JP5273599B2 - Road gradient measuring device and road gradient measuring method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To measure a road gradient with high accuracy, while making a vehicle travel. <P>SOLUTION: A pitch angle in course of travel of the vehicle is detected by using a gyroscope sensor. Moreover, the inclination angle of the vehicle is detected, by detecting the distances between the body of the vehicle and a road surface, at a plurality of spots which are different at positions in the longitudinal direction of the vehicle. Based on the deviation of the inclination angle of the vehicle from the pitch angle, the gradient of the road in course of travel is detected. The pitch angle is determined by only the inclination angle of the vehicle and the road gradient, and the pitch angle can be detected with high accuracy by using the gyroscope sensor. Accordingly, the road gradient can be calculated with high accuracy from the deviation of the inclination angle of the vehicle from the pitch angle, by detecting the distances from the road surface in front of and at the back of the vehicle and finding its inclination angle. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a technique for measuring a road gradient while driving a vehicle.

  Against the backdrop of increasing environmental awareness, efforts have been made to reduce harmful substances contained in the exhaust gas of internal combustion engines mounted on vehicles or to reduce fuel consumption of internal combustion engines. As a result, under defined evaluation conditions (such as mode tests using chassis dynamo equipment), emissions of hazardous substances and fuel consumption have been steadily decreasing. There has also been a great deal of interest in evaluation on conditions.

  Here, there is a new factor of “road gradient” in the evaluation under the actual driving condition of the vehicle. Even if the traveling speed and acceleration are the same, the operating conditions of the internal combustion engine mounted on the vehicle are completely different on an uphill road, a flat road, and a downhill road. Along with this, the evaluation results of the discharge amount of harmful substances contained in the exhaust gas and the fuel consumption amount are greatly different. Therefore, when the evaluation is performed by actually traveling on the road with the vehicle, it is necessary to accurately measure not only the traveling speed of the vehicle but also the road gradient as a test condition.

  For these reasons, various methods for measuring the road gradient have been proposed. For example, an acceleration sensor is mounted on a vehicle, and the deviation between the acceleration obtained by the acceleration sensor and the acceleration calculated from the rotational speed of the wheel (corresponding to the traveling speed) corresponds to the road gradient. As a technique for calculating the gradient, Patent Document 1, Patent Document 2, and the like have been proposed. Further, various improvements have been attempted for the purpose of making it possible to measure the road gradient as accurately as possible even when some disturbance is applied to the output of the acceleration sensor (Patent Document 3, Patent Document 4, etc.). Furthermore, a technology for obtaining the absolute position information (latitude, longitude, altitude) of the vehicle from time to time based on a signal from a so-called GPS (Global Positioning System) and calculating the road gradient from the change in altitude. Or (patent document 5), the technique of calculating a road gradient from the change of an altitude by measuring atmospheric pressure with high accuracy and calculating the altitude of the vehicle is proposed (patent document 6).

JP-A-6-201380 JP-A-8-327378 Japanese Patent Laid-Open No. 7-083659 JP 2001-296122 A JP 2001-331832 A JP 2004-110590 A

  However, any of these proposed techniques has a problem that the road gradient cannot be measured with sufficiently practical accuracy. For example, in the method using an acceleration sensor, when the road gradient is measured while the vehicle is running and the altitude is calculated from the obtained road gradient, even if the vehicle returns to the same point as the departure point, the departure point and the end point The current situation is that the altitudes are different. Therefore, the method using the acceleration sensor has insufficient measurement accuracy to be applied to at least evaluation of harmful substances in the exhaust gas and fuel consumption. In addition, it is difficult to measure the road gradient with sufficient accuracy in the method using GPS and the method using atmospheric pressure for the following reason. First, the method using GPS is difficult to measure with sufficient accuracy in terms of altitude due to the limitation in principle. Furthermore, with respect to a method using atmospheric pressure, there is no device capable of measuring atmospheric pressure with high accuracy to the extent that altitude can be calculated with sufficient accuracy. Thus, since the altitude cannot be measured with sufficient accuracy, it is difficult to measure the road gradient with sufficient accuracy by a method using GPS or atmospheric pressure.

  The present invention has been made to solve the above-described problems of the prior art, and is sufficiently applicable to the evaluation of harmful substances and fuel consumption in exhaust gas while the vehicle is running. The purpose is to provide technology for measuring road gradient with high accuracy.

In order to solve at least a part of the problems described above, the road gradient measuring apparatus of the present invention employs the following configuration. That is,
A road gradient measuring device that measures the road gradient of a road mounted on a vehicle and running,
Pitch that uses a gyro sensor to detect a pitch angle, which is the angle at which the front and rear shaft tip side set with respect to the vehicle from the rear to the front rotates in the vertical direction along the direction of gravity. Angle detection means;
Vehicle inclination for detecting a vehicle inclination angle indicating the inclination of the vehicle with respect to the road surface by detecting the distance between the vehicle body and the road surface at a plurality of locations provided at different positions in the longitudinal direction of the vehicle. Angle detection means;
A first initial value setting means for setting a temporary initial value of the road gradient when measuring the road gradient;
When measuring the road gradient , the pitch angle at the time when the provisional initial value of the road gradient was set was set as the initial value of the pitch angle , and the provisional initial value of the road gradient was set Second initial value setting means for setting the vehicle inclination angle at the time as an initial value of the vehicle inclination angle;
Based on a deviation between the variation of the pitch angle and the change amount of the vehicle tilt angle from the initial value set in the second initial value setting means from the initial value set in the second initial value setting means Road gradient calculating means for calculating a change amount of the road gradient and calculating a temporary road gradient using the change amount and the temporary initial value;
Travel speed detecting means for detecting the travel speed of the vehicle;
An altitude calculating means for calculating an altitude at the position of the vehicle based on the provisional road gradient and the traveling speed;
The tentative initial value of the road gradient is corrected so that the altitude calculated by the altitude calculating means at the reference position where the altitude is known in advance approaches the known altitude, and the temporary road gradient is restored. A gist is provided with a road gradient correction means for correcting the provisional road gradient by calculation.

In addition, the road gradient measuring method of the present invention corresponding to the road gradient measuring device described above,
A road gradient measuring method for measuring a road gradient of a road mounted on a vehicle and running,
A first step of setting a provisional initial value of the road gradient when measuring the road gradient;
For the pitch angle that is the angle at which the front end of the front-rear axis set for the vehicle from the rear to the front of the vehicle rotates in the vertical direction along the direction of gravity, the provisional of the road gradient A second step of setting the value of the pitch angle at the time of setting the initial value as the initial value of the pitch angle ;
As for the vehicle inclination angle indicating the inclination of the vehicle with respect to the road surface , a value of the vehicle inclination angle at the time when the provisional initial value of the road gradient is set is set as an initial value of the vehicle inclination angle . And the process of
A fourth step of detecting the pitch angle using a gyro sensor;
A fifth step of detecting the vehicle inclination angle by detecting the distance between the vehicle body and the road surface at a plurality of locations provided at different positions in the longitudinal direction of the vehicle;
A change amount of the road gradient is calculated based on a deviation between a change amount of the pitch angle from the initial value and a change amount of the vehicle inclination angle from the initial value, and the change amount and the temporary initial value are calculated. A sixth step of calculating a temporary road gradient using the value;
A seventh step of detecting the traveling speed of the vehicle;
An eighth step of calculating an altitude at the position of the vehicle based on the provisional road gradient and the traveling speed;
By recalculating the provisional road gradient by correcting the provisional initial value of the road gradient so that the elevation calculated at the reference position where the elevation is known in advance approaches the known elevation, And a ninth step of correcting the provisional road gradient.

In the road gradient measuring apparatus and the road gradient measuring method of the present invention, a provisional initial value of the road gradient is set when the road gradient is measured. Furthermore, the pitch angle and the vehicle tilt angle at the time of setting the tentative initial value of the road slope, the initial value of each pitch angle, and is set as the initial value of the vehicle inclination angle. And the variation | change_quantity from the initial value of the pitch angle during driving | running | working of a vehicle is detected using a gyro sensor. Here, the pitch angle is an angle indicating how much the vehicle is inclined in a direction in which the front and rear of the vehicle rotate up and down in opposite directions. In addition, the amount of change from the initial value of the vehicle tilt angle is detected by detecting the distance between the vehicle body and the road surface at a plurality of locations whose positions are different in the front-rear direction of the vehicle. Then, based on the deviation between the change amount of the change amount and the vehicle inclination angle of the pitch angle, it calculates the amount of change in road gradient, and the change in weight of the obtained road gradient and the tentative initial value of road gradient Use to calculate provisional road gradient. Furthermore, the traveling speed of the vehicle is detected. Then, based on the calculated temporary road gradient and the traveling speed, the temporary road gradient is measured while calculating the altitude at the position of the vehicle. As a result, when the vehicle passes a reference position where the elevation is known in advance, the calculated elevation is compared with the known elevation so that the calculated elevation approaches the known elevation. The road gradient may be corrected by correcting the temporary initial value and recalculating the temporary road gradient.

If a gyro sensor is used, the amount of change in pitch angle can be detected with high accuracy. As will be described in detail later, only the vehicle inclination angle and the road gradient exist as factors that affect the pitch angle. Furthermore, the amount of change in the vehicle tilt angle can be detected with high accuracy by detecting the distance from the road surface before and after the vehicle. Therefore, by obtaining the difference between the change amount of the change amount and the vehicle inclination angle of the pitch angle, it is possible to accurately detect the amount of change in road gradient. In addition, the amount of change in the road gradient, since it is to be determined by the difference between the change amount of the change amount and the vehicle inclination angle of the pitch angle, the initial value of the initial value and the vehicle inclination angle of the pitch angle is not necessarily It is not necessary to know the exact value, and an arbitrary value can be used as the initial value . Therefore, a temporary initial value of the road gradient is set, and the pitch angle and the vehicle inclination angle at the time of setting the temporary initial value of the road gradient are set as the initial value of the pitch angle and the vehicle , respectively. is set to an initial value of the inclination angle, it detects the amount of change from the initial value of the change amount and the vehicle tilt angle from the initial value of the pitch angle. Then, if the road gradient change amount is calculated from the detected deviation of the pitch angle change amount and the vehicle inclination angle change amount , the road gradient change amount can be calculated relatively easily. Furthermore, there are a plurality of points on the actual road whose precise altitude is known. Therefore, if the altitude is calculated from the tentatively calculated road slope, when passing through a point where the exact altitude is known, the calculated altitude is compared with the altitude that is known in advance. It can be determined whether or not the calculated value of the typical road gradient is correct. And if the altitude is different, correct the temporary initial value of the road gradient so that the calculated altitude approaches the correct altitude, and recalculate the road gradient using the corrected initial value, The road gradient with the correct measurement value can be obtained.

  Further, in the road gradient measuring device of the present invention, signals from a plurality of GPS satellites orbiting the earth are received, and GPS information indicating the latitude and longitude of the vehicle at the time when the road gradient is detected is acquired. Also good.

  This is preferable because it is possible to accurately and easily specify at which point the measured road gradient is the road gradient.

In the road gradient measuring device of the present invention that measures the road gradient while acquiring GPS information, the measurement may be performed while correcting the road gradient as follows. First, map data in which an altitude is set for each set of latitude and longitude is stored in advance. Further, the traveling speed of the vehicle is detected, and the altitude at the position of the vehicle is calculated based on the provisional road gradient and the traveling speed. Then, when the altitude is calculated, the map data is referred to based on the GPS information acquired at the same time, and measurement is performed while correcting the road gradient so that the calculated altitude approaches the altitude set in the map data.

  In this way, the road gradient can be corrected while referring to the map data, so that the road gradient can be measured with high accuracy.

Hereinafter, in order to clarify the contents of the present invention described above, examples will be described in the following order.
A. Device configuration:
B. Road slope measurement principle:
C. Variations:

A. Device configuration :
FIG. 1 is an explanatory diagram showing a configuration of a road gradient measuring apparatus 100 according to the present embodiment. FIG. 1A shows a state in which the road gradient measuring device 100 of the present embodiment is mounted on the vehicle 10. As shown in FIG. 1A, a road gradient measuring apparatus 100 according to the present embodiment includes a gyro sensor 102 fixed to the vehicle 10, height sensors 104 provided at the front portion and the rear portion of the vehicle 10, The data processing unit 106 is configured to perform data processing on data from the gyro sensor 102 and the height sensor 104.

  The gyro sensor 102 is a sensor that detects a speed at which an object rotates (that is, an angular speed) by using a Coriolis force generated when the object rotates. In addition, although there are three directions in which the object (here, the vehicle 10) rotates, the gyro sensor 102 of this embodiment can detect the angular velocity in the direction in which the front of the vehicle 10 rotates up and down (pitch direction). It is attached to the state. Note that the gyro sensor 102 according to the present embodiment also includes a GPS antenna, and can acquire GPS information such as latitude and longitude.

  The height sensor 104 is attached near the axle position of the front wheel and near the axle position of the rear wheel. By irradiating the road surface with laser light, the height sensor 104 can detect the height of the vehicle body with respect to the road surface at each position. Is possible. The data processing unit 106 is a so-called computer in which a CPU, a ROM, a RAM, and the like are connected so as to exchange data, and data from the gyro sensor 102 and the height sensor 104 is input.

  FIG. 1B shows the configuration of the road gradient measuring apparatus 100 according to the present embodiment, paying attention to various functions mounted on the gyro sensor 102, the height sensor 104, and the data processing unit 106. The gyro sensor 102 is provided with a pitch angle detection unit that detects the pitch angle of the vehicle 10 and a GPS information acquisition unit that acquires GPS information, and data obtained by these is input to the data processing unit 106. The Data from height sensors 104 provided at the front and rear of the vehicle is also input to the data processing unit 106.

  The data processing unit 106 includes a setting unit, a map data storage unit, a data output unit, and the like, with a calculation unit as a center. Among these, the calculation unit has a function of calculating the road gradient by receiving data from the gyro sensor 102 and the height sensor 104 and performing calculation of contents described later. The setting unit has a function of setting an initial value of the road gradient from the outside to the calculation unit when starting the measurement of the road gradient. When the initial value is set in this way, the calculation unit calculates the road gradient based on the data from the gyro sensor 102 and the height sensor 104. In addition, the data output unit has a function of outputting the road gradient thus obtained to the outside or storing it on various recording media.

  In addition to the function of measuring the road gradient as described above, the data processing unit 106 of this embodiment is also equipped with the following functions. First, the calculation unit can calculate a change in altitude from a road gradient by reading vehicle speed data from a computer for controlling the vehicle 10. Therefore, it is possible to measure the altitude by checking the altitude at the point where the measurement is started in advance and setting the altitude as an initial value from the setting unit to the calculation unit.

  Furthermore, it is also possible to acquire GPS information (latitude and longitude) indicating the current position of the vehicle. Therefore, a map data storage unit is provided inside the data processing unit 106, and map data in which the latitude, longitude, and elevation at each point are set is stored in advance. And if a vehicle passes the point registered into map data, it is also possible to measure a road gradient and an altitude while correcting the calculated value using the altitude data stored in the map data. . In FIG. 1B, the broken line arrow indicates that the calculation unit of the data processing unit 106 refers to the map data stored in the map data storage unit.

  In FIG. 1B, the GPS information acquisition unit, the map data storage unit, and the vehicle control computer are indicated by broken-line rectangles if they only measure the road gradient. It is a function that is not.

  The road gradient measuring apparatus 100 of the present embodiment having the above-described configuration can measure the road gradient with extremely high accuracy while the vehicle 10 is traveling. Hereinafter, this point will be described in detail.

B. Road slope measurement principle:
FIG. 2 is an explanatory diagram showing the principle by which the road gradient measuring apparatus 100 of this embodiment measures the road gradient. Arrows indicated by thick broken lines in the figure are front and rear axes of the vehicle 10. Here, the front-rear axis is an axis that is set at the approximate center of the vehicle 10 from the rear part to the front part with reference to the vehicle body. The front and rear axes roughly coincide with the traveling direction of the vehicle 10, but are not strictly coincident because they are set based on the vehicle body to the last. For example, as is clear from the case where the vehicle 10 is traveling with the front part slightly raised and the rear part slightly lowered, the traveling direction of the vehicle 10 and the front and rear axes are essentially different. Strictly speaking, they do not match.

  When the vehicle 10 rotates in a direction (pitch direction) in which the front end side of the front and rear axes moves up and down along the direction of gravity, the gyro sensor 102 mounted on the vehicle 10 detects an angular velocity associated with the rotation in the pitch direction. Then, the pitch angle θp is calculated from the detected angular velocity and output. Here, the longitudinal axis of the vehicle 10 rotates even when the vehicle 10 tilts, and rotates even when the road surface tilts. As is clear from this, the pitch angle θp obtained by the gyro sensor 102 is a combination of the inclination angle (vehicle inclination angle θv) with respect to the road surface of the vehicle 10 and the road gradient θr. Therefore, the road gradient θr can be obtained by subtracting the vehicle inclination angle θv from the pitch angle θp.

Further, as described above with reference to FIG. 1, in this embodiment, the height sensor 104 is provided at each of the front portion and the rear portion of the vehicle 10, and the height of the vehicle body with respect to the road surface can be detected at each position. . Accordingly, if the distance L between the height sensors 104 in the traveling direction of the vehicle 10 is obtained in advance, the inverse sine of the value obtained by dividing the height difference (height difference dH) obtained by the front and rear height sensors 104 by L. By calculating the function (sin ⁻¹ ), the vehicle inclination angle θv can be obtained. Then, the road gradient θr can be calculated by subtracting the vehicle inclination angle θv from the pitch angle θp obtained by the gyro sensor 102.

  In the road gradient measuring apparatus 100 of the present embodiment, the road gradient θr is measured with extremely high accuracy while the vehicle 10 is traveling by such a method. Here, the reason why the accuracy of the road gradient θr measured by the method of this embodiment is extremely high will be described by comparing it with a method of calculating the road gradient θr using an acceleration sensor.

FIG. 3 is an explanatory diagram showing the principle of calculating the road gradient θr using an acceleration sensor. FIG. 3A shows a state where a flat road is accelerated at a constant acceleration. The acceleration acting on the vehicle is acceleration due to acceleration of the vehicle (running acceleration av) and gravitational acceleration g. Therefore, the acceleration (detected acceleration am) detected by the acceleration sensor mounted on the vehicle is a combination of these accelerations (running acceleration av and gravitational acceleration g). If the vehicle is traveling on a completely flat road, between the detected acceleration am detected by the acceleration sensor and the traveling acceleration av obtained from the rotation of the wheel,
(Am) ² = (av) ² + g ²
The relationship is established.

  On the other hand, FIG. 3B shows a state in which an uphill road is being accelerated. Even if the travel acceleration av and the gravitational acceleration g of the vehicle are exactly the same as in FIG. 3A, the angle of the travel acceleration av with respect to the gravitational acceleration g changes, so that the detection is actually detected by the acceleration sensor. The magnitude of the acceleration am is different from the value calculated by the above equation assuming the case of FIG. The deviation between the acceleration calculated from the traveling acceleration av and the gravitational acceleration g using the above equation and the actual detected acceleration am detected by the acceleration sensor increases as the road gradient θr increases. In other words, the road gradient θr can be calculated by comparing the acceleration calculated from the travel acceleration av and the gravitational acceleration g with the detected acceleration am detected by the acceleration sensor. Although there are various methods in detail, the method using the acceleration sensor roughly measures the road gradient θr using such a principle. However, various disturbances resulting from the shaking of the vehicle are mixed in the detected acceleration am actually obtained by the acceleration sensor.

  FIG. 4 is an explanatory view collectively showing the shaking of the vehicle body that affects the output of the acceleration sensor. FIG. 4A shows a state in which the front portion and the rear portion of the vehicle are swinging up and down (pitch movement) in different directions. FIG. 4 (b) shows a situation where the front and rear parts of the vehicle are swinging up and down in the same direction (up and down movement), and FIG. 4 (c) is a movement of the vehicle swinging back and forth (front and rear). It shows a state of moving). Further, FIG. 4D shows a state in which the left and right portions of the vehicle are moving up and down (rolling) in different directions. These vehicle movements actually affect the output of the acceleration sensor.

  In particular, the vehicle has a so-called spring-mass vibration system in which a heavy vehicle body is mounted on a tire or a suspension, so that the vehicle is shown in FIG. Various movements can occur in a state where they overlap each other. When these movements occur, it is extremely difficult to remove components due to these disturbances from the output of the acceleration sensor measured while the vehicle is running. For example, as with the method of this embodiment, even if height sensors are provided near the front and rear axles to detect the magnitude of pitch movement, how much the magnitude of pitch movement affects the output of the acceleration sensor. It is not easy to accurately evaluate whether to give. Further, even if the acceleration due to the pitch motion is removed, the acceleration due to other motions must also be removed. When these various movements are superimposed on each other, it becomes extremely difficult to remove components due to these movements from the output of the acceleration sensor.

  In contrast, in the measurement method of the present embodiment described with reference to FIG. 2, the gyro sensor 102 detects the vehicle pitch angle θp, and the pitch angle θp is determined by the road gradient θr and the vehicle inclination angle θv. Determined from only two factors. For example, the output of the gyro sensor 102 is not affected by any of the movements shown in FIGS. 4 (b) to 4 (d). And if it is vehicle inclination angle (theta) v, it can detect with sufficient accuracy from the output of the height sensor 104 provided before and behind the vehicle 10. FIG. Therefore, by subtracting the vehicle inclination angle θv detected using the height sensor 104 from the pitch angle θp obtained by the gyro sensor 102, the road gradient θr can be measured with extremely high accuracy.

  FIG. 5 is an explanatory view exemplifying the result of measuring the road gradient θr while actually driving on the road by mounting the road gradient measuring apparatus 100 of this embodiment on a vehicle. Fig.5 (a) has shown the change of the driving speed with respect to driving distance, and FIG.5 (b) has shown the measurement result of the road gradient. The traveling speed can be obtained from a vehicle control computer. Alternatively, the traveling speed may be calculated by attaching a rotational speed sensor to the wheel and multiplying the obtained rotational speed by the radius of the wheel. FIG. 5C shows the result of calculating the altitude based on the measured road gradient θr and the traveling speed. That is, if the traveling speed is multiplied by the sine function (sin) of the road gradient θr, the amount of change in altitude per unit time can be calculated. Therefore, the elevation at the time of starting measurement is obtained in advance, and the elevation can be calculated from the road gradient θr by accumulating the amount of elevation change per unit time.

  In FIG. 5, the measurement results for the second time are shown. The first measurement result is shown by a solid line, and the second measurement result is shown by a broken line. As shown in FIG. 5A, the traveling speed is considerably different between the first time and the second time. This is because the way of crowding the road is considerably different between the first measurement and the second measurement, and accordingly, the way the vehicle 10 runs is significantly different.

  In spite of the vastly different way of running the vehicle 10 as described above, the measurement result of the road gradient θr shown in FIG. 5B is very similar between the first time and the second time. Yes. Here, the road that was traveled was one lane on one side until the mileage near 1 km, but it became a plurality of lanes from around 1 km to around 2.2 km, and again one lane on one side after around 2.2 km. Then, the vehicle traveled in different lanes at the time of the first measurement and at the time of the second measurement from around 1 km to around 2.2 km, which are multiple lanes. For this reason, the mileage is shorter in the second time in which the lane change is hardly performed than in the first time in which the lane change is repeated, and as a result, after the mileage of 2 km, the second measurement result is The result is a little shifted from the measurement result.

  Similarly, the calculation result of the altitude shown in FIG. 5C is such that the second calculation result is slightly shifted from the first calculation result after the travel distance of 2.2 km. ing. In addition, the difference between the first and second altitude calculation results between the travel distances of 1 km and 2.2 km is due to the difference in the travel lane.

  Observing FIG. 5B and FIG. 5C, it can be seen that the road gradient θr can be measured with extremely high accuracy in the road gradient measuring apparatus 100 of the present embodiment. For example, until the travel distance of about 1 km where the difference in travel distance does not appear, both the road gradient θr shown in FIG. 5B and the altitude calculation result shown in FIG. High reproducibility is shown in the second measurement. In addition, for a distance of 2.2 km or more, which becomes one lane on one side again, taking into account that the distance traveled up to that time is different between the first and second times, if one data is moved in parallel, Both the road gradient θr shown in FIG. 5 (b) and the altitude calculation result shown in FIG. 5 (c) almost overlap. These indicate that the road gradient θr and the altitude data can be acquired with extremely high accuracy by one measurement if the traveling lane is determined. Therefore, if the road gradient θr (and altitude) is measured using the road gradient measuring apparatus 100 of the present embodiment, the road gradient θr (and altitude) is used as long as the vehicle travels in the same lane (even if the vehicles are different). ), It is possible to use the data measured previously.

C. Modified example:
As described above, the road gradient measuring apparatus 100 according to the present embodiment can measure the road gradient θr with high accuracy only by being mounted on a vehicle and traveling on the road only once. Also, the altitude can be calculated with high accuracy from the road gradient θr measured with high accuracy. In this way, if the measured road gradient θr is converted into elevation, it is possible to measure the road gradient θr while correcting the measurement result using already obtained elevation data. Below, such a modification is demonstrated.

  FIG. 6 is an explanatory diagram showing a measurement route of the road gradient θr on a map. The thick solid line shown in the figure represents the measurement route of the road gradient θr. Moreover, the broken line shown in the drawing represents a road running around the measurement route. As shown in the figure, the measurement route usually intersects with a plurality of roads. Therefore, if altitude data has already been obtained for some of these surrounding roads, the altitude data already obtained at the intersecting position is combined with the newly measured data to obtain measurement data. It is considered possible to measure the road gradient θr and altitude while correcting.

  The thick broken line shown in FIG. 6 represents a road from which altitude data is already obtained by measuring the road gradient θr. As described above with reference to FIG. 1, the gyro sensor 102 according to the present embodiment has a GPS function, and can acquire the latitude and longitude of a point where the vehicle exists. Therefore, by measuring the road gradient θr and the altitude, and simultaneously acquiring the latitude and longitude of the point, it is possible to obtain altitude data along the road on the map as shown in FIG. . The data thus obtained (data in which the altitude is set for the set of latitude and longitude) is stored in advance. Note that data in which elevation is set for a set of latitude and longitude is referred to as “map data” in this specification. In the example shown in FIG. 6, map data along four routes is stored in advance.

  Further, when measuring the road gradient θr (and elevation) along the measurement path indicated by the thick solid line in FIG. 6, the road gradient θr (and elevation) is measured and at the same time using the GPS function. Get the latitude and longitude of the. Then, it is determined whether or not the acquired latitude and longitude values are stored in the map data, and if stored, the altitude value being measured is corrected using the altitude of the map data. . For example, since the measured route intersects with the road where the map data is stored at the point “a” shown in FIG. 6, the altitude value being measured is corrected by the altitude data stored in the map data. . Also, the cause of such an elevation difference is thought to be because an error was included in the road gradient θr set as the initial value at the start of measurement, so the initial value was corrected so as not to cause an elevation difference. The road gradient θr, altitude, etc. may be recalculated.

  As shown in FIG. 6, map data also exists at “b” point, “c” point, and “d” point on the measurement route, so that the measured value of the road gradient θr is similar to the “a” point. And altitude calculation results can be modified. At this time, the measurement accuracy of the road gradient θr and the altitude can be improved by making correction using the result of the correction already made. For example, when the “b” point is described, the error included in the initial value is removed by the correction performed at the “a” point. Therefore, the difference in elevation between the elevation of the map data at the point “b” and the elevation being measured is caused by a slight error included in the road gradient θr at the point “a”. Conceivable. Therefore, the road gradient θr at the point “a” is corrected so as not to cause an elevation difference at the point “b”, and the road gradient θr and the elevation from the point “a” to the point “b” are recalculated. . Similarly, the “c” point and the “d” point can be corrected based on the map data, and the road gradient θr and the altitude can be measured to ensure extremely high accuracy.

  Note that GPS signals are not always receivable. Since the correction method described above requires latitude and longitude data, if the GPS signal cannot be received at the “a”, “b”, “c”, and “d” points, it is corrected. You will not be able to. However, even in such a case, if the Kalman filter (a filter that estimates the time-varying amount of time for measurements with discrete errors) is used, the latitude and longitude information is estimated and corrected. As a result, the road gradient θr and the altitude can be measured with high accuracy.

  In the above description, the map data is described as data obtained by simultaneously measuring the latitude and longitude while measuring the altitude using the road gradient measuring apparatus 100 of the present embodiment. In this case, it is necessary that the road gradient θr and the altitude are already measured and stored as map data on a road that intersects the measurement route. However, such map data does not always exist. In such a case, it is also possible to perform the above-mentioned correction while using the terrain data (latitude and longitude and the altitude at that point) provided by a reliable organization as map data, It is possible to accurately measure the road gradient θr and the altitude.

  In addition, on actual roads, they are elevated and straddle over other roads, diving underground and passing under other roads, and multiple roads running in parallel vertically There are cases. doing. In such a case, there are a plurality of correct elevations at the same latitude and longitude. Therefore, it is conceivable that just because map data exists, if the measurement result is corrected, the measurement accuracy is lowered. In addition, when using topographic data as map data, if the measurement result is corrected using the altitude of the topographic data in a part where the road is elevated or in the basement, the measurement accuracy decreases. It is conceivable to let you.

  FIG. 7 is an explanatory diagram showing the result of calculating the altitude from the road gradient θr measured along the route including the highway. The solid line shown in the figure is the altitude calculated from the road gradient θr. Moreover, the broken line shown in the figure represents the altitude on the measurement route obtained from the topographic data. In the figure, the highway is from about 1 km to about 17 km, and the other part is a general road.

  As shown in the figure, the elevation value calculated from the road gradient θr in the portion of the general road (up to about 1 km travel distance and after 17 km) is the same as the elevation obtained from the map data (terrain data here). Match. However, for a while after entering the expressway (from about 1 km to about 3 km as the travel distance), the altitude calculated from the road gradient θr is lower than the altitude indicated by the map data. In this section, it is considered that the highway passes through the tunnel. Further, after passing through the tunnel (from about 3 km to about 17 km as the travel distance), the altitude calculated from the road gradient θr is higher than the altitude indicated by the map data. It is considered that the expressway is elevated in this section. In such a section, if the measurement result is corrected using the altitude of the map data, the measurement accuracy is reduced.

  Therefore, a flag indicating whether or not the altitude of the map data can be used for correction is set in advance for each point (latitude and longitude) in the map data, and the setting of the flag is confirmed and used for correction. Only at points where it can be corrected using the elevation of the map data. For example, in the example shown in FIG. 7, a flag indicating that it cannot be used for correction is set in the map data at a point where the highway passes. In this way, the road gradient θr and the altitude are measured while making corrections up to the vicinity of the travel distance of 1 km, and are measured without correction while traveling on the expressway. Then, the correction is performed again based on the map data near the travel distance of 17 km on the general road. In the correction immediately after exiting the expressway, it is only necessary to correct the data of the section (data near the travel distance of 1 km to 17 km) measured without correction during traveling on the expressway. In this way, it is possible to measure the road gradient θr and the altitude with extremely high accuracy even in parts such as overpasses and tunnels.

  Moreover, since it is troublesome to set a flag for each point of the map data, it may be as follows. That is, the altitude calculated from the road gradient θr is compared with the altitude of the map data, and if the altitude difference is larger than a predetermined value, it is determined that the vehicle passes through an elevated or tunnel and is not corrected. It is good as well. In addition, the determination as to whether or not to correct using map data is not performed for each point, but may be made with reference to an elevation difference at a point before that. For example, if there are three or more consecutive points where the elevation difference between the elevation calculated from the road gradient θr and the elevation of the map data is greater than or equal to a predetermined value, it is determined that correction is not performed at points excluding both ends. May be. Or, conversely, if a point where the altitude difference is greater than or equal to the predetermined value is isolated, in other words, if the altitude difference is less than or equal to the predetermined value at points before and after that point, it is not corrected at that point You may judge.

  Furthermore, the distance between the points is calculated in consideration of the traveling speed of the vehicle, and if the section where the altitude difference is equal to or greater than the predetermined value continues for the predetermined distance or more, the correction using the altitude of the map data is performed. You may judge that it is not. Or conversely, if the section where the elevation difference is equal to or greater than the predetermined value is too short, it may be determined that no correction using map data is performed in that section.

  As mentioned above, although the Example of this invention was described, this invention is not limited to this, Unless it deviates from the range described in each claim, it is not limited to the description word of each claim, and those skilled in the art Improvements based on the knowledge that a person skilled in the art normally has can be added as appropriate to the extent that they can be easily replaced.

  For example, in the above-described embodiments, the height sensor 104 is described as directly detecting the distance between the vehicle body and the road surface. However, any method can be used as long as the distance between the vehicle body and the road surface can be detected. For example, the distance between the vehicle body and the road surface may be detected indirectly by detecting the distance between the axle that supports the wheel and the vehicle body.

  Further, in the above-described embodiments, the height sensor 104 is described as being provided near the front wheel axle position and the rear wheel axle position. When each height sensor 104 is accurately provided at the axle position, the so-called wheelbase length can be used as the distance L when calculating the vehicle inclination angle θv, so it takes time to measure the distance L. The vehicle inclination angle θv can be calculated without any problem. On the other hand, the front height sensor 104 may be provided in front of the front wheel axle position, and the rear height sensor 104 may be provided behind the rear wheel axle position. In this way, since a long distance L can be secured, the vehicle inclination angle θv can be calculated with higher accuracy. Of course, if there is no other suitable mounting location, the height sensor 104 can be mounted inside the front axle and the rear axle.

It is explanatory drawing which showed the structure of the road gradient measuring apparatus 100 of a present Example. It is explanatory drawing which showed the principle which the road gradient measuring apparatus 100 of a present Example measures a road gradient. It is explanatory drawing which showed the principle which calculates road gradient (theta) r using an acceleration sensor. It is explanatory drawing which showed the various aspects of the shaking of the vehicle body which affects the output of an acceleration sensor. It is explanatory drawing which illustrated the result of having mounted the road gradient measuring apparatus 100 of a present Example in the vehicle, and measuring road gradient (theta) r, actually drive | working a road. It is explanatory drawing which showed the measurement path | route of road gradient (theta) r on the map. It is explanatory drawing which showed the result of having calculated the altitude after measuring road gradient (theta) r along the path | route containing a highway.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Vehicle, 100 ... Road gradient measuring device, 102 ... Gyro sensor,
104: Height sensor 106: Data processing unit

Claims (4)

A road gradient measuring device that measures the road gradient of a road mounted on a vehicle and running,
Pitch that uses a gyro sensor to detect a pitch angle, which is the angle at which the front and rear shaft tip side set with respect to the vehicle from the rear to the front rotates in the vertical direction along the direction of gravity. Angle detection means;
Vehicle inclination for detecting a vehicle inclination angle indicating the inclination of the vehicle with respect to the road surface by detecting the distance between the vehicle body and the road surface at a plurality of locations provided at different positions in the longitudinal direction of the vehicle. Angle detection means;
A first initial value setting means for setting a temporary initial value of the road gradient when measuring the road gradient;
When measuring the road gradient , the pitch angle at the time when the provisional initial value of the road gradient was set was set as the initial value of the pitch angle , and the provisional initial value of the road gradient was set Second initial value setting means for setting the vehicle inclination angle at the time as an initial value of the vehicle inclination angle;
Based on a deviation between the variation of the pitch angle and the change amount of the vehicle tilt angle from the initial value set in the second initial value setting means from the initial value set in the second initial value setting means Road gradient calculating means for calculating a change amount of the road gradient and calculating a temporary road gradient using the change amount and the temporary initial value;
Travel speed detecting means for detecting the travel speed of the vehicle;
An altitude calculating means for calculating an altitude at the position of the vehicle based on the provisional road gradient and the traveling speed;
The tentative initial value of the road gradient is corrected so that the altitude calculated by the altitude calculating means at the reference position where the altitude is known in advance approaches the known altitude, and the temporary road gradient is restored. A road gradient measuring device comprising: road gradient correcting means for correcting the provisional road gradient by calculating. The road gradient measuring device according to claim 1,
A road gradient measuring device comprising GPS information acquisition means for acquiring GPS information indicating the latitude and longitude of the vehicle at the time of detecting the road gradient by simultaneously receiving signals from a plurality of GPS satellites orbiting the earth. . The road gradient measuring device according to claim 2 ,
Comprising map data storage means for storing in advance map data in which elevation is set for each set of latitude and longitude;
When the altitude is calculated, the road gradient correction means refers to the map data based on the GPS information acquired at the same time, and the calculated altitude approaches the altitude set in the map data. And a road gradient measuring device which is means for correcting the road gradient. A road gradient measuring method for measuring a road gradient of a road mounted on a vehicle and running,
A first step of setting a provisional initial value of the road gradient when measuring the road gradient;
For the pitch angle that is the angle at which the front end of the front-rear axis set for the vehicle from the rear to the front of the vehicle rotates in the vertical direction along the direction of gravity, the provisional of the road gradient A second step of setting the value of the pitch angle at the time of setting the initial value as the initial value of the pitch angle ;
As for the vehicle inclination angle indicating the inclination of the vehicle with respect to the road surface , a value of the vehicle inclination angle at the time when the provisional initial value of the road gradient is set is set as an initial value of the vehicle inclination angle . And the process of
A fourth step of detecting the pitch angle using a gyro sensor;
A fifth step of detecting the vehicle inclination angle by detecting the distance between the vehicle body and the road surface at a plurality of locations provided at different positions in the longitudinal direction of the vehicle;
A change amount of the road gradient is calculated based on a deviation between a change amount of the pitch angle from the initial value and a change amount of the vehicle inclination angle from the initial value, and the change amount and the temporary initial value are calculated. A sixth step of calculating a temporary road gradient using the value;
A seventh step of detecting the traveling speed of the vehicle;
An eighth step of calculating an altitude at the position of the vehicle based on the provisional road gradient and the traveling speed;
By recalculating the provisional road gradient by correcting the provisional initial value of the road gradient so that the elevation calculated at the reference position where the elevation is known in advance approaches the known elevation, A road gradient measuring method comprising: a ninth step of correcting a provisional road gradient.

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