CN105740510A - Simulation system and method of evacuation crowd behavior based on grid-density-relation - Google Patents

Abstract

The invention discloses an evacuation crowd behavior simulation system and method based on grid-density-relationship, the system includes an evacuation scene model building unit, which is used to extract the features of the evacuation scene according to the structural information of the evacuation scene, and obtain the evacuation The three-dimensional model of the scene; the global path planning unit of the evacuation scene, which is used to plan the global path of the evacuation scene according to the three-dimensional model of the evacuation scene, and calculates the global path of all entrances and exits in the evacuation scene; the crowd activity generation unit, which is used for according to the evacuation scene The number of all entrances and exits in the crowd, the relationship between individuals in the crowd, and the individual location information are used to group the crowd; the crowd simulation unit is used to calculate the real-time speed of the individual during the simulation process according to the social force model, and correct the same group in real time during the simulation process. The movement speed of each individual in the group is controlled to maintain the consistency of each group's progress and realize the behavior simulation of the evacuated crowd.

Description

Evacuation Crowd Behavior Simulation System and Method Based on Grid-Density-Relationship

technical field

The invention relates to the field of evacuation simulation, in particular to an evacuation crowd behavior simulation system and method based on grid-density-relationship.

Background technique

Large-scale gathering of people is an important feature of modern cities and even modern society. There are great potential safety hazards hidden in densely populated places, and emergencies are prone to occur. Once the panic of the crowd is caused, crowding and trampling accidents occur, and the casualties are often very heavy. Especially with the accelerated development of my country's urbanization process, large-scale activities with high gatherings of people have increased, and crowding and trampling accidents are more likely to occur.

Crowd evacuation under emergencies is a complex system engineering. In practical applications, evacuation experiments are usually used to obtain suitable evacuation plans. This method has the characteristics of strong pertinence and rich information. However, due to unavoidable problems such as the inability to guarantee the safety of personnel and the large investment in experiments, computer simulation has become the most effective method for studying crowd evacuation under emergencies.

The use of computers to simulate crowd evacuation needs to take into account many factors that affect group movement. According to social psychology, groups can be divided into small groups with different characteristics. In a small group, individuals have certain common characteristics to form a group. For example, the most common groups include family relationship groups, classmates and friends groups, colleagues groups, and the like. These groups are linked by one or more social relationships.

Observable facts show that in the evacuation of crowds in critical situations, the behavior of the same group of people will always remain consistent. They negotiate the direction of movement with each other and may leave the group together at some point. Therefore, each individual in the same group will try to adjust their own movement speed to maintain consistency with the entire group.

None of the existing crowd evacuation simulation methods consider the relationship between crowds and the influence of the formed groups on movement. Although, Helbing and Molnar proposed that the social force model simulates crowd behavior based on the formula of Newtonian mechanics, which can well reproduce some phenomena, such as "the faster you think, the slower you get" and the arch phenomenon at the exit. But it oversimplifies the behavior of pedestrians, without considering the relationship between crowds and the impact of formed groups on motion.

According to the characteristics of crowd behavior, Dirk Helbing established a social force model based on Newtonian mechanics. Social force refers to the force exerted on a person by the environment (including people and objects in the environment) when he is exercising, not the force of the physical concept that directly acts on him. In the social force model, according to the different motivations of pedestrians and the influence they receive in the environment, there are three kinds of forces: driving force, force between people and force between people and obstacles. The resultant of these forces acts on the pedestrian, producing an acceleration. There is always a certain force acting on the whole individual walking process and between individuals. For example, the driving force will guide the individual to move towards the target direction; the force between people prevents individuals in the crowd from colliding with each other before physical contact; the force between people and the environment prevents individuals in the crowd from colliding with each other. Obstacle collision. This stage can be explained by the classical Newton's second law.

Therefore, in order to solve the problems of crowd safety and personnel evacuation and carry out crowd evacuation safety drills, a crowd behavior simulation system and its method that consider the impact of groups on sports are needed to achieve building evacuation performance based on detection, maintenance of group behavior order, and optimization The evacuation process and the purpose of improving evacuation efficiency.

Contents of the invention

The invention provides a grid-density-relationship-based evacuation crowd behavior simulation system and method thereof. The present invention considers the characteristics of the crowd relationship, and groups the crowd by the weighted relationship value and the weighted density value to simulate the natural grouping of the crowd evacuation and the arch phenomenon at the exit of the crowd, and is used to guide the safety of the crowd evacuation drill.

To achieve the above object, the present invention adopts the following technical solutions:

A grid-density-relationship-based evacuation crowd behavior simulation system, including:

An evacuation scene model building unit, which is used to extract the features of the evacuation scene according to the structural information of the evacuation scene, and obtain a three-dimensional model of the evacuation scene;

An evacuation scene global path planning unit, which is used to plan the global path of the evacuation scene according to the three-dimensional model of the evacuation scene, and calculate the global path of all entrances and exits in the evacuation scene;

A crowd activity generation unit, which is used to group the crowd according to the number of all entrances and exits in the evacuation scene, the relationship between individuals in the crowd, and the location information of the individual;

The crowd simulation unit is used to calculate the real-time speed of the individual during the simulation process according to the social force model, and correct the movement speed of each individual in the same group in real time during the simulation process to maintain the consistency of each group's progress, Realize the behavior simulation of the evacuated crowd.

The crowd activity generation unit includes:

A crowd individual location information generation module, which is used to establish a mapping relationship between the crowd data set and the crowd activity area in the three-dimensional model of the evacuation scene, and generate the position of the crowd individual in the crowd activity area according to the mapping relationship;

The evacuation scene grid division module determines the number of crowd groups according to the number of all entrances and exits in the evacuation scene, and divides the crowd activity area in the 3D model of the evacuation scene;

Grid relationship-density value calculation module, which is used to calculate the grid density value and grid relationship value of each grid unit according to the number of individuals in each grid unit and the relationship value between individuals, and calculate the grid Weighted superposition of density value and grid relationship value to obtain the grid relationship-density value of each grid unit;

Crowd grouping module, which is used to use the grid with the largest grid relationship-density value as the core grid to construct the group center, and assign the individual grid to the group where each core grid is located according to the physical distance between the individual and the group center , complete the grouping of the crowd.

A simulation method for an evacuated crowd behavior simulation system based on grid-density-relationship, comprising:

Step (1): According to the structural information of the evacuation scene, the features of the evacuation scene are extracted to obtain a three-dimensional model of the evacuation scene;

Step (2): Carry out global path planning for the evacuation scene according to the three-dimensional model of the evacuation scene, and calculate the global paths of all entrances and exits in the evacuation scene;

Step (3): Determine the crowd grouping information according to the relationship between individuals in the crowd, the density of the crowd in the evacuation scene, and the location information of the individual;

Step (4): According to the social force model, calculate the real-time speed of the individual during the simulation process, and correct the movement speed of each individual in the same group in real time during the simulation process, so as to maintain the consistency of the entire group and realize the evacuation of the crowd behavior simulation.

The process of determining crowd grouping information in the step (3) includes:

Step (3.1): Establish the mapping relationship between the crowd data set and the crowd activity area in the 3D model of the evacuation scene, and generate the position of the crowd individual in the crowd activity area according to the mapping relationship;

Step (3.2): Determine the number of crowd groups according to the number of all entrances and exits in the evacuation scene, and divide the crowd activity area in the three-dimensional model of the evacuation scene;

Step (3.3): Calculate the grid density value and grid relationship value of each grid unit according to the number of individuals in each grid unit and the relationship value between individuals, and calculate the grid density value and grid relationship value Perform weighted superposition to obtain the grid relationship-density value of each grid unit;

Step (3.4): The grid with the highest grid relationship-density value is used as the core grid to construct the group center, and according to the physical distance between the individual and the group center, the grid where the individual is located is assigned to the group where each core grid is located, Complete the grouping of the crowd.

In the step (3.4), the process of assigning the individual grid to the group where each core grid is located includes:

Step (3.4.1): According to the size of the grid relationship-density value of each grid unit, sort the grid units from large to small to form a queue to be grouped;

Step (3.4.2): Select the first grid in the queue to be grouped as the core grid, from the second grid to the last grid in the queue to be grouped, and judge whether it is an adjacent grid of the core grid , if so, merge the grid into the core grid, and delete the grid in the queue to be grouped; move the merged core grid from the queue to be grouped to the grouped queue, and mark the group number;

Step (3.4.3): Repeat step (3.4.2) until the number of grids in the queue to be grouped is 0, and the grouping ends; otherwise, go to the next step;

Step (3.4.4): The number of grids in the queue to be grouped is non-zero, and the number of grids in the queue to be grouped is equal to the determined number of groups, then according to each individual in the grid of the queue to be grouped and the grouped queue The physical distance of the center of the group, assign the corresponding grids to the group where each core grid is located, until the number of grids in the queue to be grouped is 0.

In the step (3.3), the weights for weighting the grid density value and the grid relationship value are 0.5 and 0.5 respectively.

The density values of the grids in the queue to be grouped in the step (3.4.1) are all non-zero values.

In the step (3.4), the number of groups is equal to 3 times the number of exits in the plane area to be evacuated.

In the step (3.4), the number of unit grids for dividing the crowd activity area in the three-dimensional model of the evacuation scene is equal to 10 times the number of groups.

In the step (3.3), the grid relationship value of each grid unit is equal to the sum of the relationship values between all individuals in the grid unit divided by 2.

The beneficial effects of the present invention are:

(1) The grid-density-relationship-based evacuation crowd behavior simulation system of the present invention takes into account the relationship between crowds and the impact of the formed groups on movement, and groups the crowds by weighted relationship values and weighted density values To simulate the natural grouping of crowd evacuation and the arch phenomenon at the crowd exit, it provides an important basis for crowd evacuation safety drills, and can also detect building evacuation performance, optimize the actual evacuation process and improve evacuation efficiency;

(2) The crowd evacuation simulation method of the present invention is applicable to areas such as flat rooms with doors and large flat venues, and the influence of obstacles is not considered for the time being, and can be extended to flat areas such as squares with multiple exits.

Description of drawings

Fig. 1 is the structural representation of the evacuated crowd behavior simulation system based on grid-density-relationship of the present invention;

Fig. 2 is the schematic flow sheet of the evacuated crowd behavior simulation method based on grid-density-relationship of the present invention;

Fig. 3 is a diagram of the crowd activity area of the evacuation scene of four doors in the embodiment of the present invention;

Fig. 4 is that the crowd activity area of the evacuation scene in the embodiment of the present invention is divided into 120 grids;

Fig. 5 is a schematic diagram of grid density in an embodiment of the present invention;

Fig. 6 is a schematic diagram of grid relationship values in an embodiment of the present invention;

Fig. 7 is a schematic diagram of all adjacent grids of the core grid in the embodiment of the present invention;

Fig. 8 is a schematic diagram of a surface adjoining mesh of a core mesh in an embodiment of the present invention;

Fig. 9 is a schematic diagram of a point-adjacency grid of a core grid in an embodiment of the present invention;

Fig. 10 is a schematic diagram of the crowd after initialization in the embodiment of the present invention;

Fig. 11 is a schematic diagram of the crowd grouping process in the crowd evacuation simulation in the embodiment of the present invention;

Fig. 12 is a state diagram of moving towards the exit after grouping and approaching the exit in the embodiment of the present invention.

detailed description

Below in conjunction with accompanying drawing and embodiment the present invention will be further described:

In the evacuated crowd behavior simulation system based on grid-density-relationship of the present invention:

(1) Crowd data set P={p _i ,i=1,2,...,N}, p _i =(p _i1 ,p _i2 ,...,p _im ) means the i-th individual in the data set, p _ij means the i-th individual The jth attribute of the i individual.

(2) The relationship between individuals in the crowd:

For two individuals p _l and p _m , the relationship value represents the degree of closeness between the two individuals, ranging from 0 to 1, represented by rel(p _i , p _m ).

If the two individuals have no relationship, the relationship value is 0, and if it is a mother-child or lover relationship, the relationship value tends to 1. In order to reflect the emergency evacuation, find a tour guide or the leader of a group, and establish a relationship between everyone in the tour team and the tour guide, and the relationship is 1. In the same way, each collective individual and the team leader are also established. relationship, and the relationship value is 1. The value range of the relationship between individuals in the population dataset to be evacuated is:

(3) The mapping relationship between the crowd individual and the crowd activity area in the evacuation scene:

The crowd activity area in the evacuation scene of the present invention is defined as S=L×W, which is a rectangular plane area whose length is L and width is W, and each point above can use coordinates (x, y) formed by two numbers To represent.

Among them, the mapping of P→S is M: the mapping M={p _i (x, y)} of the data set P of the population to be evacuated to the plane area;

p _i is the i-th individual in the data set of people to be evacuated, 1≤i≤N, (x, y) is the coordinate on a two-dimensional plane, 1≤x≤W, 1≤y≤L, p _i (x, y) indicates that the position of the i-th individual on the plane area is (x, y).

(4) Determination of the number of groups of people and the number of grid units:

According to the number of exits E in the crowd activity area of the evacuation scene, determine the number of groups T and the number of grid units G to be divided: as shown in Figure 3, there are 4 exits in the plane area of the evacuation scene, and the number of groups T=E×3, mainly It is considered to correspond to an exit, and there can be groups in three directions of left, center and right to evacuate to the exit.

Grid number G=T×10, this value is obtained through experience, and can also be adjusted dynamically.

Among them, the process of grid division is:

Divide the planar area S evenly into h×k rectangular grids (divided into squares as much as possible), h×k=G.

The division method is:

S is a rectangular plane area with length L and width W, which is divided into G grid units, then the area of each grid unit is a=(L×W)/G, and the side length is h=L/e, k=W/e.

As shown in Figure 4, for example, a rectangular plane area with a length of 300 and a width of 250 is divided into 120 grids, the area of each grid is a=(300×250)/120, a=625, and the side length e=25, the area is divided into h=300/25 in the horizontal direction, h=12, and k=10 in the vertical direction.

(5) Grid unit:

Without loss of generality, let the coordinates of the lower left corner of the plane area be (0,0), and each rectangular grid c _{i, j} is represented by the coordinates of the lower left corner and upper right corner as x _i =x _i-1 +e, y _j =y _j-1 +e, 1≤i≤h, 1≤j≤k, then each rectangular grid is a grid unit.

(6) Grid density:

The grid density is the total number of individuals in the grid cell.

For a given grid cell c _i,j , 1≤i≤h, 1≤j≤k, count how many individuals fall in the grid cell. The individual p _i (x, y) falls in the grid c _{i, j} , and the coordinate range of x, y is in It is judged within the interval, that is, x _i-1 <x≤x _i , y _i-1 <y≤y _i .

As shown in Figure 5, grid density den(c _i,j )=count(p _i (x,y)), x _i-1 <x≤x _i , y _i-1 <y≤y _i , count is count function.

(7) Relationship value of the grid:

Grid relationship value: For a given grid cell c _i,j , 1≤i≤h, the sum of the relationship values between individuals in grid cell c _i,j is divided by 2.

As shown in Figure 6, the grid relation value $rel\left(c_{i,j}\right)=\underset{(x_2,{\mathrm{the\; y}}_2)\&Element;c_{i,j}}{\underset{(x_1,{\mathrm{the\; y}}_1)\&Element;c_{i,j}}{\&Sigma;}}rel\left(p_l\right(x_1,{\mathrm{the\; y}}_1),p_m(x_2,{\mathrm{the\; y}}_2\left)\right)/2,$ x _i-1 < x ₁ ≤ x _i , y _i-1 < y ₁ ≤ y _i , _xi-1 < x ₂ ≤ x _i , y _i-1 < y ₂ ≤ y _i .

The sum of the relationship values between individuals in the grid cell c _i,j is divided by 2, because if p _l (x ₁ ,y ₁ ) has a relationship with p _m (x ₂ ,y ₂ ), then p _m (x ₂ ,y ₂ ) is also related to p _l (x ₁ ,y ₁ ), and it is a symmetrical relationship. Therefore, when summing, the relationship between p _l (x ₁ ,y ₁ ) and p _m (x ₂ ,y ₂ ) The relationship is calculated twice.

(8) Grid relationship - density value:

The grid relationship-density value is the sum of the weighted relationship value and the weighted density value,

That is, RelDen(ci _,j )=w ₁ ×rel(ci _,j )+w ₂ ×den(ci _,j ).

Among them, w ₁ and w ₂ are the weights of relationship and density respectively, which are generally 0.5 and 0.5. If the requirement for grouping speed is relatively high, the weight of w ₂ is increased, and the weight of w ₁ is decreased.

According to the speed requirement of crowd grouping in the crowd evacuation simulation model, the weighted weight of the grid relationship value is greater than 0.5, and the weighted weight of the grid density value is less than 0.5.

(9) Relationship distance value:

The relationship distance between two individuals p _l (x ₁ ,y ₁ ), p _m (x ₂ ,y ₂ ) is the sum of the weighted relationship value and the weighted physical distance value, namely:

RelDist(p _l (x ₁ ,y ₁ ),p _m (x ₂ ,y ₂ ))＝w ₁ ×rel(p _l (x ₁ ,y ₁ ),p _m (x ₂ ,y ₂ ))+w ₂ ×dist(p _l (x ₁ ,y ₁ ),p _m (x ₂ ,y ₂ )) where: $di\mathrm{the\; s}t\left(p_l\right(x_1,{\mathrm{the\; y}}_1),p_m(x_2,{\mathrm{the\; y}}_2\left)\right)=\sqrt{{(x_2-x_1)}^2+{({\mathrm{the\; y}}_2-{\mathrm{the\; y}}_1)}^2}.$

As shown in Figure 1, the evacuated crowd behavior simulation system based on grid-density-relationship of the present invention includes:

An evacuation scene model building unit, which is used to extract the features of the evacuation scene according to the structural information of the evacuation scene, and obtain a three-dimensional model of the evacuation scene;

An evacuation scene global path planning unit, which is used to plan the global path of the evacuation scene according to the three-dimensional model of the evacuation scene, and calculate the global path of all entrances and exits in the evacuation scene;

A crowd activity generation unit, which is used to group the crowd according to the number of all entrances and exits in the evacuation scene, the relationship between individuals in the crowd, and the location information of the individual;

The crowd simulation unit is used to calculate the real-time speed of the individual during the simulation process according to the social force model, and correct the movement speed of each individual in the same group in real time during the simulation process to maintain the consistency of each group's progress, Realize the behavior simulation of the evacuated crowd.

Further, the crowd activity generation unit includes:

A crowd individual location information generation module, which is used to establish a mapping relationship between the crowd data set and the crowd activity area in the three-dimensional model of the evacuation scene, and generate the position of the crowd individual in the crowd activity area according to the mapping relationship;

The evacuation scene grid division module determines the number of crowd groups according to the number of all entrances and exits in the evacuation scene, and divides the crowd activity area in the 3D model of the evacuation scene;

Grid relationship-density value calculation module, which is used to calculate the grid density value and grid relationship value of each grid unit according to the number of individuals in each grid unit and the relationship value between individuals, and calculate the grid Weighted superposition of density value and grid relationship value to obtain the grid relationship-density value of each grid unit;

Crowd grouping module, which is used to use the grid with the largest grid relationship-density value as the core grid to construct the group center, and assign the individual grid to the group where each core grid is located according to the physical distance between the individual and the group center , to complete the grouping of the crowd.

As shown in Figure 2, the simulation method of the evacuated crowd behavior simulation system based on the grid-density-relationship of the present invention includes:

Step (1): According to the structural information of the evacuation scene, the features of the evacuation scene are extracted to obtain a three-dimensional model of the evacuation scene;

Step (2): Carry out global path planning for the evacuation scene according to the three-dimensional model of the evacuation scene, and calculate the global paths of all entrances and exits in the evacuation scene;

Step (3): Determine the crowd grouping information according to the relationship between individuals in the crowd, the density of the crowd in the evacuation scene, and the location information of the individual;

Step (4): Calculate the real-time speed of the individual during the simulation process according to the social force model, and correct the movement speed of each individual in the same group in real time during the simulation process, so as to maintain the consistency of the entire group and realize the evacuation of the crowd behavior simulation.

Further, the process of determining crowd grouping information in step (3) includes:

Step (3.1): Establish the mapping relationship between the crowd data set and the crowd activity area in the 3D model of the evacuation scene, and generate the position of the crowd individual in the crowd activity area according to the mapping relationship;

Step (3.2): Determine the number of crowd groups according to the number of all entrances and exits in the evacuation scene, and divide the crowd activity area in the three-dimensional model of the evacuation scene;

Step (3.3): Calculate the grid density value and grid relationship value of each grid unit according to the number of individuals in each grid unit and the relationship value between individuals, and calculate the grid density value and grid relationship value Perform weighted superposition to obtain the grid relationship-density value of each grid unit;

Step (3.4): Use the grid with the largest grid relationship-density value as the core grid to construct the group center, and assign the individual grid to the group where each core grid is located according to the physical distance between the individual and the group center. Complete the grouping of the crowd.

The grid whose relationship-density value is higher than all adjacent grids is called the core grid, denoted by core( _ci,j ). Among them, adjacency grids are divided into comprehensive adjacency grids, surface adjacency grids and point adjacency grids, as shown in Fig. 7, Fig. 8 and Fig. 9 respectively.

Each element wq _i in the WaitQueue to be grouped is a non-empty grid unit, that is, den(wq _i )≠0.

The element fq _i in the grouped queue FinishQueue is a grid unit whose group has been determined.

In step (3.4), the process of assigning the individual grid to the group where each core grid is located includes:

The first step: Sorting: According to the weighted grid relationship-density value, the grids are sorted from high to low to form a queue WaitQueue, and there are u elements in the column. A grid with a density value of zero, that is, there are no individuals in the grid, will not enter the queue.

Step 2: core grid core(ci _,j ) selection and merging: select the first grid in the WaitQueue to be grouped as the core grid, start from the second grid, and proceed to the u-1th grid compare with the core grid one by one, if a certain grid is the adjacent grid of the core grid, then merge the grid into the core grid, u=u-1; after the cycle, merge the core grid The grid is moved from the waiting queue WaitQueue to the grouping queue FinishQueue, and the group number is marked, u=u-1;

Step 3: Repeat step 2 until the number of grids in WaitQueue to be grouped is 0 or the number of grids in FinishQueue in grouped queue is T;

Step 4: If the number of WaitQueue grids in the queue to be grouped is 0, the grids in the finished queue FinishQueue are the grouping of individuals, and turn to step 5; otherwise, if the number of grids in the FinishQueue is T, and the WaitQueue If the number of grids in the middle is not 0, the grids are taken out one by one from the WaitQueue, and for each individual in the grid, the individual relationship-distance value with the center point of the core grid in the FinishQueue is calculated one by one, and merged with the center point Individual relationship - the core grid with the smallest distance value until the number of WaitQueue elements is 0.

Step 5: End the grouping process.

A simulation example is provided below:

Computer crowd evacuation simulation is carried out on a 300×250 plane area with 300 people, as shown in Figure 10-12. In Figure 10, the state after initialization, individuals with the same gray level indicate that there is a relationship between individuals. In Figure 11, it can be seen from the state that each group moves toward the exit after the crowd is grouped, individuals with the same gray level are classified into the same group. It can be seen from Figure 12 that in the process of moving towards the exit, the related individuals basically remain in the same group, and each individual in the same group will try to adjust its own movement speed to keep the same pace as the entire group. sex.

Although the specific implementation of the present invention has been described above in conjunction with the accompanying drawings, it does not limit the protection scope of the present invention. Those skilled in the art should understand that on the basis of the technical solution of the present invention, those skilled in the art do not need to pay creative work Various modifications or variations that can be made are still within the protection scope of the present invention.

Claims (10)

1. A grid-density-relationship-based evacuation crowd behavior simulation system, characterized in that it comprises: An evacuation scene model building unit, which is used to extract the features of the evacuation scene according to the structural information of the evacuation scene, and obtain a three-dimensional model of the evacuation scene; An evacuation scene global path planning unit, which is used to plan the global path of the evacuation scene according to the three-dimensional model of the evacuation scene, and calculate the global path of all entrances and exits in the evacuation scene; A crowd activity generation unit, which is used to group the crowd according to the number of all entrances and exits in the evacuation scene, the relationship between individuals in the crowd, and the location information of the individual; The crowd simulation unit is used to calculate the real-time speed of the individual during the simulation process according to the social force model, and correct the movement speed of each individual in the same group in real time during the simulation process to maintain the consistency of each group's progress, Realize the behavior simulation of the evacuated crowd. 2. A kind of evacuation crowd behavior simulation system based on grid-density-relationship as claimed in claim 1, is characterized in that, described crowd activity generation unit comprises: A crowd individual location information generation module, which is used to establish a mapping relationship between the crowd data set and the crowd activity area in the three-dimensional model of the evacuation scene, and generate the position of the crowd individual in the crowd activity area according to the mapping relationship; The evacuation scene grid division module determines the number of crowd groups according to the number of all entrances and exits in the evacuation scene, and divides the crowd activity area in the 3D model of the evacuation scene; Grid relationship-density value calculation module, which is used to calculate the grid density value and grid relationship value of each grid unit according to the number of individuals in each grid unit and the relationship value between individuals, and calculate the grid Weighted superposition of density value and grid relationship value to obtain the grid relationship-density value of each grid unit; Crowd grouping module, which is used to use the grid with the largest grid relationship-density value as the core grid to construct the group center, and assign the individual grid to the group where each core grid is located according to the physical distance between the individual and the group center , to complete the grouping of the crowd. 3. a simulation method based on the evacuation crowd behavior simulation system of grid-density-relationship as described in any one of claims 1-2, it is characterized in that, comprising: Step (1): According to the structural information of the evacuation scene, the features of the evacuation scene are extracted to obtain a three-dimensional model of the evacuation scene; Step (2): Carry out global path planning for the evacuation scene according to the three-dimensional model of the evacuation scene, and calculate the global paths of all entrances and exits in the evacuation scene; Step (3): Determine the crowd grouping information according to the relationship between individuals in the crowd, the density of the crowd in the evacuation scene, and the location information of the individual; Step (4): Calculate the real-time speed of the individual during the simulation process according to the social force model, and correct the movement speed of each individual in the same group in real time during the simulation process, so as to maintain the consistency of the entire group and realize the evacuation of the crowd behavior simulation. 4. the simulation method of the evacuated crowd behavior simulation system based on grid-density-relationship as claimed in claim 3, is characterized in that, the process of determining crowd grouping information in the described step (3) comprises: Step (3.1): Establish the mapping relationship between the crowd data set and the crowd activity area in the 3D model of the evacuation scene, and generate the position of the crowd individual in the crowd activity area according to the mapping relationship; Step (3.2): Determine the number of crowd groups according to the number of all entrances and exits in the evacuation scene, and divide the crowd activity area in the three-dimensional model of the evacuation scene; Step (3.3): Calculate the grid density value and grid relationship value of each grid unit according to the number of individuals in each grid unit and the relationship value between individuals, and calculate the grid density value and grid relationship value Perform weighted superposition to obtain the grid relationship-density value of each grid unit; Step (3.4): The grid with the highest grid relationship-density value is used as the core grid to construct the group center, and according to the physical distance between the individual and the group center, the grid where the individual is located is assigned to the group where each core grid is located, Complete the grouping of the crowd. 5. the simulation method of the evacuated crowd behavior simulation system based on grid-density-relationship as claimed in claim 4, it is characterized in that, in described step (3.4), the individual grid is assigned to each core grid where The processes in the group include: Step (3.4.1): According to the size of the grid relationship-density value of each grid unit, sort the grid units from large to small to form a queue to be grouped; Step (3.4.2): Select the first grid in the queue to be grouped as the core grid, from the second grid to the last grid in the queue to be grouped, and judge whether it is an adjacent grid of the core grid , if so, merge the grid into the core grid, and delete the grid in the queue to be grouped; move the merged core grid from the queue to be grouped to the grouped queue, and mark the group number; Step (3.4.3): Repeat step (3.4.2) until the number of grids in the queue to be grouped is 0, and the grouping ends; otherwise, go to the next step; Step (3.4.4): The number of grids in the queue to be grouped is non-zero, and the number of grids in the queue to be grouped is equal to the determined number of groups, then according to each individual in the grid of the queue to be grouped and the grouped queue The physical distance of the center of the group, assign the corresponding grids to the group where each core grid is located, until the number of grids in the queue to be grouped is 0. 6. the simulation method of the evacuated crowd behavior simulation system based on grid-density-relationship as claimed in claim 4, is characterized in that, in described step (3.3), weighting is carried out to grid density value and grid relationship value The weights are 0.5 and 0.5 respectively. 7. the simulation method of the evacuation crowd behavior simulation system based on grid-density-relationship as claimed in claim 5, is characterized in that, the density value of grid in the queue to be grouped in described step (3.4.1) averages is a non-zero value. 8. the simulation method of the evacuation crowd behavior simulation system based on grid-density-relationship as claimed in claim 4, is characterized in that, in described step (3.4), grouping number is equal to 3 of the exit number of plane area to be evacuated times. 9. the simulation method of the evacuation crowd behavior simulation system based on grid-density-relationship as claimed in claim 4, is characterized in that, in described step (3.4), in the three-dimensional model of evacuation scene, crowd activity area is divided The number of cell grids is equal to 10 times the number of groups. 10. the simulation method of the evacuation crowd behavior simulation system based on grid-density-relationship as claimed in claim 4, is characterized in that, in described step (3.3), the grid relation value of each grid unit is equal to this The sum of the relationship values between all individuals in the grid cell is divided by 2.