.5 Hz. The purpose is to measure the dynamic quality of the aircraft system, including the measurement of stability margin. It can also be used for parameter identification. This action only performs single-axis control of longitudinal, lateral and heading each time.

[0140] (3) Tight turn. The key points are: keep the Mach number constant, gradually press the stick to increase the roll angle, pull the stick to the bottom to gradually increase the normal overload until the maximum overload and angle of attack. The purpose is to verify the maximum overload and angle of attack, check the stick force gradient, and check the control coordination. This action involves the combination of lateral and longitudinal control.

[0141] (4) Coordinated sideslip, keep the altitude and speed constant, press the stick and rudder, keep the aircraft heading constant. The purpose is to check the coordination of the aircraft's longitudinal, lateral and heading, check the quality of steady-state sideslip and crosswind landing. This action involves the combined control of three axes;

[0142] The pilot will ultimately give a satisfactory evaluation of the flight control system through the flight quality test flight to provide support for the aircraft finalization. The flight quality test flight is also divided into three-axis test flights: longitudinal, lateral and heading. Taking the longitudinal as an example, its test flight items include longitudinal static stability, aircraft short-cycle response and control feel during maneuvering flight.

[0143] (1) Static longitudinal stability: Test flight by horizontal straight line acceleration and deceleration maneuvers;

[0144] (2) Aircraft short-cycle response: Test flight through single pulse, multiple pulse or step control actions;

[0145] (3) Control feel during maneuvering flight: There are many test flight methods for this project, including stable circling, deceleration turning and convergence turning;

[0146] After the above flight phases, control actions and flight quality test flight items are integrated, the situations with more stringent control surface combinations are selected, including: tight turns, deceleration turns, maximum roll and pitch combination control, coordinated sideslip, lateral heading control under asymmetric thrust, takeoff and landing in strong crosswind, etc. After the simulation model is established, the combined motion of each control surface can be obtained directly according to the selected control given input and the control law output;

[0147] S3. Calculate the hydraulic flow demand based on the configuration of the rudder energy, including the hydraulic flow RT_Q required by the j-th rudder for the i-th set of hydraulic sources i [j] and the final hydraulic flow requirement of the i-th hydraulic source;

[0148] The calculation formula for the hydraulic flow required by the j-th rudder for the i-th hydraulic source is as follows:

[0149]

[0150] By calculating the hydraulic flow required for a specific rudder, it is possible to ensure that the output of the hydraulic source matches the needs of the rudder, thereby ensuring that the rudder can respond to control instructions quickly and accurately as expected. In the formula, RT_Q i [j] represents the hydraulic flow required by the j-th rudder for the i-th hydraulic source, represents the movement speed of the j-th rudder surface, SQ[j] represents the conversion coefficient of the rudder surface movement speed to flow, which is calculated by the connecting rod length and piston area of ​​the actuator, and ST[j] represents the use status of the j-th rudder surface for the i-th set of hydraulic source, 0 for not used and 1 for used. Calculating the hydraulic flow demand can enable the system to dynamically adjust under different flight states and environmental conditions to meet different control requirements and flight performance, thereby improving the adaptability of the system;

[0151] The final hydraulic flow requirement is calculated as follows:

[0152]

[0153] By calculating the final hydraulic flow demand, it is possible to ensure that the hydraulic system can meet the aircraft's control requirements under various flight conditions, thereby maintaining good flight performance. In the formula, H_Q i represents the final hydraulic flow demand of the i-th hydraulic source, RT_Qi [j] represents the hydraulic flow required by the j-th rudder for the i-th set of hydraulic sources, and n represents the number of hydraulic sources. Accurate calculation of hydraulic flow requirements can avoid over-design, reduce unnecessary energy consumption, and improve the energy efficiency of the system, which is of great significance for improving the economy and long-term flight of aircraft.

[0154] S4. Through the control model with hydraulic flow calculation, the control system simulation analysis is carried out to obtain the flow demand at any time, verify the requirements proposed in the scheme demonstration stage and the preliminary design stage, and provide a reference for the optimal design of the aircraft.

[0155] See also Figure 5 As shown, the flight control system of this application has a control model for hydraulic flow calculation. Through the control model, the flow demand can be obtained at any time during the control system simulation analysis, which is convenient for verifying the requirements put forward in the scheme demonstration stage and the preliminary design stage. When the flow is insufficient, an alarm is given in time to facilitate the optimization design of the aircraft, so that the flight control system can provide accurate hydraulic flow demand input for the hydraulic system design, and the flow of the hydraulic system is not wasted under the premise of meeting the flight control system requirements, so as to achieve the optimal overall design index of the aircraft.

[0156] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for calculating the hydraulic flow demand of a flight control system based on flight quality requirements, characterized in that: The following steps are involved: S1. Select the flight quality related to hydraulic flow; The target aircraft model is constructed according to the selected flight quality, and the transfer function of the target aircraft is given according to the equivalent matching formula of the aircraft's longitudinal short-period pitch rate and normal overload; According to the inverse function from the aircraft body to the aircraft response parameter, the control surface command required to realize the response parameter is inversely solved; Calculate the required movement rate of the rudder according to the rate limit of the rudder actuator model The power required to move all control surface actuators of the flight control system simultaneously; S2. Compare the original calculation method of rudder surface combination in which all rudder surfaces move simultaneously, conduct rudder surface combination motion analysis based on actual test flight, analyze the division of flight phases and control actions in actual test flight, and select the more stringent rudder surface combination conditions in combination with the flight quality test flight items, including tight turns, deceleration turns, maximum roll and pitch combination control, coordinated sideslip, lateral heading control under asymmetric thrust, and takeoff and landing in strong crosswind; S3. Calculate the hydraulic flow demand based on the configuration of the rudder energy, including the hydraulic flow RT_Q required by the j-th rudder for the i-th set of hydraulic sources i [j] and the final hydraulic flow requirement of the i-th hydraulic source; S4. Through the control model with hydraulic flow calculation, the control system simulation analysis is carried out to obtain the flow demand at any time, verify the requirements proposed in the scheme demonstration stage and the preliminary design stage, and provide a reference for the optimal design of the aircraft.

2. The method for calculating the hydraulic flow demand of a flight control system based on flight quality requirements according to claim 1, characterized in that: In S1, before selecting the flight quality related to the hydraulic flow, the maximum power required to overcome the hinge torque to control the control surface at a specified deflection speed is calculated, and the formula is as follows: In the formula, N max It indicates the maximum power required for a certain control surface of the flight control system to move, K indicates the coefficient of the working characteristics of different control surface actuators, M max represents the maximum hinge moment of the rudder surface, Indicates the required rate of movement of the control surface.

3. The method for calculating the hydraulic flow demand of a flight control system based on flight quality requirements according to claim 2, characterized in that: In S1, the aircraft longitudinal short-period pitch rate criterion has the following characteristics in its flight quality response: (1) The effective delay time t1 is within the following range: Level 1: t1≤0.12s; Level 2: t1≤0.17s; Level 3: t1≤0.21s; (2) The transient peak ratio Δω2 / Δω1 meets the following requirements: Level 1: less than or equal to 0.3; Level 2: less than or equal to 0.6; Level 3: less than or equal to 0.85; (3) The effective rise time Δt is within the following range: ① Non-terminal flight phase: Level 1: 29.6 / V T ≤t1≤1645 / V T ; Level 2: 10.5 / V T ≤t1≤5263 / V T ; ②Terminal flight phase: Level 1: 29.6 / V T ≤t1≤658 / V T ; Level 2: 10.5 / V T ≤t1≤2122 / V T ; In the formula, V T Indicates true airspeed.

4. The method for calculating the hydraulic flow demand of a flight control system based on flight quality requirements according to claim 3, characterized in that: In S1, the aircraft longitudinal short-period normal overload criterion has the following characteristics in its flight quality response: V 表 ≥1.5V 表机动 When the overload value reaches 0.95*n yss The rise time t r Not more than: Level 1: 1.5s; Level 2: 2.0s; Level 3: 2.5s; V 表机动 ≤V 表 ≤1.5V 表机动 When the overload value reaches 0.95*n yss The rise time t r Not more than: Level 1: 2.0s; Level 2: 2.5s; Level 3: 3.0s; V 表 ≥1.5V 表机动 When overload overshoot (n ymax -n yss ) / n yss Not more than: Level 1: 10%; Level 2: 20%; Level 3: 30%; Overload response attenuation to plus or minus 5% yss The number of oscillations is no more than 3 times, where V 表 V is the speed indicator; 表机动 It refers to the minimum indicated speed of the aircraft for maneuvering flight, n yss is the steady-state overload, n ymax is the maximum overload.

5. The method for calculating the hydraulic flow demand of a flight control system based on flight quality requirements according to claim 4, characterized in that: In S1, a target aircraft model is constructed according to the selected flight quality, and a transfer function of the target aircraft is given according to an equivalent pseudo-matching formula of short-period pitch angle rate and normal overload, wherein the equivalent pseudo-matching formula is a Laplace transform formula, as shown below: In the formula, s is the Laplace operator, represents the transfer function of the pitch rate to the stick force or displacement, is the numerator proportionality coefficient of the pitch rate transfer function, τ ω is the equivalent delay time of the pitch angle rate, ε n1 is the short-period equivalent damping ratio, ω n1 is the short-period equivalent frequency; represents the transfer function of the normal overload with respect to the rod force or displacement, is the numerator proportionality coefficient of the normal overload transfer function, τ n is the overload equivalent delay time, Represents the molecular time constant of the short period, and e is the base of the natural logarithm.

6. The method for calculating the hydraulic flow demand of a flight control system based on flight quality requirements according to claim 5, characterized in that: In S1, the required movement rate of the rudder is calculated according to the rate limit of the rudder actuator model. The calculation process is as follows: Taking the pitch rate response parameter and the normal overload response parameter as input, according to the inverse function of the aircraft body to each response parameter, the control surface instruction δ required to achieve the pitch rate and normal overload response parameter is inversely solved. cmd ; Set the control surface instruction δ cmd Input to the actuator model with rate limiting, then simulate through the aircraft body model, output the pitch rate and normal overload response, and compare it with the pitch rate response parameters and normal overload response parameters. If the flight quality requirements of the pitch rate response parameters and normal overload response parameters are met, the rate limit value is further reduced until the requirements are no longer met. At this time, the rate limit value is the required motion rate value.

7. A method for calculating the hydraulic flow demand of a flight control system based on flight quality requirements according to claim 6, characterized in that: In S1, the power required for all the control surface actuators of the flight control system to move simultaneously is calculated according to the rate limit of the control surface actuator model. The calculation formula is as follows: In the formula, N represents the power required by all actuators of the flight control system, N max Indicates the maximum power required for a certain control surface of the flight control system to move. Represents the power loss factor.

8. The method for calculating the hydraulic flow demand of a flight control system based on flight quality requirements according to claim 7, characterized in that: In S2, according to the different requirements of the flight mission, the various stages of the test flight are clearly divided, including take-off, climb, cruise, approach, landing, etc. Each stage will correspond to different control actions and control surface combination requirements, and each stage will be quantified and calibrated through speed, altitude and attitude parameters.

9. A method for calculating the hydraulic flow demand of a flight control system based on flight quality requirements according to claim 8, characterized in that: In S3, the hydraulic flow demand is calculated based on the configuration of the rudder energy, including the hydraulic flow RT_Q required by the j-th rudder for the i-th set of hydraulic sources. i [j], the calculation formula is as follows: In the formula, RT_Q i [j] represents the hydraulic flow required by the j-th rudder for the i-th hydraulic source, represents the movement speed of the j-th rudder surface, SQ[j] represents the conversion coefficient of the rudder surface movement speed to flow, which is calculated by the connecting rod length and piston area of ​​the actuator, and ST[j] represents the usage status of the j-th rudder surface for the i-th hydraulic source.

10. The method for calculating the hydraulic flow demand of a flight control system based on flight quality requirements according to claim 9, characterized in that: In S3, the hydraulic flow demand is calculated based on the configuration of the rudder energy source, and the final hydraulic flow demand calculation formula of the i-th set of hydraulic sources is as follows: In the formula, H_Q i represents the final hydraulic flow demand of the i-th hydraulic source, RT_Q i [j] represents the hydraulic flow required by the j-th rudder surface for the i-th set of hydraulic sources, and n represents the number of hydraulic sources.

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