A fixed-wing fire extinguishing machine forest fire extinguishing approach path planning system and method

Abstract

The application relates to the technical field of computer simulation, and provides a fixed-wing fire extinguishing machine forest fire extinguishing approach path planning system and method. The method comprises the following steps: analyzing a fire extinguishing task model of the fixed-wing fire extinguishing machine, determining aircraft related parameters, and writing in accordance with an aviation emergency force database format supported by simulation software; dividing a new node position into a corresponding grid through an improved new node selection rule; performing grid scale range planning based on three-dimensional grid scale of position change operation precision requirements of the fixed-wing fire extinguishing machine under small action, updating boundary restrictions, and setting a dynamic optimization step length meeting requirements between operation speed and safety; in the update of the boundary restriction each time, the A* algorithm is optimized at a speed to find an optimal point, and approach path planning in a short time is completed. The application scheme has greater advantages in water-throwing fire extinguishing tasks; can continuously throw water to curb the fire; has small calculation amount, simple method and strong practicability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of computer simulation, and in particular to a forest fire extinguishing approach path planning system and method for a fixed-wing fire extinguishing machine. BACKGROUND

[0002] Forest is the main body of terrestrial ecosystem, and as an extremely important ecological protection barrier, plays an important role in sustainable development and ecological protection construction. Forest fire is very serious to the destruction of forest resources and ecological environment. China has vast territory, and forest and grassland is widely distributed, which brings high-quality resources to the natural ecological environment, but also faces great pressure of forest and grassland fire fighting, especially in the northeast Greater Khingan Range and Yunnan-Guizhou-Chongqing area, which are high-risk areas of forest and grassland fire in China. Due to the complex ground conditions of forest, ground fire fighting is difficult.

[0003] With the continuous development of national scientific and technological level and aviation strength, China's aviation emergency rescue construction has also gradually been realized. However, the construction of aviation fire fighting equipment in China is still in its infancy, and the use of fire extinguishing machines is mainly based on helicopters, lacking experience in the production and use of large fixed-wing aircraft. Although the helicopter flies slowly and can hover, the helicopter has limited range and limited transportation capacity, and cannot quickly and continuously pour water to suppress the fire in severe fire conditions. SUMMARY

[0004] Therefore, the present application provides a fixed-wing fire extinguishing machine forest fire extinguishing approach path planning system and method to solve the problems of small load, slow speed, and insufficient range of aviation fire fighting equipment in the prior art, which cannot enter the forest fire area in time to extinguish the fire at an ideal speed in the water pouring fire extinguishing task.

[0005] The present application provides a fixed-wing fire extinguishing machine forest fire extinguishing approach path planning system, which comprises an environment model setting module, a motion model improvement module, an optimization index improvement module and a simulation verification module.

[0006] The environment model setting module comprises a terrain obstacle model and a flight restricted area obstacle model, which is used to set the environmental conditions of forest fire;

[0007] The motion model improvement module is used to describe and calculate the motion characteristics of the fixed-wing fire extinguishing machine based on the aviation emergency force database;

[0008] The optimization index improvement module comprises a cost index and a safety index, which is used for three-dimensional path optimization in terms of cost and safety;

[0009] The simulation verification module simulates the approach path of the fixed-wing fire-fighting machine for different types of obstacles and fixed-wing fire-fighting machines based on an environment model and a motion model, tests whether the A* algorithm has corresponding path rapid planning capability, and visually displays the motion characteristics of the fixed-wing fire-fighting machine, the optimized path, and the water-throwing parameters.

[0010] Further, the terrain obstacle model includes a mountain terrain model and a single mountain model, which are used to establish terrain obstacles in a three-dimensional space to realize mountain collision detection and avoid collision of the fixed-wing fire-fighting machine during path planning.

[0011] The mountain terrain model includes a mountain model three-dimensional body simplified in a transverse section, which is subjected to translation and rotation transformation by using a Gaussian height distribution.

[0012] The single mountain model includes a mountain model three-dimensional body simplified as a two-dimensional Gaussian distribution with a certain height in the middle.

[0013] Further, the flight restricted area obstacle model includes a high-voltage line restricted area model and a meteorological cloud cluster restricted area model, which are used to simulate areas that have a great impact on the safe flight of the fixed-wing fire-fighting machine due to human or natural factors.

[0014] The high-voltage line restricted area model includes a polyline-shaped high-voltage line no-fly area model three-dimensional body.

[0015] The meteorological cloud cluster restricted area model includes a mountainous cloud cluster model three-dimensional body formed by the comprehensive action of air pressure, temperature, airflow, and terrain.

[0016] Further, the motion model improvement module calculates the motion models of the fixed-wing fire-fighting machine turning, ascending, and descending based on the traditional A* algorithm, spatial grid discretization method, and improved new node selection rules considering the direction of the fixed-wing fire-fighting machine, determines the boundary points of acceleration, deceleration, left turn, right turn, ascent, and descent at a set time step t step , and considers the combination of different motions to reflect the nonlinear motion and changing motion under real driving.

[0017] Further, the aviation emergency force database includes aircraft information, aircraft task execution link information, and water-throwing parameter information, which are used to provide data support for algorithm verification.

[0018] The aircraft information includes the model, cruise speed, cruise altitude, effective water load, oil load, oil consumption, and turning radius of the fixed-wing fire-fighting machine performing the fire extinguishing task.

[0019] The aircraft task execution link information includes the oil consumption and time information required by the aircraft in each link of the task execution.

[0020] The water dropping parameter information includes water tank capacities corresponding to different models and equivalent radii of the airplane water dropping.

[0021] Further, the optimization index improvement module is based on an improved A* algorithm, and the three-dimensional path optimization including cost and safety is performed through a path optimization efficiency function, wherein the path optimization efficiency function can be expressed as:

[0022] f(n)=w c C(n)+w s S(n)

[0023] C(n)=w c1 C start (n)+w c2 C goal (n)

[0024] S(n)=w s1 S hori (n)+w s2 S ver (n)

[0025] wherein C(n) is a cost function, S(n) is a safety function, w c is a cost function weight, w s is a safety function weight, C start represents an actual path length of the fire extinguishing machine from an initial position to a current position, C goal represents an estimated path length of the fire extinguishing machine from the current position to a target position, w c1 is a path weight from a starting point to the current node, w c2 is a path weight from the current node to the target point, w s1 is a horizontal threat function weight, w s2 is a vertical threat function weight, S ver (n) is a vertical threat function value, S hori (n) is a horizontal threat function value.

[0026] Further, the approach path is a path of the fixed-wing fire extinguishing machine from an entry point to a water dropping fire extinguishing point.

[0027] The entry point is a place where the fire extinguishing machine changes from a cruising path to perform a water dropping fire extinguishing task.

[0028] The water dropping fire extinguishing point is a task place where the fire extinguishing machine performs water dropping fire extinguishing.

[0029] A forest fire extinguishing approach path planning method of a fixed-wing fire extinguishing machine, comprising:

[0030] S1, for the fixed-wing fire extinguishing machine fire extinguishing task model analysis, determine the aircraft entry point speed, hovering height, water throwing strategy and aviation emergency force database, and write according to the aviation emergency force database format supported by the simulation software;

[0031] S2, based on the aviation emergency force database format writing, through the improved new node selection rule, the new node position is approximated, and the new node position is divided into the corresponding grid, so that the position change under the action of the fixed-wing fire extinguishing machine is set range and the three-dimensional grid scale meeting the operation precision requirement is met;

[0032] S3, based on the three-dimensional grid scale meeting the position change under the action of the fixed-wing fire extinguishing machine set range and the operation precision requirement, the grid scale range planning is carried out, the boundary limit is updated, and the dynamic optimization step meeting the requirements of operation speed and safety is set;

[0033] S4, based on the dynamic optimization step, the optimization speed of A* algorithm in each update of the boundary limit, the nearest set number of nodes in the target point in the exploration set is found to compare the performance function, the optimal point of the performance function is selected, and the approach path planning in a short time is completed.

[0034] 9. The fixed-wing fire extinguishing machine forest fire extinguishing approach path planning method according to claim 8, wherein the expression of the dynamic optimization step is as follows:

[0035]

[0036] t step The dynamic optimization step is represented by dis min The minimum distance of the aircraft from the obstacle is represented.

[0037] Compared with the prior art, the present application has the beneficial effects that:

[0038] 1. The fixed-wing aircraft selected in the present application has the characteristics of large load, high speed and long range, which can play a greater advantage in water throwing fire extinguishing task;

[0039] 2. The present application can be applied to sparsely populated, inconveniently located primitive forests and grassland areas, and can also be used for rapid and continuous water throwing to suppress the fire in the case of long burning time and serious burning situation;

[0040] 3. Compared with the prior art, the calculation amount is greatly reduced;

[0041] 4. The method of the present application is simple and practical. BRIEF DESCRIPTION OF DRAWINGS

[0042] In order to more clearly illustrate the technical solutions in the present application, the drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0043] Figure 1 is a fixed-wing fire extinguishing machine approach path planning system schematic diagram of forest fire extinguishing task provided by the present application;

[0044] Figure 2 is a path planning algorithm technical path diagram provided by the present application;

[0045] Figure 3 is an improved A* algorithm pseudo code and algorithm application flowchart provided by the present application;

[0046] Figure 4 is a simulation system interface schematic diagram provided by the present application;

[0047] Figure 5 is a flowchart of a fixed-wing fire extinguishing machine forest fire extinguishing approach path planning method provided by the present application

[0048] Figure 6 is an improved A* algorithm optimized running time schematic diagram provided by the present application. DETAILED DESCRIPTION

[0049] In the following description, specific details are set forth in order to provide a thorough understanding of embodiments of the application. However, persons of ordinary skill in the art will readily recognize that embodiments of the application can be practiced without these specific details. In other instances, well-known structures, devices, circuits, and processes have not been described in detail so as not to unnecessarily obscure aspects of the application.

[0050] A fixed-wing fire extinguishing machine forest fire extinguishing approach path planning system and method according to the present application will be described in detail below with reference to the drawings.

[0051] Figure 1 is a fixed-wing fire extinguishing machine forest fire extinguishing approach path planning system schematic diagram provided by the present application. Figure 2 is a path planning algorithm technical path diagram provided by the present application.

[0052] As shown in Figure 1 , the fixed-wing fire extinguishing machine forest fire extinguishing approach path planning system comprises:

[0053] an environment model setting module, a motion model improvement module, an optimization index improvement module, and a simulation verification module;

[0054] The environment model setting module comprises a terrain obstacle model and a flight restricted area obstacle model, and is used for setting the environment conditions of the forest fire;

[0055] The terrain obstacle model comprises a mountain terrain model and a single mountain peak model, and is used for establishing the terrain obstacles in the three-dimensional space to realize the mountain collision detection and avoid the collision of the fixed-wing fire extinguishing machine with the mountains in the path planning process.

[0056] The mountain terrain model comprises a mountain model three-dimensional body which is simplified on a transverse section, and is subjected to translation transformation and rotation transformation by using a Gaussian height distribution.

[0057] The single mountain peak model comprises a mountain peak model three-dimensional body which is simplified as a two-dimensional Gaussian distribution and has a certain height in the middle.

[0058] The flight restricted area obstacle model comprises a high-voltage line restricted area model and a meteorological cloud cluster restricted area model, and is used for simulating the areas which have a great influence on the safe flight of the fixed-wing fire extinguishing machine due to human or natural factors.

[0059] The high-voltage line restricted area model comprises a polyline-shaped high-voltage line no-fly area model three-dimensional body.

[0060] The meteorological cloud cluster restricted area model comprises a mountainous cloud cluster model three-dimensional body which is formed due to the comprehensive action of air pressure, temperature, airflow and terrain.

[0061] The motion model improvement module is used for describing and calculating the motion characteristics of the fixed-wing fire extinguishing machine based on the aviation emergency force database.

[0062] Figure 3 The present application provides an improved A* algorithm pseudo code and an algorithm application flowchart.

[0063] The motion model improvement module calculates the motion models of the turning, ascending and descending of the fixed-wing fire extinguishing machine based on the traditional A* algorithm, the spatial grid discretization method and the improved new node selection rule considering the direction of the fixed-wing fire extinguishing machine, determines the boundary points of the acceleration, deceleration, left turn, right turn, ascending and descending in the set time step t step , and considers the combination of different motions to reflect the nonlinear motion and changing motion under the real driving.

[0064] The improved new node selection rule comprises a grid scale range planning rule and a node selection rule considering the new direction.

[0065] The grid scale range planning rule considers that the aircraft needs to have a height drop from the cruising path to the water dropping point, and meanwhile, the aircraft can carry an optical-electricity pod to further confirm the terrain and fire site, and the effective range of the optical-electricity pod is about 10 kilometers.

[0066] The grid scale range planning rule sets the planning range length to 13-15 kilometers and the planning range width to 5 kilometers to ensure that the fire extinguishing machine has sufficient range to adjust the attitude, position and speed and has sufficient space to perform horizontal obstacle avoidance and heading correction;

[0067] Due to the grid scale range planning rule, the aircraft needs to have a height drop when changing from the cruise path to the water dropping point, and the aircraft may carry an optical-electrical pod to further confirm the terrain and fire site. The effective range of the optical-electrical pod is about 10 kilometers. Therefore, the above settings are made.

[0068] The node selection rule of the new direction takes the aircraft direction as a constraint. For each node update, the node near the direction of the old node is selected by obtaining the direction of the old node, and the horizontal direction and the vertical direction are decoupled. The direction is represented as N NE E SE S SW W NW, which corresponds to eight directions of 45-degree integer multiples. Among them, the up, down, left and right four directions correspond to nine nodes in the forward direction of the aircraft, and the remaining four corner directions correspond to three nodes in the corner and six nodes on both sides, a total of nine nodes.

[0069] Nodes are added at the midpoint of the connecting line of the boundary points of acceleration, deceleration, left turn, right turn, ascent and descent. Without considering other constraints, one node will generate 23 new nodes.

[0070] Before the improvement, the A* algorithm calculates 26 neighborhoods in a single node update, which has a large amount of calculation. After the improvement, the direction of the aircraft is considered as a constraint. For each node update, the node near the direction of the old node is selected by obtaining the direction of the old node. The horizontal direction and the vertical direction are decoupled. In each iteration, vertical displacement is allowed, but the direction calculation after each node update only calculates the horizontal direction projection. In this way, the direction is eight, which can be represented as N NE E SE S SW W NW, which corresponds to 45-degree integer multiples. Among them, the up, down, left and right four directions correspond to nine nodes, and the remaining four corner directions correspond to three nodes in the corner and six nodes on both sides, a total of nine nodes.

[0071] The motion model is based on the node selection rule considering the new direction, including the aircraft turning radius, flight speed, angular velocity, horizontal distance under aircraft turning action, aircraft flight new direction, aircraft forward distance and ascent and descent motion;

[0072] The turning radius is considered to be constant when the aircraft maintains a constant speed during turning.

[0073] The angular velocity calculation formula is:

[0074]

[0075] ω = ω0 + ω1 + ω2 + ω3 + ω4 + ω5 + ω6 + ω7 + ω8 turnR is the turning radius of the airplane, V is the flight speed of the airplane; turn R is the turning radius of the airplane, V is the flight speed of the airplane; turn R is the turning radius of the airplane, V is the flight speed of the airplane;

[0076] The formula for calculating the horizontal distance under the turning action of the airplane is:

[0077]

[0078] R is the turning radius of the airplane, dis is the horizontal distance under the turning action of the airplane, t is the time step, turn R is the turning radius of the airplane, dis is the horizontal distance under the turning action of the airplane, t is the time step, turn R is the turning radius of the airplane, dis is the horizontal distance under the turning action of the airplane, t is the time step, strp R is the turning radius of the airplane, dis is the horizontal distance under the turning action of the airplane, t is the time step,

[0079] The formula for calculating the new direction of the airplane flight is:

[0080]

[0081] R is the turning radius of the airplane, dis is the horizontal distance under the turning action of the airplane, t is the time step, turb R is the turning radius of the airplane, dis is the horizontal distance under the turning action of the airplane, t is the time step, R is the turning radius of the airplane, dis is the horizontal distance under the turning action of the airplane, t is the time step,

[0082] The forward distance of the airplane is the corresponding forward distance of the airplane maintaining straight flight with constant acceleration or deceleration motion, and the calculation formula is:

[0083]

[0084] R is the turning radius of the airplane, dis is the horizontal distance under the turning action of the airplane, t is the time step, acc / dec R is the turning radius of the airplane, dis is the horizontal distance under the turning action of the airplane, t is the time step, step R is the turning radius of the airplane, dis is the horizontal distance under the turning action of the airplane, t is the time step, acc / dec R is the turning radius of the airplane, dis is the horizontal distance under the turning action of the airplane, t is the time step, acc / dec R is the turning radius of the airplane, dis is the horizontal distance under the turning action of the airplane, t is the time step;

[0085] The upward and downward motion is to consider the motion in the vertical direction by changing the lift through the action of the aerodynamic surface under the condition that the speed is unchanged, and the corresponding upward and downward displacement in the height is determined by the upward rate and the downward rate.

[0086] The aviation emergency force database includes airplane information, airplane task execution link information and water throwing parameter information, which is used to provide data support for algorithm verification;

[0087] The airplane information includes the model, cruising speed, cruising height, effective water carrying capacity, oil carrying capacity, oil consumption, turning radius of the fixed-wing fire extinguishing machine for executing the fire extinguishing task;

[0088] The airplane task execution link information includes the oil consumption and time information required by the airplane in each link of the task execution;

[0089] The water-throwing parameter information includes water tank capacities corresponding to different models and an equivalent radius of water-throwing of the airplane.

[0090] The optimization index improvement module includes a cost index and a safety index, and is used for three-dimensional path optimization in terms of cost and safety, so as to obtain an optimized path.

[0091] The optimization index improvement module is based on an improved A* algorithm, and performs three-dimensional path optimization through a path optimization performance function including cost and safety, wherein the path optimization performance function can be expressed as:

[0092] f(n)=w c C(n)+w s S(n)

[0093] C(n)=w c1 C start (n)+w c2 C goal (n)

[0094] S(n)=w s1 S hori (n)+w s2 S ver (n)

[0095] wherein f(n) is a path optimization performance function, C(n) is a cost function, S(n) is a safety function, w c is a cost function weight, w s is a safety function weight, C start represents an actual path length of the fire extinguishing machine from an initial position to a current position, C goal represents an estimated path length of the fire extinguishing machine from the current position to a target position, w c1 is a path weight from the starting point to the current node, w c2 is a path weight from the current node to the target point, w s1 is a horizontal threat function weight, w s2 is a vertical threat function weight, S ver (n) is a vertical threat function value, and S hori (n) is a horizontal threat function value.

[0096] The cost function includes an actual path length C start of the fire extinguishing machine from the initial position to the current position and an estimated path length C goal of the fire extinguishing machine from the current position to the target position, which respectively correspond to a path weight w c1 from the starting point to the current node and a path weight w c2 from the current node to the target point;

[0097] The safety function includes a horizontal threat function S start and a vertical threat function S goal .hori and represents the vertical threat function S ver , respectively, corresponding to the horizontal threat function weight w s1 and the vertical threat function weight w s2 .

[0098] The estimated path length is calculated using the Euclidean distance, which can be expressed as:

[0099]

[0100] where D(i,j) represents the estimated path length using the Euclidean distance, (x i , y i , z i ) represents the current position coordinates, and (x j , y j , z j ) represents the target position coordinates.

[0101] The cost function weight is divided into the path weight w c1 from the starting point to the current node and the path weight w c2 from the current node to the target point, which can be expressed as:

[0102]

[0103] where dis(start,goal) is the Euclidean distance from the initial point to the target point.

[0104] The safety function weight is divided into the horizontal threat function weight w s1 and the vertical threat function weight w s2 .

[0105] When the safety threat is less than the set threat, the distance to the mountain, cloud layer, and high-voltage line obstacle is greater than the set distance, the cost function weight is equal to the safety function weight, and the shortest path is considered to enable the fire extinguishing machine to reach the target area as quickly as possible.

[0106] When the safety threat is greater than the set threat, the distance to the mountain, cloud layer, and high-voltage line obstacle is less than the set distance, and the safety function is determined according to the type of three-dimensional body. The horizontal threat function weight w s1 and the vertical threat function weight w s2 are determined as follows:

[0107]

[0108]

[0109]

[0110] The three-dimensional body type corresponds to the obstacle type, including three obstacle types and four three-dimensional bodies. Type 1 is a mountain type obstacle corresponding to the minimum distance, including a Gaussian elongated body and a Gaussian spin body. Type 2 is a high-voltage line type no-fly zone obstacle corresponding to the minimum distance or within 2000 meters of the high-voltage line type no-fly zone, corresponding to a three-prism three-dimensional body. Type 3 is a cloud cluster type no-fly zone obstacle, corresponding to an ellipsoid three-dimensional body.

[0111] The minimum distance is the minimum value of the horizontal distance of the current position of the fire extinguishing machine from the four obstacles under horizontal threat, corresponding to the minimum value of the horizontal distance of the four three-dimensional bodies;

[0112] For the Gaussian elongated body, the horizontal distance is calculated by first determining whether the point is on the longitudinal side of the Gaussian elongated body, i.e. the y-axis coordinate is within If it is outside, the horizontal projection distance of the point to the bottom center of the nearest side section of the Gaussian elongated body is calculated. If it is within, it is not in the part of the mountain height, the distance is the distance dis(gaus1, x, y) from the calculation point to the center line of the two side section bottoms of the Gaussian elongated body, and within the mountain height, it is the difference between the above distance and the absolute value of the section coordinate corresponding to the height, i.e. the horizontal distance of the point to the surface of the Gaussian elongated body. The vertical distance is the z-axis coordinate after coordinate transformation, and the two distances can be represented as:

[0113]

[0114] wherein,

[0115] represents the horizontal distance of the current position of the fire extinguishing machine from the Gaussian

[0116] elongated body, L gaus1 represents the longitudinal length of the Gaussian elongated body, H gaus1 represents the mountain height of the Gaussian elongated body corresponding to the obstacle, the fire extinguishing machine

[0117] when

[0118] the height corresponds to the square of the standard deviation of the horizontal coordinate of the cross section,

[0119]

[0120] For the Gaussian spin body, the horizontal distance is calculated by calculating the horizontal distance of the point after coordinate transformation to the bottom center point of the Gaussian spin body. The vertical distance is the z-axis coordinate after coordinate transformation, i.e. the vertical distance from the surface of the Gaussian elongated body,

[0121]

[0122] ​

[0123] in, This indicates the horizontal distance between the current position of the fire extinguisher and the Gaussian spin. Let x be the x-coordinate of the center point of the bottom of the Gaussian spin body. Let y be the y-coordinate of the center point of the bottom of the Gaussian spin body. Represents the z-axis coordinate;

[0124] For a triangular prism, the method for calculating the horizontal distance is similar to that for a Gaussian extension. The horizontal distance is calculated to determine if the point lies on the longitudinal lateral surface of the prism, i.e., if the y-axis coordinate is in [0, L]. gaus1 If the point is inside the prism, then the calculation point is located at the center of the bottom of the nearest side section of the prism. The horizontal projection distance is calculated as follows: If the distance is within the height of the triangular prism, for the portion not exceeding the height of the prism, the distance is the distance from the calculation point to the line connecting the center of the bottom of the two side sections of the triangular prism. If the distance is within the height of the triangular prism, it is the difference between the above distance and the absolute value of the section coordinate corresponding to that height, i.e., the horizontal distance dis(tri,x,y) from the point to the surface of the triangular prism. When calculating the vertical distance, since high-voltage line obstacles are relatively long, the fire extinguisher avoids them by raising its height to pass through the high-voltage line area. However, these obstacles are still established from the ground surface, so the vertical distance is also the z-axis coordinate after the above coordinate transformation. The two distances can be expressed as:

[0125]

[0126]

[0127] in, Indicates vertical distance. The z-axis coordinate represents the vertical distance between the current position of the fire extinguisher and the triangular prism. Let x be the x-axis coordinate of the center of the bottom of the nearest side section of the triangular prism. Let L be the y-axis coordinate of the center of the bottom of the nearest side section of the triangular prism. tri D is the length of the longitudinal section of the triangular prism. tri The diameter H of the circumcircle of the base of the triangular prism tri The height of the triangular prism;

[0128] For an ellipsoid, calculate the intersection of the line connecting the transformed point to the center of the ellipsoid and the surface of the ellipsoid. The horizontal projection of the distance between the intersection point and the given point is taken as the horizontal distance, and the vertical distance is taken as the vertical distance.

[0129]

[0130]

[0131] The boundary of the change of the cost function weight and the safety function weight is determined according to the horizontal distance, and the safety distance is 800 meters, if the threat of all obstacles is greater than 800 meters, the cost function weight and the safety function weight are equal, if there is an obstacle within 800 meters, the safety function weight is gradually improved, and the change of the cost function weight and the safety function weight is represented as:

[0132]

[0133]

[0134] Wherein, dis min is the minimum value of the horizontal distance in the above four three-dimensional bodies.

[0135] The horizontal threat function and the vertical threat function are calculated by the horizontal threat coefficient and the vertical threat coefficient respectively, and the horizontal threat coefficient and the vertical threat coefficient are calculated according to the horizontal distance and the vertical distance respectively.

[0136] The scale of the vertical distance under different three-dimensional obstacle bodies is similar, and there is no boundary mutation, and the vertical threat function can be represented as:

[0137]

[0138] Wherein, num_gaus1, num_gaus2, num_tri, num_sphe respectively correspond to the number of Gaussian elongated bodies, Gaussian spin bodies, three-prism bodies and ellipsoid bodies.

[0139] The simulation verification module is based on the environment model and the motion model, and is used for simulating the approach path of the fixed-wing fire extinguishing machine for different types of obstacles and fixed-wing fire extinguishing machines, testing whether the A* algorithm has corresponding path rapid planning ability, and visually displaying the motion characteristics, optimized path and water throwing parameters of the fixed-wing fire extinguishing machine.

[0140] The approach path is the path of the fixed-wing fire extinguishing machine from the entry point to the water throwing fire extinguishing point;

[0141] The entry point is a place where the fire extinguishing machine changes from the cruising path to perform the water throwing fire extinguishing task;

[0142] The water throwing fire extinguishing point is a task place where the fire extinguishing machine performs water throwing fire extinguishing.

[0143] Based on the same concept, the application also provides a fixed-wing fire extinguishing machine approach path planning for forest fire extinguishing tasks, comprising:

[0144] Figure 4 It is the simulation system interface schematic diagram provided by the application.

[0145] Figure 5It is a flow chart of a fixed-wing fire-fighting machine approach path planning method for a forest fire-fighting task provided by the application.

[0146] S1, for the fixed-wing fire-fighting machine fire-fighting task model analysis, determine the aircraft entry point speed, hovering height, water throwing strategy and aviation emergency force database, and write according to the aviation emergency force database format supported by the simulation software;

[0147] S2, based on the aviation emergency force database format writing, through the improved new node selection rule, the new node position is approximated, and the new node position is divided into the corresponding grid, so as to meet the position change of the fixed-wing fire-fighting machine under the set amplitude action and meet the three-dimensional grid scale of the operation precision requirement;

[0148] Among them, the set amplitude, for example, the amplitude generated corresponding to the flight time of about 1 second.

[0149] S3, based on the three-dimensional grid scale meeting the position change of the fixed-wing fire-fighting machine under the set amplitude action and meeting the operation precision requirement, the grid scale range planning is carried out, the boundary limit is updated, and the dynamic optimization step meeting the requirements between operation speed and safety is set;

[0150] S4, based on the dynamic optimization step, the optimization speed of A* algorithm in each boundary limit update, find the nearest set number of nodes in the target point in the exploration set to compare the performance function, select the optimal point of the performance function, and complete the approach path planning in a short time.

[0151] Figure 6 It is an improved A* algorithm optimization running time schematic diagram provided by the application.

[0152] The improved A* algorithm optimization running speed is accelerated, and the accelerated optimization running time is as shown in Figure 6 .

[0153] The expression of the dynamic optimization step is as follows:

[0154]

[0155] Among them, dis min Indicates the minimum distance of the aircraft from the obstacle.

[0156] The fixed-wing fire-fighting machine adopted by the application has strong maneuverability, can quickly rush to the task area, and has less restrictions on terrain and objects, and can efficiently and quickly enter the fire-fighting state;

[0157] By adopting the method of the application, the fixed-wing fire-fighting machine forest fire-fighting approach path planning can be quickly completed, so that the fire-fighting action can be quickly carried out at the initial stage of the fire, the fire can be better controlled, and the loss can be reduced;

[0158] All the optional technical solutions can be combined to form optional embodiments of the present application, and will not be described one by one here.

[0159] It should be understood that the size of the serial number of each step in the above embodiments does not mean the order of execution, and the execution order of each process should be determined according to its function and inherent logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0160] The above embodiments are only used to illustrate the technical solutions of the present application, but not to limit it; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can still be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application.

Claims

1. A fixed-wing fire-fighting aircraft forest fire-fighting approach path planning system, characterized by, The environment model setting module, the motion model improving module, the optimization index improving module and the simulation verification module are included. The environment model setting module includes a terrain obstacle model and a flight restricted area obstacle model, and is used for setting the environmental conditions of the forest fire. The motion model improving module is used for describing and calculating the motion characteristics of the fixed-wing fire extinguishing machine based on an aviation emergency force database. The optimization index improving module includes a cost index and a safety index, and is used for three-dimensional path optimization in the aspects of cost and safety, so as to obtain an optimized path. The simulation verification module simulates different types of obstacles and the approach path of the fixed-wing fire extinguishing machine based on the environment model and the motion model, tests whether the A* algorithm has corresponding path rapid planning capability, and visually displays the motion characteristics of the fixed-wing fire extinguishing machine, the optimized path and the water dropping parameters. The motion model improvement module calculates the motion models of the fixed-wing fire extinguishing machine turning, ascending and descending based on the traditional A* algorithm, the spatial grid discretization method and the improved new node selection rule considering the direction of the fixed-wing fire extinguishing machine, determines the boundary points of the acceleration, deceleration, left turn, right turn, ascending and descending at the set time step The boundary points of the acceleration, deceleration, left turn, right turn, ascending and descending are considered, and the combinations of different motions are considered to reflect the nonlinear motion and changing motion under real driving. The optimization index improving module is based on the improved A* algorithm, and performs three-dimensional path optimization including cost and safety through a path optimization efficiency function, wherein the path optimization efficiency function is expressed as: wherein, is a cost function, is a safety function, is a cost function weight, is a safety function weight, represents the actual path length traveled by the fire extinguishing machine from the initial position to the current position, represents the estimated path length of the fire extinguishing machine from the current position to the target position, is a path weight from the start point to the current node, is a path weight from the current node to the target point, is a horizontal threat function weight, is a vertical function threat weight, is a vertical threat function value, is a horizontal threat function value.

2. The fixed-wing firetrucks forest fire-extinguishing approach path planning system according to claim 1, characterized in that, The terrain obstacle model includes a mountain terrain model and a single mountain peak model, and is used for establishing terrain obstacles in a three-dimensional space to realize mountain collision detection and avoid collision of the fixed-wing fire extinguishing machine in the path planning process. The mountain terrain model includes a mountain model three-dimensional body which is simplified on a transverse section, and is subjected to translation transformation and rotation transformation by using a Gaussian height distribution. The single mountain peak model includes a mountain peak model three-dimensional body which is simplified as a two-dimensional Gaussian distribution and has a certain height in the middle.

3. The fixed-wing firetrucks forest fire-extinguishing approach path planning system according to claim 1, characterized in that, The flight restricted area obstacle model includes a high-voltage line restricted area model and a meteorological cloud cluster restricted area model, and is used for simulating areas which have a great influence on the safe flight of the fixed-wing fire extinguishing machine due to human or natural factors. The high-voltage line restricted area model includes a polyline high-voltage line no-fly area model three-dimensional body. The meteorological cloud cluster restricted area model includes a mountainous cloud cluster model three-dimensional body formed by the comprehensive action of air pressure, temperature, airflow and terrain.

4. The fixed-wing firetrucks forest fire extinguishing approach path planning system according to claim 1, characterized in that, The aviation emergency force database includes aircraft information, aircraft task execution link information and water dropping parameter information, and is used for providing data support for algorithm verification. The aircraft information includes the model, cruising speed, cruising altitude, effective water carrying capacity, oil carrying capacity, oil consumption and turning radius of the fixed-wing fire extinguishing machine performing the fire extinguishing task. The aircraft task execution link information includes the oil consumption and time information required by the aircraft in each link of the task execution. The water dropping parameter information includes the water tank capacity corresponding to different models and the equivalent radius of the aircraft water dropping.

5. The fixed-wing firetrucks forest fire extinguishing approach path planning system according to claim 1, characterized in that, The approach path is the path of the fixed-wing fire extinguishing machine from the entry point to the water dropping fire extinguishing point. The entry point is the place where the fire extinguishing machine changes from the cruising path to perform the water dropping fire extinguishing task. The water dropping fire extinguishing point is the task place where the fire extinguishing machine performs water dropping fire extinguishing.

6. The method of claim 1-5, wherein the method is a method of fixed-wing aircraft forest fire attack approach path planning for a fixed-wing aircraft forest fire attack approach path planning system according to any one of claims 1-5, characterized in that, The method includes the following steps: S1, analyzing the fire extinguishing task model of the fixed-wing fire extinguishing machine, determining the aircraft entry point speed, hovering height, water dropping strategy and aviation emergency force database, and writing in accordance with the aviation emergency force database format supported by the simulation software; S2, based on the aerial emergency force database format writing, through improved new node selection rules, the new node position is approximated, and the new node position is divided into the corresponding grid to meet the position change under the action of the fixed-wing fire extinguishing machine set amplitude and the three-dimensional grid scale meeting the operation precision requirement; S3, based on the three-dimensional grid scale meeting the position change under the action of the fixed-wing fire extinguishing machine set amplitude and meeting the operation precision requirement, grid scale range planning is carried out, the boundary limit is updated, and a dynamic optimization step length meeting the requirements between operation speed and safety is set; S4, based on the dynamic optimization step length, in each update of the boundary limit, the A* algorithm optimization speed, the nearest set number of nodes to the target point in the exploration set is found to compare the performance function, the optimal point of the performance function is selected, and the approach path planning in a short time is completed.

7. The fixed-wing firetrucks forest fire-extinguishing approach path planning method according to claim 6, characterized in that, The expression of the dynamic optimization step length is as follows: t step represents a dynamic optimization step, dis min represents the minimum distance of the aircraft from the obstacle.

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