Method of analysis

Abstract

To provide a method of analysis that allows for creating a car-body model at a low cost.SOLUTION: A method of analysis includes: creating a car-body model 30 by a mass distribution Da which is a distribution of mass in two or more positions on a body of a vehicle; creating a vehicle model 20 with the created car-body model 30 and a vehicle's tire model 40 connected together; and analyzing the behavior of the created vehicle model 20. This makes it possible to analyze the behavior of the vehicle by a difference between mass in one position and mass in another position. As a result, there is no need to measure inertial moment so that the car-body model 30 can be created at a low cost.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an analysis method, and particularly to an analysis method capable of creating a vehicle body model at low cost.

Background Art

[0002] There is known a technique for analyzing vehicle vibration (behavior) using a vehicle body model created by setting a mass, a center of gravity position, and a moment of inertia acting on the center of gravity position for a rigid body representing a vehicle body of a vehicle (Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the above-described conventional technique, it is necessary to measure the moment of inertia in order to create a vehicle body model. For measuring the moment of inertia, it is necessary to use a large facility capable of mounting the entire actual vehicle simulated by the vehicle body model, and man-hours for measuring the moment of inertia are also required, so that extra costs are incurred. Therefore, there has been a problem of creating a vehicle body model at low cost without measuring the moment of inertia.

[0005] The present invention has been made to solve the above-described problems, and an object thereof is to provide an analysis method capable of creating a vehicle body model at low cost.

Means for Solving the Problems

[0006] To achieve this object, the analysis method of the present invention causes a computer to analyze the behavior of a vehicle model simulating a vehicle, and includes a vehicle body creation step of creating a vehicle body model based on a mass distribution that is the distribution of masses at two or more positions on the vehicle body of the vehicle, a vehicle creation step of connecting the vehicle body model created in the vehicle body creation step and the tire model of the vehicle to create the vehicle model, and an analysis step of analyzing the behavior of the vehicle model created in the vehicle creation step.

Advantages of the Invention

[0007] According to the analysis method described in claim 1, since the vehicle body model is created based on the mass distribution that is the distribution of masses at two or more positions on the vehicle body of the vehicle, the behavior at each position of the vehicle can be simulated from the magnitude relationship of the masses between one position and other positions. Therefore, it is possible to eliminate the measurement of the moment of inertia for creating the vehicle body model. Thus, since the equipment for measuring the moment of inertia and the man-hours for the measurement can be eliminated, there is an effect that the vehicle body model can be created at low cost.

[0008] According to the analysis method described in claim 2, in addition to the effect exhibited by the analysis method described in claim 1, since the vehicle body model is created based on a two-dimensional mass distribution in which masses are set at two or more positions on a virtual plane including the vehicle body, compared with the case where the vehicle body model is created based on a one-dimensional mass distribution in which masses are set at two or more positions on a virtual line including the vehicle body, the behavior can be analyzed with a vehicle body model closer to the actual mass distribution of the vehicle body. Thus, there is an effect that the accuracy of the analysis can be improved.

[0009] According to the analysis method described in claim 3, in addition to the effects achieved by the analysis method described in claim 1, since the vehicle body model is created based on a three-dimensional mass distribution with masses set at two or more positions of a virtual solid including the vehicle body, compared with the case where the vehicle body model is created based on a one-dimensional mass distribution with masses set at two or more positions on a virtual line including the vehicle body or a two-dimensional mass distribution with masses set at two or more positions on a virtual plane including the vehicle body, the behavior can be analyzed using a vehicle body model closer to the actual mass distribution of the vehicle body. Therefore, there is an effect that the accuracy of the analysis can be further improved.

[0010] According to the analysis method described in claim 4, in addition to the effects achieved by the analysis method described in any one of claims 1 to 3, since the vehicle body model is created based on a mass distribution with masses set for each region obtained by partitioning the vehicle body into a finite number of regions, even when changing the vehicle parts, the mass distribution can be easily changed by changing the mass of the target region. Therefore, there is an effect that the vehicle body model can be easily changed.

[0011] According to the analysis method described in claim 5, in addition to the effects achieved by the analysis method described in any one of claims 1 to 3, since the vehicle body model is created by a function that outputs the mass corresponding to each position of the vehicle body, compared with the case where the vehicle body model is created based on a mass distribution with masses set for each region obtained by partitioning the vehicle body into a finite number of regions, the value of the mass at an arbitrary position can be easily obtained. Therefore, there is an effect that the behavior of the vehicle at an arbitrary position can be easily analyzed.

[0012] According to the analysis method described in claim 6, in addition to the effects achieved by the analysis method described in claim 1, the difference between the analysis value obtained by analyzing the virtual vehicle model and the measured value measured on the vehicle is calculated. When the optimization condition is satisfied according to the calculated result, the virtual mass distribution when the optimization condition is satisfied is obtained as the mass distribution for creating the vehicle body model, and the vehicle body model is further created based on the obtained mass distribution. In this way, since the mass distribution of the vehicle body model is determined based on the measured value of the behavior of the actual vehicle measured on the actual vehicle, the behavior of the vehicle can be analyzed using a vehicle body model closer to the actual vehicle body. Therefore, there is an effect that the accuracy of the analysis can be improved.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Modes for Carrying Out the Invention

[0014] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. First, referring to FIG. 1, the outline of the PC1 of this embodiment will be described. FIG. 1 is an external view of the PC1. The PC1 is an information processing apparatus (computer) that executes a behavior analysis process on a vehicle model 20 imitating a vehicle in order to analyze the behavior of the vehicle. The PC1 is provided with a mouse 2 and a keyboard 3 for inputting instructions from the user, and a display device 4 for displaying the analysis results. A vehicle model 20 imitating an automobile (vehicle) is created based on the user's instructions input from the mouse 2 and the keyboard 3, and the analysis results using the created vehicle model 20 are displayed on the display device 4. Here, referring to FIG. 2, the vehicle model 20 will be described.

[0015] FIG. 2 is a diagram showing a vehicle model 20 in the first embodiment. The vehicle model 20 is a virtual three-dimensional model simulating an automobile (vehicle), and is composed of a vehicle body model 30 and a tire model 40, which will be described later. Note that as the vehicle model 20, a model simulating other vehicles such as a motorcycle, a railway vehicle, or a construction vehicle may be adopted.

[0016] The vehicle body model 30 is a virtual three-dimensional model simulating a vehicle body part in a vehicle, that is, a part excluding parts around the wheels such as wheels and suspensions (hereinafter referred to as "parts around the wheels") from the vehicle. Connection positions P1, P2, P3, and P4 are set on the vehicle body model 30 to be connected to the tire model 40 simulating the parts around the wheels. In the present embodiment, the vehicle body model 30 is a model in which a one-dimensional mass distribution Da is set in a rigid body model, that is, a model simulating only a shape that does not deform even when an external force is applied.

[0017] An X coordinate extending in the front-rear direction ((X)-(-X) direction) is set on the vehicle body model 30. The position of the front end of the vehicle body model 30 is set to X = 0, and the X coordinate of the position on the rear end side of the vehicle body model 30 from the position of the front end by Δx is set to x(1). Next, the X coordinate of the position on the rear end side of the vehicle body model 30 from the coordinate x(1) by another Δx is set to x(2). In the direction approaching the position of the rear end of the vehicle body model 30 from the coordinate x(2), the X coordinates are sequentially set to x(3), x(4), ···, x(α - 1), and the X coordinate of the position of the rear end of the vehicle body model 30 is set to x(α).

[0018] On the X coordinate, a line Lx, which is a virtual line extending from the front end (X = 0) to the rear end (X = x(α)) of the vehicle body model 30, is set. The line Lx is divided into α sections at equal intervals Δx. The region from the coordinate X = 0 to x(1) of the α-divided line Lx is the region Ra(1), the region from x(1) to x(2) is the region Ra(2), ···, the region from x(α - 2) to x(α - 1) is the region Ra(α - 1), and the region from x(α - 1) to x(α) is the region Ra. In the present embodiment, α is set to 8, but α may be set to 8 or more or 8 or less.

[0019] Each of the regions Ra(1) to Ra(α) into which the line Lx is divided into α parts is set with region masses m(1) to m(α) which are the masses obtained by collecting the mass of each of the regions Ra(1) to Ra(α) at a point of 1. The sum of the region masses m(1) to m(α) is the mass of the entire vehicle body (vehicle body model 30). The regions Ra(1) to Ra(α) and the region masses m(1) to m(α) set a one-dimensional (in the X direction in this embodiment) mass distribution Da in the vehicle body model 30. That is, the mass distribution Da is the distribution of the region masses m(1) to m(α) set in each of the regions Ra(1) to Ra(α) obtained by dividing the virtual line Lx including the vehicle body into α parts.

[0020] For each of the region masses m(1) to m(α), the length of the arrow represents the magnitude of the mass, indicating that the longer the arrow, the greater the mass. In this embodiment, as shown in FIG. 2, the region masses m(1) and m(2) are set to be larger in mass than the region masses m(α - 1) and m(α).

[0021] Four tire models 40 are respectively connected to the connection positions P1, P2, P3, and P4 of the vehicle body model 30. The tire model 40 is a virtual three-dimensional model simulating the wheelhouse part. Although a known model is used for the tire model 40, it is possible to appropriately change the tires and suspensions mounted on the wheels, change the spring constant of the bush which is a component, change the damping constant of the damper which is a component, and change the rigidity of each component and the coupling conditions between each component.

[0022] Although details will be described later, in this embodiment, the user sets analysis conditions such as the load input from the road surface for the vehicle model 20 in which the vehicle body model 30 with the mass distribution Da set and the tire model 40 are connected, and analyzes the behavior of the vehicle.

[0023] At this time, since a model with a mass distribution Da is used as the vehicle body model 30, the behavior of the vehicle such as rotation and vibration of the vehicle can be analyzed based on the relative mass differences of the regional masses m(1) to m(α) of each region Ra(1) to Ra(α) of the vehicle body model 30 and the analysis conditions set by the user. Therefore, it is possible to eliminate the need for measuring the moment of inertia using an actual vehicle.

[0024] Here, in the conventional technology of setting the moment of inertia for the vehicle body model, since the entire actual vehicle is placed on a large facility for measuring the moment of inertia and measured, it is not possible to measure the moment of inertia for each component constituting the vehicle body. Therefore, when it is desired to perform analysis by changing some components of the vehicle body, the mass of the component to be changed was added to the mass of the vehicle body model for which the moment of inertia was measured and the analysis was performed. For this reason, the mass was calculated twice, and there was room for improvement in the accuracy of the analysis.

[0025] On the other hand, in this embodiment, since the vehicle body model 30 with the mass distribution Da set is used, the vehicle body model 30 can be changed by changing the mass of the section corresponding to the section (regions Ra(1) to Ra(α)) where the component is to be changed. Therefore, it is possible to analyze the behavior of the vehicle without the mass of the changed part being calculated twice. Therefore, the accuracy of the analysis can be improved. Furthermore, since the equipment and man-hours required for measuring the moment of inertia can be eliminated, the cost for creating the vehicle body model 30 can be reduced.

[0026] Referring to FIG. 3, the electrical configuration of the PC1 will be described. FIG. 3 is a block diagram showing the electrical configuration of the PC1. The PC1 has a CPU 10, a hard disk drive (HDD) 11, and a RAM 12, and these are respectively connected to an input / output port 14 via a bus line 13. Further connected to the input / output port 14 are the above-described mouse 2, keyboard 3, and display device 4.

[0027] The CPU 10 is an arithmetic unit that controls each unit connected by the bus line 13. The HDD 11 is a rewritable non-volatile storage device that stores programs, fixed-value data, etc. to be executed by the CPU 10, and stores an analysis program 11a, measured data 11b, and model data 11c. When the analysis program 11a is executed in the CPU 10, the behavior analysis process of FIG. 4 is executed. In the present embodiment, as the analysis program 11a, a commercially available software (so-called 1D·CAE software capable of concept design, function design, and downstream design thereof) that can perform vehicle behavior analysis processing by setting various parameters is used.

[0028] The measured data 11b stores measured values obtained by measuring various vehicle behaviors (vibration in the present embodiment) acquired from an actual vehicle. Further, the model data 11c stores a vehicle model 20 described later, a temporary vehicle model created by the process of S13 described later, a vehicle body model 30, a temporary vehicle body model created by the process of S12 described later, a tire model 40, and a temporary tire model used in the process of S13.

[0029] The RAM 12 is a memory for storing parameters and the like in various settings in a rewritable manner when the CPU 10 executes the analysis program 11a. The RAM 12 stores, for example, the parameters of the analysis conditions set in the condition setting step S4 described later, the parameters of the optimization conditions set in the optimization condition setting step S11, and the parameters of the temporary analysis conditions set in the temporary condition setting step S13.

[0030] Referring to FIG. 4, the behavior analysis process executed by the CPU 10 of the PC 1 will be described. FIG. 4 is a flowchart of the behavior analysis process. The behavior analysis process is a process executed when an execution instruction of the analysis program 11a of the PC 1 is given.

[0031] As shown in FIG. 4, the behavior analysis process first creates a vehicle body model 30 according to the flowchart of the vehicle body creation process (see FIG. 5) described later (S1). In the process of S1, the vehicle body model 30 is created by a one-dimensional mass distribution Da in which region masses m(1) to m(α) are set at α positions on a virtual line Lx including the vehicle body, and a rigid body model representing the shape of the vehicle body.

[0032] After the process of S1, the tire model 40 is acquired from the model data 11c (S2), and the tire model 40 acquired by the process of S2 and the vehicle body model 30 created by the process of S1 are connected (S3). At this time, the connection parts of the tire model 40 are connected to the connection positions P1, P2, P3, P4 of the vehicle body model 30.

[0033] After the process of S3, data representing the uneven state and gradient of the road surface for calculating the load input to the vehicle model 20 created by the process of S3, the traveling speed of the vehicle, the friction coefficient of the tire with respect to the road surface, the output position of the vehicle model 20 for outputting the analysis result, output items output as the analysis result (in this embodiment, the transition of the acceleration in the Z direction), etc. are set as analysis conditions (S4).

[0034] After the process of S4, analysis is performed on the vehicle model 20 to which the analysis conditions set in the process of S4 are input, and as the analysis result (analysis value), the acceleration in the Z direction with respect to time at the output position of the vehicle model 20 (see FIG. 6) is output (S5).

[0035] After the process of S5, the user checks the analysis result output in the process of S5 and checks whether to continue the analysis (S6). If the user wants to continue the analysis (S6: No), the processes from S2 and below are repeated. At this time, the parameters of each element of the tire model 40 (the mass, spring constant, damping constant, and shape of each component) are changed and repeated until the user determines to end the analysis. If the user determines to end the analysis (S6: Yes), the behavior analysis process ends.

[0036] Here, referring to FIGS. 5 and 6, the vehicle body creation process of S1 will be described in detail. FIG. 5 is a flowchart of the vehicle body creation process. FIG. 6(a) is a diagram showing the relationship between acceleration and time before the optimization process in the vehicle body creation process, and FIG. 6(b) is a diagram showing the relationship between acceleration and time after the optimization process in the vehicle body creation process. In this embodiment, the processes from S10 to S19 described later will be collectively referred to as the optimization process for explanation.

[0037] As shown in FIG. 5, in the vehicle body creation process, the shape of the vehicle body (rigid body model) used for analysis is acquired from the model data 11c, and a temporary mass distribution, which is a temporary mass distribution for the shape of the vehicle body, is set (S10).

[0038] After the process of S10, an optimization condition for determining whether to repeat the process of S17 described later is set (S11). In this embodiment, whether the number of calculation times of the process of S16 described later has reached 1,000 times is set as the optimization condition. Note that the upper limit of the number of calculation times is not limited to 1,000 times, and it may be less than 1,000 times or more than 1,000 times.

[0039] After the process of S11, a temporary vehicle body model, which is a temporary vehicle body model, is created based on the temporary mass distribution set in the process of S10 (S12). After the process of S12, a temporary tire model, which is a temporary tire model acquired from the model data 11c, is connected to the temporary vehicle body model created in S12 to create a temporary vehicle model, which is a temporary vehicle model. At this time, the temporary tire model is connected to the connection positions P1, P2, P3, and P4 of the temporary vehicle body model.

[0040] After the process of S13, a temporary analysis condition for analyzing the temporary vehicle model is set (S14). The temporary analysis condition is substantially the same as the condition when the behavior of an actual vehicle is measured to obtain the actual measurement values described later. Note that the items set in the temporary analysis condition are the same as the items of the analysis condition set in the process of S4.

[0041] After the process of S14, the behavior of the temporary vehicle model is analyzed according to the temporary analysis conditions set in the process of S14 (S15). In the process of S15, the output position and output items set in the process of S14 (in this embodiment, the transition of the acceleration in the Z direction) are output as analysis results. This analysis result is output as a graph showing the relationship between the acceleration in the Z direction and time at the output position, for example, like the analysis result line L2 in Fig. 6(a).

[0042] After the process of S15, the difference between the analysis result (analysis result line L2) output in the process of S15 and the measured value 1 of the measured data 11b (measured value line L1 in Fig. 6) is calculated (S16), and then it is confirmed whether the optimization conditions set in the process of S11 are satisfied (judgment step S17).

[0043] In the process of S17, if the optimization conditions (number of calculation times) set in the process of S11 are not satisfied (S17: No), the temporary mass distribution set in S10 is corrected so as to reduce the difference calculated in the process of S16 (S18). The correction of the temporary mass distribution in the process of S18 is, for example, when the entire analysis result is larger than the measured value, the overall mass of the temporary mass distribution is increased, and conversely, when the entire analysis result is smaller than the measured value, the overall mass of the temporary mass distribution is decreased. Then, the processes from S12 and below are repeated. In the process of S17, when the optimization conditions set in the process of S11 are satisfied (S17: Yes), the temporary mass distribution at that time is determined as the final mass distribution Da (S19).

[0044] As shown in Fig. 6(b), in the process of S17, when the optimization conditions set in the process of S11 are satisfied, the analysis result (analysis result line L3) is closer to the measured value (measured value line L1) than the analysis result (analysis result line L2) before the optimization process due to the optimization process.

[0045] After the process of S19, the vehicle body model 30 is created according to the final mass distribution Da determined by the process of S19 (S20), and after the process of S20, the vehicle body creation process is terminated.

[0046] By the vehicle body creation process, the mass distribution Da of the vehicle body model 30 can be made close to the mass distribution of the actual vehicle body. Since the subsequent processes (processes of S2 to S6) are executed using the vehicle body model 30 with the mass distribution close to that of the actual vehicle body, the accuracy of the analysis of the behavior of the vehicle can be improved.

[0047] Also, in the present embodiment, the mass distribution Da of the vehicle body model 30 is set by using the analysis result of the behavior of the vehicle (in the present embodiment, the transition of acceleration) output in the process of S15 and the measured value of the behavior of the vehicle in the measured data 11b. By this, it is not necessary to measure the mass distribution of the actual vehicle body, so the man-hours for measuring the mass distribution of the actual vehicle body can be reduced. As a result, the vehicle body model 30 can be created at low cost.

[0048] Next, with reference to FIG. 7, the vehicle body model 30 in the second embodiment will be described. In the first embodiment, the case where the vehicle body model 30 is created with the one-dimensional mass distribution Da has been described. In the second embodiment, the case where the vehicle body model 30 is created with the three-dimensional mass distribution Db will be described. FIG. 7 is a diagram showing the vehicle body model 30 in the second embodiment. Note that the same parts as those in the first embodiment are denoted by the same reference numerals and their description is omitted (the same applies in FIG. 8). The behavior analysis process using the vehicle body model 30 in the second embodiment is the same as the behavior analysis process using the vehicle body model 30 in the first embodiment, so its description is omitted (the same applies in the following first modification example, second modification example, and third modification example).

[0049] As shown in FIG. 7, X, Y, and Z coordinates extending in the (X)-(-X) direction, (Y)-(-Y) direction, and (Z)-(-Z) direction are set for the vehicle body model 30. In the X coordinate, the position of the front end of the vehicle body model 30 is set to X = 0, and the X coordinate of the position on the rear end side of the vehicle body model 30 from the position of the front end is set to x(1) with a distance of Δx. Next, the X coordinate of the position on the rear end side of the vehicle body model 30 from the coordinate x(1) is further set to x(2) with a distance of Δx. In the direction approaching the position of the rear end of the vehicle body model 30 from the coordinate x(2) in order, the X coordinates are set to x(3), x(4), ···, x(α - 1), and the X coordinate of the position of the rear end of the vehicle body model 30 is set to x(α).

[0050] Similar to the X coordinate, in the Y coordinate, the position of the left end of the vehicle body model 30 is set to Y = 0, and the position of the right end is set to Y = y(b). Also, in the Z coordinate, the position of the lower end of the vehicle body model 30 is set to Z = 0, and the position of the upper end is set to Z = z(γ).

[0051] On the X coordinate, a virtual line Lx extending from the front end (X = 0) to the rear end (X = x(α)) of the vehicle body model 30 is set. The line Lx is divided into α sections at equal intervals of Δx. On the Y coordinate, a virtual line Ly extending from the left end (Y = 0) to the right end (Y = y(β)) of the vehicle body model 30 is set. The line Ly is divided into β sections at equal intervals of Δy. On the Z coordinate, a virtual line Lz extending from the lower end (Z = 0) to the upper end (Z = z(γ)) of the vehicle body model 30 is set. The line Lz is divided into γ sections at equal intervals of Δz.

[0052] In the second embodiment, α is set to 16, β is set to 3, and γ is set to 6 respectively. However, α may be set to 16 or more or 16 or less, β may be set to 3 or more or 3 or less, and γ may be set to 6 or more or 6 or less.

[0053] In the regions Rb(1, 1, 1) to Rb(α, β, γ) obtained by dividing the lines Lx, Ly, and Lz into α, β, and γ sections respectively, region masses m(1, 1, 1) to m(α, β, γ) are set, which are the masses obtained by collecting the mass of each region Rb(1, 1, 1) to Rb(α, β, γ) at a point of 1 respectively.

[0054] Note that the first numbers (characters) 1 to α inside the parentheses of the regional masses m(1,1,1) to m(α,β,γ) and Rb(1,1,1) to Rb(α,β,γ) represent the X coordinates, the middle numbers (characters) 1 to β inside the parentheses represent the Y coordinates, and the last numbers (characters) inside the parentheses represent the Z coordinates, respectively. Also, in FIG. 7, the regional masses m(1,1,1) to m(α,β,γ) other than the portions extracted in the regions Rb(1,1,1) to Rb(α,β,γ) are omitted from the illustration.

[0055] The sum of the regional masses m(1,1,1) to m(α,β,γ) is defined as the mass of the entire vehicle body (vehicle body model 30). The regions Rb(1,1,1) to Rb(α,β,γ) and the regional masses m(1,1,1) to m(α,β,γ) define a three-dimensional (in this embodiment, in the X, Y, and Z directions) mass distribution Db for the vehicle body model 30. The mass distribution Db is the distribution of the regional masses m(1,1,1) to m(α,β,γ) set for each of the regions Rb(1,1,1) to Rb(α,β,γ) that partition a virtual solid including the vehicle body.

[0056] For each of the regional masses m(1,1,1) to m(α,β,γ), the length of the arrow represents the magnitude of the mass, indicating that the longer the arrow, the greater the mass.

[0057] According to the vehicle body model 30 in the second embodiment, compared with the vehicle body model 30 in the first embodiment, since the mass distribution Db of the vehicle body model 30 also has a mass distribution in the Y and Z directions, when analyzing the behavior of the vehicle, the rotation and vibration of the vehicle caused by the differences in the regional masses of each region in the width direction ((Y)-(-Y) direction) and the height direction ((Z)-(-Z) direction) of the vehicle body model 30 can be reflected in the analysis results. Therefore, the accuracy of the analysis when performing the behavior analysis process can be improved.

[0058] Although the present invention has been described based on the embodiments, it is easily conceivable that the present invention is not limited to the above embodiments at all, and various improvements and modifications can be made without departing from the spirit of the present invention.

[0059] In each of the above embodiments, the case where a one-dimensional mass distribution Da or a three-dimensional mass distribution Db is set for the vehicle body model 30 has been described. However, a two-dimensional mass distribution Dc may be set for the vehicle body model 30. This form will be described as a first modification example (vehicle body model 30 with the mass distribution Dc set) with reference to FIG. 8(a). FIG. 8(a) is a diagram showing the vehicle body model 30 in the first modification example. In FIG. 8(a), some of the arrows of the regional mass m(c) are illustrated only as points with the arrows omitted.

[0060] As shown in FIG. 8(a), a two-dimensional mass distribution Dc in which each regional mass m(c) is set at two or more positions on a virtual plane including the vehicle body is set for the vehicle body model 30. The virtual plane including the vehicle body is a plane extending in the X and Y directions from the position of X, Y = 0.

[0061] The regional mass m(c) is the mass obtained by collecting the mass within each region Rc at a point of 1 in each region Rc partitioned at equal intervals by the distances of Δx and Δy. That is, the sum of the regional masses m(c) of each region Rc is defined as the mass of the entire vehicle body (vehicle body model 30).

[0062] In this case, since the amount of information processed by the CPU 10 can be reduced compared to the case where a three-dimensional mass distribution Db is set for the vehicle body model 30, the speed of the analysis process can be improved. Also, compared to the case where a one-dimensional mass distribution Da is set for the vehicle body model 30, the dimension in which the mass distribution is set can be increased. Therefore, the rotation and vibration of the vehicle caused by the difference in the regional masses of the regions distributed in the increased dimension can be reflected in the analysis results. Thus, the accuracy of the analysis can be improved.

[0063] In each of the above embodiments, the case of creating the vehicle body model 30 by a mass distribution that sets the mass for each of the finitely partitioned regions Ra, Rb (Rc) of the vehicle body has been described. However, the vehicle body model 30 may be created by a function that outputs the mass corresponding to each position of the vehicle body. This embodiment will be described as a second modification example (vehicle body model 30 with a mass distribution D1) and a third modification example (vehicle body model 30 with a mass distribution D2) with reference to FIGS. 8(b) and 8(c). FIG. 8(b) is a diagram showing the vehicle body model 30 in the second modification example, and FIG. 8(c) is a diagram showing the vehicle body model 30 in the third modification example.

[0064] As shown in FIG. 8(b), in the vehicle body model 30 in the second modification example, the mass distribution D1 is set by a plurality of linear functions that output the mass corresponding to each position on the virtual line Lx including the vehicle body. The mass distribution D1 set by the plurality of linear functions outputs, for example, the mass m(a) corresponding to the X coordinate x(a) at an arbitrary X coordinate x(a) among the coordinates from X = 0 to X = x(α) of the virtual line Lx extending in the X direction, and at any other X coordinate x(b), the mass m(b) corresponding to that X coordinate x(b) is output.

[0065] In this case, at the coordinates from X = 0 to X = x(α), the mass corresponding to any coordinate is output. Therefore, compared to the case of creating a vehicle body model by a mass distribution in which the mass is set for each finitely partitioned region, the behavior of the vehicle at an arbitrary coordinate (position) can be easily analyzed.

[0066] Although the case where the mass distribution D1 is set by a combination of a plurality of linear functions for the vehicle body model 30 has been described, the vehicle body model 30 may be one in which the mass distribution is set by a single linear function. For example, when the front side of the vehicle body model 30 is heavy and the rear side is light, the mass distribution is set by a linear function having a negative slope (a slope that decreases as it goes from the front side to the rear side). Conversely, when the rear side of the vehicle body model 30 is heavy and the front side is light, the mass distribution is set by a linear function having a positive slope (a slope that increases as it goes from the front side to the rear side).

[0067] Also, as shown in FIG. 8(c), in the third modification, the vehicle body model 30 in the third modification has a mass distribution D2 set by a higher-order (in this embodiment, fourth-order) non-linear function that outputs the mass corresponding to each position on the virtual line Lx including the vehicle body.

[0068] In this case, in addition to the effect exhibited by the second modification, since the mass distribution D2 is set by a non-linear function, the difference from the actual vehicle body mass distribution can be made smaller than the mass distribution D1 of the second modification set by a combination of linear functions. Therefore, the accuracy of the analysis of the vehicle behavior can be improved.

[0069] Note that the vehicle body model 30 may have a mass distribution set by combining any two or all of the mass distribution Da in which mass is set in each of the finite number of regions in the first embodiment, the mass distribution D1 represented by a linear function in the second modification, and the mass distribution D2 represented by a non-linear function in the third modification. In this case, for example, the mass distribution D1 may be set for the front half of the vehicle body model 30, and the mass distribution D2 may be set for the rear half of the vehicle body model 30.

[0070] In each of the above embodiments, in the process of S17, the case of determining whether or not the number of operations set in the process of S16 has been reached has been described, but it may be determined whether or not the elapsed time from the start of the process (the processing time after the virtual vehicle creation step S12) has reached the set time. In addition, it may be determined whether or not the difference between the acceleration in the Z direction output as the analysis result and one measured value (acceleration in the Z direction) of the measured data 11b is equal to or less than a threshold value.

[0071] In each of the above embodiments, the case where one measured value of the analysis result and the measured data 11b is the acceleration in the Z direction has been described, but it may be the acceleration in the X direction, the acceleration in the Y direction, or the acceleration obtained by combining (synthesizing) two of the X, Y, and Z directions, or the acceleration obtained by combining all three of them. As the combination (synthesis) of two of the X, Y, and Z directions, the combination of the X and Y directions, the Y and Z directions, or the X and Z directions may be adopted.

[0072] In each of the above embodiments, one measured value of the analysis result and the measured data 11b has been described as being acceleration, but it may be other physical quantities such as velocity or displacement amount.

[0073] In each of the above embodiments, the vehicle body model 30 has been described as being set as a rigid body, but it may be set as an elastic body. In this case, elastic coefficients are set in each region Ra, Rb (Rc) of the vehicle body model 30, and in the analysis process, the deformation of each of the regions Ra, Rb (Rc) of the vehicle body model 30 is considered. Therefore, the accuracy of the analysis can be improved.

[0074] In each of the above embodiments, the case where the optimization process (the processes of S10 to S19) is executed in the vehicle body creation process (see FIG. 5) has been described, but the optimization process may be omitted. In this case, the single vehicle body model stored in the model data 11c (a vehicle body model in which a mass distribution has already been set in a rigid body model) may be set as the vehicle body model 30 used for creating the vehicle model 20, or the vehicle body model 30 may be set (created) by other methods.

[0075] In each of the above embodiments, the PC1 has been exemplified as the computer that executes the analysis program 11a, but it is not limited thereto, and the analysis program 11a may be executed by an information processing device such as a smartphone or a tablet terminal. Further, the present invention may be applied to a dedicated device that stores the analysis program 11a in a ROM or the like and executes only the analysis program 11a.

[0076] In the above first embodiment, the case where the distances in the X coordinate direction of the regions Ra(1) to Ra(α) are set at equal intervals of Δx has been described. However, the distances in the X coordinate direction of the regions Ra(1) to Ra(α) may be set to arbitrary distances. In this case, for example, by setting the distance of the region where the engine, which is a portion with a relatively large mass in the vehicle body, is arranged to be narrower than the distances of the other regions, the behavior of the region where the engine, which has a great influence on the behavior of the vehicle, is arranged can be analyzed in more detail. Therefore, the accuracy of the analysis when performing the behavior analysis process can be improved. Similarly, in the above second embodiment, the distances in the X, Y, and Z coordinate directions of the regions Rb(1,1,1) to Rb(α,β,γ) may be set to arbitrary distances.

[0077] In the above first embodiment, the case where the mass distribution Da is set on the line Lx extending in the X direction has been described. However, the mass distribution Da may be set on the Ly extending in the Y direction or the Lz extending in the Z direction. Similarly, in the first modification, the case where the mass distribution Dc is set on the X-Y plane has been described. However, the mass distribution Dc may be set on the X-Z plane or the Y-Z plane.

Explanation of Reference Numerals

[0078] 1 PC (Computer) 20 Vehicle Model 30 Vehicle Body Model 40 Tire Model Da, Db, Dc, D1, D2 Mass Distribution S1 Vehicle Body Creation Process (Vehicle Body Creation Step) S10 Temporary Mass Distribution Setting Step S11 Optimization Condition Setting Step S12 Temporary Vehicle Body Creation Step S13 Temporary Vehicle Creation Step S15 Temporary Analysis Step S16 Calculation Step S19 Acquisition Step S3 Vehicle Creation Step S5 Analysis Step

Claims

1. An analysis method for causing a computer to analyze the behavior of a vehicle model simulating a vehicle, comprising: a vehicle body creation step of creating a vehicle body model based on a mass distribution that is the distribution of masses at two or more positions on the vehicle body of the vehicle; a vehicle creation step of creating the vehicle model by connecting the vehicle body model created in the vehicle body creation step and the tire model of the vehicle; and an analysis step of analyzing the behavior of the vehicle model created in the vehicle creation step.

2. The analysis method according to claim 1, wherein the vehicle body creation step creates the vehicle body model based on a two-dimensional mass distribution in which masses are set at two or more positions on a virtual plane including the vehicle body.

3. The analysis method according to claim 1, wherein the vehicle body creation step creates the vehicle body model based on a three-dimensional mass distribution in which masses are set at two or more positions on a virtual solid including the vehicle body.

4. The analysis method according to any one of claims 1 to 3, wherein the vehicle body creation step creates the vehicle body model based on a mass distribution in which masses are set for each region obtained by partitioning the vehicle body into a finite number of regions.

5. The analysis method according to any one of claims 1 to 3, wherein the vehicle body creation step creates the vehicle body model by a function that outputs a mass corresponding to each position of the vehicle body.

6. The vehicle body creation step includes a temporary mass distribution setting step of setting a temporary mass distribution that is the temporary mass distribution in the vehicle body of the vehicle; an optimization condition setting step of setting an optimization condition for determining the mass distribution; a temporary vehicle body creation step of creating a temporary vehicle body model that is a temporary vehicle body model based on the temporary mass distribution set in the temporary mass distribution setting step; a temporary vehicle creation step of creating a temporary vehicle model that is a temporary vehicle model by connecting the temporary vehicle body model created in the temporary vehicle body creation step and the temporary tire model of the vehicle; a temporary analysis step of analyzing the behavior of the temporary vehicle model created in the temporary vehicle creation step; a calculation step of calculating a difference between an analysis value obtained by analyzing the temporary vehicle model in the temporary analysis step and a measured value measured in the vehicle; and an acquisition step of acquiring, as the mass distribution, the temporary mass distribution at the time when the optimization condition is satisfied when the optimization condition is satisfied according to the result calculated in the calculation step. The analysis method according to claim 1, characterized in that the vehicle body model is created based on the mass distribution obtained in the acquisition step.

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