JP6657054B2 - How to create a road surface pattern - Google Patents

Description

  The present invention relates to a method for creating a rough road pattern to be attached to an outer peripheral surface of a roller of a chassis dynamometer.

  FIG. 7 is an explanatory diagram schematically showing a usage environment example in which a vehicle is fixed to a chassis dynamometer. FIG. 7A is a top view showing a state where the car 52 is fixed, FIG. 7B is a side view showing a state where the car 52 is fixed, and FIG. It is explanatory drawing which shows typically the side structure of the roller 7 for chassis dynamometers. FIGS. 7A to 7C each show an XYZ orthogonal coordinate system.

  As shown in FIG. 7, the chassis dynamometer rollers 7 are exposed at four locations from the pit cover 51 serving as the floor surface. Then, the wheels (tires) 56 of the automobile 52 are mounted on the respective rollers 7. Further, on the pit cover 51, securing posts 53 having a total of four predetermined heights are installed in front of and behind the automobile 52. Then, the automobile 52 is fixed to each of the securing posts 53 using a chain (or a belt) 54 (see FIG. 7).

  In the configuration example of FIG. 7, a microphone 55 for sound measurement is also provided in the pit cover 51. While the roller 7 is rotated in the test environment shown in FIG. 7, the sound of the automobile 52 traveling on the roller 7 (sound felt by a person) is collected by the microphone 55, and a sound evaluation test is performed as vehicle performance. it can.

  Thus, the chassis dynamometer is provided with four rollers 7 corresponding to the front wheels and the rear wheels of the automobile 52.

  FIG. 8 is a perspective view showing a pair of rollers 7 provided in the drum device 3 for the chassis. The pair of rollers 7 are provided corresponding to the front wheels or the rear wheels of the automobile 52 shown in FIG.

  In the example shown in FIG. 8, the roller 7 is configured by a combination of a convex portion forming road surface portion 7r serving as a rough road surface and a smooth road surface portion 7f. Note that the configuration shown in FIG. 8 is an example, and for example, in the case where it is detachable with screws or the like, the entire surface may be set to the smooth road surface portion 7f or the entire surface may be set to the uneven road surface portion 7r.

  Hereinafter, a conventional method of creating a road pattern for rough road corresponding to the convex portion forming road surface portion 7r will be described.

  Conventionally, a road pattern for rough road to be attached to the outer peripheral surface of a roller for a chassis dynamometer has been created as follows.

  First, silicon rubber is poured into a mold provided on a test course, which is an actual road surface, to collect a road surface pattern mold 77P.

  FIG. 9 is an explanatory view schematically showing a road pattern mold. As shown in the figure, a road surface pattern mold 77P that accurately reflects the unevenness of the road surface of the test course can be obtained.

  Thereafter, a mixture of a ceramic sand and an epoxy resin was poured into the road surface pattern mold 77P to form a rough road pad as the road surface pattern 77. By attaching this road surface pattern 77 to the outer peripheral surface of the chassis dynamometer roller 7, a rough road surface corresponding to the convex portion forming road surface portion 7r of the roller 7 shown in FIG. 8 can be realized.

  FIG. 10 is an explanatory diagram schematically showing the use situation of the road surface pattern 77. As shown in the drawing, by attaching the road surface pattern 77 to the outer peripheral surface of the roller 7, the roller 7 in which the convex portion forming road surface portion 7r is exposed at the opening of the pit cover 151 can be obtained.

  As such a road surface pattern 77 obtained by molding from an actual road surface, for example, there is a rough road block disclosed in Patent Document 1.

Japanese Utility Model Publication No. 6-17062

  Since the conventional road surface pattern 77 is created by reflecting the actual road surface of the test course, the shape characteristics of the actual road surface of the test course, such as undulations, steps, and cracks, also appear in the road surface pattern 77 as they are. The “undulation” is obtained by sampling the average height of the protrusions (convex portions) per contact area of the tire for one round of the outer peripheral surface of the roller 7 and obtaining a plurality of sampled values. Means the difference between the value and the minimum value. Further, “the average height of the protrusions per contact area of the tire” is the average height of the protrusion vertices that the tire can actually contact.

  On the other hand, since the road surface pattern 77 is attached to the outer peripheral surface of the roller 7 for the chassis dynamometer, the length of the road surface pattern 77 is at most about 5 m.

  Therefore, when the peculiar shape existing at one place on the test course is reflected on the road surface pattern 77, the peculiar shape is changed every 5 m at the time of the test by the chassis dynamometer in which the road surface pattern 77 is attached to the outer peripheral surface of the roller 7. Will appear repeatedly. As a result, vibrations and noises which adversely affect the evaluation of the vehicle performance such as a sound evaluation test result are generated due to the unique shape. For this reason, there has been a problem that it is difficult to accurately measure the vehicle performance.

  The present invention has been made in order to solve the above-mentioned problems, and an object of the present invention is to provide a method of creating a rough road pattern to be attached to a roller of a chassis dynamometer, which can accurately measure vehicle performance.

The method for producing a road surface pattern according to claim 1 of the present invention is a method for producing a road pattern for rough road to be attached to an outer peripheral surface of a roller of a chassis dynamometer, wherein (a) a shape, a size and an arrangement relating to a convex portion Generating temporary three-dimensional data that defines a road surface pattern having a plurality of convex portions based on a convex portion generation parameter designating at least one of the above. Determining whether the three-dimensional data is good or bad, wherein in the step (a), the provisional three-dimensional data is generated while changing the convex part generation parameter until a good determination is received in the step (b). (C) determining the provisional three-dimensional data determined as good in step (b) as the main three-dimensional data; and (d) roughing the main three-dimensional data based on the main three-dimensional data. Creating a road surface pattern for road, and the predetermined criterion in the step (b) is that a height change of the temporary three-dimensional data along a sampling direction coinciding with a rotation direction of the roller. Is sampled as time-series data, and whether or not the frequency distribution of the Fourier operation result obtained by performing the Fourier transform on the sampled time-series data matches a desired frequency distribution .

  In the method for creating a road surface pattern according to the first aspect of the present invention, a step of generating temporary three-dimensional data in a process of creating temporary three-dimensional data, which is a stage before actually completing a road surface pattern (a) Is repeatedly executed until a good judgment is received in step (b), and finally, in step (c), provisional three-dimensional data that satisfies the predetermined criterion of step (b) is obtained as the main three-dimensional data. Can be.

  Therefore, the method for creating a road surface pattern of the present invention described in claim 1 can surely obtain a rough road surface pattern that satisfies a predetermined criterion in the pass / fail determination processing in step (b).

  As a result, there is an effect that vehicle performance can be accurately measured by the chassis dynamometer having the road surface pattern obtained by the road surface pattern forming method of the present invention.

It is a flowchart which shows the processing procedure of the preparation method of the road surface pattern which is embodiment of this invention. 3 is a flowchart illustrating details of a process of creating provisional three-dimensional data in FIG. 1. It is explanatory drawing (the 1) which shows the example of provisional three-dimensional data typically. It is explanatory drawing (the 2) which shows the example of provisional three-dimensional data typically. FIG. 2 is an explanatory diagram schematically showing the contents of a Fourier transform process, which is one of pass / fail judgment processes executed in step S2 of FIG. 1. It is explanatory drawing which shows typically the example of the road surface pattern created by this Embodiment. It is explanatory drawing which shows typically the usage environment example which performs fixing a motor vehicle to a chassis dynamometer. It is a perspective view which shows a pair of rollers provided in the drum device for chassis. It is explanatory drawing which shows the pattern for road surface patterns typically. It is explanatory drawing which shows the use condition of a road surface pattern typically.

<Embodiment>
(Processing flow)
FIG. 1 is a flowchart showing a processing procedure of a road surface pattern creating method according to an embodiment of the present invention. Hereinafter, a method of creating a road surface pattern according to the embodiment will be described with reference to FIG. The processing of steps S1 to S3 described below is executed by, for example, program processing using a CPU (computer) based on software.

  First, in step S1, temporary three-dimensional data 73 defining a road surface pattern having a plurality of convex portions is created based on the convex portion generation parameters. Hereinafter, an example of creating the provisional three-dimensional data 73 will be specifically described.

  FIG. 2 is a flowchart showing details of the process of creating the provisional three-dimensional data 73 in step S1 of FIG. Referring to FIG. 11, a process of generating a three-dimensional structure is executed in step S11.

  In the present embodiment, an elliptical sphere, a sphere, a cylinder, an elliptic cylinder, or the like is employed as a three-dimensional structure corresponding to a rough road stone or the like which is a component of the rough road convex portion. As parameters for defining the three-dimensional structure, a structure type parameter for defining a shape type such as a sphere and a cylinder, and a size of the three-dimensional structure such as a radius of the sphere, a bottom radius of the cylinder, and a height are individually defined. There are individual size parameters and the like. These structure type parameters and individual size parameters (size parameters) are included in the above-described convex portion generation parameters.

  In step S11, a plurality of three-dimensional structures are generated by randomly and sequentially generating these structure type parameters and individual size parameters. Next, in step S12, a three-dimensional structure arrangement process is executed.

  In step S12, the plurality of three-dimensional structures generated in step S11 are arranged on a virtual formation area of a road surface pattern prepared in advance. Specifically, for example, the plurality of three-dimensional structures generated in step S11 are randomly arranged on the virtual formation area according to randomly generated individual arrangement parameters. At this time, the newly arranged three-dimensional structure is not overlapped with the arranged three-dimensional structure while referring to the arranged position of the arranged three-dimensional structure. The individual arrangement parameters are also included in the above-described convex part generation parameters.

  In the case of an elliptical sphere or an elliptical cylinder, the arrangement of the major axis and the minor axis, the arrangement angle of the major axis, and the like are also randomly arranged as the individual arrangement parameters.

  In addition, for each of the plurality of three-dimensional structures, for example, an individual height parameter (height parameter) that defines the height of the road surface pattern 70 protruding from the reference surface BS is randomly generated, for example, so that The protrusion height from the reference plane BS can be determined. Further, a common height parameter (height parameter) common to a plurality of three-dimensional structures may be set instead of the individual height parameter.

  The individual arrangement parameters are also included in the above-described convex part generation parameters. The reference plane BS refers to the surface height of the smooth road surface of the virtual formation area before the three-dimensional structure arrangement processing is performed.

  For example, when the three-dimensional structure is a sphere with a diameter of 10 mm and the individual height parameter is 2 mm, only the upper 2 mm of the sphere protrudes from the reference plane BS, and the partially protruding structure becomes a convex portion, and the remaining 8 mm corresponds to the reference. It is buried under the surface BS and does not participate in the convex portion.

  As described above, in the present embodiment, the protruding portion is realized as a partially protruding structure obtained by protruding a part of a three-dimensional structure such as an elliptical sphere, an elliptic cylinder, a cylinder, and a sphere from the reference plane BS.

  When generating the above-described convex portion generation parameters (such as the structure type parameter, the individual size parameter, the individual arrangement parameter, and the individual height parameter), the generation of the convex portion is performed by adding a weighting process to the random generation. The parameter may be biased.

  When the randomness is realized in steps S11 and S12 described above, for example, a mode in which a random function provided in existing software (application) is used may be considered.

  When step S12 is completed, in step S13, based on the convex part generation parameters generated in step S11 and step S12, the road surface pattern is executed by executing the three-dimensional CAD processing of the existing software (CAD application). Temporary three-dimensional data 73 defining 70 as a virtual three-dimensional model is created.

  FIG. 3 is an explanatory diagram (part 1) schematically showing an example of the provisional three-dimensional data 73, and is a top view as viewed from above (+ Z direction). FIG. 3 shows an XYZ orthogonal coordinate system. As shown in the drawing, the provisional three-dimensional data 73A forms a plurality of elliptical protrusions 81t in a road surface pattern formation region R70 that is a virtual formation region of the road surface pattern 70. Each of the plurality of elliptical projections 81t has a partially projected structure in which a part of an elliptical cylinder or an elliptical sphere is projected from the reference plane BS, and realizes a convex part. The ellipse includes a circle, and the ellipse sphere includes a normal sphere.

  FIG. 4 is an explanatory diagram (part 2) schematically showing an example of the provisional three-dimensional data 73. FIG. 4 (a) is a top view and FIG. 4 (b) is a sectional perspective view. FIGS. 4A and 4B show XYZ orthogonal coordinate systems, respectively. As shown in FIG. 4, the provisional three-dimensional data 73B forms a plurality of ball protrusions 82t in the road surface pattern formation region R70. The ball projection 82t has a partially projecting structure in which a part of the ball projects from the reference plane BS.

  As shown in FIG. 4 (b), a plurality of types of spheres 82 including spheres 82A to 82C having different radii are employed as a three-dimensional structure, and the sphere projections 82t have respective spheres 82A to 82C. The upper part protrudes from the reference plane BS at the same height Δh. That is, the provisional three-dimensional data 73B unifies the protruding height from the reference plane BS with Δh.

  The shape of the road surface pattern forming region R70 shown in FIG. 3 and FIG. 4A is schematically shown, and does not accurately reflect the actual forming region of the road surface pattern 70.

  Returning to FIG. 1, in step S1, temporary three-dimensional data 73 that virtually defines the three-dimensional shape of the road surface pattern 70, such as the temporary three-dimensional data 73A and 73B shown in FIGS. You.

  Thereafter, in step S2, the quality evaluation processing of the provisional three-dimensional data 73 is executed. In step S1, which is executed again after the execution of step S2, all or part of the convex part generation parameters are changed, and the processing of steps S11 to S13 in FIG. 73 is generated.

  That is, in the step S1, the generation of the provisional three-dimensional data 73 is repeatedly executed while changing the convex part generation parameters until a good judgment is received in the step S2. Thereafter, the processing of steps S1 and S2 is repeated until a “good” determination is made in step S2.

  FIG. 5 is an explanatory diagram schematically showing the processing contents of the Fourier transform processing by FFT (Fast Fourier Transform), which is one of the quality judgment processing executed in step S2 of FIG.

  As shown in the drawing, the X direction which is the outer peripheral surface forming direction along the rotation direction of the roller 7 is set as a sampling direction, and the height change in the Z direction appearing in the temporary three-dimensional data 73 along the sampling direction is represented by time-series data. Get as. The height in the Z direction is represented, for example, as a height based on the reference plane BS.

  In FIG. 5, the height in the Z direction, which changes in the range of height H1 to height H3 (H3> H1), is sampled at each sampling interval Δd. The “height” to be sampled is the “height” at a predetermined position (eg, the center position in the width direction) of the provisional three-dimensional data 73 in the width direction (Y direction), or a predetermined range (entire range) ), A statistical value including an average value, a maximum value, a minimum value, and an intermediate value of the “height” at a plurality of locations selected from the list. Also, the example of FIG. 5 shows a case of a triangular wave road surface for easy understanding.

  For example, the formed length (the outer peripheral length of the roller 7) along the rotation direction (sampling direction) of the outer peripheral surface of the road surface pattern 70 is 5 m, and the roller 7 rotates at a rotational speed of 1 / s (one rotation per second). At this time, it is assumed that the sampling interval Δd is 1 mm and the height in the Z direction is sampled. In this case, the change in the height in the Z direction can be sampled as time-series data having a sampling period Δs of (1/5000) seconds.

  Then, by performing a Fourier transform process on the sampled time-series data, a Fourier operation result can be obtained.

  As a result, it is possible to recognize a frequency distribution based on a change in height of the temporary three-dimensional data 73 in the sampling direction from the Fourier operation result. For this reason, for example, the quality of the provisional three-dimensional data 73 created in step S1 can be determined based on whether or not the frequency distribution recognized from the Fourier operation result matches the desired frequency distribution. That is, a Fourier operation result can be adopted as a quality criterion (predetermined criterion) in step S2.

  Note that the desired frequency distribution may be a frequency distribution in which the bias is relatively small, a frequency distribution in which a height bias occurs in a certain frequency region, or the like.

  In addition, as the pass / fail evaluation in step S2, pass / fail judgment by visually observing the three-dimensional shape of the appearance obtained from the provisional three-dimensional data 73 is conceivable. In this case, the quality judgment criterion in step S2 is the external shape of the road surface pattern defined by the provisional three-dimensional data 73.

  Returning to FIG. 1, when a good determination is made in step S2, the process proceeds to step S3. In step S3, the provisional three-dimensional data 73 determined as good in step S2 is determined as the main three-dimensional data.

  Then, in step S4, based on the three-dimensional data determined in step S3, a three-dimensional printer or a five-sided processing machine is used to create a road surface type serving as a road surface pattern model.

  Next, in step S5, the road surface mold created in step S4 is placed in a mold, silicon rubber is poured into the mold, and a mold for a road surface pattern (molding mold) is collected as in the related art.

  Thereafter, in step S6, a mixture of ceramic sand and epoxy resin is poured into a mold for a road surface pattern, as in the related art, to complete the road surface pattern 70.

  Step S4 may be omitted, and a mold for the road surface pattern may be directly obtained in existing step S5 based on the provisional three-dimensional data 73 determined in step S3.

  FIG. 6 is an explanatory diagram schematically showing an example of the road surface pattern 70 (70A to 70C) created in the present embodiment. 6A to 6C show XYZ orthogonal coordinate systems, respectively.

  As shown in FIG. 7A, a spherical road surface pattern 70A is formed in which a part of a sphere, which is a three-dimensional structure, protrudes from the reference surface BS at the same height as a convex portion 75A.

  As shown in FIG. 7B, a cylindrical road surface pattern 70B is formed in which a part of a cylinder as a three-dimensional structure protrudes from the reference surface BS at the same height as a convex portion 75B. The outer peripheral portion of the surface of the convex portion 75B is rounded by R chamfering.

  As shown in FIG. 3C, an elliptic cylinder road surface pattern 70C is formed in which a part of the elliptical cylinder, which is a three-dimensional structure, protrudes from the reference plane BS at the same height as a convex portion 75C. In addition, like the convex portion 75B, the outer peripheral portion of the surface of the convex portion 75C is rounded by R chamfering.

  The shapes shown in FIGS. 6A to 6C are examples, and the height of each of the convex portions 75A to 75C is set randomly so as to be close to the actual road surface shape without making the height uniform. May be. The reason why the formation density of each of the convex portions 75A to 75C is relatively low is also to make it easier to manufacture (work) a road surface die and a road surface pattern die (molding die). Further, regarding the R chamfering of the convex portions 75B and 75C shown in (b) and (c) of FIG. 6, a mode in which a parameter component indicating R (radius) is included in the structure type parameter or the individual size parameter may be considered. At this time, R may be set at random.

(Effects, etc.)
In the method of creating a road surface pattern according to the present embodiment, in the process of creating the temporary three-dimensional data 73, which is a stage prior to actually completing the road surface pattern 70, the step S1 of generating the temporary three-dimensional data 73 is determined as good in step S2 By repeatedly executing until the information is received, the provisional three-dimensional data 73 that satisfies the quality criterion (the predetermined criterion) of step S2 can be finally obtained as the main three-dimensional data in step S3.

  For this reason, the method for creating a road surface pattern according to the present embodiment can reliably obtain the rough road surface pattern 70 that satisfies the quality judgment criterion in the quality judgment processing in step S2.

  As a result, there is an effect that the vehicle performance can be accurately measured by the chassis dynamometer having the road surface pattern 70 obtained by the road surface pattern forming method of the present embodiment.

  In the method of creating a road surface pattern according to the present embodiment, as the road surface pattern 70, a part in which a part of a three-dimensional structure such as a sphere, an elliptical sphere, an elliptic cylinder, and a cylinder protrudes from the reference plane BS. The road surface pattern 70 having a plurality of convex portions having a protruding structure can be generated.

  Further, in the method of creating a road surface pattern according to the present embodiment, in the pass / fail determination processing in step S2, the pass / fail determination criterion is set to the above-described Fourier calculation result, thereby referring to the frequency distribution of the height change obtained from the Fourier calculation result. Then, when a Fourier calculation result that matches the desired frequency distribution is obtained, the provisional three-dimensional data 73 from which the Fourier calculation result has been obtained can be determined as the main three-dimensional data.

  Further, in the method for creating a road surface pattern according to the present embodiment, in the pass / fail determination processing in step S2, the pass / fail determination criterion is set to the external shape of the road surface pattern defined by the provisional three-dimensional data 73, thereby referring to the external shape. Then, the provisional three-dimensional data 73 defining the desired appearance shape can be determined as the main three-dimensional data.

<Others>
In the present invention, the embodiments can be appropriately modified and omitted within the scope of the invention. For example, the following modifications are possible.

  Even if a structure other than the above-described sphere, elliptical sphere, elliptic cylinder, and cylinder is adopted as the three-dimensional structure, a plurality of types of three-dimensional structures are obtained, such as obtaining temporary 3D data 73 by mixing spheres and cylinders. May be combined.

  In addition, as the quality judgment criterion in the quality judgment processing in step S2 in FIG. 1, a criterion other than the above-described Fourier calculation result and the appearance shape of the road surface pattern may be used.

7 Roller 70 Road surface pattern 70A Spherical road surface pattern 70B Cylindrical road surface pattern 70C Elliptic cylinder road surface pattern 73, 73A, 73B Temporary three-dimensional data 75A to 75C Convex portion 81t Elliptical protrusion 82t Spherical protrusion 82, 82A to 82C Ball R70 Road surface pattern formation region

Claims (2)

A method for creating a road pattern for rough road mounting on an outer peripheral surface of a roller of a chassis dynamometer,
(a) generating temporary three-dimensional data that defines a road surface pattern having a plurality of convex portions, based on a convex portion generation parameter indicating at least one of the shape, size, and arrangement of the convex portions;
(b) determining whether the provisional three-dimensional data is good or bad according to a predetermined criterion, wherein the step (a) is performed for generating the convex portion until the good judgment is received in the step (b). Repeatedly generating the provisional three-dimensional data while changing the parameters,
(c) deciding the provisional three-dimensional data that has received the good judgment in the step (b) as the present three-dimensional data;
(d) creating a road pattern for rough road based on the three-dimensional data,
The predetermined criterion in the step (b) is that a change in height of the provisional three-dimensional data is sampled as time-series data along a sampling direction that matches the rotation direction of the roller, and the sampled time-series data is Fourier- Whether the frequency distribution of the Fourier operation result obtained by the conversion matches the desired frequency distribution ,
How to create a road pattern. It is a preparation method of the road surface pattern of Claim 1, Comprising:
The convex portion includes an elliptical sphere, an elliptic cylinder, a partial projection structure obtained by projecting a part of a three-dimensional structure including at least one of a cylinder and a sphere from a reference plane,
The convex part generation parameter is:
A structure type parameter indicating the shape of the three-dimensional structure,
A size parameter indicating the size of the three-dimensional structure;
A height parameter indicating a height of protrusion of the three-dimensional structure from a reference plane,
How to create a road pattern.

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