Tire evaluation method and tire evaluation device

Abstract

To provide a tire evaluation method and a tire evaluation device capable of evaluating the followability of a tire with respect to vehicle control.SOLUTION: A tire evaluation method evaluates a tire mounted on a vehicle that travels by automatic driving on a course with a reference path determined. The tire evaluation method includes: a step (S1) of acquiring data on a travel route of the vehicle and data on a target path set during traveling so that the vehicle passes through the reference path; a step (S4) of extracting a specific region from the data on the target path; a step (S7) of calculating a positional deviation between the specific region and the travel route of the vehicle; and a step (S8) of evaluating the control followability of the tire with respect to the vehicle on the basis of the positional deviation.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present disclosure relates to a tire evaluation method and a tire evaluation device. [Background technology]

[0002] In recent years, technological developments related to autonomous driving of vehicles have been progressing. In autonomous driving, a reference path for the course to be traveled is generally determined. In actual driving, the route deviates from the reference path, so control is performed to estimate and correct the vehicle's position using sensors or the like. For example, Patent Document 1 discloses a control that sets pass points according to the driving mode based on the driving time zone, traffic volume, etc. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-174304 Summary of the Invention [Problem to be solved by the invention]

[0004] Here, a known tire testing method is the real-vehicle testing method. In this real-vehicle testing method, various tests are conducted while the vehicle is actually driven along a circuit course designed specifically for testing. In this real-vehicle testing method, the vehicle is also driven automatically so that it follows a reference path on the circuit course. In this real-vehicle testing method, vehicle control can be evaluated based on the degree to which the reference path and the vehicle's driving path match. However, the matching between the controlled vehicle and the tires (tire tracking ability) cannot be strictly evaluated based solely on the match between the reference path and the vehicle's driving path. Therefore, a method is needed that can evaluate how tires behave in conjunction with vehicle control.

[0005] In view of the above circumstances, an object of the present disclosure is to provide a tire evaluation method and a tire evaluation device that are capable of evaluating tire compliance with vehicle control. [Means for solving the problem]

[0006] A tire evaluation method according to one embodiment of the present disclosure is a tire evaluation method for evaluating tires mounted on a vehicle that travels autonomously along a course having a predetermined reference path, and includes the steps of acquiring data on the vehicle's travel route and data on a target path that is set while the vehicle is traveling along the reference path, extracting a specific area from the target path data, calculating a positional deviation between the specific area and the vehicle's travel route, and evaluating the tire's ability to follow the vehicle based on the positional deviation. This configuration makes it possible to evaluate the tire's ability to follow vehicle control.

[0007] In one embodiment of the present disclosure, the specific area is defined as a distance range based on the speed of the vehicle from the starting point of the target path in the traveling direction of the vehicle. This configuration allows for the determination of an area that indicates the movement of the vehicle immediately after the direction of the tires is changed by steering the vehicle.

[0008] In one embodiment of the present disclosure, the specific area is defined by dividing the target path and excluding the divided area closest to the starting point of the target path. This configuration makes it possible to easily define a specific region.

[0009] In one embodiment of the present disclosure, the specific area is determined based on the speed of the vehicle. With this configuration, the specific area can be accurately determined even when the vehicle travels along the course while changing speed.

[0010] In one embodiment of the present disclosure, the travel path of the vehicle used to calculate the positional deviation is located in a direction perpendicular to the traveling direction of the vehicle with respect to the specific area. This configuration makes it possible to calculate a positional deviation that better indicates the tire tracking ability, excluding the influence of factors such as acceleration in the traveling direction.

[0011] In one embodiment of the present disclosure, the course is a circular course, and the positional deviation is calculated using the specific area and a travel route of the vehicle in one lap. This configuration allows for more appropriate tire evaluation by driving on a circuit course where the influence of tire tracking is more pronounced than on a straight course, for example.

[0012] A tire evaluation device according to one embodiment of the present disclosure is a tire evaluation device that evaluates tires mounted on a vehicle that travels autonomously along a course having a predetermined reference path, and includes an acquisition unit that acquires data on the vehicle's travel route and data on a target path that is set while the vehicle is traveling so that it passes through the reference path, a specific area extraction unit that extracts a specific area from the target path data, a position deviation calculation unit that calculates the position deviation between the specific area and the vehicle's travel route, and an evaluation unit that evaluates the controllability of the tire with respect to the vehicle based on the position deviation. This configuration makes it possible to evaluate the tire's ability to follow vehicle control. [Effects of the Invention]

[0013] According to the present disclosure, it is possible to provide a tire evaluation method and a tire evaluation device capable of evaluating tire compliance with vehicle control. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a block diagram showing an example of the configuration of a tire evaluation system including a tire evaluation device according to an embodiment of the present disclosure. [Figure 2]FIG. 2 is a plan view showing an example of a course on which the vehicle shown in FIG. 1 travels. [Figure 3] FIG. 3 is a diagram illustrating a reference path and a vehicle travel route in the course of FIG. [Figure 4] FIG. 4 is a diagram for explaining the forward gaze model. [Figure 5] FIG. 5 is a diagram for explaining a specific area in a target path. [Figure 6] FIG. 6 is a diagram illustrating a specific area on the vehicle's travel route and the target path on the course of FIG. [Figure 7] FIG. 7 is a flowchart illustrating the process of a tire evaluation method according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0015] A tire evaluation method and a tire evaluation device according to an embodiment of the present disclosure will be described below with reference to the drawings. In each drawing, identical or corresponding parts are designated by the same reference numerals. In the description of this embodiment, the description of identical or corresponding parts will be omitted or simplified as appropriate.

[0016] 1 is a block diagram showing an example configuration of a tire evaluation system 300 including a tire evaluation device 100 according to an embodiment of the present disclosure. The tire evaluation system 300 includes a vehicle 1 equipped with a tire 7 and a tire evaluation device 100 that evaluates the control tracking capability of the tire 7 relative to the vehicle 1. In this embodiment, the tire evaluation system 300 is described as including one vehicle 1, but the tire evaluation system 300 may include multiple vehicles 1. When the tire evaluation system 300 includes multiple vehicles 1, the tire evaluation device 100 may evaluate tires 7 equipped on each of the multiple vehicles 1.

[0017] First, a description will be given of the configuration of vehicle 1. Vehicle 1 has an automatic driving function and automatically drives along course 200 shown in Fig. 2. Details of course 200 will be described later.

[0018] As shown in Fig. 1, the vehicle 1 includes an engine 2, a power transmission device 3, a steering device 4, a braking device 5, tires 7, a battery 12, and an automatic driving processing unit 13. The automatic driving processing unit 13 includes a vehicle communication unit 8, an on-board sensor 9, a vehicle control unit 10, and a vehicle memory unit 11. The automatic driving processing unit 13 provides an automatic driving function for the vehicle 1. Here, the configuration of the automatic driving processing unit 13 is not limited to the configuration shown in Fig. 1, and may include various configurations for providing the automatic driving function for the vehicle 1.

[0019] The engine 2 is a power source that drives the vehicle 1. The engine 2 is started by power supplied from the battery 12. The vehicle 1 may be provided with a motor as a power source instead of the engine 2. Alternatively, the vehicle 1 may be provided with both the engine 2 and a motor as power sources.

[0020] The power transmission device 3 transmits the power generated by the engine 2 to tires 7. The power transmission device 3 includes a transmission and the like.

[0021] The steering device 4 is a steering device that controls the steering angle of the tires 7 .

[0022] The braking device 5 brakes the tires 7. The braking device 5 includes a brake and the like.

[0023] The battery 12 is, for example, a secondary battery such as a lead-acid battery or a lithium-ion battery. The battery 12 supplies power to a power source such as the engine 2 of the vehicle 1. The battery 12 may also supply power to various electrical or electronic devices mounted on the vehicle 1, including the automatic driving processing unit 13.

[0024] The vehicle communication unit 8 includes a communication module capable of wireless communication. The vehicle communication unit 8 may include, for example, a communication module compatible with mobile communication standards such as 4G (4th Generation) and 5G (5th Generation). The vehicle communication unit 8 may communicate with fixed sensors or the like that are provided around the course 200 and detect information about the course 200. The information about the course 200 may include information about the situation on the course 200 (such as the presence or absence of other vehicles or objects such as obstacles). The fixed sensors may include, for example, a 3D-LiDAR (Light Detection and Ranging) sensor that emits electromagnetic waves such as infrared rays or millimeter waves and detects waves reflected by surrounding objects to three-dimensionally detect surrounding objects and distances to the surrounding objects. The vehicle communication unit 8 may output the received information about the course 200 to the vehicle control unit 10.

[0025] The vehicle communication unit 8 also includes a communication module capable of communicating with external devices including the tire evaluation device 100. In this embodiment, the vehicle communication unit 8 performs wireless communication with the tire evaluation device 100. When the external device includes an on-board device mounted on the vehicle 1, the vehicle communication unit 8 may perform wired communication with the on-board device. The external device may include, for example, a server device, a PC (Personal Computer), a tablet terminal, etc. However, data may be transferred to the external device without using communication.

[0026] Furthermore, the vehicle communication unit 8 outputs driving data of the vehicle 1 driving on the course 200 to at least the tire evaluation device 100. The driving data includes "driving state data" including the speed and acceleration of the vehicle 1, "driving route data" and "target path data." Details of the driving route and target path will be described later.

[0027] The on-board sensor 9 detects information about the vehicle 1. In this embodiment, the information detected by the on-board sensor 9 includes the position, speed, and acceleration of the vehicle 1. The information detected by the on-board sensor 9 may further include information about the surrounding conditions of the vehicle 1. The on-board sensor 9 may acquire information from various meters mounted on the vehicle 1, such as a speedometer, tachometer, fuel meter, and odometer. The on-board sensor 9 may include a GPS sensor that detects the position of the vehicle 1 using a positioning system such as a GPS (Global Positioning System). The on-board sensor 9 may include a speed sensor and an acceleration sensor that detect the speed and acceleration of the vehicle 1 using the GPS. The on-board sensor 9 may include a camera that captures images of the surroundings of the vehicle 1, such as a monochrome camera or a stereo camera. The on-board sensor 9 may include a LiDAR sensor. The on-board sensor 9 outputs the detected information about the vehicle 1 to the vehicle control unit 10.

[0028] The vehicle control unit 10 is one or more processors. The processor may be a general-purpose processor such as a CPU (Central Processing Unit) or a dedicated processor specialized for a specific process. The vehicle control unit 10 may include one or more dedicated circuits. Furthermore, in the vehicle control unit 10, one or more processors may be replaced with one or more dedicated circuits. For example, an FPGA (Field-Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit) may be used as the dedicated circuit.

[0029] The vehicle control unit 10 controls the behavior of the vehicle 1 in an autonomous driving manner by controlling the engine 2, the power transmission device 3, the steering device 4, and the braking device 5. The autonomous driving level may be, for example, level 3-5 defined by the Society of Automotive Engineering (SAE).

[0030] The vehicle control unit 10 acquires detection results from all or some of the on-board sensors 9 and fixed point sensors, and based on the acquired detection results, detects the position of the vehicle 1 and obstacles around the vehicle 1. The vehicle control unit 10 controls the traveling of the vehicle 1 based on the detection results of the position of the vehicle 1 and obstacles around the vehicle 1.

[0031] The vehicle storage unit 11 is one or more memories. The memories may be, for example, semiconductor memories, magnetic memories, optical memories, or the like, but are not limited to these and may be any memories. The vehicle storage unit 11 is accessed by the vehicle control unit 10 via any interface, but may also be configured to be built into the vehicle control unit 10, for example. The vehicle storage unit 11 may store, for example, driving data of the vehicle 1 that is output to the tire evaluation device 100.

[0032] Next, the configuration of the tire evaluation device 100 will be described. As shown in Fig. 1, the tire evaluation device 100 includes a communication unit 101, a storage unit 102, and a control unit 103. The control unit 103 includes an acquisition unit 111, a specific region extraction unit 112, a position deviation calculation unit 113, and an evaluation unit 114. The configuration of the tire evaluation device 100 is not limited to the configuration shown in Fig. 1, and may include various configurations for evaluating the control follow-up ability of the tire 7 with respect to the vehicle 1.

[0033] The communication unit 101 includes a communication module capable of wireless communication. The communication unit 101 may include, for example, a communication module compatible with mobile communication standards such as 4G and 5G. The communication unit 101 receives the above-described traveling data from the vehicle 1. The communication unit 101 may output the traveling data to the control unit 103 or store the traveling data in the memory unit 102 in accordance with a control signal from the control unit 103.

[0034] The storage unit 102 is one or more memories. The memories are, for example, semiconductor memories, magnetic memories, optical memories, etc., but are not limited to these and may be any memories. The storage unit 102 is accessed by the control unit 103 or the like via any interface, but may also be configured to be built into the control unit 103, for example.

[0035] The control unit 103 is one or more processors. The processor may be, for example, a general-purpose processor or a dedicated processor specialized for a specific process, but is not limited to these and may be any processor. The control unit 103 controls the overall operation of the tire evaluation device 100.

[0036] Here, the tire evaluation device 100 may have the following software configuration: One or more programs used to control the operation of the tire evaluation device 100 are stored in the storage unit 102. When the program stored in the storage unit 102 is read by the processor of the control unit 103, it causes the control unit 103 to function as an acquisition unit 111, a specific area extraction unit 112, a positional deviation calculation unit 113, and an evaluation unit 114.

[0037] The acquisition unit 111 acquires data on the driving route of the vehicle 1 and data on a target path that is set while the vehicle 1 is driving so that it follows a reference path. The reference path is a reference route within the course 200 according to the driving scenario of the vehicle 1. The target path is a route for correcting the driving of the vehicle 1 that is set at a predetermined timing so that the vehicle 1 drives along the reference path. The predetermined timing may be, for example, at regular intervals, or when deviation from the reference path becomes greater than a threshold. In this embodiment, the acquisition unit 111 acquires driving data from the vehicle 1, including data on the driving route and data on the target path. As described above, the driving data further includes driving state data, including the speed and acceleration of the vehicle 1.

[0038] The specific area extraction unit 112 extracts a specific area from the target path data acquired by the acquisition unit 111. As will be described in detail later, the specific area is an area that better indicates the tracking ability of the tire 7 compared to other areas of the target path.

[0039] The positional deviation calculation unit 113 calculates the positional deviation between the specific area extracted by the specific area extraction unit 112 and the travel route of the vehicle 1.

[0040] The evaluation unit 114 evaluates the control follow-up ability of the tire 7 with respect to the vehicle 1 based on the positional deviation calculated by the positional deviation calculation unit 113. It can be evaluated that the smaller the positional deviation, the higher the control follow-up ability of the tire 7 with respect to the vehicle 1.

[0041] As described above, the vehicle 1 uses an automatic driving function to automatically drive the course 200. The course 200 is, for example, a circular course for testing the tire 7. FIG. 2 is a plan view showing an example of the course 200 that the vehicle 1 drives to test the tire 7.

[0042] As shown in Fig. 2, the course 200 is a closed circuit course consisting of two straight paths 200a, 200b extending parallel to each other and semicircular curved paths 200c, 200d located at both ends of the straight paths 200a, 200b and connected to connect the ends of the straight paths 200a, 200b. The vehicle 1 travels around the circuit course 200 in a predetermined direction. In the example of Fig. 2, the predetermined direction is counterclockwise.

[0043] The course 200 is divided into multiple sections. For example, the course 200 includes a test section 210 that starts at position P1 and ends at position P2. Positions P1 and P2 are included in a straight road 200a. Therefore, the test section 210 is a straight section. The test section 210 is a section for performing various measurements related to testing of the tire 7. Tests other than tracking of the tire 7 may be performed in the test section 210. For example, the road surface in the test section 210 may be a road surface based on the ISO 10844 standard, and a pass-by noise test may also be performed.

[0044] The course 200 further includes a regulation section 220 , a bank section 230 , and an acceleration section 240 .

[0045] The adjustment section 220 is a section that starts at position P2 and ends at position P3. Position P3 is the location where the straight road 200b and the curved road 200d are connected. The adjustment section 220 is a section of the straight road 200a that includes the section after the test section 210, the curved road 220c, and the straight road 200b. In other words, the adjustment section 220 is a section that connects the end point of the test section 210 and the start point of a banked section 230, which will be described later. In the adjustment section 220, the vehicle 1 is allowed to overtake other vehicles, and other vehicles are allowed to overtake the vehicle 1.

[0046] The bank section 230 is a section that starts at position P3 and ends at position P4. Position P4 is the location where the straight road 200a and the curved road 200d are connected. The bank section 230 has a slope such that the road surface becomes higher from the inner periphery of the curve toward the outer periphery. In other words, the course 200 includes a curved bank section 230 where the road surface is sloped such that the road surface becomes higher from the inner periphery of the curve toward the outer periphery. Due to this slope, the vehicle 1 travels on the outside of the semicircular corner in the bank section 230, utilizing centrifugal force to maintain a constant speed (for example, 60 km / h).

[0047] The acceleration section 240 is a section that starts at position P4 and ends at position P1. In other words, the acceleration section 240 is a section that is connected to the start point (position P1) of the test section 210. In the acceleration section 240, the vehicle control unit 10 accelerates the vehicle 1 to a speed required for entering the test section 210, for example, at a predetermined acceleration rate.

[0048] Next, the control of the behavior of the vehicle 1 by the vehicle control unit 10 will be described.

[0049] The vehicle control unit 10 detects the speed and position of the vehicle 1 based on the detection results of the on-board sensor 9 and the fixed point sensors. The vehicle control unit 10 controls the behavior of the vehicle 1 so that the detected speed and position of the vehicle 1 follow a driving scenario that defines the driving speed and driving route of the vehicle 1 in the tire 7 test.

[0050] FIG. 3 is a diagram illustrating a reference path RP and a travel route SP of the vehicle 1 on the course 200. The travel route SP is the route actually traveled by the vehicle 1, and is obtained by mapping the position of the vehicle 1 detected by the on-board sensor 9 onto map information of the course 200. Because the on-board sensor 9 detects the position of the vehicle 1 at regular time intervals, the position of the vehicle 1 that constitutes the travel route SP is displayed discretely. The vehicle control unit 10 controls the travel of the vehicle 1 so that the travel route SP coincides with the reference path RP.

[0051] Specifically, the vehicle control unit 10 calculates a control value for the steering angle of the vehicle 1 so that the position of the vehicle 1 follows a reference path (i.e., reference path RP) defined in the driving scenario, and controls the steering angle of the vehicle 1 according to the calculated control value. The vehicle control unit 10 also calculates a control value for controlling the acceleration / deceleration of the vehicle 1 so that the speed of the vehicle 1 follows a target driving speed defined in the driving scenario, and controls the acceleration / deceleration of the vehicle 1 according to the calculated control value.

[0052] The method by which the vehicle control unit 10 calculates the control value of the steering angle is not particularly limited, and for example, a forward-gazing model may be used. FIG. 4 is a diagram for explaining the forward-gazing model. In the forward-gazing model, a point a predetermined distance (L in FIG. 4) away from the current position of the vehicle 1 in the traveling direction of the vehicle 1 is set as a gaze point, and the steering angle is controlled based on the lateral deviation (ε in FIG. 4) between this gaze point and the reference path RP. The vehicle control unit 10 controls the steering angle by performing calculations using the forward-gazing model, for example, at predetermined time intervals. For example, in the case of the vehicle 1 traveling at 60 km / h, the predetermined time interval may be set to less than 1 second, for example, 0.5 seconds. The vehicle control unit 10 may adjust the predetermined time interval according to the speed of the vehicle 1. For example, when the speed of the vehicle 1 exceeds 60 km / h, the predetermined time interval may be adjusted to be shorter. Furthermore, the predetermined time interval may be linked to the timing when the on-board sensor 9 detects the position of the vehicle 1, as in this embodiment. In this way, the vehicle control unit 10 controls the steering angle, etc. at predetermined time intervals so that the vehicle 1 follows the reference path RP. The route of the vehicle 1 set by this control so that it heads toward the reference path RP is the target path.

[0053] Here, the control executed by the vehicle control unit 10 can be evaluated based on the degree to which the travel path SP of the vehicle 1, which is determined by the control of the steering angle and acceleration / deceleration of the vehicle 1 by the vehicle control unit 10, matches with the reference path RP. However, the matching between the controlled vehicle 1 and the tires 7 (the tracking ability of the tires 7) cannot be strictly evaluated based only on the coincidence between the travel path SP of the vehicle 1 and the reference path RP. Here, as described above, the target path is set based on the control of the steering angle, etc., by the vehicle control unit 10. The tire evaluation device 100 according to this embodiment evaluates the control tracking ability of the tires 7 with respect to the vehicle 1 by evaluating how the tires 7 move with respect to the target path.

[0054] FIG. 5 is a diagram illustrating a specific region SR on a target path TP. First, the left diagram in FIG. 5 shows a travel route SP of the vehicle 1 on the course 200. The right diagram shows an enlarged portion of the travel route SP, illustrating the target path TP at times t1, t2, and t3. Time t2 is the time when a predetermined time interval has elapsed since time t1. Time t3 is the time when a predetermined time interval has elapsed since time t2. Furthermore, when the course 200 includes a curve, as in this embodiment, the traveling direction of the vehicle 1 changes depending on the position of the vehicle 1. As shown in FIG. 5, the traveling direction of the vehicle 1 during normal traveling is the forward direction, and the direction opposite to the forward direction is the backward direction. Furthermore, the right side of the vehicle 1 during normal traveling is the right side, and the direction opposite to the right side is the left side, which are directions perpendicular to the forward and backward directions of the vehicle 1. Hereinafter, the right side and the left side may be collectively referred to as the left-right direction. Furthermore, the terms traveling direction, forward direction, and left-right direction may be used to describe positional relationships.

[0055] In the example of FIG. 5, the positions (travel path SP) of vehicle 1 at times t1, t2, and t3 are indicated by SP(t1), SP(t2), and SP(t3), respectively. At time t1, vehicle control unit 10 controls the steering angle and acceleration / deceleration to return vehicle 1 from the position SP(t1) to the reference path RP, thereby determining a target path TP(t1). Then, vehicle control unit 10 controls vehicle 1 to move along the target path TP(t1). Similarly, at times t2 and t3, vehicle control unit 10 controls the steering angle and acceleration / deceleration to return vehicle 1 from the positions SP(t2) and SP(t3) to the reference path RP, thereby determining target paths TP(t2) and TP(t3).

[0056] Here, the target path TP can be divided into at least three regions depending on the ease of observing the tracking of the tires 7 in response to steering. Taking the target path TP(t1) in FIG. 5 as an example, TP(t1) includes three regions indicated by A, B, and C.

[0057] Area A is the area closest to SP(t1), where the change in the direction and rotation of the tires 7 due to the steering at time t1 is insufficient and the area is largely influenced by the inertia of the vehicle 1 up to that point. Therefore, the positional deviation between area A of the target path TP(t1) and the driving path SP of the vehicle 1 is largely influenced by factors other than the tracking ability of the tires 7. Therefore, evaluation using area A is not suitable for evaluating the tires 7.

[0058] Area B is an area further forward from area A, and is the area where instantaneous movement occurs after the tire 7 changes due to steering at time t1. In other words, area B is the area where the cornering force generated by steering at time t1 is realized. Therefore, the positional deviation between area B of the target path TP(t1) and the driving path SP of the vehicle 1 becomes smaller if the tracking performance of the tire 7 is high, and becomes larger if the performance is low. In other words, evaluation using area B is suitable for evaluating the tire 7.

[0059] Area C is an area further ahead than area B, and is an area that is affected not only by the steering at time t1, but also by acceleration / deceleration, the inertia of the vehicle 1, and the road surface characteristics over which the vehicle 1 is traveling, all of which are integrated and have an impact. Therefore, the positional deviation between area C of TP(t1) and the vehicle 1's driving path SP is influenced by many factors other than the tire tracking ability of the tire 7, making it difficult to isolate only the influence based on the tire tracking ability. Furthermore, before the vehicle 1 reaches the end of area C, the vehicle control unit 10 may determine a new target path TP(t2), and control of the vehicle 1 may shift to one based on the target path TP(t2). Therefore, evaluation using area C is not suitable for evaluating the tire 7.

[0060] The tire evaluation device 100 extracts the above-mentioned region B as the specific region SR of the target path TP, calculates the positional deviation between the specific region SR and the travel path SP of the vehicle 1, and can evaluate the tire 7 based on the calculated positional deviation. Here, the positional deviation is calculated as the lateral distance (dp in FIG. 5) between the specific region SR and the position of the vehicle 1 (travel path SP) included in the range of the specific region SR in the traveling direction. In other words, the position of the vehicle 1 (travel path SP) used to calculate the positional deviation is located in a direction perpendicular to the traveling direction of the vehicle 1 with respect to the specific region SR. The tire evaluation device 100 calculates the lateral positional deviation excluding the influence of, for example, acceleration that appears significantly in the traveling direction. The positional deviation calculated in this manner better indicates the tracking ability of the tire 7.

[0061] Furthermore, although the travel path SP is shown as a set of discrete vehicle 1 positions, the specific region SR has a width in the travel direction, and therefore it is possible to compare it with the position of any of the vehicles 1. The tire evaluation device 100 can evaluate the tire 7 as having high controllability with respect to the vehicle 1 when the positional deviation between the specific region SR and the travel path SP is small. The tire evaluation device 100 may use one or more threshold values and compare the positional deviation with the threshold values to perform an evaluation that ranks the level of controllability of the tire 7 with respect to the vehicle 1.

[0062] Here, multiple positional deviations between the specific region SR and the travel path SP may be calculated. FIG. 6 is a diagram illustrating an example of the travel path SP of the vehicle 1 on the course 200 and the specific region SR on the target path TP. The tire evaluation device 100 may map multiple specific regions SR extracted from multiple target paths TP onto map information of the course 200, as shown in the right diagram of FIG. 6. Then, for each of the multiple specific regions SR, the positional deviation from the corresponding position of the vehicle 1 (travel path SP) may be calculated. The tire evaluation device 100 may average the multiple positional deviations obtained and evaluate the tire 7 using the average value.

[0063] When the course 200 is a circular course as in this embodiment, it is preferable to calculate the positional deviation using the specific region SR in one lap and the travel path SP of the vehicle 1. This is because, for example, traveling on a circular course, which is more susceptible to the influence of the tracking ability of the tires 7 than on a straight course, allows for a more appropriate evaluation of the tires 7.

[0064] As described above, the tire evaluation device 100 evaluates the tire 7 by extracting the region B as the specific region SR. However, the specific region SR may vary depending on factors such as the speed of the vehicle 1. When the vehicle 1 travels on the test course 200 at a substantially constant speed, as in this embodiment, the tire evaluation device 100 may define the specific region SR as a distance range. More specifically, the tire evaluation device 100 may define the specific region SR as a distance range based on the speed of the vehicle 1 from the starting point of the target path TP. For example, when the speed of the vehicle 1 is approximately 60 km / h, the distance range of the specific region SR in the traveling direction may be 10-α [m] to 10+α [m] from the starting point of the target path TP. α may be determined based on the timing at which the on-board sensor 9 detects the position of the vehicle 1 so that the position of the vehicle 1 falls within the range of the specific region SR in the traveling direction in calculating the positional deviation. This distance may vary depending on the speed of the vehicle 1. In this way, the tire evaluation device 100 can determine a region (specific region SR) that indicates the movement of the vehicle 1 immediately after the direction of the tire 7 is changed by the steering operation of the vehicle 1.

[0065] As another example, the tire evaluation device 100 may define the specific region SR as a region obtained by dividing the target path TP. The tire evaluation device 100 divides the target path TP into three or more regions. The division may or may not be equal. Of the divided regions of the target path TP, the region closest to the starting point of the target path TP corresponds to region A in FIG. 5. Therefore, the tire evaluation device 100 can define the specific region SR using a region excluding the divided region closest to the starting point of the target path TP (corresponding to region A). When defining the specific region SR, the tire evaluation device 100 also excludes a divided region far from the starting point of the target path TP (corresponding to region C). In the closest divided region, the positional deviation from the travel path SP of the vehicle 1 is significantly influenced by factors other than the tracking ability of the tire 7. Therefore, evaluation using this region is not suitable for evaluating the tire 7. Furthermore, in a divided region far from the starting point of the target path TP, the vehicle control unit 10 may determine a new target path TP before the vehicle 1 reaches the end of the region, and control of the vehicle 1 may transition to control based on the new target path TP. Therefore, evaluation using this region is not suitable for evaluating the tire 7. In addition, in the specific region SR, the positional deviation from the vehicle 1's travel path SP becomes smaller if the tire 7 has high tracking performance, and becomes larger if the performance is low. In other words, evaluation using the specific region is suitable for evaluating the tire 7. The tire evaluation device 100 may determine the divided region second closest to the starting point of the target path TP as the specific region SR. The tire evaluation device 100 can easily determine the specific region SR by dividing the target path TP.

[0066] Furthermore, the tire evaluation device 100 may calculate the range of the specific region SR using speed data acquired from the vehicle 1. For example, the specific region SR may correspond to the range in which the vehicle 1 travels a predetermined time after the steering operation of the vehicle 1, and the tire evaluation device 100 may calculate the range of the specific region SR based on the speed of the vehicle 1 and the predetermined time. In this case, the tire evaluation device 100 can accurately determine the specific region SR even when the vehicle 1 travels on the course 200 while changing its speed.

[0067] 7 is a flowchart illustrating the processing of a tire evaluation method according to an embodiment of the present disclosure. The tire evaluation device 100 can evaluate the tracking ability of the tire 7 with respect to vehicle control by executing the processing according to the flowchart of FIG.

[0068] The acquisition unit 111 acquires driving data from the vehicle 1 (step S1). The driving data includes driving state data, driving route SP data, and target path TP data. In this embodiment, the driving data is a plurality of pieces of time-series data stored in the vehicle memory unit 11 while the vehicle 1 makes at least one lap around the course 200. However, the acquisition unit 111 may acquire driving data in real time from the vehicle 1 traveling along the course 200. Furthermore, the acquisition unit 111 may acquire one piece of driving data instead of multiple pieces of data.

[0069] As described above, the driving state data includes the speed and acceleration of the vehicle 1. The driving route SP data is data indicating the actual driving position of the vehicle 1 detected by the on-board sensor 9. The target path TP data is data indicating the route of the vehicle 1 set by the vehicle control unit 10 to head towards the reference path RP.

[0070] The acquisition unit 111 selects the traveling data. Specifically, if the traveling state data satisfies the condition, the acquisition unit 111 selects the traveling data to be used (Yes in step S2). If the traveling state data does not satisfy the condition, the acquisition unit 111 does not use the traveling data and returns to the process of step S1 to acquire the next traveling data (No in step S2). In this embodiment, the traveling state data satisfies the condition when the speed of the vehicle 1 is within a first range and the lateral acceleration of the vehicle 1 is within a second range. The first range is, for example, 57 km / h to 63 km / h, which is a narrow speed range in which the vehicle 1 can be treated as traveling at a substantially constant speed. The second range is, for example, -0.5 G to +0.5 G, which is a wide acceleration range in which the vehicle 1 is expected to turn various curves. Here, G represents gravitational acceleration. By the acquisition unit 111 selecting the traveling data according to the above conditions, it is possible to perform evaluation using only traveling data that is highly influenced by the response of the tires 7.

[0071] As preprocessing, the specific area extraction unit 112 executes a coordinate conversion process for the data of the travel route SP (step S3). The coordinate conversion process converts the coordinates of the data of the travel route SP into coordinates of an orthogonal coordinate system having a coordinate axis pointing forward in the direction of travel from the start point of the vehicle 1 and a coordinate axis pointing left and right. This coordinate conversion process makes it possible to avoid problems such as overlapping of coordinates that arise when the course 200 is a circular course.

[0072] The specific area extraction unit 112 extracts a specific area SR of the data of the target path TP (step S4). The extracted specific area SR may be mapped onto the map information of the course 200, for example, as shown in the right diagram of FIG.

[0073] The specific area extraction unit 112 performs coordinate conversion processing of the specific area SR in the same manner as in step S3 (step S5). By this coordinate conversion processing, the coordinates of the specific area SR are converted into the same coordinate system as the travel route SP, making them comparable.

[0074] The specific region extraction unit 112 may further perform an alignment process for the specific regions SR (step S6). The alignment process is a process of arranging multiple specific regions SR in order from the starting point of the vehicle 1 when there are multiple specific regions SR. Furthermore, the alignment process may include a process of averaging multiple specific regions SR to determine their coordinates when multiple specific regions SR exist at a certain position in the traveling direction from the starting point of the vehicle 1. For example, the alignment process may be performed when the vehicle 1 completes two or more laps around the course 200 and the tire evaluation device 100 collectively acquires the obtained travel data to evaluate the tire 7. By aligning and averaging the travel data obtained from multiple laps, the influence of errors and the like can be reduced, enabling a highly reliable evaluation of the tire 7.

[0075] The positional deviation calculation unit 113 calculates the positional deviation between the specific area SR and the travel route SP (step S7). The positional deviation calculation unit 113 extracts the position of the vehicle 1 (travel route SP) included in the range of the specific area SR in the traveling direction. Then, the positional deviation calculation unit 113 calculates the distance in the left-right direction between the extracted travel route SP and the specific area SR as the positional deviation. If there are multiple specific areas SR, the positional deviation calculation unit 113 calculates the positional deviation for each specific area SR.

[0076] The evaluation unit 114 evaluates the control follow-up ability of the tire 7 relative to the vehicle 1 based on the positional deviation calculated by the positional deviation calculation unit 113 (step S8). The smaller the positional deviation, the higher the evaluation can be that the control follow-up ability of the tire 7 relative to the vehicle 1. When there are multiple specific regions SR, the evaluation unit 114 may perform the evaluation based on an average value or a median value obtained by performing statistical processing. The evaluation unit 114 may perform ranking, etc. by comparing the positional deviation value with a threshold value. The evaluation unit 114 may display the evaluation result on a display device, etc. via the communication unit 101. A user (for example, an operations manager of the vehicle 1) can determine whether to continue or change the tire 7 to be installed based on the displayed evaluation result.

[0077] As described above, the tire evaluation device 100 and tire evaluation method according to this embodiment can evaluate the tracking ability of the tire 7 relative to vehicle control using the above-described configuration and steps. Here, the tire evaluation device 100 and tire evaluation method according to this embodiment can evaluate the control tracking ability of the tire 7 relative to the vehicle 1 without requiring detailed control of the autonomous driving, as long as data such as the target path TP is obtained. Therefore, it is possible to appropriately evaluate the tracking ability of the tire 7 even for a vehicle 1 that performs autonomous driving using a model other than the above-described look-ahead model, or autonomous driving in which information on the timing of acceleration and deceleration is not obtained.

[0078] Although the embodiments of the present disclosure have been described based on the drawings and examples, it should be noted that those skilled in the art would easily be able to make various modifications or alterations based on the present disclosure. Therefore, it should be noted that these modifications and alterations are included within the scope of the present disclosure. For example, functions included in each component or step (process) can be rearranged so as not to cause logical inconsistencies, and multiple components or steps can be combined or divided into one. The embodiments of the present disclosure can also be realized as a program executed by a processor included in an apparatus or a storage medium on which a program is recorded. It should be understood that these are also included within the scope of the present disclosure.

[0079] Furthermore, in the above embodiment, the tire evaluation device 100 has been described as evaluating the tire 7 as part of a tire test, but it may also be used to determine the suitability of the tire 7 for a general autonomous vehicle. For example, the autonomously driven vehicle 1 may be a public transportation system such as a bus that travels along a set route on a public road, rather than along the course 200. Based on the evaluation by the tire evaluation device 100, a tire 7 suitable for the autonomous vehicle, which is public transportation, may be selected.

[0080] Furthermore, in the above-described embodiment, the tire evaluation device 100 acquires data on the target path TP from the vehicle 1, but may calculate the target path TP based on the reference path RP, data on the traveling state, and data on the traveling route SP.

[0081] Furthermore, there is no particular limitation on the configuration of the tire evaluation device 100. For example, the processing executed by the tire evaluation device 100, which is one computer in the above embodiment, may be executed by distributed processing among a plurality of computers. [Explanation of symbols]

[0082] 1 vehicle 2 engines 3 Power transmission device 4 Steering gear 5 Braking device 7 Tires 8 Vehicle Communication Unit 9. In-vehicle sensors 10 Vehicle control unit 11 Vehicle memory unit 12 Battery 13 Autonomous driving processing unit 100 Tire evaluation device 101 Communications Department 102 Storage section 103 Control Unit 111 Acquisition Department 112 Specific area extraction part 113 Position deviation calculation unit 114 Evaluation Department 200 courses 200a, 200b straight road 200c, 200d curved road 210 Test Section 220 Adjustment Section 230 Bank Section 240 Acceleration Section 300 Tire Rating System

Claims

1. A tire evaluation method for evaluating tires mounted on a vehicle that runs autonomously along a course having a predetermined reference path, comprising: acquiring data on a travel route of the vehicle and data on a target path set while the vehicle is traveling so that the vehicle passes through the reference path; extracting a specific area from the target path data; calculating a positional deviation between the specific area and a travel route of the vehicle; and evaluating a control tracking capability of the tire with respect to the vehicle based on the positional deviation, The specific area is defined as a distance range based on the speed of the vehicle from the starting point of the target path in the traveling direction of the vehicle.

2. A tire evaluation method for evaluating tires mounted on a vehicle that runs autonomously along a course having a predetermined reference path, comprising: acquiring data on a travel route of the vehicle and data on a target path set while the vehicle is traveling so that the vehicle passes through the reference path; extracting a specific area from the target path data; calculating a positional deviation between the specific area and a travel route of the vehicle; and evaluating a control tracking capability of the tire with respect to the vehicle based on the positional deviation, A tire evaluation method, wherein the specific area is determined by dividing the target path and excluding the divided area closest to the starting point of the target path.

3. The tire evaluation method according to claim 1 or 2, wherein the travel path of the vehicle used for calculating the positional deviation is located in a direction perpendicular to a traveling direction of the vehicle with respect to the specific area.

4. The course is a circular course, The tire evaluation method according to claim 1 , wherein the positional deviation is calculated using the specific area in one revolution and a travel path of the vehicle.

5. A tire evaluation device for evaluating tires mounted on a vehicle that runs automatically along a course having a predetermined reference path, an acquisition unit that acquires data on a travel route of the vehicle and data on a target path that is set while the vehicle is traveling so that the vehicle passes through the reference path; a specific area extraction unit that extracts a specific area from the target path data; a positional deviation calculation unit that calculates a positional deviation between the specific area and a travel route of the vehicle; an evaluation unit that evaluates a control tracking capability of the tire with respect to the vehicle based on the positional deviation, The specific area is defined as a distance range based on the speed of the vehicle from the starting point of the target path in the traveling direction of the vehicle.

6. A tire evaluation device for evaluating tires mounted on a vehicle that runs automatically along a course having a predetermined reference path, an acquisition unit that acquires data on a travel route of the vehicle and data on a target path that is set while the vehicle is traveling so that the vehicle passes through the reference path; a specific area extraction unit that extracts a specific area from the target path data; a positional deviation calculation unit that calculates a positional deviation between the specific area and a travel route of the vehicle; an evaluation unit that evaluates a control tracking capability of the tire with respect to the vehicle based on the positional deviation, The specific area is determined by dividing the target path and excluding the divided area closest to the starting point of the target path.

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