Data processing method and system based on vehicle and pedestrian lower limb collision analysis model

Abstract

The present application relates to the technical field of traffic safety, and discloses a data processing method and system based on a vehicle and pedestrian lower limb collision analysis model to realize rapid prediction of lower limb injury. The method comprises the following steps: constructing a vehicle and pedestrian lower limb collision analysis model, setting a collision point on a calf mass block when subjected to a collision force brought by a vehicle head, the calf mass block moving along a collision direction under impact load, and establishing a coordinate system with the calf mass point as a system coordinate origin; and in the movement process of the vehicle and pedestrian lower limb collision, the whole lower limb system moves as a projectile relative to the coordinate system and the thigh rotates around the calf, and when the thigh collides with the front edge of the vehicle engine cover, the thigh rotates to a limit position; obtaining an analytical equation of the pedestrian lower limb freedom degree model and an acceleration solving formula of the thigh mass point, and then solving the acceleration of the pedestrian thigh and calf in the collision process according to the vehicle and pedestrian lower limb collision analysis model to perform injury assessment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of traffic safety, and in particular to a data processing method and system based on a vehicle and pedestrian lower limb collision analysis model. BACKGROUND

[0002] In recent years, the popularization rate and the possession rate of civilian cars increase year by year, and the road traffic burden in China gradually increases. However, the phenomenon of mixed walking and driving has not improved, but become more and more serious, which also leads to a significant increase in the frequency of vehicle-pedestrian collision accidents. As the weak party in the collision accident, the pedestrian injury is mainly affected by the vehicle collision speed, the bumper ground height and the windshield inclination angle and other vehicle shape structure parameters. The injury influencing parameters are complex, and the pedestrian safety evaluation index involves kinematics and biomechanics.

[0003] Currently, the research on pedestrian injury often uses a simulation dummy with multiple sensors to collide with a vehicle to simulate the collision between the pedestrian and the vehicle in the real situation. The kinematic characteristics of the dummy are output through the sensor elements to analyze the injury situation and the injury influencing factors. Another common method is to use a finite element model or a multi-body dynamics model to perform simulation tests. The pedestrian and the vehicle are parameterized, and the collision simulation is performed in the related software. The kinematic characteristics of the pedestrian are output by the software to analyze the influence of the kinematic parameters on the pedestrian injury. However, the dummy collision test research method has high cost, limited research site and complex test. The computer simulation test research method has long modeling time and low biological simulation degree in the early stage. It cannot meet the current requirements of low cost, high efficiency and high precision for injury research. SUMMARY

[0004] The present application aims to disclose a data processing method and system based on a vehicle and pedestrian lower limb collision analysis model to realize rapid prediction of lower limb injury.

[0005] To achieve the above purpose, the data processing method based on a vehicle and pedestrian lower limb collision analysis model disclosed by the present application comprises:

[0006] Step S1, a vehicle and pedestrian lower limb collision analysis model is constructed. In the analysis model, when subjected to the collision force brought by the vehicle head, the collision point is set on the calf mass block. The calf mass block moves along the collision direction under the impact load and establishes a coordinate system with the calf mass point as the system coordinate origin. The direction in which the vehicle head hits the pedestrian lower limb is the X direction, and the vertical upward direction is the Y direction. In the movement process of the vehicle and pedestrian lower limb collision, the whole lower limb system moves as a projectile relative to the coordinate system and the thigh rotates around the calf. When the thigh collides with the front edge of the vehicle engine cover, the thigh rotates to the limit position. The analytical equation of the pedestrian lower limb freedom model is obtained as:

[0007]

[0008] wherein M is the mass of the lower leg of the pedestrian, m is the mass of the upper leg of the pedestrian, l is the distance between the lower leg mass point and the upper leg mass point, θ is the angle of rotation of the upper leg relative to the lower leg mass point after the lower leg is impacted, is the translational acceleration of the lower leg during the impact, is the angular acceleration of the lower leg about the impact point during the impact, F(t) is the impact force of the vehicle on the lower leg as a function of time, is the angular velocity of the lower leg about the impact point during the impact;

[0009] During the impact, the acceleration of the upper leg mass point is:

[0010]

[0011] wherein i is the iteration round according to the calculation time advancement during the impact, a m is the acceleration value of the upper leg of the pedestrian, V a is the absolute velocity of the upper leg mass point in the coordinate system motion; t is the time interval of the iteration;

[0012]

[0013] wherein V r is the relative velocity of the upper leg mass point relative to the lower leg mass point, V e is the dependent velocity of the lower leg mass point in the coordinate system motion;

[0014] V r = l w

[0015] V e = v

[0016] wherein w is the angular velocity of the upper leg about the impact point, v is the velocity of the lower leg;

[0017] Step S2, solving the acceleration of the upper leg and the lower leg of the pedestrian during the impact according to the vehicle and pedestrian lower limb impact analysis model to perform damage assessment.

[0018] Preferably, the impact force of the vehicle on the lower leg as a function of time F(t) is generated by the MADYMO impact simulation model, wherein M c is the weight of the vehicle mass block, a c is the acceleration value of the vehicle.

[0019] Preferably, the position of the impact point is determined according to the bottom height of the bumper, the ground clearance of the lower end, the ground clearance of the upper end, and the depth of the bumper.

[0020] Preferably, the analytical model is provided with a rotary hinge between the thigh mass block and the calf mass block, which contains the freedom degree and corresponding joint mechanical characteristics consistent with the human joint.

[0021] To achieve the above object, the application further discloses a data processing system based on a vehicle and pedestrian lower limb collision analytical model, comprising a memory, a processor, and a computer program stored in the memory and capable of running on the processor, wherein the processor implements the above method when executing the computer program.

[0022] The application has the following beneficial effects:

[0023] 1. The analytical model disclosed by the application reveals the interaction mechanism between the lower limbs and the vehicle in the collision process. Therefore, the kinematic response of the lower limbs can be calculated under the condition of lacking detailed structure of the vehicle head, only by using typical vehicle head parameters such as the engine cover inclination angle and the bumper height, so as to realize the rapid prediction of the lower limb injury. The model is fast in calculation and needs few parameters, which can help engineers to quickly optimize the main structure parameters of the vehicle head in the early stage of the safety design of the vehicle head.

[0024] 2. The analytical model disclosed by the application contains typical structure characteristic parameters of the front end of the vehicle head, and can consider the heterogeneity problem of the vehicle and the pedestrian leg in the solution of the lower limb injury, which can help rescue personnel to quickly estimate the dynamic response and make preliminary injury assessment according to the on-site vehicle and pedestrian conditions after the accident.

[0025] The application will be further described in detail below with reference to the accompanying drawings. DETAILED DESCRIPTION

[0026] The accompanying drawings, which form a part of the present application, are included to provide a further understanding of the application, and are incorporated herein for purposes of illustrating the illustrative embodiments of the present application and the explanations provided herein. In the drawings:

[0027] Figure 1 is a principle diagram of the data processing method based on the vehicle and pedestrian lower limb collision analytical model disclosed by the embodiment of the application.

[0028] Figure 2 is a model collision schematic diagram disclosed by the embodiment of the application.

[0029] Figure 3 is an analytical model diagram disclosed by the embodiment of the application.

[0030] Figure 4 is a lower limb mass point model diagram disclosed by the embodiment of the application.

[0031] Figure 5is a collision reference frame disclosed by the embodiment of the present application.

[0032] Figure 6 is a schematic diagram of a rotational position limit position in a collision process of the embodiment of the present application.

[0033] Figure 7 is a schematic diagram of a movement relationship of a large leg in relative movement of a lower limb disclosed by the embodiment of the present application.

[0034] Figure 8 is a movement relationship of relative velocity, dependent velocity and absolute velocity in thigh movement analysis disclosed by the embodiment of the present application.

[0035] Figure 9 is a comparison diagram of a MADYMO output curve and a MATLAB calculated output vehicle acceleration curve disclosed by the embodiment of the present application.

[0036] Figure 10 is a comparison diagram of a MADYMO output curve and a MATLAB calculated output calf acceleration curve disclosed by the embodiment of the present application.

[0037] Figure 11 is a comparison diagram of a MADYMO output curve and a MATLAB calculated output thigh acceleration curve disclosed by the embodiment of the present application. DETAILED DESCRIPTION

[0038] The embodiments of the present application are described in detail below with reference to the accompanying drawings, but the present application can be implemented in various different ways limited and covered by the claims.

[0039] Embodiment 1

[0040] Reference Figure 1 , the embodiment discloses a data processing method based on a vehicle and a pedestrian lower limb collision analysis model.

[0041] In the embodiment, the construction process of the collision analysis model is as follows:

[0042] 1) Accident investigation and analysis, screening accident cases:

[0043] Due to the continuous increase of the automobile popularization rate and the vehicle ratio in China, the road traffic burden is gradually increased, and the phenomenon of mixed walking and driving on the road is serious, resulting in the increasing frequency of vehicle-pedestrian collision accidents. And the accident types are various, different vehicle types and pedestrians collide, and two-wheeled vehicles collide, and are affected by the road traffic environment, which is one of the reasons for the diversity of traffic accidents in China.

[0044] In the face of complex and diverse traffic accident information, the application selects a representative typical case for modeling analysis. Through statistical analysis of the accident vehicle type, it can be known that the proportion of passenger cars involved in collision accidents is the most, so the ordinary civilian car is selected as the collision vehicle model. The selection of the crash dummy is the Hybrid III 50th percentile male dummy commonly used in automobile crash tests at home and abroad.

[0045] 2) Collision accident characteristic parameter extraction:

[0046] Vehicle-pedestrian collision is a complex high-dimensional and nonlinear dynamic system. The collision behavior and damage of the pedestrian are influenced by the pedestrian, the vehicle and the environment. Therefore, the key elements are extracted from the complex collision system for the basic parameters of the subsequent vehicle-pedestrian collision analysis model.

[0047] Based on the analysis of vehicle collision accidents, the proportion of ordinary passenger cars (sedans) involved in collision accidents is the most, so the civilian car is selected as the collision case vehicle type, and its characteristics are analyzed to obtain the structural characteristics of the vehicle head, such as the geometric shape of the vehicle head, the structure of the parts, etc. Through the analysis of pedestrian collision accidents, the lower limbs of normal male body position are selected for simulation analysis. The lower limb model used in the above vehicle-pedestrian lower limb collision analysis model refers to the lower limbs of the 50th percentile male dummy model (Hybrid III 50% Male). Referring to Figure 2 , based on the accident collision process, when the accident occurs, the front bumper of the vehicle hits the lower end of the pedestrian's lower limbs, the thigh and calf rotate around the collision point, and the engine cover is in contact with the collision. Extract the collision significant features of the process to obtain the collision parameters of the vehicle head bumper, engine cover, and pedestrian lower limb damage.

[0048] (1) Pedestrian characteristic parameters:

[0049] The statistical pedestrian data is parameterized by referring to the dummy model, the main motion parts and joints of the pedestrian in the collision process are extracted, the length of the lower limbs of the pedestrian Hp and the mass of the lower limbs of the pedestrian Mp are defined; mass blocks are used to represent parts of the human thigh and calf, such as calf mass point 1 and thigh mass point 2, which are used as the composition elements of the human lower limb model in the subsequent analysis model to reduce the freedom degrees of the lower limbs of the pedestrian in the model, the mass of the calf M and the mass of the thigh m are defined; the distance between the calf mass point 1 and the thigh mass point 2 is defined as l.

[0050] (2) Vehicle characteristic parameters:

[0051] The obtained vehicle head geometric shape is parameterized, and Figure 3, define bumper bottom height BBH, bumper lower end of the ground height BLH; bumper upper end of the ground height BUH; bumper depth BUD; engine cover front edge height BLEH; engine cover length BL; engine cover cover angle angle a and front windshield angle β; and the front of the car overall parameters: vehicle mass Mcar, vehicle front end of the lateral length Lcar, longitudinal width Bcar.

[0052] (3) Environmental characteristic parameters:

[0053] According to the collision accident information, the vehicle collision speed V car , the pedestrian walking speed V P , the pedestrian relative to the car δ, the collision area, the pedestrian after the collision basic motion characteristics and other environmental factors; subsequently define multiple different collision speeds, and compare and analyze the analytical model to verify its accuracy.

[0054] 3) Vehicle-pedestrian lower limb collision analytical model construction

[0055] The lower limb model of the pedestrian uses a mass block to represent the thigh, calf and other parts, and a rotating hinge to represent the human knee joint, and the rotating hinge includes the degrees of freedom consistent with the human joint and the corresponding joint mechanical properties. The knee joint part of the 50th percentile male human biomechanical model was subjected to static loading and dynamic impact simulation test, from which the viscoelastic mechanical property curve of the joint, the loading upper limit and the motion interval were extracted, and finally integrated into the mechanical properties of the rotating hinge in the analytical model. According to the motion relationship between the vehicle and the lower limbs of the pedestrian in the collision, a multi-degree-of-freedom collision analytical model is established to solve the motion state of the lower limbs of the pedestrian after the collision. The collision analytical model is shown in Figure 3 .

[0056] The collision accident characteristic parameters in this embodiment are:

[0057] a c is the vehicle acceleration value, i.e. the braking acceleration value corresponding to the vehicle-pedestrian lower limb collision, with the unit of m / s 2 .

[0058] a is the acceleration value of the lower leg of the pedestrian, i.e. the motion acceleration value generated after the lower leg is collided by the vehicle, with the unit of m / s 2 .

[0059] a m is the acceleration value of the thigh of the pedestrian, i.e. the motion acceleration value generated after the lower leg is collided by the vehicle, with the unit of m / s 2 .

[0060] x is the distance moved by the lower limbs of the pedestrian after being collided by the vehicle, with the unit of m.

[0061] x mis the projection of the motion displacement of the thigh after being impacted in the direction of the coordinate axis x, in units of m.

[0062] y m is the projection of the motion displacement of the thigh after being impacted in the direction of the coordinate axis y, in units of m.

[0063] is the angle of rotation of the thigh relative to the mass center of the lower leg after the lower leg is impacted, in units of °.

[0064] m is the mass of the thigh mass block of the pedestrian, in units of kg.

[0065] M is the mass of the lower leg mass block of the pedestrian, in units of kg.

[0066] M c is the mass of the vehicle mass block, in units of kg.

[0067] l is the distance between the lower leg mass point 1 and the thigh mass point 2, in units of m.

[0068] The mass point model of the lower leg in this embodiment can refer to Figure 4 . Wherein, the solving of the motion process of the lower leg of the pedestrian by the multi-degree-of-freedom analytical model refers to:

[0069] (1) the motion process of the lower leg of the pedestrian after being impacted is solved by using the analytical model, the lower leg of the pedestrian is simplified into mass blocks M and m, and the collision process between the vehicle and the lower leg of the pedestrian is simplified into the process that the lower leg mass block is subjected to an impact load. The lower leg mass block makes a forward compound motion (the whole lower leg makes a projectile motion and the lower leg and the calf make rotary motions around the knee joint respectively) under the action of the impact load, so the damage severity of the lower leg of the pedestrian is judged by studying the motion acceleration of the lower leg.

[0070] (2) according to the set MADYMO collision simulation model, the vehicle output acceleration curve and the acceleration curve of the lower leg of the pedestrian after being impacted can be obtained, and the collision motion process of the vehicle and the lower leg of the pedestrian can be directly obtained by the simulation model. The obtained vehicle acceleration curve is functionized, and is used as an input variable to solve the motion process of the lower leg model by using the iterative algorithm of the multi-degree-of-freedom analytical model.

[0071] (3) the motion state of the lower leg subjected to the impact load is described by using generalized coordinates, the Lagrange equation is established by analyzing the mechanics of the vehicle and the lower leg of the pedestrian collision system, and then the Lagrange equation is analytically solved to obtain the analytical solution of the system motion; the obtained analytical equation is iteratively processed by using the iterative algorithm, and is calculated in the MATLAB software to obtain the acceleration curve diagram of the corresponding analytical model of the lower leg of the pedestrian.

[0072] 4) based on theoretical mechanics and Lagrange function solving:

[0073] The coordinate system is established with the calf mass block as the coordinate origin:

[0074] As shown in Figure 5 , since the lower limbs of the pedestrian are represented by a two-degree-of-freedom mass concentration model, when subjected to the impact force brought by the vehicle head, the impact point is assumed to be on the calf mass block, so the calf mass block moves along the impact direction under the impact load, at this time, the coordinate system is established with the calf mass point as the system coordinate origin, wherein the direction in which the vehicle head collides with the lower limbs of the pedestrian is the X direction, and the vertical upward direction is the Y direction; and in the movement process of the vehicle-lower limb collision, the rotation of the lower limbs of the pedestrian is constrained by the structure of the vehicle head, the thigh mass block of the pedestrian rotates around the impact point (calf) due to the action of inertia, when the thigh collides with the front edge of the vehicle engine cover, the thigh rotates to the limit position, i.e. θ is the maximum value, at the moment of impact, as shown in Figure 6 .

[0075] The generalized coordinates are introduced: q1=x; q2=θ;

[0076] Wherein, q1 is the translational distance of the system, and q2 is the rotation angle of the thigh around the calf.

[0077] Therefore, the position of the thigh mass point (m') of the lower limbs is:

[0078] x m =x-l sinθ

[0079] y m =l cosθ

[0080] The motion velocity of the thigh mass point is:

[0081]

[0082]

[0083] The Lagrange function is introduced:

[0084] L=T-V

[0085] Wherein, T is the kinetic energy of the system, including the kinetic energy of the calf mass block and the kinetic energy of the thigh mass block; V is the potential energy of the system, since the mass block M is translational, it is approximately considered that no up and down movement is generated, therefore, the change of the potential energy of the system can be considered to be caused only by the "falling" of the thigh mass block m".

[0086] According to the theoretical analysis:

[0087] The potential energy of the lower limbs system is:

[0088] V=mg·y m =mg·l cosθ

[0089] The kinetic energy of the lower limbs system is:

[0090]

[0091] Substitute the formula of the femur mass point motion velocity into the kinetic energy formula of the lower limb system, and the following formula can be obtained:

[0092]

[0093] Further, the following formula can be obtained:

[0094]

[0095] The Lagrange function can also be written as:

[0096]

[0097] Wherein, L is the Lagrange equation of the system; q i is the generalized coordinate of the system, i.e. the translational distance x and the rotation angle θ; Q i is the generalized force corresponding to the generalized coordinate, Q1 is the generalized force of the generalized coordinate x, i.e. the external force acting on the shank mass block M, in this system, the external force is the time-varying impact force F(t) of the vehicle on the shank; Q2 is the generalized torque of the generalized coordinate θ, i.e. the external torque acting on the femur mass block m, the lower limb system mass block m is only affected by the gravity, therefore Q2 is mglsinθ.

[0098] 1) q1=x, Q1=F(t) is substituted into the above Lagrange function formula, and the following formula can be obtained:

[0099]

[0100] 2) q2=θ, Q2=mglsinθ is substituted into the above Lagrange function formula, and the following formula can be obtained:

[0101]

[0102] Therefore, the analytical equation of the pedestrian lower limb degree of freedom model is:

[0103]

[0104] Let 2mgl sinθ=F B .

[0105] The model response result is obtained through calculation:

[0106]

[0107]

[0108] The equation iteration process is:

[0109] The initial motion parameters and mechanical parameters are 0, and the iteration time is t (t = 0.001 s).

[0110] According to the vehicle acceleration curve output by MADYMO, the curve is functionized as follows:

[0111]

[0112]

[0113]

[0114]

[0115]

[0116]

[0117] The acceleration function of the lower leg of the pedestrian when colliding can be obtained through the above iteration formula, and the acceleration function of the lower leg of the pedestrian when colliding can be obtained through the above iteration formula. The physical relationship between velocity (v) and displacement (x) can be derived to obtain the velocity and displacement of the lower leg during the motion; similarly, through the angular acceleration The angular velocity (w) and rotation angle (θ) can also be derived, and the specific formula is as follows:

[0118]

[0119] x (i) = x (i-1) + v (i-1) * t

[0120]

[0121] θ (i) = θ (i-1) + w (i-1) * t

[0122] According to the kinematic analysis of the vehicle-pedestrian lower limbs, during the collision process, the entire lower limb system moves approximately as a projectile relative to the coordinate system, and for the two mass points of the thigh and the lower leg, the thigh rotates around the lower leg, so with reference to Figure 7 According to the point synthesis motion theory analysis, the original coordinate system is taken as the fixed reference system, and the moving lower leg after the collision is taken as the moving reference system for motion analysis:

[0123] Moving point: thigh (m).

[0124] Moving reference system: lower leg (M).

[0125] Fixed reference system: original xoy coordinate system.

[0126] Relative velocity V r : thigh mass point m relative to the motion of the calf mass point M.

[0127] Tied velocity V e : calf mass point M relative to the motion of the fixed reference frame xoy.

[0128] Absolute velocity V a : thigh mass point m relative to the motion of the fixed reference frame xoy.

[0129] From the motion relationship:

[0130] V r = lw

[0131] V e = v

[0132] And the absolute velocity V a The calculation formula is as follows:

[0133]

[0134] Referring to Figure 8 The motion relationship of relative velocity V r , tied velocity V e and absolute velocity V a , combined with the geometric relationship of the three velocities, we can get:

[0135]

[0136] The above formula is iterated to get:

[0137]

[0138] Therefore, the acceleration of the thigh mass point is:

[0139]

[0140] 5) Build MATLAB calculation program

[0141] According to the mechanical properties and motion trend of vehicle-pedestrian lower limb collision, the solving program is written in matlab.

[0142] 6) Output of calculation results —— acceleration of pedestrian thigh and calf

[0143] A vehicle-pedestrian lower limb collision model is established by MADYMO, in which the lower limbs of the pedestrian are replaced by two ellipsoids, endowed with mass and mechanical properties, etc., to keep the response characteristics consistent with those of the real human lower limbs. Through collision simulation calculation, the vehicle motion acceleration, pedestrian thigh and calf acceleration are obtained. Taking the vehicle acceleration as input, substitute it into the above MATLAB analytical model to solve the acceleration of the lower limbs of the thigh and calf.

[0144] The following further illustrates the above process with a specific example:

[0145] This example is based on the car head and lower limb collision accident information of pedestrians, and the construction of the vehicle-pedestrian lower limb collision analysis model according to the kinematic characteristics of the lower limb collision. The vehicle speed is set to 11 m / s, the lower limb of the pedestrian is in a static state, the vehicle head collides with the lower limb model, and the influence of secondary collision is not considered. The parameters of the car head and the lower limb of the pedestrian are as follows:

[0146] BBH is the height of the bumper bottom, unit m; BBH = 0.35 m.

[0147] BLH is the height of the lower end of the bumper from the ground, unit m; BLH = 0.583 m.

[0148] BUH is the height of the upper end of the bumper from the ground, unit m; BUH = 0.842 m.

[0149] BUD is the depth of the bumper, unit m; BUD = 0.214 m.

[0150] BLEH is the height of the front edge of the engine cover, unit m; BLEH = 0.943 m.

[0151] BL is the length of the engine cover, unit m; BL = 0.854 m.

[0152] α is the engine cover angle, unit °.

[0153] β is the front windshield angle, unit °.

[0154] H is the length of the lower limb of the pedestrian, i.e. from the hip to the foot, unit m; H = 0.25 m.

[0155] m is the mass of the thigh of the pedestrian, unit kg; m = 10 kg.

[0156] M is the mass of the lower leg of the pedestrian, unit kg; M = 8 kg.

[0157] M c is the mass of the vehicle, unit kg; M c = 1590 kg.

[0158] 1. According to the above parameters, the model is constructed by using MADYMO software

[0159] According to the PC-Crash reconstruction case, the vehicle head features are extracted from the PC-Crash vehicle data chart and other ways. The basic size of the head needs to be consistent with the original car, and the head features also need to be captured, and the real vehicle is restored. Then the head parameters obtained are modeled by MADYMO modeling software.

[0160] Because the lower limb model of the pedestrian in this system is simplified into two-particle calculation, the lower limb model is also simplified in the process of modeling the lower limb in MADYMO, and two ellipsoids are used to replace the thigh and calf of the lower limb of the pedestrian, which are connected by a hinge and simulate the motion characteristics of the knee joint of the lower limb.

[0161] The vehicle-lower limb impact contact parameters are set by MADYMO software, the material property card, the loading function, and various mechanical parameters are set, and the model is simulated and calculated to obtain the acceleration curve generated by the vehicle-pedestrian lower limb impact. Then, according to the vehicle acceleration curve output by MADYMO, the curve is functionized:

[0162]

[0163]

[0164]

[0165]

[0166] Through the above motion analysis, it can be obtained that:

[0167] Relative velocity:

[0168] V r = lw = 0.25w

[0169] Relative velocity:

[0170] V e = v

[0171] Absolute velocity:

[0172]

[0173] Thigh particle acceleration:

[0174]

[0175] 3. Verification of vehicle-pedestrian impact analysis model

[0176] A typical vehicle-pedestrian impact accident reconstruction case of the research group is selected, and a collision analysis model and a numerical simulation model under the same conditions are established to verify the accuracy of the analysis model. The characteristic parameters obtained are substituted into the MATLAB program for calculation and analysis, and the various characteristic parameters in MADYMO and MATLAB are ensured to be consistent before solving the model. The functionized vehicle acceleration curve is compared with the vehicle acceleration curve in MADYMO to ensure the correctness of the input of the analysis model. Figure 9The MADYMO output curve is compared with the MATLAB calculation output curve.

[0177] As shown in the above figure, the vehicle acceleration curve is basically consistent, and can meet the subsequent calculation for the analytical model. Through the subsequent calculation by the MATLAB program, the thigh and calf acceleration curves of the lower limbs of the pedestrian after being collided are obtained. The obtained curves are compared and analyzed with the original MADYMO output curve to verify the accuracy of the established analytical model. The curve comparison is shown in Figure 10 and Figure 11 .

[0178] Through comparison, it is found that the vehicle-pedestrian lower limb dynamics equation based on Lagrange mechanics can effectively calculate the lower limb response of the pedestrian under a specific vehicle speed. As shown in the above image analysis, the acceleration curve trends of MADYMO and MATLAB are roughly the same, and the analytical model can be better applied to the solution of the lower limb motion state under a specific speed to predict the lower limb injury.

[0179] Embodiment 2

[0180] The embodiment discloses a data processing system based on a vehicle and pedestrian lower limb collision analytical model, comprising a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor implements the method corresponding to the above-mentioned embodiment when executing the computer program.

[0181] In summary, based on the methods and systems respectively disclosed in the above embodiments, the present application has at least the following beneficial effects:

[0182] 1. The analytical model disclosed in the present application reveals the interaction mechanism of the lower limbs and the vehicle in the collision process. Therefore, the kinematic response of the lower limbs can be calculated under the condition of lacking detailed structure of the vehicle head, only using typical vehicle head parameters such as engine cover inclination angle and bumper height, and the rapid prediction of lower limb injury can be realized. The model is fast in calculation and needs few parameters, which can help engineers to quickly optimize the main structure parameters of the vehicle head in the early stage of vehicle head safety design.

[0183] 2. The analytical model disclosed in the present application contains typical structure characteristic parameters of the front end of the vehicle head, and can consider the heterogeneity problem of the vehicle and the lower limbs of the pedestrian in solving the lower limb injury, which can help rescue personnel to quickly estimate the dynamic response and make preliminary damage assessment according to the on-site vehicle and pedestrian conditions after the accident.

[0184] The above merely provides the preferred embodiments of the present application, and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the principles and technical scope of the present application shall fall into the scope of the present application.

Claims

1. A data processing method based on a vehicle-pedestrian lower limb collision analytical model, characterized in that, include: Step S1: Construct an analytical model of the collision between a vehicle and a pedestrian's lower limbs. In this model, when subjected to the impact force from the vehicle's front end, the collision point is set on the lower leg mass block. The lower leg mass block moves along the collision direction under the impact load. A coordinate system is established with the lower leg mass point as the origin of the system coordinates, where the direction of the vehicle's front end impacting the pedestrian's lower limbs is the X direction, and the vertically upward direction is the Y direction. During the collision between the vehicle and the pedestrian's lower limbs, the entire lower limb system undergoes an approximate projectile motion relative to the coordinate system, and the thigh rotates around the lower leg. When the thigh collides with the front edge of the vehicle's hood, the thigh rotates to its limit position. The analytical equations of the pedestrian's lower limb degree of freedom model are obtained as follows: Where M is the mass of the pedestrian's lower leg mass, m is the mass of the pedestrian's thigh mass, l is the distance from the lower leg mass to the thigh mass, and θ is the angle of rotation of the thigh relative to the mass concentration point of the lower leg after the collision. Let be the translational acceleration of the lower leg during the collision. Let F(t) be the angular acceleration of the lower leg rotating around the point of impact during the collision, and let F(t) be the time-varying impact force exerted by the vehicle on the lower leg. Let ω be the angular velocity of the lower leg rotating around the point of impact during the collision. During the collision, the acceleration of the thigh particle is: Where i represents the iteration number advancing according to the calculation time during the collision process, and a m V is the acceleration value of the pedestrian's thigh. a t represents the absolute velocity of the thigh mass in the coordinate system; t is the iteration time interval. Among them, V r V represents the relative velocity of the thigh mass relative to the lower leg mass. e Let be the velocity of the lower leg mass moving in the coordinate system. V r =lw V e =v Where w is the angular velocity of the thigh rotating around the point of impact, and v is the velocity of the lower leg. Step S2: Based on the vehicle-pedestrian lower limb collision analytical model, calculate the acceleration of the pedestrian's thigh and lower leg during the collision to assess the damage.

2. The method according to claim 1, characterized in that, The time-varying impact force F(t) of the vehicle on the lower leg was generated by the MADYMO collision simulation model. Among them, M c Let a be the weight of the vehicle mass block. c This represents the vehicle's acceleration value.

3. The method according to claim 1, characterized in that, The location of the collision point is determined based on the bottom height of the bumper, the ground clearance of the lower end, the ground clearance of the upper end, and the depth of the bumper.

4. The method according to any one of claims 1 to 3, characterized in that, The analytical model has a rotational hinge between the thigh mass block and the calf mass block. The rotational hinge includes degrees of freedom that correspond to human joints and corresponding joint mechanical properties.

5. A data processing system based on a vehicle-pedestrian lower limb collision analysis model, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the method described in any one of claims 1 to 4.

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