JP2011247871A - Route search device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a route search device for shortening a calculation time in case of calculating the optimal flight route.SOLUTION: This route search device is configured to calculate an altitude reduction rate as altitude reduction amounts per unit turning angle in tuning flight, and to calculate an attitude angle to minimize the calculated altitude reduction rate, and to calculate a turning radius in the turning flight based on the attitude angle, and to search a flight route corresponding to the calculated turning radius. Thus, it is possible to shorten a calculation time for performing the arithmetic operation of the optimal flight route by limiting trial conditions in case of searching the flight route.

Description

  The present invention relates to a route search device for searching for a flight route.

  As a technology in such a field, there is a technology that supports the landing of an aircraft by automatically generating a highly safe flight route up to the landing point of the aircraft and providing information on the generated flight route to a pilot or an autopilot device. It is known (see, for example, Patent Document 1). In the flight path calculation device described in Patent Document 1, an optimum obstacle avoidance flight path that optimizes an avoidance distance for avoiding an obstacle, other flight distances, a final approach path, and the like using fuzzy inference is searched. ing.

JP-A-8-63700 JP-A-9-251600

  However, in the technique described in Patent Document 1, the calculation time for calculating the flight route and the amount of conditions (range, density) that can be tried conflict with each other. There is a risk of becoming.

  The present invention has been made to solve such a problem, and an object of the present invention is to provide a route search device capable of shortening the calculation time when calculating an optimal flight route.

  A route search device according to the present invention is a route search device that searches for a flight route between an aircraft's own position and a target point, and has an altitude reduction rate that is an altitude reduction amount per unit turning angle in a turning flight of an airplane. A posture calculated by the posture angle calculating means, and a posture angle calculating means for calculating an attitude angle that minimizes the altitude reduction rate calculated by the height reduction rate calculating means. Based on the angle, the turning radius in the turning radius is calculated.

  According to such a route search device, it is possible to calculate an altitude reduction rate that is an altitude reduction amount per unit turning angle in a turn flight, and to calculate an attitude angle that minimizes the calculated altitude reduction rate. Therefore, the turning radius in the turning flight can be calculated based on the attitude angle. As a result, it is possible to search for a flight path according to the calculated turning radius, so that it is possible to reduce the calculation time for calculating the optimal flight path by limiting trial conditions when searching for a flight path. Can be achieved.

  A route search device according to the present invention is a route search device that searches for a flight route between an airplane's own position and a target point, and is an altitude reduction that is an amount of altitude reduction per unit turning angle in airplane turning flight. An altitude reduction rate calculating means for calculating a rate, an attitude angle calculating means for calculating an attitude angle that minimizes the altitude reduction rate calculated by the altitude reduction rate calculating means, and an attitude angle calculated by the attitude angle calculating means Based on the turning radius calculating means for calculating the turning radius in the turning flight, and calculating the flying distance in the turning flight based on the turning radius calculated by the turning radius calculating means, and according to the calculated flying distance. Flight path searching means for searching for a flight path.

  According to such a route search device, it is possible to calculate an altitude reduction rate that is an altitude reduction amount per unit turning angle in a turn flight, and to calculate an attitude angle that minimizes the calculated altitude reduction rate. Therefore, the turning radius in the turning flight can be calculated based on the attitude angle, and the flight path corresponding to the calculated turning radius can be searched. Thereby, it is possible to reduce the calculation time for calculating the optimum flight path by limiting the trial conditions when searching for the flight path.

  Here, the turning flight and the straight flight necessary for flying along the searched flight path and landing at the target point are set, and the moving distance in the horizontal plane direction of the set turning flight and the straight flight is calculated. A plane-of-horizon movement distance calculation means and a plane-of-flight search means that calculates a required altitude that is the altitude required to land on the target point based on the movement distance in the horizontal plane direction. It is preferable that the flight path is searched using the actual altitude that is the actual altitude of the airplane. Thereby, since it is possible to search for a flight path using a combination of a straight line and one type of arc, it is possible to calculate an appropriate flight path with a reduced calculation load.

  Further, it is preferable that the flight path search means searches for a flight path where the difference between the required altitude and the actual altitude is zero. Thereby, it is possible to easily calculate the flight path in which the lowered altitude is adjusted by continuing the turning flight or making the straight flight longer.

  In addition, a terrain data storage means storing terrain data including data indicating the height of the terrain is provided, and the flight route search means can reach within 360 degrees in the horizontal plane centering on its own position based on the terrain data. The range of the target point can be calculated, and the flight route to the target point existing in the calculated range can be searched. Thereby, at the time of emergency landing such as when the airplane engine stops, the reachable landing point area can be obtained with a small calculation load. For this reason, it is possible to select a route for ensuring safety when the engine is stopped with a small calculation load.

  In the above route search apparatus, a flight path capable of increasing the flight distance during a turn flight is calculated by calculating an attitude angle that minimizes the altitude decrease rate calculated by the altitude decrease rate calculating means. Can be explored. Further, during a straight flight, the flight distance is increased by flying at a posture angle and speed that maximizes the lift / drag ratio L / D, which is the ratio of the lift L and the drag D acting on the airplane. be able to. That is, by flying so that these flight states are established, the flight distance in the gliding flight state can be maximized. Hereinafter, such a flight state in which the longest glide flight distance can be obtained is referred to as a “longest glide flight state”.

  The “longest gliding flight state” is a flight state in which the longest gliding flight distance may be realized. In straight flight, the attitude angle and speed at which the lift / drag ratio L / D is maximized are set. In a turning flight, the attitude angle is such that the altitude decrease rate calculated by the altitude decrease rate calculating means is minimized. It is possible to obtain the longest gliding flight distance when flying while maintaining the state quantity in the above longest gliding flight state, but since it is not always flying in that state quantity, It is necessary to bridge the difference between the state quantity in the flight state and the state quantity in the actual flight state.

  Here, the route search device according to the present invention calculates the maximum value of the altitude increase required for the transition from the own position to the longest gliding flight state based on the flight state quantity indicating the flight state at the own position. The longest gliding flight state in the straight flight is a state in which a posture angle and a speed are established such that the lift / drag ratio L / D, which is the ratio of the lift L acting on the airplane and the drag D, is maximized. Yes, the longest gliding flight state in turning flight is a state in which the attitude angle that minimizes the altitude drop rate is established, and the flight path searching means is the required altitude in the longest glide state, the actual altitude at the own position, and the altitude It is preferable to search for a flight path based on the maximum value of the rise. As a result, the minimum altitude required for reaching the destination is calculated, and whether or not the destination can be reached is determined by calculating the altitude increase (or altitude decrease) from the current flight state at the current position. (Arrival determination) can be performed.

  Further, the target angle-of-attack value storage means for storing the preset optimum angle-of-attack value, and the target angle-of-attack value based on the optimum angle-of-attack value and the amount of flight state at its own position before the transition to the longest glide state is completed. It is preferable to include target angle-of-attack value setting means for setting In this way, by storing the optimum angle of attack value (optimum angle of attack map) that maximizes the altitude rise (recovery amount) while keeping the angle of attack constant, the amount of flight state at that time (speed, path angle) It is possible to fly by setting an angle-of-attack value according to the above.

  Further, it is preferable that the target angle-of-attack value setting means sets the target angle-of-attack value based on the turning angle necessary for heading to the destination. In this way, in addition to the control parameters (speed, path angle) when traveling straight ahead, the optimal elevation angle value (optimum elevation angle map) using the remaining turning angle until reaching the target azimuth as a parameter is calculated. It is possible to fly at an angle of attack according to the condition.

  Further, the route search apparatus includes the above-described flight route search means, and can calculate the reachable point by the flight route searched by the flight route search means. Therefore, the reachable point is compared with the target point, It can be determined whether or not a point can be reached.

  ADVANTAGE OF THE INVENTION According to this invention, the route search apparatus in which the calculation time at the time of calculating an optimal flight route was shortened can be provided.

It is a block diagram which shows the route search apparatus which concerns on embodiment of this invention. It is a graph which shows the relationship between the angle of attack (alpha) and L / D at the time of the straight flight of the airplane of this embodiment. It is a schematic side view which shows the attitude angle at the time of the turning flight of the airplane of this embodiment. It is a schematic front view which shows the attitude angle at the time of the turning flight of the airplane of this embodiment. It is the schematic which shows an example of the flight path | route to a landing target point. It is a graph which shows the relationship between a horizontal flight distance and an altitude. It is the schematic which shows an example of the flight path | route until it avoids an obstruction and arrives at a landing target point. It is the schematic which shows an example of the flight path in the case of extending a straight flight in order to land on the landing target point. It is the schematic which shows an example of the combination of the flight path | route at the time of the turning flight, and the flight path | route at the time of the straight flight after the turning flight. It is the schematic which shows an example of the flight path _| route at the time of carrying out the straight flight after the turning flight by turning radius _Ropt and turning angle (psi). It is a graph which shows the relationship between topographic data, an altitude, and a horizontal flight distance. It is the schematic which shows an example of distribution of a glide possible range and an unreachable range. It is the schematic which shows an example of the flight path _| route at the time of considering the straight flight for two turning radii _Ropt, and the turning flight for 180 degrees of turning angles as a required margin. It is a block diagram which shows the route search apparatus which concerns on 2nd Embodiment of this invention. 6 is a chart showing a flight path L _K and a required altitude H _req in a steady gliding flight state. It is a chart which shows the altitude rise required for transfer to the longest gliding flight state (at the time of going straight), and altitude change. It is a flowchart which shows the process performed by ECU which concerns on embodiment of this invention. It is a chart which shows the flight locus by the selected optimal angle-of-attack value. It is a block diagram which shows the route search apparatus which concerns on 3rd Embodiment of this invention. It is a chart which shows the flight path | route in the longest gliding flight state including a turning flight, and an altitude rise. It is a flowchart which shows the process performed by ECU which concerns on embodiment of this invention.

  Preferred embodiments of the present invention will be described below with reference to the drawings. In the description of the drawings, the same or corresponding elements are denoted by the same reference numerals, and redundant description is omitted.

(First embodiment)
A route search apparatus 1 shown in FIG. 1 is mounted on, for example, an airplane 10 (see FIGS. 3 and 4), and searches for a flight route between the position of the airplane 10 and a target point. The route search apparatus 1 includes an electronic control unit (ECU) 3 that executes arithmetic processing for performing a route search, and various sensors 2 and an output unit 3 are electrically connected to the ECU 3.

  The various sensors 2 include a navigation sensor for detecting the current position (latitude and longitude) of the airplane 10, an altimeter for detecting the actual altitude of the airplane 10, and a flight attitude (posture angle) of the airplane 10. A sensor, a sensor for detecting the state of the engine of the airplane 10, a sensor for detecting a failure of the airplane 10, a fuel consumption sensor for grasping the fuselage mass, and the like. Various sensors 2 output various detected information to the ECU 3.

  The output unit 4 is a part that outputs a calculation result by the ECU 3, and is a display unit that displays a flight path that is a calculation result. Examples of the output unit 4 include an automatic pilot device for performing a flight along a flight path.

  The ECU 3 includes a CPU that performs arithmetic processing, a ROM and a RAM that serve as the storage unit 39, an input signal circuit, an output signal circuit, a power supply circuit, and the like. In the ECU 3, an altitude decrease rate calculation unit 31, an attitude angle calculation unit 32, a turning radius calculation unit 33, and a route search unit 34 are configured by executing an application program stored in the storage unit by the CPU.

  The altitude decrease rate calculating unit 31 calculates the altitude decrease rate of the airplane 10, and calculates the altitude decrease rate ΔH, which is the altitude decrease amount per unit turning angle in the turning flight of the airplane 10, according to the present invention. It functions as a calculation means.

  The attitude angle calculation unit 32 calculates the attitude angle of the airplane 10, and functions as an attitude angle calculation unit of the present invention that calculates an attitude angle at which the altitude decrease rate ΔH is minimized.

  The turning radius calculation unit 33 calculates the turning radius of the airplane 10, and functions as a turning radius calculation unit of the present invention that calculates the turning radius when the altitude decrease rate ΔH is minimized based on the attitude angle. .

  The route search unit 34 searches for the flight route of the airplane 10, calculates the flight distance in the turn flight based on the turn radius calculated by the turn radius calculation unit 33, and responds to the calculated flight distance. It functions as a flight path search means of the present invention for searching for a flight path.

  Further, the storage unit 39 stores aerodynamic characteristic data (such as drag coefficient and lift coefficient) of the airplane 10. Furthermore, a terrain database is constructed in the storage unit 39. This landform database stores information on points where landing is possible and information (position, height, etc.) on obstacles (for example, mountains and high-rise buildings) that hinder flight.

The aerodynamic characteristic data stored in the storage unit 39 includes data shown in FIG. FIG. 2 is a graph showing an example of the relationship between the angle of attack α and the lift / drag ratio L / D (= lift L / drag D) during straight flight of the airplane 10. In FIG. 2, the horizontal axis indicates the elevation angle α, and the vertical axis indicates the lift / drag ratio L / D. As shown in FIG. 2, when the elevation angle α is α _opt , the lift / drag ratio L / D becomes the maximum lift / drag ratio (L / D) _MAX .

ただし、ΔＨ_Ｓ：飛行機１０の直線飛行時の高度低下、Ｌ：揚力、Ｄ：抗力である。 Based on the detected attitude angle (elevation angle α _opt ), the ECU 3 calculates the longest reach distance L _MAX during straight flight. The ECU 3 refers to the aerodynamic characteristic data stored in the storage unit 39 and calculates the longest reach distance L _MAX based on the maximum lift / drag ratio (L / D) _MAX . This longest reach distance L _MAX can be calculated by the following equation (1).

However, ΔH _{S is a} decrease in altitude during straight flight of the airplane 10, L is lift, and D is drag.

ただし、Ｒ_ｏｐｔ：旋回半径、γ：経路角、Ｖ：機体速度、ω：角加速度である。経路角γは、水平面と飛行機１０の進行方向との角度である。 The altitude reduction rate calculation unit 31 of the ECU 3 calculates the altitude reduction rate of the airplane 10 and calculates the altitude reduction rate ΔH, which is the altitude reduction amount per unit turning angle in the turning flight of the airplane 10. It functions as a reduction rate calculation means. The turning altitude decrease rate ΔH can be calculated by the following equation (2).

Where R _opt : turning radius, γ: path angle, V: aircraft speed, ω: angular acceleration. The path angle γ is an angle between the horizontal plane and the traveling direction of the airplane 10.

ただし、ｍ：機体質量、Ｖ：機体速度、経路角γ、Ｌ：揚力、φ：バンク角、ｇ：重力加速度、Ｄ：抗力である。バンク角φは、飛行機１０の上下方向に延在する垂直軸（垂直尾翼１５の延在する方向）と水平面との角度である。 3 and 4 are a side view and a front view showing the attitude of the airplane 10 during a turn flight. Moreover, the balance of the force which acts on the airplane 10 at the time of turning flight is expressed by the following formulas (3) to (5).

However, m: body mass, V: body speed, path angle γ, L: lift force, φ: bank angle, g: gravitational acceleration, D: drag force. The bank angle φ is an angle between a vertical axis extending in the vertical direction of the airplane 10 (the direction in which the vertical tail 15 extends) and the horizontal plane.

ただし、ρ：空気密度、Ｓ：翼面積（空力係数を計算する際の基準面積）、Ｃ_Ｌ：揚力係数、Ｃ_Ｄ：抗力係数である。 Here, the lift L and the drag D can be calculated by the following formulas (6) and (7).

However, ρ: air density, S: blade area (reference area when calculating aerodynamic coefficient), C _L : lift coefficient, C _D : drag coefficient.

ここで、

式（８）のうち揚力係数Ｃ_Ｌは、仰角αで決まるため、式（８）は、仰角αおよびバンク角φによって決定される。そこで、パラメータとして、仰角α、バンク角φを式（８）に代入し、旋回高度低下率ΔＨの最小値であるΔＨ_ｏｐｔとなる仰角（α_ｏｐｔＢ）、バンク角（φ_ｏｐｔ）を求める。求められた仰角α_ｏｐｔＢ、バンク角φ_ｏｐｔが最小旋回高度低下率ΔＨ_ｏｐｔを成立させるための条件となる。この条件が成立する場合には、機体速度Ｖ_ｏｐｔ、経路角γ_ｏｐｔといった、力のバランスが取れた飛行（トリム）となる。 And Formula (2) is put together using Formula (3)-(7), and can be expressed by following formula (8).

here,

Coefficient of lift C _L of the formula (8) is determined depending on a elevation alpha, equation (8) is determined by the elevation angle alpha and bank angle phi. Therefore, the elevation angle α and the bank angle φ are substituted into the equation (8) as parameters, and the elevation angle (α _optB ) and the bank angle (φ _opt ) that are ΔH _opt which is the minimum value of the turning height reduction rate ΔH are obtained. The obtained elevation angle α _optB and bank angle φ _opt are conditions for establishing the minimum turning height reduction rate ΔH _opt . When this condition is satisfied, the flight (trim) with balanced forces such as the body speed V _opt and the path angle γ _opt is obtained.

Further, the turning radius (R _opt ) at this time can be obtained by the following equation (10).

Further, the ECU 3 obtains a relative azimuth angle and a landing direction between the airplane's own position and the landing position, and calculates an appropriate combination of a turning flight and a straight flight in a horizontal plane based on the relative azimuth angle and the landing direction. The ECU 3 uses the above-described turning radius R _opt to calculate a combination of turning flight and straight line flight that minimizes the total turning angle, and sets a target point that is a landing position from its own position (hereinafter, “landing target point”). Set the flight route to.

  Further, the ECU 3 functions as a required altitude calculating means of the present invention that calculates the altitude necessary for landing at the landing target point based on the moving distance in the horizontal plane direction. The ECU 3 calculates the minimum altitude necessary for flying along the flight path.

  Further, the route search unit 34 of the ECU 3 compares the relative altitude between the own position and the landing target point to determine whether landing is possible at the landing target point, and searches for a flight route.

Next, an example of route creation in the horizontal plane will be described with reference to FIGS. 5 and 6. FIG. 5 is a schematic diagram showing an example of a flight route to the landing target point. Here, the route search in the case where the airplane 10 flying in the traveling direction D ₀ flies from the own position P ₀ to the landing target point P ₃ and landing in the landing direction D ₃ will be described. In the horizontal plane, the ECU 3 selects a combination of the turning flight with the turning radius R _opt and the straight flight based on the relative position of the landing target point P ₃ with respect to the own position P ₀ and the landing direction, Calculate the optimal flight path. The ECU 3 performs a turn flight with a turn radius R _opt and calculates an optimal flight route that provides the shortest flight distance. Specifically, the sum (ΣΨ) of the turning angle Ψ ₁ for heading to the landing target point P ₃ and the turning angle Ψ ₂ for landing and the total of the flight distance L _S in straight flight (ΣL _S ) are the smallest. The combination of turning flight and straight flight is selected so that

ＥＣＵ３は、飛行機１０の実高度が必要高度Ｈ_ｒｅｑよりも大きい場合に、着陸目標点Ｐ_３に着陸可能であると判定する。そして、ＥＣＵ３は、実高度と必要高度との差がゼロとなる飛行経路を探索する。 The ECU 3 determines whether it is possible to land at the landing target point P ₃ by comparing the required altitude H _req obtained by the following equation (11) with the actual altitude.

ECU3 determines that if the actual altitude of the aircraft 10 is greater than the required height _{H req,} can be landed on the landing target point _{P 3.} Then, the ECU 3 searches for a flight path where the difference between the actual altitude and the required altitude is zero.

FIG. 6 is a graph showing the relationship between horizontal flight distance and altitude. In FIG. 6, the horizontal axis indicates the horizontal flight distance, and the vertical axis indicates the (necessary) altitude. The altitude drop ΔH _{T1 in the} case of turning flight with the turning angle ψ ₁ from the own position P _{0 with the} turning radius R _opt can be calculated by the equation (8). Similarly, highly reduced [Delta] H _T2 in the case of performing the turning angle [psi ₂ of the revolving flight turning radius _{R opt} from the position _{P 2} can be calculated by Equation (8).

Also, the altitude drop ΔH when performing a straight flight from the end point P ₁ of the turning flight (angle ψ ₁ ) to the landing point to the start point P ₂ of the turning flight (angle ψ ₂ ) for landing. _S can be calculated by equation (1).

In this way, during straight flight and turning flight, the conditions for minimizing altitude reduction are determined based on the characteristics unique to the aircraft when the fuel mass is small relative to the aircraft mass. It is possible to calculate. Therefore, only the flight path (flight trajectory) on the horizontal plane needs to be calculated online, and the condition is determined by a low-load calculation that corrects the mass even when the change in the mass of the aircraft is large. It is possible. In the route search device 1, since it is possible to obtain the flight route on the horizontal plane by combining the straight flight and the turning flight along the circular arc of one kind of turning radius R _opt , the calculation load (cost) is reduced. Suppressing and finding a safe landing point.

  In the route search device 1 according to the present embodiment as described above, an altitude reduction rate that is an altitude reduction amount per unit turning angle in a turn flight is calculated, and an attitude angle that minimizes the calculated altitude reduction rate is calculated. Therefore, the turning radius in the turning flight based on the attitude angle can be calculated, and the flight path corresponding to the calculated turning radius can be searched. Thereby, it is possible to reduce the calculation time for calculating the optimum flight path by limiting the trial conditions when searching for the flight path.

  Here, the route search device 1 sets the turning flight and the straight flight necessary for flying along the searched flight route and landing at the target point, and the horizontal direction of the set turning flight and the straight flight is set. A horizontal plane movement distance calculation unit that calculates the movement distance of the vehicle, and a necessary altitude calculation unit that calculates a necessary altitude that is an altitude necessary for landing on the target point based on the movement distance in the horizontal plane direction. Since the flight path search unit searches for the flight path using the required altitude and the actual altitude of the airplane, the flight path is searched using a combination of a straight line and one type of arc. Therefore, it is possible to calculate an appropriate flight path with a reduced calculation load.

  In addition, by setting the calculation result by the route search device 1 of the present embodiment as an initial value, the calculation range in the case of obtaining a strict flight route in consideration of the motion characteristics (steering delay, etc.) of the airplane 10 and the influence of disturbance, etc. Since it can be significantly reduced, the calculation load can be reduced.

Figure 7 is a schematic diagram showing an example of a flight path until they reach to avoid the obstacle B to the landing target point P _15. In the route search device 1, when the immediately preceding moving direction D ₀ of the current position P ₀ obstacle B exists, by determining the flight path to avoid the obstacles B in the horizontal plane, you can land on the target point P ₁₅ The arrival determination which determines whether it is is performed.

Then, the ECU 3 calculates the optimum flight route that makes a turn flight with the turn radius R _opt and has the shortest flight distance. Specifically, “a turning angle Ψ ₁₁ for avoiding the obstacle B”, “a turning angle Ψ ₁₂ for moving to the landing target point P ₁₅ after avoiding the obstacle B”, and “for landing” The combination of the swirl flight and the straight flight is selected so that the sum (Σψ) with the swivel angle ψ ₁₃ ”and the sum of the flight distances L _S11 and L _S12 (ΣL _S ) in the straight flight are minimized. The ECU 3 determines whether it is possible to land at the landing target point P ₃ by comparing the required altitude H _req obtained by the above equation (11) with the actual altitude.

Next, a case where the lowered altitude is adjusted in order to land at the target point will be described. FIG. 8 is a schematic diagram showing an example of a flight path when a straight flight is extended to land on a target point. In order to land at the landing target point, the actual altitude of the airplane 10 needs to be zero when the position in the horizontal plane is reached. The route search unit 34 of the ECU 3 searches for a flight route in which the difference between the required altitude for landing at the target point and the actual altitude of the airplane 10 is zero. Therefore, the route search unit 34 adjusts the lowered altitude in consideration of the extension of the turning flight and the extension of the straight flight, and selects an appropriate flight route. For example, in the situation shown in FIG. 8, by adding the straight flights L _S22 and L _S23 , the required altitude is increased, and a flight path in which the difference between the required altitude and the actual altitude is zero is searched. The airplane 10 does not fly on the shortest path from its own position P ₀ to the landing target point P ₂₅ , but flies on the added straight flight path (L _S22 , L _S23 ) and land on the target point P ₂₅ . become.

Next, based on the current position P ₀ to the surrounding terrain data, it will be described the case of searching the area reachable within a 360 degree circumference. The ECU 3 can acquire the maximum lift-drag ratio (L / D) _MAX based on the aerodynamic characteristic data of the airplane 10 and can acquire the best glide performance data using the above equation (1). In addition, the ECU 3 can acquire the best glide performance data at the time of turning flight using the above equation (8). The best glide performance data during the straight flight and the turning flight can be acquired in advance offline.

  The ECU 3 acquires surrounding terrain data as necessary data online. The ECU 3 acquires terrain data around its own position from the terrain database. For example, as shown in FIG. 10, the ECU 3 acquires terrain data including data relating to the position in the horizontal direction and data relating to elevation.

The ECU 3 sets the flight path that minimizes the altitude drop out of the flight path that is a combination of the turning flight that minimizes the altitude drop rate ΔH in Equation (8) and the straight flight that satisfies Equation (1). Can be searched (within a range of 360 degrees in the horizontal plane). ECU3, as shown in FIG. 9, the turning flight _T R at the current position _{P 0,} and _{T L,} the turning flight _T R, searching for a flight path which consist of a combination of straight flight _{D 31,} continuous to the _{T L} To do.

Further, as shown in FIG. 10, the position (x0, y0) of an arbitrary point that is a landing target point candidate uses a combination of a turning flight with a turning angle Ψ and a straight flight with a flying distance LS as shown below. It is expressed by equations (12) and (13).

Using the above (12) and (13), the ECU 3 searches for the combination of the turning flight and the straight flight to go to the position (x0, y0) of the landing target point, and reaches the position (x0, y0). The altitude drop (minimum required altitude H _req ) up to is calculated using equation (11).

In such a route search device 1, since it is possible to search for landing target point candidates in all directions and search for a flight route to a target point that can be landed, as shown in FIG. 11 and FIG. It is possible to grasp the reachable range A ₀ and the gray zone (behind the obstacle A ₁ ) A ₂ . In FIG. 11, the relationship between the altitude drop F _{53 of the} flight path along the traveling direction D ₅₃ and the terrain data E ₅₃ is shown.

The “gray zone” here cannot be reached linearly from its own position P ₀ because there are obstacles, but it can be reached by avoiding the obstacles and going around to the back. Indicates a range. When present, such as land available flat within the range of the gray zone A ₂ performs a search for flight path in view of the turning flight to avoid obstacles, compared with the required altitude and actual altitude To determine whether landing at the landing target point is possible.

  Data on the flight path for the entire circumference and data on the altitude reduction rate in the flight path can be calculated in advance (offline). Therefore, at the time of actual flight, it is possible to execute a route search only by performing a comparison between glide performance data acquired offline and terrain data acquired online. As a result, for example, when the engine of the airplane 10 is stopped, an emergency landing area can be searched with a small calculation load.

  As described above, the route search device 1 includes the storage unit 39 in which the terrain data including the data indicating the height of the terrain is stored. A range of target points that can be reached within a range of 360 degrees can be calculated, and a flight route to the target points existing within the calculated range can be searched. Thereby, at the time of emergency landing such as when the airplane engine stops, the reachable landing point area can be obtained with a small calculation load. For this reason, it is possible to select a route for ensuring safety when the engine is stopped with a small calculation load.

Next, with reference to FIG. 13, a description will be given of a case where an area where landing is possible in any landing direction is calculated. The ECU 3 considers a margin that is a margin required to be able to cope with any landing direction. In order to be able to land from any landing direction, landing in a direction opposite to the traveling direction D _{0 at} the own position P ₀ is the most critical case because the turning angle becomes large. In such a case, the route search device 1 secures, as a margin, a straight flight L _{S60 that} is twice the turning radius (2R _opt ) and a turning flight L _T62 for a turning angle of 180 degrees as a margin. It is possible to search for a flight path that can cope with the above.

  Further, when the flight route search result is displayed on the display unit that is the output unit 4, the flight route that is the search result is displayed and the land that can be landed (including the airport) is displayed so that the driver can land. It is possible to provide useful information in determining the location.

  In the route search device 1, after determining the location of the candidate site where the landing is possible, a rough flight by a combination of a turning flight that minimizes the altitude drop rate ΔH in equation (8) and a straight flight that satisfies equation (1). By performing a more detailed route search calculation after determining the route, the extra calculation can be greatly reduced. Therefore, it is possible to search for a flight path while reducing the calculation time.

(Second Embodiment)
Next, a route search device according to a second embodiment of the present invention will be described. FIG. 14 is a block diagram illustrating a route search apparatus according to the second embodiment. The route search device 1 according to the second embodiment shown in FIG. 14 is different from the route search device 1 according to the first embodiment in that the altitude increase calculation unit 51, the arrival determination unit 52, the transition determination unit 53, and the target reception. An angle value setting unit 54, a control unit 55, and an optimum angle-of-attack value map 59 are provided. Note that a description similar to that of the route search apparatus 1 of the first embodiment is omitted.

  In the ECU 3 of the second embodiment, the application program stored in the storage unit 39 is executed by the CPU, whereby the altitude reduction rate calculation unit 31, the attitude angle calculation unit 32, the turning radius calculation unit 33, the route search unit 34, An altitude increase calculation unit 51, an arrival determination unit 52, a transition determination unit 53, a target angle-of-attack value setting unit 54, and a control unit 55 are configured.

  The route search device 1 searches for a flight path that can increase the flight distance of a turning flight by calculating an attitude angle that minimizes the altitude decrease rate calculated by the altitude decrease rate calculating unit 31. To do. Further, in the route search device 1, in a straight flight, the flight is performed by flying at a posture angle and speed that maximizes the lift / drag ratio L / D, which is the ratio of the lift L and the drag D acting on the airplane 10. Search for a flight path that can increase the distance. That is, the flight distance in the gliding flight state is maximized by flying so that such a flight state is established. A flight state in which such a longest glide flight distance can be obtained is referred to as a “longest glide flight state”.

  The “longest gliding flight state” is a flight state in which the longest glide flight distance may be realized. For example, in straight flight, the attitude angle and the maximum lift-drag ratio L / D This is a state in which the speed is established, and in a turning flight, a posture angle is established in which the altitude reduction rate calculated by the altitude reduction rate calculating means is minimized. It is possible to obtain the longest gliding flight distance when flying while maintaining the state quantity in the above longest gliding flight state, but since it is not always flying in that state quantity, It is necessary to bridge the difference between the state quantity in the flight state and the state quantity in the actual flight state. The route search apparatus 1 of this embodiment is for filling the difference between the state quantity in the longest gliding flight state and the state quantity in the actual flight state.

The route search unit 34 calculates a required altitude (required altitude H _req ) based on the flight trajectory in the longest gliding flight state. FIG. 15 is a chart showing the flight trajectory L _K and the required altitude H _req in a steady gliding flight state. The route search unit 34 is calculated by a combination of a minimum required turning flight condition (a turning flight condition that minimizes altitude drop) and an optimum glide condition when going straight (a straight flight condition that minimizes altitude drop). A necessary altitude (required altitude H _req ) is calculated based on the flight trajectory in the longest gliding flight state.

The altitude increase calculation unit 51 calculates the maximum altitude increase (ΔH _Amax ) required for transition from the current flight state (speed, path angle, etc.) of the airplane 10 to the longest gliding flight state (details will be described later). ).

ここで、Ｈ：飛行機１０の高度である。 The arrival determination unit 52 determines whether or not the airplane 10 can reach the target landing point from its own position. Arrival determining unit 52, the current position definitive real altitude H, longest highly necessary in gliding flight conditions H _0, based on the maximum value [Delta] H _Amax altitude increment [Delta] H _A, the determination of whether reachable to the destination Do. The arrival determination unit 52 determines that the airplane 10 can reach the target landing point when the following formula (14) is established.

Here, H: the altitude of the airplane 10.

The transition determination unit 53 determines whether or not the state quantity in the longest glide flight state (target glide route) is satisfied. Shift determining unit 53, for example, determining the aircraft speed if they match the speed V _G at maximum gliding flight conditions, it is flying the longest gliding flight conditions and (as the transition to the longest gliding flight conditions is complete) To do. Note that the longest gliding flight state is an optimal glide state (including candidates) in order to maximize the flight distance of the airplane 10 as described above.

  The target angle-of-attack value setting unit 54 sets the angle-of-attack value of the airplane 10. The target angle-of-attack value setting unit 54 sets the angle-of-attack value so as to enable landing at the target landing point. For example, when flying in the longest gliding flight state, the angle-of-attack value is set so as to maintain the flight state. On the other hand, in the state before flying in the longest gliding flight state, the angle of attack value is set with reference to the optimum angle of attack value map 59.

  The control unit 55 controls the actuator (output unit) so that the attack angle value set by the target attack angle value setting unit 54 is obtained. The actuator is an actuator for changing the angle of attack of the airplane 10, for example, a driving means for inclining a flap provided on the wing.

The optimum angle-of-attack value map 59 stores a map of optimum elevation angle values for maximizing the altitude increase ΔH _Amax . For example, a map of optimum angle-of-attack values that maximizes an evaluation function to be described later is prepared in advance with the angle-of-attack value being constant. The optimum angle-of-attack value is performance unique to the airplane and can be calculated in advance. A map of the calculated attack angle values for each aircraft speed of the airplane 10 is stored in the optimum attack angle value map 59. The optimum angle-of-attack value map 59 functions as an angle-of-attack value storage unit that records a preset optimum angle-of-attack value.

(Evaluation function to maximize the flight distance when going straight)
Next, a description will be given of the evaluation for maximizing the flight distance when traveling straight. FIG. 16 is a chart showing the altitude increase ΔH required for the transition to the longest gliding flight state (straight forward). In FIG. 16, the abscissa indicates the moving distance of the airplane 10, and the ordinate indicates the altitude. Flight trajectory L _G in the longest gliding flight conditions are those reachable to landing candidate point (target point). Flight conditions (longest gliding conditions) in the longest gliding flight state are an attack angle α _G , a path angle γ _G , and a speed V _G.

In the route search device 1, the current aircraft velocity V _A1 at the current position P _A1 is, it is determined whether the speed V _G or more at maximum gliding flight conditions L _G. Current speed V _A1 at the current position P _A1 is, if it is the speed V _G or more, as high rise [Delta] H _A is maximum, explore the flight path until the transition to steady gliding flight condition L _G To do.

ここで、Ｈ_Ｍ１は、飛行経路Ｌ_Ａ１による実高度上昇分、Ｈ_Ｍ２は、前進による高度余裕分である。飛行経路Ｌ_Ａ１による高度上昇分Ｈ_Ｍ１は、自位置Ｐ_Ａ１（高度Ｈ_Ａ１）から最長滑空飛行状態における飛行軌跡Ｌ_Ｇ（点Ｐ_Ｇ２，高度Ｈ_Ｇ１）に移行するまでの飛行機１０の実高度の変化量であり、高度Ｈ_Ｇ２と高度Ｈ_Ａ１との差である。 Advanced rise [Delta] H _A can be calculated using the following equation (15).

Here, H _M1 is an actual altitude increase due to the flight path L _A1 , and H _M2 is an altitude margin due to advance. The altitude increase H _M1 due to the flight path L _A1 is the actual altitude of the airplane 10 from the current position P _A1 (altitude H _A1 ) to the flight locus L _G (point P _G2 , altitude H _G1 ) in the longest gliding flight state. And the difference between the altitude H _G2 and the altitude H _A1 .

ここで、Ｘは、飛行機１０の前進距離あり、２点間（点Ｐ_Ａ１，Ｐ_Ｇ２）の水平距離であり、γ_Ｇは、最長滑空飛行状態における経路角α_Ｇである。 Advanced margin _{H M2} by advancing to the airplane 10 moves from the current position _{P A1} to the point _{P G2} corresponds to the height change amount from the point _{P G1} to the point _{P G2} in flight trajectory _{L G} of the longest gliding flight conditions . Advanced margin H _M2 by the advancement can be calculated using equation (16).

Here, X is a forward distance of the airplane 10 and is a horizontal distance between two points (points P _A1 and P _G2 ), and γ _G is a path angle α _G in the longest gliding flight state.

(Optimum flight method during gliding: straight ahead)
Next, with reference to FIG. 17, the process procedure in the route search apparatus 1 of 2nd Embodiment is demonstrated. FIG. 17 is a flowchart showing a process executed by the ECU according to the embodiment of the present invention. First, the ECU 3 detects the flight state amount of the airplane 10 (S1). Specifically, the speed, path angle, and attitude angle of the airplane 10 are calculated based on the signal output from the sensor 2.

Then, ECU 3 determines whether the aircraft 10 is flying the longest gliding flight conditions _{L G} (S2). Specifically, shift determining unit 53 of the ECU3 compares the speed V _G at maximum gliding flight conditions and the aircraft velocity V, and if they match, is flying the longest gliding flight conditions L _G (airplane 10 is the longest gliding flight state). If you are flying at maximum gliding flight condition L _G sets the target of attack angle value = α _G (S3). Elevation value alpha _G at maximum gliding flight conditions L _G is precomputed and stored in the optimum attack angle value map 59.

On the other hand, if it is determined in step S2 that the aircraft is not flying in the longest gliding flight state, the target angle of attack value is set with reference to the optimum angle of attack value map 59 (S4). Target attack angle value setting unit 54 of the ECU3 refers to the optimum attack angle value map 59, on the basis of the flight conditions of the airplane 10, and select the optimum elevation value [Delta] H _A is maximum, set the target of attack angle value To do. In the route search device 1 according to the present embodiment, once the longest gliding flight state is reached, the target angle-of-attack value = α _G is not always set, and the flight state is determined every moment. When determining whether or not the airplane 10 is flying in the longest gliding flight state, an allowable error is considered in accordance with the characteristics of the aircraft and the accuracy of the required route.

  After the processing of step S3 or step 4 is completed, the ECU 3 proceeds to step S5, calculates the gain by the feedback control controller (control unit 55), performs actuator control, and controls the elevation angle. Thereby, the flight in the longest gliding flight state is realized.

FIG. 18 is a chart showing a flight trajectory according to the selected optimum angle of attack value. ECU3, if determined not to be flying at maximum gliding state is controlled so that the angle of attack to maximize the high rise (evaluation function) [Delta] H _A. In the airplane 10, the longest gliding flight state is realized by performing automatic control using the selected angle-of-attack value as a target value in accordance with the current flight state amount at its own position. Alternatively, the airplane 10 may be put into the longest gliding flight state by the pilot maneuvering manually. The ECU 3 notifies the operator by outputting the selected angle-of-attack value to the display unit. Also, the flight conditions of actual at the current position of the aircraft 10, when the difference between the state quantity of the longest gliding flight conditions are set (constant glide flight) occurs, the maximum altitude increment [Delta] H _A The flight distance can be increased by transitioning to the longest steady gliding flight in the flight state.

In the route search device 1 according to the present embodiment, the speed V _G or more and may search for a flight path that maximizes the evaluation function [Delta] H _A. According to such a route search device 1, an optimum route can be searched and guided so as to be in the longest gliding flight state. In the route search device 1, since the map of the optimal angle of attack value calculated in advance is stored in the storage unit, an appropriate angle of attack value can be easily acquired according to the current flight state. As a result, optimal control flight can be realized and the airplane 10 can be in the longest gliding flight state without increasing the calculation load.

In addition, arrival determination to the destination can be executed online for any flight state. Further, the longest flight distance by gliding flight may be predicted based on the current altitude and the maximum value ΔH _Amax of the altitude increase of the airplane 10. If the angle of attack is determined when the engine is stopped, the speed and route angle are determined based on the angle of attack, so it is also possible to use a map of speed and route angle instead of the above angle of attack map.

  These mapped data may not be stored in the optimum angle-of-attack value map 59. A configuration may be used in which the optimum elevation angle value is calculated using data stored in other storage means. For example, the structure which receives the data transmitted from the work station on the ground by the airplane 10 side and uses this received data may be sufficient.

(Third embodiment)
Next, a route search device according to a third embodiment of the present invention will be described. FIG. 19 is a block diagram illustrating a route search apparatus according to the third embodiment. The route search device 1 according to the third embodiment shown in FIG. 19 is different from the route search device 1 according to the second embodiment in that a bank angle calculation unit 35 is further provided. Note that a description similar to that of the route search apparatus 1 of the first and second embodiments is omitted.

  In the ECU 3 of the third embodiment, the application program stored in the storage unit 39 is executed by the CPU, whereby the altitude reduction rate calculation unit 31, the attitude angle calculation unit 32, the turning radius calculation unit 33, the route search unit 34, A bank angle calculation unit 35, an altitude increase calculation unit 51, an arrival determination unit 52, a transition determination unit 53, a target attack angle value setting unit 54, and a control unit 55 are configured.

ここで、γ：経路角、γ_Ｇ：高度低下を最小にする旋回飛行時の経路角、Ｃ_Ｌ：揚力係数、Ｃ_ＬＧ：高度低下を最小にする旋回飛行時の揚力係数、Φ_Ｇ：高度低下を最小にする旋回飛行時のバンク角である。 The bank angle calculation unit 35 calculates the bank Φ using the following equation (17) in order to set the same turning radius as the turning that minimizes the altitude drop calculated by the turning radius calculation unit 33 described above.

Here, γ: path angle, γ _G : path angle at the time of turning flight that minimizes altitude reduction, C _L : lift coefficient, C _LG : lift coefficient at the time of turning flight that minimizes altitude reduction, Φ _G : altitude This is the bank angle during a turn flight that minimizes the drop.

ここで、ρ：空気密度、Ｖ：飛行速度、ｓ：翼面積、Ｒ：旋回半径、ｍ：機体質量である。 Derivation of the above equation (17) will be described. The balance of force during a turn flight can be expressed by the following equation (18).

Here, ρ: air density, V: flight speed, s: wing area, R: turning radius, m: airframe mass.

Next, the following equation (19) is derived from the above equation (18).

Then, equation (17) is derived from equation (19).

In Equation (17), γ _G , Φ _G , and C _LG are constant values because the optimum conditions are determined by the inherent characteristics of the airplane. Therefore, it is possible to calculate the bank angle Φ by path angle γ and the lift coefficient C _L at that time.

  When the flight with the same turning radius as that of the turn that minimizes the altitude decrease calculated by the turning radius calculation unit 33 is not performed, the flight trajectory in the longest gliding flight state calculated by the route search unit 34 may be adopted as a reference. For this reason, it is necessary to perform high-load arithmetic processing.

(Evaluation function for obtaining the angle of attack value that maximizes the altitude rise during turning)
Next, an evaluation function for obtaining the angle of attack value that maximizes the altitude increase during turning will be described. FIG. 20 is a flowchart showing the flight trajectory in the longest gliding flight state and the altitude increase during turning. In FIG. 20, the horizontal axis indicates the horizontal movement distance of the airplane 10, and the vertical axis indicates the altitude.

（ここで、Ψ：必要な旋回角度、ｄＨ_ｔｕｒｎ：単位旋回角度当りの高度低下量） The route search device 1 searches for a flight route that maximizes one of the following evaluation functions. When the turning angle required for flight in the airplane 10 has not been reached, the following equation (20) is adopted as the evaluation function ΔH _B.

(Here, Ψ: Necessary turning angle, dH _turn : Altitude reduction per unit turning angle)

When the required turning angle has not been reached, the route search device 1 searches for the flight route L _B1 that is equal to or higher than the speed V _G and maximizes the evaluation function ΔH _{B according} to the above equation (20).

（ここで、ΔＨ_ｍａｘ１：旋回後に続く直進滑空時の最大高度上昇分） On the other hand, when the turning angle that requires flight in the airplane 10 is reached, the following equation (21) is adopted as the evaluation function ΔH _B.

(Here, ΔH _max1 : Maximum altitude increase during straight _run after glide)

In the route search device 1, when the necessary turning angle is reached, the flight route L _B2 that maximizes the evaluation function ΔH _{B according} to the above equation (21) is searched.

For example, in the case of reaching the flight trajectory L _G of the longest gliding flight conditions the turning angle previously required, but it is the most efficient flight trajectory, when the turning angle is small, forcibly longest gliding flight conditions If it is made to reach the flight trajectory, the efficiency may decrease. In the route search device 1 of the present embodiment, the evaluation function ΔH _B can be set in consideration of the altitude increase ΔH _Amax in the straight flight section that follows the turning flight, and the optimum angle of attack value corresponding to the turning angle is set. Can be sought. Note that ΔH _Amax can be calculated in advance using the evaluation function for maximizing the flight distance in a straight line described in the second embodiment, and is obtained when the turning angle is reached (point P _A1 ). Based on the flight state quantity, the altitude increase in the straight flight section is calculated.

(Optimum flight method during gliding: when turning)
Next, with reference to FIG. 21, the process procedure in the route search apparatus 1 of 3rd Embodiment is demonstrated. FIG. 21 is a flowchart showing a process executed by the ECU according to the embodiment of the present invention. First, the ECU 3 detects the flight state quantity of the airplane 10 (S11). Specifically, the speed, own position, traveling direction, and attitude angle of the airplane 10 are calculated based on the signal output from the sensor 2.

  Next, the ECU 3 calculates a turning angle required to go to the destination (S12). Specifically, the route search unit 34 of the ECU 3 calculates a necessary turning angle based on the turning radius by the turning radius calculation unit 33.

Then, ECU 3 proceeds to step S2, determines whether the airplane 10 is flying the longest gliding flight condition _{L G.} If you are flying at maximum gliding flight condition L _G, the process proceeds to step S13, both sets the target of attack angle value = alpha _G, sets the target bank angle = [Phi _G. When the required turning angle is 0 or less, the target bank angle = 0 is set. It progresses to step S5 after the process of step S13.

On the other hand, if it is determined in step S2 that the flight is not performed in the longest gliding flight state, the process proceeds to step S4, the optimum angle-of-attack value map 59 is referred to, and the target angle-of-attack value is set. After the process of step S4, the process proceeds to step S14, and a target bank angle for maintaining the turning radius (R _opt ) is calculated. In the route search device 1 according to the present embodiment, once the longest gliding flight state is reached, the target angle-of-attack value = α _G and the target bank angle = Φ _G are not always set, and the flight state is in every moment. Determine. When determining whether or not the airplane 10 is flying in the longest gliding flight state, an allowable error is considered in accordance with the characteristics of the aircraft and the accuracy of the required route.

  After the processing of step S13 or step 14 is completed, the ECU 3 proceeds to step S5, calculates a gain by the feedback control controller (control unit 55), and performs actuator control. Thereby, the flight in the longest gliding flight state is realized.

In the route search device 1 according to the present embodiment, rather than migrating to the longest gliding flight conditions L _G during turning flight, during straight flight segment after turning flight better to shift to the longest gliding flight conditions L _G If good, the flight path to shift the longest gliding flight condition L _G in straight flight after turning flight can explore, it is possible to extend the flight distance of the aircraft 10. In addition, since the configuration includes the optimum angle-of-attack value map 59 that stores a preset optimum angle-of-attack value, it is possible to reduce the calculation load and search for the optimum flight path.

  As mentioned above, although this invention was concretely demonstrated based on the embodiment, this invention is not limited to the said embodiment. In the route search device 1 of the above embodiment, the horizontal plane movement distance calculation unit and the necessary height calculation unit are configured. However, even in the route search device 1 that does not include the horizontal plane movement distance calculation unit and the necessary height calculation unit. Good.

  Further, the route search device 1 of the above embodiment searches for a flight route in which the difference between the required altitude and the actual altitude is zero, but searches for a flight route in which the difference between the required altitude and the actual altitude is not zero. It may be configured.

  Moreover, although the route search apparatus 1 of the said embodiment is set as the structure provided with the terrain data storage means which memorize | stores terrain data, the route search apparatus 1 which is not provided with the terrain data storage means may be sufficient.

DESCRIPTION OF SYMBOLS 1 ... Route search apparatus, 2 ... Sensor, 3 ... ECU (electronic control unit), 31 ... Altitude reduction rate calculation part, 32 ... Attitude angle calculation part, 33 ... Turning radius calculation part, 34 ... Path search part, 35 ... Bank Angle calculation unit, 39 ... storage unit, 4 ... output unit, 10 ... airplane, 13 ... main wing, 15 ... vertical tail, 51 ... altitude increase calculation unit, 52 ... arrival determination unit, 53 ... transition determination unit, 54 ... target Angle-of-attack value setting unit, 55... Control unit, 59... Optimum angle-of-attack value map (attack angle value storage means), L ... Lift, D ... Drag, G ... Gravity, L ₁ , L ₂ . distance, Ls ... linear distance, V ... speed, alpha ... attack angle, gamma ... path angle, the turning angle for towards the [psi _{1 ...} landing point, turning angle for the [psi _{2 ...} landing, B ... obstacles.

Claims (8)

A route search device for searching for a flight route between an aircraft's own position and a target point,
Altitude reduction rate calculating means for calculating an altitude reduction rate that is an altitude reduction amount per unit turning angle in the turning flight of the airplane;
Attitude angle calculation means for calculating an attitude angle that minimizes the altitude decrease rate calculated by the altitude decrease rate calculation means;
A route search device that calculates a turning radius in the turning flight based on the posture angle calculated by the posture angle calculating means. A route search device for searching for a flight route between an aircraft's own position and a target point,
Altitude reduction rate calculating means for calculating an altitude reduction rate that is an altitude reduction amount per unit turning angle in the turning flight of the airplane;
Attitude angle calculation means for calculating an attitude angle that minimizes the altitude decrease rate calculated by the altitude decrease rate calculation means;
A turning radius calculating means for calculating a turning radius in the turning flight based on the posture angle calculated by the attitude angle calculating means;
Flight path searching means for calculating a flight distance in the turning flight based on the turning radius calculated by the turning radius calculating means and searching for the flight path according to the calculated flight distance. A route search device characterized by the above. A horizontal plane for setting a turning flight and a straight flight necessary for flying along the searched flight path and landing at the target point, and calculating a movement distance in the horizontal plane direction of the set turning flight and the straight flight A moving distance calculating means;
A required altitude calculating means for calculating a required altitude that is an altitude necessary for landing on the target point based on the moving distance in the horizontal plane direction, and
3. The route search device according to claim 2, wherein the flight route search means searches for the flight route using the required altitude and an actual altitude that is an actual altitude of the airplane.   4. The route search device according to claim 3, wherein the flight route search means searches for the flight route in which a difference between the required altitude and the actual altitude is zero. Comprising terrain data storage means in which terrain data including data indicating the level of terrain is stored;
The flight path search means calculates a range of the target point that can be reached in a 360-degree range in the horizontal plane centered on the own position based on the terrain data, and exists within the calculated range The route search device according to any one of claims 2 to 4, wherein a flight route to a target point is searched. Based on the flight state amount indicating the flight state at the own position, further comprising an altitude increase calculation means for calculating the maximum value of the altitude increase required for the transition from the own position to the longest gliding flight state,
The longest gliding flight state in straight flight is a state in which a posture angle and a speed are established such that a lift-drag ratio L / D, which is a ratio of lift L and drag D acting on the airplane, is maximized,
The longest gliding flight state in the turning flight is a state in which an attitude angle is established such that the altitude decrease rate is minimized,
The flight path search means searches for the flight path based on a required altitude in the longest gliding flight state, an actual altitude at its own position, and a maximum value of the altitude increase. The route search device according to any one of 5. An angle-of-attack value storage means for storing a preset optimum angle-of-attack value;
And a target angle-of-attack value setting means for setting a target angle-of-attack value based on the optimum angle-of-attack value and the amount of flight state at the position before completion of the transition to the longest glide state, The route search device according to claim 6.   The route search device according to claim 7, wherein the target angle-of-attack value setting unit sets the target angle-of-attack value based on a turning angle necessary to go to the destination.

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