CN106873615A - Emergent landing speed instruction set design method of giving an encore - Google Patents

Abstract

The invention belongs to the flight control technology, and proposes a method for designing an emergency return landing speed command set, including: (1) constructing quality, roll angle, airport height, height, and speed parameter grids, calculating the angle of attack and elevator for the aircraft to glide at a constant speed , lift-to-drag ratio, trajectory angle, and sink rate, determine the maximum lift-to-drag ratio speed and the maximum available speed for air-sliding with the mass, roll angle, airport height, and altitude. The speed range between is divided into N+1 equal parts, plus the maximum lift-to-drag ratio speed and the maximum available speed during air sliding, a total of N+2 speed command sets are established, and the content of each speed command set includes the angle of attack corresponding to the speed. . Select the appropriate speed command set gear for execution.

Description

Design method of emergency return landing speed command set

technical field

The invention belongs to the flight control technology, and in particular relates to an autonomous guidance and control technology for an aircraft without power to return to the field and land.

Background technique

When the aircraft has an engine shutdown failure in the air, the performance of the aircraft is degraded and it can only fly downhill. In order to ensure flight safety, it is necessary to control the speed of the aircraft and modify the flight trajectory to avoid stalling caused by excessive trajectory pull-up. At the same time, the lift-to-drag ratio of the aircraft glide can be adjusted to land the aircraft on the airport runway as much as possible. The literature "Design of Emergency Landing Control Law for Wheeled Take-off and Landing UAVs" provides a difficult analysis and solution to the problem of idling back and landing: 1) In the transitional flight phase, use the maximum lift-to-drag ratio speed to glide to maximize The flying distance of the aircraft ensures that the aircraft still has the ability to reach the vicinity of the airport under various uncertainties and interference factors; 2) When the flying distance of the aircraft is too long, that is, when the energy is too high when reaching the vicinity of the airport, hovering The way of lowering consumes excess energy. The scheme has clear physical meaning and simple operation. However, when it is applied to engineering practice, it lacks the consideration of the following three issues: 1) In the process of idling return, the engine must be started in the air, and gliding with the maximum lift-to-drag ratio may not be able to reach the speed condition of the engine idling; 2) If the maximum lift-to-drag ratio speed is used to descend, the flying speed should be relatively low within the flying speed range. Compared with other speeds, the flying distance and time are relatively long, and the battery may be exhausted before the aircraft slides to the airport. Still unable to land safely. 3) The conditions for the engine to stop in the air are uncertain. For the parking situation at the same height but with different distances and energy states, the actual flight distance is almost the same, and the glide speed strategy is not flexible enough.

Contents of the invention

The purpose of the present invention is: the present invention proposes a method for designing an emergency return landing speed command set, which can provide more flexible and changeable command selection schemes for the air-skid guidance law, and improve the feasibility that the idle time is less than the available time of the battery.

The technical solution of the present invention is: a method for designing an emergency return landing speed instruction set, comprising:

(1) Build mass, roll angle, airport altitude, altitude, and speed parameter grids, calculate the angle of attack, elevator, lift-drag ratio, trajectory angle, and sinking rate of the aircraft at a constant speed, and determine the parameters that vary with mass, roll angle, airport altitude, Maximum lift-to-drag ratio speed and maximum available speed for air-sliding at height change, N+1 equal divisions of the speed range between maximum lift-drag ratio speed and maximum available speed for air-sliding, plus maximum lift-to-drag ratio speed and maximum air-sliding maximum speed Available speed, a total of N+2 speed command sets are established, and the content of each speed command set includes the angle of attack, elevator, lift-to-drag ratio, trajectory angle, and sink rate corresponding to the speed;

(3) The aircraft records the N+2 gear speed instruction set, and when the aircraft returns to the field in an emergency, according to the quality of the aircraft, the height of the airport, the altitude, the speed and the distance from the airport, select the appropriate gear of the speed instruction set to execute.

Include between step (1) and step (3):

(2) Correct the N+2 speed command set with the corresponding relationship between the height and speed required for engine restart in the air and idling landing, and update the content of each speed command set, including the angle of attack, elevator, Lift-to-drag ratio, trajectory angle, sink rate.

Step (1) includes:

(11) Construct a calculation grid within the variable range of aircraft mass m, airport height gnd, roll angle φ, height H, and speed V;

(12) At each point of the calculation grid, the calculation of the aircraft's constant speed glide performance is performed using the trim condition with roll angle:

Where: W=mg is the gravity of the aircraft, g is the acceleration of gravity; L, D are the lift and drag of the aircraft, and M _y is the pitching moment of the aircraft, all of which vary with the angle of attack α, the elevator δ _e , the height H and the speed V aerodynamic parameters. θ is the pitch angle of the aircraft;

Use the numerical solution method of equations to obtain the angle of attack α, elevator δ _e , and pitch angle θ that meet the trim conditions; solve the lift L and drag D according to the calculation method of aerodynamic parameters;

Calculate the lift-to-drag ratio K _L/D :

K _L/D = L/D

Calculate the trajectory angle γ:

γ=θ-α

Calculate sink rate V _s :

V _s =Vsinγ

(13) Under the conditions of given mass, roll angle, altitude, and airport altitude, the maximum lift-to-drag ratio speed is taken as the farthest speed of the track, and the maximum calculated speed is taken as the shortest speed of the track, and the interval between the two speeds is N+1 Equally divided, according to the order of the farthest speed on the track, the speed at equal intervals of 1...N, and the closest speed on the track, the speed command set of N+2 gears is obtained. The content of each speed command set includes the attack speed corresponding to the speed of the gear. angle, elevator, lift-to-drag ratio, track angle, sink rate.

Step (2) includes:

(21) Represent the conditions of the engine idle window and the idle approach window as the speed command of the corresponding altitude layer, and replace the original speed command correspondingly;

(22) Carry out linear interpolation smoothing processing to the junction of the new speed command and the original speed command, and calculate the shortest length of the interpolation segment according to the average sinking rate;

(23) At the altitude after the engine is empty, the speed command of each gear is selected as the speed command of the most middle gear;

(24) The relative altitude between the aircraft and the airport is greater than the updated speed command at 300m, and its corresponding angle of attack, elevator, lift-to-drag ratio, trajectory angle, and sinking rate are obtained by interpolation from the calculation results of the parameter grid; the relative altitude between the aircraft and the airport For the speed command updated at a distance less than 300m, the angle of attack, elevator, lift-to-drag ratio, trajectory angle, and sinking rate of the skid when the landing gear is lowered need to be additionally calculated.

Step (3) includes:

(31) According to the current speed V of the aircraft and the maximum available roll angle φ _max , estimate the maximum range required for the aircraft to turn around

According to the airport height gnd, height H and the distance Dis to the airport, calculate the average lift-to-drag ratio K _need needed for the aircraft to slide back

(32) Check the speed command table to obtain the aircraft mass m, the airport altitude gnd, and the N+2 speed command under the roll angle φ _max condition. Solve the average lift-to-drag ratio from the airport altitude to the aircraft altitude for the speed command of the i-th gear where i=1, 2, ..., N+2;

(33) If there exists i such that choose to use The minimum speed command of the first gear is used for trajectory design and guidance decision-making of return from skid. Otherwise, the current state may not be able to return safely, so select the first gear speed command with the largest lift-to-drag ratio for the trajectory design and guidance decision-making of the air slide return, so as to maximize the gliding ability.

The advantages of the present invention are: the present invention provides a method for designing the idling speed instruction set based on the aircraft's unpowered glide performance and the air restart condition of the engine, and provides better instructions for the engineering realization of the aircraft's idling return and landing design approach. The obtained multi-gear command set can not only support engine air start, but also the same speed command design after restart can make the flight state converge to the desired landing state, and at the same time, the step-by-step speed command design at the initial stage of parking enables the guidance law to be controlled online. Scheduling realizes the flexible adjustment of the flying distance and flight time. Compared with the flight with the maximum lift-to-drag ratio, the multi-speed speed command set can realize more glide flight trajectories, and can save more than 20% of the flight time under the initial conditions of high altitude and low energy.

Description of drawings

Figure 1 is a distribution diagram of trim lift-to-drag ratio with speed at different heights for a certain model when the mass is given and the roll angle is zero.

Figure 2 is a design result diagram of 11 speed commands for a certain model under a given mass and airport altitude.

detailed description

The present invention will be described in further detail below.

A method for designing an emergency return landing speed instruction set, comprising:

(1) Build mass, roll angle, airport altitude, altitude, and speed parameter grids, calculate the angle of attack, elevator, lift-drag ratio, trajectory angle, and sinking rate of the aircraft at a constant speed, and determine the parameters that vary with mass, roll angle, airport altitude, Maximum lift-to-drag ratio speed and maximum available speed for air-sliding at height change, N+1 equal divisions of the speed range between maximum lift-drag ratio speed and maximum available speed for air-sliding, plus maximum lift-to-drag ratio speed and maximum air-sliding maximum speed Available speed, a total of N+2 speed command sets are established, and the content of each speed command set includes the angle of attack, elevator, lift-to-drag ratio, trajectory angle, and sink rate corresponding to the speed;

(3) The aircraft records the N+2 gear speed instruction set, and when the aircraft returns to the field in an emergency, according to the quality of the aircraft, the height of the airport, the altitude, the speed and the distance from the airport, select the appropriate gear of the speed instruction set to execute.

Include between step (1) and step (3):

(2) Correct the N+2 speed command set with the corresponding relationship between the height and speed required for engine restart in the air and idling landing, and update the content of each speed command set, including the angle of attack, elevator, Lift-to-drag ratio, trajectory angle, sink rate.

Step (1) includes:

(11) Construct a calculation grid within the variable range of aircraft mass m, airport height gnd, roll angle φ, height H, and speed V;

(12) At each point of the calculation grid, the calculation of the aircraft's constant speed glide performance is performed using the trim condition with roll angle:

Where: W=mg is the gravity of the aircraft, g is the acceleration of gravity; L, D are the lift and drag of the aircraft, and M _y is the pitching moment of the aircraft, all of which vary with the angle of attack α, the elevator δ _e , the height H and the speed V aerodynamic parameters. θ is the pitch angle of the aircraft;

Use the numerical solution method of equations to obtain the angle of attack α, elevator δ _e , and pitch angle θ that meet the trim conditions; solve the lift L and drag D according to the calculation method of aerodynamic parameters;

Calculate the lift-to-drag ratio K _L/D :

K _L/D = L/D

Calculate the trajectory angle γ:

γ=θ-α

Calculate sink rate V _s :

V _s =Vsinγ

(13) Under the conditions of given mass, roll angle, altitude, and airport altitude, the maximum lift-to-drag ratio speed is taken as the farthest speed of the track, and the maximum calculated speed is taken as the shortest speed of the track, and the interval between the two speeds is N+1 Equally divided, according to the order of the farthest speed on the track, the speed at equal intervals of 1...N, and the closest speed on the track, the speed command set of N+2 gears is obtained. The content of each speed command set includes the attack speed corresponding to the speed of the gear. angle, elevator, lift-to-drag ratio, track angle, sink rate.

Step (2) includes:

(21) Represent the conditions of the engine idle window and the idle approach window as the speed command of the corresponding altitude layer, and replace the original speed command correspondingly;

(22) Carry out linear interpolation smoothing processing to the junction of the new speed command and the original speed command, and calculate the shortest length of the interpolation segment according to the average sinking rate;

(23) At the altitude after the engine is empty, the speed command of each gear is selected as the speed command of the most middle gear;

(24) The relative altitude between the aircraft and the airport is greater than the updated speed command at 300m, and its corresponding angle of attack, elevator, lift-to-drag ratio, trajectory angle, and sinking rate are obtained by interpolation from the calculation results of the parameter grid; the relative altitude between the aircraft and the airport For the speed command updated at a distance less than 300m, the angle of attack, elevator, lift-to-drag ratio, trajectory angle, and sinking rate of the skid when the landing gear is lowered need to be additionally calculated.

Step (3) includes:

(31) According to the current speed V of the aircraft and the maximum available roll angle φ _max , estimate the maximum range required for the aircraft to turn around

According to the airport height gnd, height H and the distance Dis to the airport, calculate the average lift-to-drag ratio K _need needed for the aircraft to slide back

(32) Check the speed command table to obtain the aircraft mass m, the airport altitude gnd, and the N+2 speed command under the roll angle φ _max condition. Solve the average lift-to-drag ratio from the airport altitude to the aircraft altitude for the speed command of the i-th gear where i=1, 2, ..., N+2;

(33) If there exists i such that choose to use The minimum speed command of the first gear is used for trajectory design and guidance decision-making of return from skid. Otherwise, the current state may not be able to return safely, so select the first gear speed command with the largest lift-to-drag ratio for the trajectory design and guidance decision-making of the air slide return, so as to maximize the gliding ability.

Example

Taking a certain model as an example, given the conditions of the aircraft mass and the airport altitude of 1500m, and given the engine restart window as flying at a speed of 450km/h at an altitude of 3-6km, the main steps and results of designing a multi-speed instruction set are given:

Step 1: Generate parameter grids, calculate air-sliding performance and design multi-gear speed commands. The distribution curve of lift-to-drag ratio with speed at some grid points is shown in Figure 1.

1) Take 100m as the altitude interval to form an altitude calculation sequence from the airport altitude to the maximum altitude; take the roll angle sequence of 0:10:30; query the flight envelope corresponding to the current quality, and calculate the speed range of each point in the altitude sequence And carry out 50 equal divisions to obtain the roll angle-height-velocity parameter grid; at each point of the parameter grid, calculate the angle of attack, pitch angle, elevator, lift-to-drag ratio and sinking rate of the constant-speed glide trim.

2) Combine the roll angle and altitude sequence to obtain the roll angle-height grid; at each point of the roll angle-height grid, search for the point with the largest lift-to-drag ratio in trim, as the farthest speed of the track, and set the maximum speed The point is taken as the shortest speed of the track; the speed interval formed by the farthest speed of the track and the shortest speed of the track is divided into 10 equal parts, and arranged according to the order of the farthest speed of the track, the speed of 1...9 equal intervals, and the shortest speed of the track. After searching, the 11 points are arranged to obtain the speed command of 11 gears; the trim trajectory angle, lift-to-drag ratio and elevator corresponding to the speeds of 1...9 gears are interpolated from the performance calculation results.

Step 2: According to the engine restart window conditions, landing window conditions, etc. to regenerate the binning command set, the speed command design results are shown in Figure 2:

1) Flight section before air take-off (flight section above 7km): directly adopt the design result of multi-gear speed command.

2) Engine idle section (2-7km height section): According to the engine idle window conditions, the speed command is designed to be 450km/h in the 3-6km altitude layer, and after calculating the average sinking rate, the speed between 2-3km and 6- Two 1000m transitional altitudes are set at 7km, and the speed command is smoothly transitioned through linear interpolation.

3) Flight segment after engine empty start failure: In this example, the relative altitude of the end of the engine empty start segment has reached 500m, and has reached the vicinity of the approach window, so the flight segment after engine empty start failure is cancelled.

4) Approach flight section (1515-2000m): The landing speed is selected as 240km/h, and the flight performance parameters correspond to the landing gear down state.

Claims (5)

1. a kind of emergent landing speed instruction set design method of giving an encore, it is characterised in that including：

(1) quality, roll angle, airport height, height, speed parameter grid, meter are built The angle of attack, elevator, lift-drag ratio, track angle, deflection ratio that aircraft at the uniform velocity glides are calculated, it is determined that with Quality, roll angle, airport height, the maximum lift-drag ratio speed of height change and empty sliding maximum can With speed, the velocity interval between maximum lift-drag ratio speed and empty sliding maximum available velocity is carried out N+1 deciles, add maximum lift-drag ratio speed and empty sliding maximum available velocity, build together vertical N+2 grades Speed command collection, the content per notch speed degree instruction set includes the corresponding angle of attack of notch speed degree, the lifting Rudder, lift-drag ratio, track angle, deflection ratio；

(3) aircraft records the N+2 notch speeds degree instruction set, when aircraft is emergent gives an encore, root According to Aircraft Quality, airport height, height, speed and distance with airport, what selection was adapted to Speed command collection gear is performed.

2. as claimed in claim 1 a kind of emergent landing speed instruction set design method of giving an encore, Characterized in that, including between step (1) and step (3)：

(2) closed with the height needed for engine over-the-air rekey and empty sliding landing is corresponding with speed System's amendment N+2 notch speed degree instruction set, and update the content per notch speed degree instruction set, including the shelves The corresponding angle of attack of speed, elevator, lift-drag ratio, track angle, deflection ratio.

3. as claimed in claim 1 a kind of emergent landing speed instruction set design method of giving an encore, Characterized in that, step (1) includes：

(11) in Aircraft Quality m, airport height gnd, roll angle φ, height H, speed V In the range of alterable, build and calculate grid；

(12) grid each point is being calculated, aircraft is being carried out at the uniform velocity using the trim condition with roll angle The calculating of gliding ability：

$\left.\begin{array}{c}L-W(\sin \mathrm{\α}\sin \mathrm{\θ}+\cos \mathrm{\α}\cos \mathrm{\θ}\cos \mathrm{\φ})-\frac{{\mathrm{Wsin}}^2{\mathrm{\φcos}}^2\mathrm{\θ}}{(\sin \mathrm{\α}\sin \mathrm{\θ}+\cos \mathrm{\α}\cos \mathrm{\θ}\cos \mathrm{\φ})}=0\\ -D+W(-\cos \mathrm{\α}\sin \mathrm{\θ}+\sin \mathrm{\α}\cos \mathrm{\θ}\cos \mathrm{\φ})=0\\ M_y=0\end{array}\right\}$

Wherein：W=mg is the gravity of aircraft, and g is acceleration of gravity；L, D are the lift of aircraft And resistance, M_yIt is the pitching moment of aircraft, is with angle of attack, elevator δ_e, height H and The aerodynamic parameter of speed V changes.θ is the angle of pitch of aircraft；

Equation group method of value solving is used, angle of attack, the elevator δ of trim condition is met_e, Pitching angle theta；Lift L and resistance D is solved according to aerodynamic coefficient method；

Calculate lift-drag ratio K_L/D：

K_L/D=L/D

Calculate track angle γ：

γ=θ-α

Calculate deflection ratio V_s：

V_s=Vsin γ

(13) under the conditions of by given quality, roll angle, height, airport height, most rise higher resistance Specific rate as the farthest speed of flight path, max calculation speed as the nearest speed of flight path, to two Interval N+1 deciles between speed, according to the farthest speed of flight path, 1 ... N at equal intervals speed, The nearest speed order's arrangement of flight path, obtains the N+2 speed command set of gear, per notch speed degree The content of instruction set include the corresponding angle of attack of notch speed degree, elevator, lift-drag ratio, track angle, Deflection ratio.

4. as claimed in claim 2 a kind of emergent landing speed instruction set design method of giving an encore, Characterized in that, step (2) includes：

(21) empty window of engine and sky are slided into nearly window considerations, is characterized as corresponding height The speed command of layer, correspondence replaces original speed command；

(22) the smooth place of linear interpolation is carried out to new speed command and the joining place of former speed command Reason, interpolation section shortest length is calculated according to average deflection ratio；

(23) height layer after empty window of engine, the speed command of each gear is selected With the speed command of most intervening gears；

(24) aircraft is more than the speed command updated at 300m with the relative altitude on airport, its The corresponding angle of attack, elevator, lift-drag ratio, track angle, deflection ratio are by parametric grid result of calculation Interpolation is obtained；Aircraft and the speed command of the relative altitude less than renewal at 300m on airport, need The empty sliding angle of attack under gear down state of supplement calculation, elevator, lift-drag ratio, track angle, Deflection ratio.

5. as claimed in claim 1 a kind of emergent landing speed instruction set design method of giving an encore, Characterized in that, step (3) includes：

(31) roll angle φ can be used according to aircraft present speed V and maximum_max, estimation aircraft tune Ultimate run needed for turning direction

$Cir=\frac{2{\mathrm{\πV}}^2}{g{\mathrm{tan\φ}}_{max}}$

According to airport height gnd, height H and with airport apart from Dis, aircraft is calculated empty Average lift-drag ratio K needed for sliding return_need

$K_{need}=\frac{Dis+Cir}{H-gnd}$

(32) speed command table is looked into, Aircraft Quality m, airport height gnd, roll angle is obtained φ_maxUnder the conditions of N+2 grades of speed command.I-th speed command of gear is solved from airport Average value of the height to the lift-drag ratio in the range of aircraft altitudeWherein i=1,2 ..., N+2；

(33) if there is i so thatThen selection makesMinimum First gear speed is instructed, for the sliding Trajectory Design for returning of sky and guidance decision-making.Otherwise, current shape State possibly cannot be returned safely, and being used for empty cunning from the 1st grade of maximum speed command of lift-drag ratio returns The Trajectory Design returned and guidance decision-making, play gliding ability as far as possible.