Road gradient calculation device

Abstract

To accurately and easily calculate a road grade of a road where a vehicle (10) travels.SOLUTION: Time series data of a travel speed and a drive power when a vehicle travels on a road are read, and time series data of a reproduction drive force when the travel speed is reproduced by a chassis dynamometer (50) by using the vehicle are further read. A deviation (drive force deviation) between the read drive force and the reproduction drive force is calculated, and the drive force deviation is converted to a road grade by referencing a correspondence between the drive force deviation and the road grade. When reproducing the travel speed in the chassis dynamometer, if a road grade of the chassis dynamometer is set to a grade of 0, the drive force deviation corresponds to the road grade. Accordingly, by converting the drive force deviation to the road grade, the road grade of the road where the vehicle travels can be accurately and easily calculated.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a technique for calculating the road gradient of a road on which a vehicle has traveled.

Background Art

[0002] There are various performances required for a vehicle, such as power performance, fuel consumption performance, and exhaust gas performance. Among these performances, there are many that have a relationship (so-called antinomy relationship) in which when one is improved, the other deteriorates, and when the other is improved, the one deteriorates. For example, the power performance and the exhaust gas performance. And since it is difficult to improve these performances at the same time, it is important to balance these performances at as high a level as possible.

[0003] In order to balance the performances required for a vehicle, it is necessary to grasp the actual usage of the vehicle (for example, driving speed, acceleration, and their time changes). And since the driving speed, acceleration, etc. of the vehicle are greatly affected by the road gradient, it is necessary to measure the road gradient as accurately as possible.

[0004] As a technique for measuring the road gradient, there are proposed techniques such as a technique (Patent Document 1) for acquiring vehicle position information (latitude, longitude, altitude) using a satellite positioning system such as GPS and detecting the road gradient from the change in altitude, and a technique (Patent Document 2) for accurately measuring the atmospheric pressure during driving, converting the atmospheric pressure into the altitude of the vehicle, and calculating the road gradient from the change in altitude.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, the proposed technology had a problem that the road gradient could not be accurately and easily measured. For example, in the method using a satellite positioning system, the altitude accuracy tends to be lower than the latitude and longitude, and it is difficult to calculate an accurate road gradient using the low-accuracy altitude. Also, in the method using the atmospheric pressure measured during driving, the change in the measured value tends to lag behind the change in the atmospheric pressure, so the road gradient tends to be calculated on the lower side. Furthermore, since it is easily affected by disturbances due to weather conditions, it is difficult to calculate an accurate road gradient. Of course, it is possible to calculate the road gradient by measuring the change in the altitude of the road using surveying techniques, but this requires a great deal of effort, so it is hard to say that it is a simple method.

[0007] This invention was made to solve the above-described problems of the conventional technology, and an object thereof is to provide a technology capable of accurately and easily calculating the road gradient of the road on which the vehicle has traveled.

Means for Solving the Problem

[0008] In order to solve the above-described problems, the First road gradient calculation device of the present invention adopts the following configuration. That is, a road gradient calculation device for calculating the road gradient of the road on which the vehicle has traveled, a running data reading unit that reads, in time series, the running speed when the vehicle travels on the road and the driving force generated by the vehicle; a reproduction data reading unit that reads, in time series, the reproduction driving force, which is the driving force generated by the vehicle when the running speed is reproduced using the vehicle on a chassis dynamometer; a driving force deviation calculation unit that calculates a driving force deviation, which is the deviation between the driving force and the reproduction driving force; a road gradient conversion unit that converts the driving force deviation into the road gradient by referring to the correspondence relationship between the driving force deviation and the road gradient stored in advance 、 A gradient data reading unit that reads, in time series, the traveling speed of the vehicle, the gradient driving force that is the driving force of the vehicle, and the road gradient while changing the road gradient on the chassis dynamometer capable of setting the road gradient; A gradient-free data reading unit that reads, in time series, the gradient-free driving force that is the driving force of the vehicle when reproducing the traveling speed with the road gradient set to 0 on the chassis dynamometer; A gradient presence / absence driving force deviation calculation unit that calculates a gradient presence / absence driving force deviation that is a deviation between the gradient driving force and the gradient-free driving force; A correspondence relationship generation unit that generates a correspondence relationship between the gradient presence / absence driving force deviation and the road gradient by organizing the gradient presence / absence driving force deviation with respect to the road gradient is provided with The road gradient conversion unit converts the driving force deviation into the road gradient by referring to the correspondence relationship generated by the correspondence relationship generation unit characterized by comprising

[0009] In such a road gradient acquisition device of the present invention First time-series data of the traveling speed and driving force when the vehicle travels on a road are read, and further, time-series data of the reproduced driving force, which is the driving force when the traveling speed is reproduced on a chassis dynamometer using the vehicle, are also read. Then, a driving force deviation, which is the deviation between the read driving force and the reproduced driving force, is calculated, and the driving force deviation is converted into a road gradient by referring to the correspondence relationship between the driving force deviation and the road gradient stored in advance. Also, the correspondence relationship to be referred to at this time is generated as follows. First, on a chassis dynamometer capable of setting the road gradient, by driving the vehicle while changing the road gradient, time-series gradient data measuring the traveling speed of the vehicle, the gradient driving force that is the driving force of the vehicle, and the road gradient is read. Next, time-series gradient-free data measuring the gradient-free driving force that is the driving force of the vehicle when reproducing the traveling speed with the road gradient set to 0 on the chassis dynamometer is read. Then, a gradient presence / absence driving force deviation that is a deviation between the read gradient driving force and the gradient-free driving force is calculated, and a correspondence relationship between the gradient presence / absence driving force deviation and the road gradient is generated by organizing the obtained gradient presence / absence driving force deviation with respect to the road gradient.

[0010] When reproducing the traveling speed of the vehicle on a road on a chassis dynamometer, if the road gradient of the chassis dynamometer is set to gradient 0, the deviation (i.e., the driving force deviation) between the driving force when the vehicle travels on the road and the reproduced driving force when the traveling speed is reproduced on the chassis dynamometer is considered to correspond to the road gradient of the road on which the vehicle travels. Therefore, if the correspondence relationship between the driving force deviation and the road gradient is obtained in advance and the driving force deviation is converted into a road gradient by referring to this correspondence relationship, it becomes possible to accurately and easily calculate the road gradient of the road on which the vehicle travels. In addition, since the correspondence relationship referred to when converting the driving force deviation into the road gradient is a correspondence relationship generated based on the results measured by actually driving the vehicle, a correspondence relationship reflecting a plurality of factors (for example, vehicle weight, friction inside the vehicle, motor efficiency, etc.) that affect the relationship between the driving force deviation and the road gradient can be obtained. For this reason, it becomes possible to calculate a more accurate road gradient.

[0011] Also, in order to solve the above-described problems, the second road gradient calculation device of the present invention employs the following configuration. That is, A road gradient calculation device that calculates the road gradient of the road on which the vehicle has traveled A running data reading unit that reads, in time series, the running speed when the vehicle travels on the road and the driving force generated by the vehicle; A reproduction data reading unit that reads, in time series, the reproduction driving force, which is the driving force generated by the vehicle when the running speed is reproduced using the vehicle on a chassis dynamometer; A driving force deviation calculation unit that calculates a driving force deviation, which is the deviation between the driving force and the reproduction driving force; A road gradient conversion unit that converts the driving force deviation into a road gradient by referring to the correspondence relationship between the driving force deviation and the road gradient stored in advance; A standard data reading unit that reads, in time series, the standard running speed, which is the running speed when the vehicle travels on a standard road with a known road gradient, and the standard driving force, which is the driving force of the vehicle; A reproduction standard data reading unit that reads, in time series, the reproduction standard driving force, which is the driving force of the vehicle when the standard running speed is reproduced using the vehicle on the chassis dynamometer with the road gradient set to 0; A standard driving force deviation calculation unit that calculates a standard driving force deviation, which is the deviation between the standard driving force and the reproduction standard driving force; A correspondence relationship generation unit that generates a correspondence relationship between the standard driving force deviation and the road gradient by arranging the standard driving force deviation with respect to the road gradient of the standard road; It is provided with: The road gradient conversion unit converts the driving force deviation into a road gradient by referring to the correspondence relationship generated by the correspondence relationship generation unit. This is the feature.

[0012] In such a second road gradient acquisition device of the present invention, time series data of the running speed and the driving force when the vehicle travels on the road are read. Further, time series data of the reproduction driving force, which is the driving force when the running speed is reproduced using the vehicle on a chassis dynamometer, are also read. Then, a driving force deviation, which is the deviation between the read driving force and the reproduction driving force, is calculated, and the driving force deviation is converted into a road gradient by referring to the correspondence relationship between the driving force deviation and the road gradient stored in advance. Also, the correspondence relationship to be referred to at this time is generated as follows. First, by driving a vehicle on a standard road with a known road gradient, time-series standard data is read, which includes the standard driving speed that is the driving speed of the vehicle and the standard driving force that is the driving force of the vehicle. Next, time-series reproduced standard data is read, which is the driving force of the vehicle when reproducing the standard driving speed with the road gradient set to 0 on a chassis dynamometer. Then, a standard driving force deviation that is the deviation between the read standard driving force and the reproduced standard driving force is calculated, and the obtained standard driving force deviation is organized with respect to the road gradient of the standard road to generate a correspondence relationship between the driving force deviation and the road gradient.

[0013] By doing so, an accurate correspondence relationship between the driving force deviation and the road gradient can be obtained without using a chassis dynamometer capable of changing the road gradient during vehicle driving, so that the road gradient can be accurately calculated.

[0017] Also, in the road gradient calculation device of the present invention described above, when traveling on a road with an electric vehicle driven by the power of a motor, it is also possible to read the current value charged and discharged from the battery of the electric vehicle to the motor during travel as the driving force of the vehicle.

[0018] Since the torque generated by the motor is determined by the current value supplied to the motor, in this way, it becomes possible to measure the driving force more simply than the method of directly measuring the driving force by installing a torque sensor on the vehicle axle of the vehicle.

Brief Explanation of Drawings

[0019]

Figure 1

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Mode for Carrying Out the Invention

[0020] FIG. 1 is an explanatory diagram showing a rough structure of the road gradient calculation device 100 of the present embodiment. As shown in FIG. 1, the road gradient calculation device 100 of the present embodiment is a so-called microcomputer configured by a CPU, a memory, an input / output port, and the like. As is well known, a microcomputer can realize various functions by executing a program stored in the memory, but the road gradient calculation device 100 of the present embodiment can calculate the road gradient of the road on which the vehicle 10 has traveled by processing the data measured by the vehicle 10.

[0021] In calculating the road gradient, various functions of the microcomputer are combined and used. Focusing on these functions, it can be considered that the road gradient calculation device 100 includes a driving data reading unit 101, a storage unit 102, a driving data output unit 103, a reproduction data reading unit 104, a driving force deviation calculation unit 105, a road gradient conversion unit 106, a correspondence relationship generation unit 107, and so on. Note that these "units" conceptually represent the functions realized inside the road gradient calculation device 100 for calculating the road gradient, and do not necessarily indicate that devices corresponding to these "units" are installed inside the road gradient calculation device 100. In reality, these "units" may be realized software-wise by a program, may be realized hardware-wise using a dedicated IC chip or the like, or may even be realized by a combination of these.

[0022] The driving data reading unit 101 realizes the function of reading the time-series data of the driving speed and the driving force when the vehicle 10 travels on the road. Note that the data of the driving speed only needs to be data that can be converted into the driving speed, and does not necessarily have to be the data of the driving speed itself. For example, it may be the data of the frequency of the pulse output each time the tire of the vehicle 10 rotates by a predetermined angle. Also, regarding the data of the driving force, it only needs to be data that can be converted into the driving force, and does not necessarily have to be the data of the driving force itself. In this embodiment, as the vehicle 10, an electric vehicle that travels by the driving force of a motor is used, and the driving force of the motor is determined by the current value supplied to the motor (accurately, the electric power obtained by multiplying the voltage value). From this, as the data indicating the driving force of the vehicle 10, the current value or the electric power supplied to the motor can also be used. Furthermore, for example, a torque sensor mounted on the axle may be used to measure the driving torque.

[0023] As shown in Fig. 1, the vehicle 10 used in this embodiment is equipped with a motor 11 and a battery 12 that supplies power to the motor 11, and travels by transmitting the driving force generated by the motor 11 to the tire 10t. The voltage of the battery 12 is supplied to the motor 11 via a constant voltage circuit 13, and an ammeter 14 for detecting the current value supplied to the motor 11 is mounted downstream of the constant voltage circuit 13. The vehicle 10 is also equipped with a vehicle speed sensor 15 for detecting the traveling speed of the vehicle 10, and the outputs of the ammeter 14 and the vehicle speed sensor 15 are input to a data collection device 16. The data collection device 16 has a function of acquiring and storing data at a predetermined time interval. Therefore, while the vehicle 10 travels on the road, the data collection device 16 stores the current value of the ammeter 14 and the traveling speed of the vehicle speed sensor 15, making it possible to store the time-series traveling data of the vehicle 10.

[0024] The traveling data reading unit 101 of the road gradient calculation device 100 reads the traveling data (i.e., traveling speed and driving force) stored in the data collection device 16 directly from the data collection device 16 or via a storage medium, and then stores it in the storage unit 102. In this embodiment, as data indicating the driving force, the current value supplied to the motor 11 is read.

[0025] The traveling data output unit 103 realizes a function of reading out the traveling speed data from the traveling data stored in the storage unit 102 and outputting it to the outside. If the traveling speed data output by the traveling data output unit 103 is supplied to the driving robot 20 mounted on the vehicle 10, the state when the vehicle 10 travels on the road can be reproduced. The time-series data of the traveling speed and current value at that time are also stored using the data collection device 16.

[0026] The reproduced data reading unit 104 realizes a function of reading the traveling data (hereinafter referred to as reproduced data) when the driving of the vehicle 10 is reproduced by the driving robot 20 directly from the data collection device 16 or via a storage medium, and then storing it in the storage unit 102.

[0027] The driving force deviation calculation unit 105 reads the driving data and reproduction data stored in the storage unit 102, and realizes the function of calculating the deviation between the driving force in the driving data and the driving force in the reproduction data (hereinafter referred to as the driving force deviation). As described above, since the driving data and the reproduction data are time-series data at a predetermined time interval, the driving force deviation calculated by the driving force deviation calculation unit 105 is also time-series data.

[0028] When the road gradient conversion unit 106 acquires the driving force deviation calculated by the driving force deviation calculation unit 105, it refers to the correspondence relationship prestored in the storage unit 102, converts the driving force deviation into a road gradient, and then stores it in the storage unit 102. The reason why the driving force deviation can be converted into a road gradient and the correspondence relationship referred to in the conversion will be described in detail later. Also, the method of generating the correspondence relationship will be described in detail later.

[0029] Since the driving force deviation is data that changes with the passage of time, the road gradient is also data that changes with the passage of time, and this change in the road gradient represents how the road gradient changes as the vehicle 10 travels on the road. From this, in the road gradient calculation device 100 of this embodiment, by reading the driving data when the vehicle 10 travels on the road and executing the processing described later, it is possible to calculate the road gradient on the route traveled by the vehicle 10.

[0030] Figure 2 is a flowchart of the road gradient calculation process executed by the road gradient calculation device 100 of this embodiment. Hereinafter, specific procedures for calculating the road gradient will be described according to this flowchart.

[0031] As shown in FIG. 2, in the road gradient calculation process, first, the vehicle 10 travels on the road for which the road gradient is to be calculated, and the driving data (that is, the driving speed and driving force) obtained at that time is read (STEP10). For example, while the vehicle 10 travels on the route indicated by the broken line from the starting point S to the destination G shown in FIG. 3, the driving speed and driving force of the vehicle 10 are acquired in time series, and the driving data obtained at that time is read into the road gradient calculation device 100. By mounting the road gradient calculation device 100 on the vehicle 10, the driving data may be read while the vehicle 10 is traveling, or the data collection device 16 may be mounted on the vehicle 10 to store the driving data, and after the driving is completed, the driving data may be read directly from the data collection device 16 or via a recording medium.

[0032] FIG. 4 is an explanatory diagram showing the driving data obtained when the vehicle 10 travels from the starting point S to the destination G. FIG. 4(a) shows how the driving speed changes with the passage of time, and FIG. 4(b) shows how the driving force changes. As described above, in this embodiment, as data representing the driving force, the current value supplied from the battery 12 to the motor 11 is measured. However, in FIG. 4(b), it is displayed in kW, which is the unit of electric power obtained by multiplying the measured current value by the supply voltage to the motor 11.

[0033] After reading the driving data as shown in FIG. 4, this time, the vehicle 10 is mounted on the chassis dynamometer, and the driving data is output to the driving robot 20 mounted on the vehicle 10. Then, the driving robot 20 operates the accelerator pedal and brake pedal of the vehicle 10 to control the driving speed of the vehicle 10 to match the driving speed indicated by the driving data. By doing so, it is possible to reproduce on the chassis dynamometer how the driving speed changes when the vehicle 10 travels from the starting point S to the destination G.

[0034] FIG. 5 shows a state where the change in the traveling speed of the vehicle 10 is reproduced on the chassis dynamometer 50. The chassis dynamometer 50 includes a traveling roller 51 on which the tire 10t of the vehicle 10 is placed, a load control device 52 that controls the rotational load of the traveling roller 51, and the like. As shown in the figure, with the tire 10t of the driving wheels (front wheels in the illustrated example) of the vehicle 10 placed on the traveling roller 51 and the tire 10t of the non-driving wheels (rear wheels in the illustrated example) fixed by the wheel stopper 53, the vehicle 10 can be made to travel on the traveling roller 51 by rotating the driving wheels.

[0035] However, even when traveling on the traveling roller 51, the vehicle 10 is stationary, so no traveling resistance due to the inertia or air resistance of the vehicle 10 occurs. By controlling the rotational load of the traveling roller 51 to be equivalent to the load corresponding to these traveling resistances, the same situation as when actually traveling on a road can be reproduced. The rotational speed of the traveling roller 51 is input to the load control device 52, and the load control device 52 can control the rotational load of the traveling roller 51 according to the rotational speed. Also, although not shown in FIG. 5, it is also possible to reproduce the traveling wind by placing a blower in front of the vehicle 10 and blowing air at a wind speed corresponding to the traveling speed. Furthermore, by adjusting the rotational load of the traveling roller 51, it is also possible to reproduce a state where the vehicle 10 is traveling on an uphill road or a downhill road.

[0036] In STEP 11 of FIG. 2, the vehicle 10 that has measured the traveling data illustrated in FIG. 4 is mounted on the chassis dynamometer 50, and the traveling data is supplied to the driving robot 20 mounted on the vehicle 10, thereby causing the driving robot 20 to reproduce the traveling speed in the traveling data. As described above, although the chassis dynamometer 50 can also set the road gradient, the road gradient is set to 0. Then, the traveling speed and the driving force (in this embodiment, the current value supplied from the battery 12 to the motor 11) at this time are measured.

[0037] In STEP 12 of FIG. 2, the running data (i.e., the reproduction data) when the running speed of the vehicle 10 is reproduced on the chassis dynamometer 50 in this way is read. Here, when the running data read in STEP 10 is compared with the reproduction data read in STEP 12, there is no significant difference in the running speed between the running speed in the running data and the running speed in the reproduction data. This is natural because the running speed in the reproduction data reproduces the running speed in the running data. However, there is a clear difference between the driving force (the current value supplied to the motor 11 in this embodiment) in the running data and the reproduction data. Hereinafter, the driving force of the reproduction data is referred to as the "reproduced driving force".

[0038] FIG. 6 is an explanatory diagram showing the difference in the driving force between when running on an actual road (during actual road running) and when reproduced on the chassis dynamometer 50 (during CDM running). In FIG. 6, the part where the driving force is a positive value represents the state where the motor 11 drives the tire 10t, and the part where the driving force is a negative value represents the state where the motor 11 is driven by the tire 10t. Also, in FIG. 6, the range of the elapsed time from 20 seconds to 40 seconds (the range surrounded by the thin broken line in FIG. 4(b)) is enlarged and displayed. Furthermore, also in FIG. 6, the driving force is displayed in kW, which is the unit of power obtained by multiplying the current value by the supply voltage.

[0039] The solid line shown in FIG. 6 represents the driving force during actual road running, and the broken line in FIG. 6 represents the driving force during CDM running (i.e., the reproduced driving force). For example, in the time period from 22 to 23 seconds of the elapsed time in FIG. 6, the driving force during actual road running is greater than the reproduced driving force during CDM running. Also, in the time period from 24 to 25 seconds of the elapsed time, the driving force during actual road running is smaller than the reproduced driving force during CDM running.

[0040] Since there is no significant difference in the driving speed between actual road driving and CDM driving, it is considered that such a difference in driving force is due to the fact that the chassis dynamometer 50 sets the road gradient to 0 despite the presence of a gradient on the road where the vehicle 10 actually traveled. That is, when the road actually traveled is an uphill gradient, a greater driving force is required than when traveling on a road with a gradient of 0. Conversely, when the road actually traveled is a downhill gradient, it is possible to drive with a smaller driving force than when traveling on a road with a gradient of 0. From this, it is considered that the fact that the driving force during actual road driving is greater than the reproduced driving force during CDM driving indicates that the road actually traveled was an uphill gradient. Conversely, the fact that the driving force during actual road driving is smaller than the reproduced driving force during CDM driving is considered to indicate that the road actually traveled was a downhill gradient. Also, the magnitude of the difference in driving force corresponds to the magnitude of the road gradient, and it is considered that the greater the difference in driving force, the greater the road gradient. Therefore, if the correspondence relationship between the difference in driving force and the road gradient is obtained in advance, it becomes possible to convert the difference in driving force into the road gradient by referring to this correspondence relationship.

[0041] Therefore, in STEP13 of FIG. 2, the driving force deviation is calculated by subtracting the reproduced driving force during CDM driving from the driving force during actual road driving. Then, the driving force deviation is converted into the road gradient by referring to the correspondence relationship between the driving force deviation and the road gradient obtained in advance (STEP14). FIG. 7 illustrates the correspondence relationship between the driving force deviation and the road gradient. Although the method for obtaining the correspondence relationship will be described later, once all the driving force deviations obtained in STEP13 are converted into the road gradient, it means that the road gradients of all the routes indicated by the broken lines in FIG. 2 have been obtained, so the road gradient calculation process in FIG. 2 is terminated.

[0042] Also, the correspondence relationship illustrated in FIG. 7 can be estimated from the weight of the vehicle 10, but in this embodiment, it is set by an experimental method using the vehicle 10 as follows. FIG. 8 is a flowchart of the process for generating the correspondence relationship between the driving force deviation and the road gradient. This process is executed by the road gradient calculation device 100.

[0043] As shown in FIG. 8, in the correspondence relationship generation process, first, the gradient data measured in advance is read (STEP50). Here, the gradient data is time-series data of the traveling speed, the driving force of the vehicle 10, and the road gradient measured by changing the setting of the road gradient of the chassis dynamometer 50 while the vehicle 10 is running on the chassis dynamometer 50. The gradient data is measured using the data collection device 16 mounted on the vehicle 10, and the traveling data reading unit 101 of the road gradient calculation device 100 reads it directly from the data collection device 16 or indirectly via a recording medium. Therefore, the traveling data reading unit 101 of the road gradient calculation device 100 also corresponds to the "gradient data reading unit" in the present invention. Further, the driving force of the gradient data read by the traveling data reading unit 101 corresponds to the "gradient driving force" in the present invention.

[0044] In addition, in this embodiment, the driving robot 20 is mounted on the vehicle 10 on the chassis dynamometer 50, the pattern of the traveling speed illustrated in FIG. 9(a) is supplied to the driving robot 20 to run the vehicle 10, and the road gradient of the chassis dynamometer 50 is changed in the pattern illustrated in FIG. 9(b), thereby obtaining the gradient data.

[0045] As described above, in this embodiment, it is assumed that the change pattern of the traveling speed and the change pattern of the road gradient are determined in advance, but it is not always necessary to determine the change patterns of the traveling speed and the road gradient. For example, while changing the road gradient of the chassis dynamometer 50 in a predetermined pattern, the vehicle 10 is freely accelerated and decelerated on the chassis dynamometer 50, and the traveling speed, driving force, and, if necessary, the road gradient of the vehicle 10 at that time are measured, so that the gradient-added data may be obtained. Alternatively, while controlling the traveling speed of the vehicle 10 to be in a predetermined traveling speed pattern, the road gradient of the chassis dynamometer 50 is freely changed, and in addition to the traveling speed and driving force of the vehicle 10 at that time, the road gradient set on the chassis dynamometer 50 is measured, so that the gradient-added data may be obtained. Further, while freely changing the road gradient of the chassis dynamometer 50, the vehicle 10 is freely accelerated and decelerated on the chassis dynamometer 50, and the traveling speed, driving force, and the road gradient set on the chassis dynamometer 50 of the vehicle 10 at that time are measured, so that the gradient-added data may be obtained.

[0046] In STEP50 of the correspondence relationship generation process shown in FIG. 8, when the gradient-added data acquired by the above method is read, subsequently, the gradient-free data is read (STEP51). The gradient-free data is the time-series data of the driving force obtained when the traveling speed of the gradient-added data is reproduced using the vehicle 10 on the chassis dynamometer 50 with the road gradient of the chassis dynamometer 50 set to 0. The gradient-free data is also obtained by mounting the driving robot 20 on the vehicle 10 on the chassis dynamometer 50 and measuring the driving force and, if necessary, the traveling speed using the data collection device 16 while the driving robot 20 reproduces the traveling speed pattern illustrated in FIG. 9(a).

[0047] Still, the gradientless data is read by the reproduction data reading unit 104 of the road gradient calculation device 100 directly from the data collection device 16 or indirectly via a recording medium. Therefore, the reproduction data reading unit 104 of the road gradient calculation device 100 also corresponds to the "gradientless data reading unit" in the present invention. Also, the driving force of the gradientless data read by the reproduction data reading unit 104 corresponds to the "gradientless driving force" in the present invention.

[0048] Thus, after reading the gradient data and the gradientless data (STEP50, STEP51), the gradient presence / absence driving force deviation is calculated by subtracting the driving force of the gradientless data (gradientless driving force) from the driving force of the gradient data (gradient driving force) (STEP52). Still, the calculation of the gradient presence / absence driving force deviation is realized by the driving force deviation calculation unit 105 of the road gradient calculation device 100. Therefore, the driving force deviation calculation unit 105 of the road gradient calculation device 100 also corresponds to the "gradient presence / absence driving force deviation calculation unit" in the present invention.

[0049] Since the gradient driving force and the gradientless driving force change in value over time, the gradient presence / absence driving force deviation also changes in value over time. And this change is considered to be caused by the road gradient set in the chassis dynamometer 50 being changed over time. Therefore, when creating a scatter diagram of the gradient presence / absence driving force deviation that changes over time and the road gradient, the scatter diagram shown in FIG. 10 is obtained. When approximating this distribution with a straight line passing through the origin, a dashed straight line can be obtained, and this straight line can be considered to show the road gradient with respect to the driving force deviation. Therefore, by obtaining the dashed straight line from the scatter diagram shown in FIG. 10, the correspondence relationship between the driving force deviation and the road gradient can be generated. The function of obtaining the dashed straight line from the scatter diagram shown in FIG. 10 is realized by the road gradient conversion unit 106 of the road gradient calculation device 100. In STEP53 of FIG. 8, the correspondence relationship generated in this way is stored in the storage unit 102 shown in FIG. 1, and the correspondence relationship generation process is terminated.

[0050] As described in detail above, in the road gradient calculation device 100 of the present embodiment, time-series data of the traveling speed and driving force when the vehicle 10 travels on an actual road is stored, and the traveling speed is reproduced by the driving robot 20 on the chassis dynamometer 50, so that the road gradient that changes moment by moment as the vehicle 10 travels on the road can be calculated. Therefore, compared with the case where the road gradient is calculated using a satellite positioning system or changes in atmospheric pressure, local changes in the road gradient can also be calculated.

[0051] Also, as described above with reference to FIG. 6, in the present embodiment, on the premise that the deviation (driving force deviation) between the driving force of the vehicle 10 during actual road travel and the reproduced driving force of the vehicle 10 when reproducing actual road travel on the chassis dynamometer 50 is due to the road gradient, the road gradient is calculated from the driving force deviation. Therefore, the reproduction accuracy when reproducing actual road travel on the chassis dynamometer 50 greatly affects the accuracy of the calculated road gradient. However, in the present embodiment, sufficient reproduction accuracy can be ensured by reproducing the traveling speed during actual road travel using the driving robot 20.

[0052] FIG. 11 is an explanatory diagram showing an example when the driving robot 20 mounted on the vehicle 10 reproduces the traveling speed during actual road travel. In FIG. 11, the traveling speed indicated by the thin solid line is shown as the thick solid line, which is the result of reproduction using the driving robot 20. Also, for reference, the result of reproduction when a human drives the vehicle 10 is shown as the thick dashed line.

[0053] When reproduced using the driving robot 20 or by a human, the change in the target speed is reproduced as a whole. However, as shown by enlarging a part in the figure, when reproduced by a human, the deviation from the target speed is greater than when reproduced by the driving robot 20. In order to improve this speed deviation, extra acceleration and deceleration occur in the reproduction by a human. In addition, when reproduced by a human, large variations occur each time of reproduction, while when reproduced by the driving robot 20, almost no variation occurs. Furthermore, in the case of the driving robot 20, it is also possible to further improve the reproduction accuracy of the target speed by improving the logic for reproducing the target speed. Thus, by using the driving robot 20, the traveling speed when actually driving on the road using the vehicle 10 can be reproduced with sufficient accuracy. For this reason, in this embodiment, it becomes possible to accurately calculate the road gradient.

[0054] In addition, in this embodiment, the correspondence relationship between the driving force deviation and the road gradient is experimentally obtained by actually driving the vehicle 10. Therefore, it is possible to obtain a correct correspondence relationship considering a plurality of factors that affect the correspondence relationship between the driving force deviation and the road gradient, such as the actual weight of the vehicle 10, the loss due to friction inside the vehicle 10, and the efficiency of the motor 11. And by referring to such a correspondence relationship and converting the driving force deviation into the road gradient, it becomes possible to calculate the accurate road gradient.

[0055] Note that the gradient data read in STEP50 of the correspondence relationship generation process of this embodiment shown in FIG. 8 has been described as data measured by changing the road gradient setting while driving the vehicle 10 on the chassis dynamometer 50 (see FIG. 9). However, actually, even without using the data measured by changing the road gradient setting with the chassis dynamometer 50, it is possible to generate the correspondence relationship between the driving force deviation and the road gradient as shown in FIG. 7.

[0056] For example, the road gradient is measured using surveying techniques, and the road is set as a standard road. Then, the correspondence relationship can also be generated by using the driving data when the vehicle 10 travels on the standard road. In the following, a method for generating the correspondence relationship between the driving force deviation and the road gradient using the driving data (hereinafter referred to as standard data) obtained by traveling on such a standard road will be described.

[0057] FIG. 12 is a flowchart of the correspondence relationship generation process of a modified example for generating the correspondence relationship using standard data. This process is also realized by the road gradient calculation device 100 shown in FIG. 1, similar to the correspondence relationship generation process of FIG. 8 described above.

[0058] In order to start the correspondence relationship generation process of the modified example, it is necessary to prepare standard data in advance. As described above, the standard data is driving data obtained by measuring the driving speed and driving force in time series while the vehicle 10 travels on a standard road with a known road gradient. For example, the road gradient on the path indicated by the dashed-dotted line in FIG. 3 can be obtained by surveying, and the standard data can be obtained by traveling on this path as a standard road with the vehicle 10. The standard data is measured using the data collection device 16 mounted on the vehicle 10, and the driving data reading unit 101 of the road gradient calculation device 100 reads it directly from the data collection device 16 or indirectly via a recording medium. Therefore, the driving data reading unit 101 of the road gradient calculation device 100 also corresponds to the "standard data reading unit" in the present invention. Further, the driving force of the gradient-added data read by the driving data reading unit 101 corresponds to the "standard driving force" in the present invention.

[0059] In STEP60 of the correspondence relationship generation process of the modified example shown in FIG. 12, when the standard data obtained by the above method is read, subsequently, the reproduced standard data is read (STEP61). The reproduced standard data is time-series data of the driving force obtained when the driving speed of the standard data is reproduced using the vehicle 10 on the chassis dynamometer 50 with the road gradient of the chassis dynamometer 50 set to 0. The reproduced standard data is obtained by mounting the driving robot 20 on the vehicle 10 on the chassis dynamometer 50 and reproducing the driving speed of the standard data using the driving robot 20.

[0060] In addition, the reproduced standard data is read by the reproduced data reading unit 104 of the road gradient calculation device 100 directly from the data collection device 16 or indirectly via a recording medium. Therefore, the reproduced data reading unit 104 of the road gradient calculation device 100 also corresponds to the "reproduced standard data reading unit" in the present invention. Also, the driving force of the reproduced standard data read by the reproduced data reading unit 104 corresponds to the "reproduced standard driving force" in the present invention.

[0061] Then, the standard driving force deviation is calculated by subtracting the driving force of the reproduced standard data from the driving force of the standard data (STEP62). In addition, the calculation of the standard driving force deviation is realized by the driving force deviation calculation unit 105 of the road gradient calculation device 100. Therefore, the driving force deviation calculation unit 105 in the present embodiment also corresponds to the "standard driving force calculation unit" in the present invention.

[0062] The deviation between the driving force of the standard data and the reproduction driving force of the reproduced standard data (i.e., the standard driving force deviation) is considered to be due to the presence or absence of a road gradient. Further, when the road gradient is 0, it is considered that the difference in driving force between the standard data and the reproduced standard data becomes 0. Therefore, a scatter diagram of the standard driving force deviation and the road gradient is created, and the road gradient with respect to the standard driving force deviation is approximated by a straight line passing through the origin, whereby the correspondence relationship between the driving force deviation and the road gradient can be generated (STEP63). Incidentally, the function of approximating the road gradient with respect to the standard driving force deviation by a straight line and generating the correspondence relationship between the driving force deviation and the road gradient is realized by the correspondence relationship generation unit 107 of the road gradient calculation device 100. After generating the correspondence relationship in this way, the obtained correspondence relationship is stored in the storage unit 102 of FIG. 1, and the correspondence relationship generation process of the modified example is terminated.

[0063] In STEP14 of the road gradient calculation process described above with reference to FIG. 2, by referring to the correspondence relationship obtained as described above and converting the driving force deviation into a road gradient, it is also possible to calculate the road gradient of the road on which the vehicle 10 has traveled.

[0064] In the correspondence relationship generation process of the modified example described above, it has been described that the accurate road gradient of the actual road is measured in advance, and the standard data is acquired by driving the vehicle 10 on that road. Since the actual road is considered to have a changing road gradient, if the actual road is used as the standard road, the driving force deviation for various road gradients can be obtained, and based on these driving force deviations, the correspondence relationship between the road gradient and the driving force deviation can be determined.

[0065] However, since it is known that the driving force deviation becomes zero when the road gradient is zero, the correspondence relationship for determining the road gradient with respect to the driving force deviation is a straight line passing through the origin of the driving force deviation and the road gradient. Therefore, instead of measuring the exact road gradient of the actual road in advance, a standard test road created with a predetermined road gradient, as illustrated in FIG. 13, may be prepared, and the correspondence relationship between the driving force deviation and the road gradient may be generated using the driving data when driving on the standard road. In this way, if it is possible to prepare the standard test road, standard data can be generated more easily than accurately measuring the road gradient of the actual road. As a result, it becomes possible to calculate the road gradient of the road on which the vehicle 10 has traveled even more easily.

[0066] As described above, the road gradient calculation device 100 of the present embodiment and various modified examples has been described. However, the present invention is not limited to the above-described embodiment and various modified examples, and can be implemented in various modes without departing from the gist thereof.

Explanation of Reference Numerals

[0067] 10…Vehicle, 10t…Tire, 11…Motor, 12…Battery, 13…Constant Voltage Circuit, 14…Ammeter, 15…Vehicle Speed Sensor, 16…Data Collection Device, 20…Driving Robot, 50…Chassis Dynamometer, 51…Running Roller, 52…Load Control Device, 53…Wheel Stopper, 100…Road Gradient Calculation Device, 101…Driving Data Reading Unit, 102…Storage Unit, 103…Driving Data Output Unit, 104…Reproduction Data Reading Unit, 105…Driving Force Deviation Calculation Unit, 106…Road Gradient Conversion Unit, 107…Correspondence Relationship Generation Unit.

Claims

1. A road gradient calculation device that calculates the road gradient of a road on which a vehicle has traveled, comprising: a driving data reading unit that reads, in time series, the driving speed when the vehicle travels on the road and the driving force generated by the vehicle; a reproduction data reading unit that reads, in time series, the reproduction driving force, which is the driving force generated by the vehicle when the driving speed is reproduced using the vehicle on a chassis dynamometer; a driving force deviation calculation unit that calculates a driving force deviation, which is the deviation between the driving force and the reproduction driving force; a road gradient conversion unit that converts the driving force deviation into the road gradient by referring to the correspondence relationship between the driving force deviation and the road gradient stored in advance; a gradient data reading unit that reads, in time series, the driving speed of the vehicle, the gradient-applied driving force, which is the driving force of the vehicle, and the road gradient when the vehicle is driven while changing the road gradient on the chassis dynamometer on which the road gradient can be set; a gradient-free data reading unit that reads, in time series, the gradient-free driving force, which is the driving force of the vehicle when the driving speed is reproduced with the road gradient set to 0 on the chassis dynamometer; a gradient presence / absence driving force deviation calculation unit that calculates a gradient presence / absence driving force deviation, which is the deviation between the gradient-applied driving force and the gradient-free driving force; a correspondence relationship generation unit that generates a correspondence relationship between the gradient presence / absence driving force deviation and the road gradient by organizing the gradient presence / absence driving force deviation with respect to the road gradient; and the road gradient conversion unit converts the driving force deviation into the road gradient by referring to the correspondence relationship generated by the correspondence relationship generation unit. A road gradient calculation device characterized by the above.

2. A road gradient calculation device that calculates the road gradient of a road on which a vehicle has traveled, comprising: a driving data reading unit that reads, in time series, the driving speed when the vehicle travels on the road and the driving force generated by the vehicle; a reproduction data reading unit that reads, in time series, the reproduction driving force, which is the driving force generated by the vehicle when the driving speed is reproduced using the vehicle on a chassis dynamometer; a driving force deviation calculation unit that calculates a driving force deviation, which is the deviation between the driving force and the reproduction driving force; a road gradient conversion unit that converts the driving force deviation into the road gradient by referring to the correspondence relationship between the driving force deviation and the road gradient stored in advance; A standard data reading unit that reads, in time series, a standard driving speed that is the driving speed when the vehicle travels on a standard road with a known road gradient, and a standard driving force that is the driving force of the vehicle; A reproduced standard data reading unit that reads, in time series, a reproduced standard driving force that is the driving force of the vehicle when the standard driving speed is reproduced using the vehicle with the road gradient set to 0 on the chassis dynamometer; A standard driving force deviation calculation unit that calculates a standard driving force deviation that is the deviation between the standard driving force and the reproduced standard driving force; A correspondence relationship generation unit that generates a correspondence relationship between the standard driving force deviation and the road gradient by arranging the standard driving force deviation with respect to the road gradient of the standard road; Comprising: The road gradient conversion unit converts the driving force deviation into the road gradient by referring to the correspondence relationship generated by the correspondence relationship generation unit. A road gradient calculation device characterized by the above.

3. The road gradient calculation device according to claim 1 or claim 2, wherein the vehicle is an electric vehicle equipped with a motor for driving the vehicle and a battery for charging and discharging electric power to and from the motor, and reads a current value charged and discharged from the battery to the motor as the driving force of the vehicle. A road gradient calculation device characterized by the above.

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