JP2021012702A - System for vehicle and course estimation method - Google Patents

Abstract

To provide a system for a vehicle for estimating the travelling direction of the vehicle.SOLUTION: A system 1 for a vehicle includes: lateral deviation measuring means for measuring the lateral deviation as a positional deviation in the vehicle width direction of a vehicle 5 with respect to a magnetic marker 10; and course estimating means for using the difference between the lateral deviations with respect to two magnetic markers 10 separately disposed on a road surface 100S on which the vehicle 5 travels, and estimating the deviation in the travelling direction of the vehicle 5 with respect to the direction of the segment interconnecting the positions of the two magnetic markers.SELECTED DRAWING: Figure 1

Description

The present invention relates to a vehicle system for estimating the traveling direction of a vehicle and a course estimation method.

In recent years, research on automatic driving has become active, and its practical application is desired (see, for example, Patent Document 1). In order to realize autonomous driving, it is indispensable to accurately grasp the surrounding environment of the vehicle such as the road structure. The road structure and the like can be obtained from map data in which the shape of the road, the lane width, the shape of the shoulder, and the like are converted into detailed data.

Japanese Unexamined Patent Publication No. 2016-91412

However, even if the surrounding environment of the own vehicle such as the road structure can be grasped, there is a problem that the direction of the course to be followed cannot be accurately determined, for example, unless the traveling direction of the vehicle can be accurately grasped.

The present invention has been made in view of the above-mentioned conventional problems, and is for estimating the traveling direction of a vehicle, for example, whether the vehicle is traveling along a traveling path or traveling across the traveling path. It is intended to provide a vehicle system and a course estimation method.

The vehicle system according to the present invention includes a lateral displacement amount measuring means for measuring a lateral displacement amount which is a positional deviation of the vehicle in the vehicle width direction with respect to a magnetic marker.
A course that estimates the deviation of the vehicle's traveling direction with respect to the line segment direction connecting the positions of the two magnetic markers by using the difference in the amount of lateral displacement of the two magnetic markers arranged at intervals on the road surface on which the vehicle travels. It is provided with an estimation means.

In the course estimation method according to the present invention, a process of measuring the amount of lateral deviation, which is a positional deviation of the vehicle in the vehicle width direction with respect to two magnetic markers arranged at intervals on the road surface on which the vehicle travels, and the above-mentioned By calculating the difference in the amount of lateral displacement with respect to the two magnetic markers, the deviation in the traveling direction of the vehicle with respect to the line segment direction connecting the positions of the two magnetic markers is estimated.

The vehicle system according to the present invention measures the amount of lateral displacement of the two magnetic markers, and estimates the deviation of the traveling direction of the vehicle with respect to the line segment direction connecting the positions of the two magnetic markers using the difference. To do. The line segment direction is a direction that can be a reference defined by the two magnetic markers. By specifying the deviation with respect to the line segment direction, the traveling direction of the vehicle can be estimated with high accuracy.
Further, according to the course estimation method according to the present invention, the deviation of the traveling direction of the vehicle with respect to the path direction can be estimated by using the two magnetic markers arranged along the path direction of the traveling road.

The explanatory view which shows the structure of the vehicle system in Example 1. FIG. The front view which looks at the vehicle which attached the sensor unit in Example 1. The block diagram which shows the electrical structure of the vehicle system in Example 1. FIG. The block diagram which shows the structure of the magnetic sensor in Example 1. FIG. The explanatory view which illustrates the temporal change of the magnetic distribution in the vehicle width direction when passing through a magnetic marker in Example 1. FIG. The explanatory view which illustrates the temporal change of the peak value of the magnetic measurement value at the time of passing through a magnetic marker in Example 1. FIG. The explanatory view of the measurement method of the lateral displacement amount in Example 1. The flow chart which shows the flow of processing by the vehicle system in Example 1. FIG. The explanatory view of the detection period of the 2nd magnetic marker in Example 1. FIG. The flow chart which shows the flow of the course estimation process in Example 1. FIG. The explanatory view which shows the relationship between the difference Offd of the lateral displacement amount at the time of passing through two magnetic markers and the course deviation angle Rf in Example 1. FIG. An explanatory diagram illustrating a situation in which a vehicle travels along a straight road in the first embodiment. An explanatory view illustrating a situation in which a vehicle skews on a straight road in the first embodiment. An explanatory diagram illustrating a situation in which a vehicle travels along a curved road in the first embodiment. An explanatory diagram illustrating a situation in which a vehicle skews on a curved road in the first embodiment. The explanatory view which shows the relationship between the difference Offd of the lateral displacement amount with respect to two magnetic markers, and the course deviation angle Rf in Example 2. FIG. The figure which illustrates the image captured by the in-vehicle camera of the vehicle traveling along a straight road in Example 3. FIG. The figure which illustrates the image taken by the in-vehicle camera of the vehicle which is oblique on a straight road in Example 3. FIG. Explanatory drawing which illustrates three-dimensional estimation of a road structure in Example 3. FIG. The explanatory view of the deviation warning in Example 4.

In the vehicle system of the present invention, the lateral displacement amount measuring means is arranged at at least two places separated in the front-rear direction of the vehicle with the same distance as the two magnetic markers.
In the course estimation means, the lateral slip amount measuring means on the front side of the two lateral slip amount measuring means separated by the same interval as the two magnetic markers is located on the traveling side of the vehicle among the two magnetic markers. It is preferable to estimate the deviation in the traveling direction by using the difference between the lateral displacement amount measured for the magnetic marker of 1 and the lateral displacement amount measured by the rearward lateral displacement amount measuring means for the other magnetic marker.

By using the difference in the amount of strike-slip measured by the two means for measuring the amount of strike-slip for each of the two magnetic markers at the same interval, the deviation in the traveling direction of the vehicle with respect to the line segment direction connecting the positions of the two magnetic markers can be accurately determined. Can be estimated.

In the vehicle system of the present invention, it is preferable that the two magnetic markers are arranged along the path direction of the traveling path on which the vehicle travels.
In this case, since the line segment direction connecting the positions of the two magnetic markers coincides with the route direction of the traveling road, the deviation of the traveling direction of the vehicle with respect to the route direction of the traveling road can be estimated.

The course estimation means may change the distance between the two magnetic markers used for estimating the deviation according to the vehicle speed.
In the low vehicle speed range, the steering angle of the steering wheel of the vehicle becomes large and the traveling direction of the vehicle changes in a relatively short distance, while in the high vehicle speed range, the steering angle becomes small and the traveling direction of the vehicle changes. It tends to take a relatively long distance. Therefore, the distance at which the traveling direction of the vehicle can be regarded as constant tends to be shorter as the vehicle speed is lower and longer as the vehicle speed is higher.

Therefore, the distance between the two magnetic markers used for estimating the deviation may be longer as the vehicle speed is higher and shorter as the vehicle speed is lower. For example, it is also possible to displace the magnetic markers at different intervals between a highway having a high vehicle speed range and an urban road having a low vehicle speed range. Alternatively, the magnetic markers may be arranged at relatively short intervals that can handle low vehicle speeds, and the combination (interval) of the two magnetic markers may be changed according to the vehicle speed.

The magnetic marker is arranged along the lane which is the division in which the vehicle travels.
Depending on the prediction means for predicting at least one of the time and distance until the vehicle deviates from the lane using the strike-slip amount, the deviation and the vehicle speed, and the time or distance predicted by the prediction means. It may be a vehicle system including an alarm means for issuing an alarm.

By using the deviation, it is possible to accurately predict the time and distance until the vehicle deviates from the lane. By using this time or distance, highly accurate deviation warning is possible. Further, by combining the lateral displacement amount and the deviation, a deviation alarm with higher accuracy becomes possible.

The magnetic marker is arranged along the lane which is the division in which the vehicle travels.
It may be a vehicle system provided with a means for estimating a three-dimensional road structure based on the own vehicle by using the lateral displacement amount and the deviation.
For example, when the traveling direction of the vehicle coincides with the direction of the lane and the deviation is close to zero, it is highly possible that the vehicle is traveling along the lane. In this case, for example, it can be estimated that the course of the vehicle predicted from the steering angle of the vehicle matches the lane, and based on this lane, the road side where guardrails, signs, etc. are present, and the road structure such as the oncoming lane. Estimates are possible.

Information that can identify the deviation of the line segment direction with respect to the route direction of the traveling path on which the vehicle travels is acquired, and the deviation of the line segment direction with respect to the route direction specified by using this information and the vehicle with respect to the line segment direction are obtained. It is also possible to estimate the deviation of the traveling direction of the vehicle with respect to the route direction of the traveling path based on the deviation of the traveling direction of.
If there is an error in the position of the magnetic marker, the deviation of the line segment direction with respect to the path direction of the traveling path may become large, and the vehicle moves to the traveling path based on the deviation of the traveling direction of the vehicle with respect to the line segment direction. It becomes difficult to judge whether or not the vehicle is traveling along. If the deviation in the line segment direction with respect to the route direction can be specified on the vehicle side, the deviation in the traveling direction of the vehicle with respect to the route direction of the traveling path can be estimated with high accuracy regardless of the positional error of the magnetic marker.
By acquiring the absolute position of the magnetic marker, it is also possible to specify the absolute position of the vehicle at the time when the deviation in the traveling direction of the vehicle is estimated.

Embodiments of the present invention will be specifically described with reference to the following examples.
(Example 1)
This example is an example relating to a vehicle system 1 for estimating the traveling direction of the vehicle 5 by using the magnetic marker 10 laid on the road. This content will be described with reference to FIGS. 1 to 15.

As shown in FIG. 1, the vehicle system 1 includes a combination of a sensor unit 11 including a magnetic sensor Cn (n is an integer of 1 to 15) and a control unit 12. Hereinafter, after the magnetic marker 10 is outlined, the sensor unit 11, the control unit 12, and the like constituting the vehicle system 1 will be described.

As shown in FIGS. 1 and 2, the magnetic marker 10 is a road marker laid on the road surface 100S of the lane 100, which is the traveling path of the vehicle 5. The magnetic markers 10 are arranged at intervals of 2 m (marker span S = 2 m) along the center of the lane 100 in the vehicle width direction. In this example, lane 100 of a road having a relatively high speed range such as an expressway is assumed.

The magnetic marker 10 has a columnar shape with a diameter of 20 mm and a height of 28 mm, and can be accommodated in a hole. The magnet forming the magnetic marker 10 is an isotropic ferrite plastic magnet in which magnetic powder of iron oxide, which is a magnetic material, is dispersed in a polymer material, which is a base material, and has a maximum energy product (BHmax) = 6.4 kJ / m. ^It has the characteristic of ³ . The magnetic marker 10 is laid in a state of being housed in a hole formed in the road surface 100S.

この磁気マーカ１０は、磁気センサＣｎの取付け高さとして想定する範囲１００〜２５０ｍｍの上限の２５０ｍｍ高さにおいて、８μＴ（８×１０^−６Ｔ）の磁束密度の磁気を作用できる。 Table 1 shows a part of the specifications of the magnetic marker 10 of this example.

The magnetic marker 10 can act on magnetism having a magnetic flux density of 8 μT (8 × ^10-6 T) at a height of 250 mm, which is the upper limit of a range of 100 to 250 mm assumed as the mounting height of the magnetic sensor Cn.

Next, the sensor unit 11 and the control unit 12 constituting the vehicle system 1 will be described.
As shown in FIGS. 1 to 3, the sensor unit 11 is a unit attached to the vehicle body floor 50, which is the bottom surface of the vehicle 5. The sensor unit 11 is attached, for example, near the inside of the front bumper. For example, in the case of the sedan type vehicle 5, the mounting height based on the road surface 100S is about 200 mm.

As shown in FIG. 3, the sensor unit 11 includes 15 magnetic sensors Cn arranged in a straight line along the vehicle width direction, and a detection processing circuit 110 incorporating a CPU and the like (not shown).
The detection processing circuit 110 is an arithmetic circuit that executes various arithmetic processing such as a marker detection processing for detecting the magnetic marker 10. The detection processing circuit 110 is an electronic circuit including a CPU (central processing unit) that executes various operations, and memory elements such as a ROM (read only memory) and a RAM (random access memory).

The detection processing circuit 110 acquires a sensor signal output by each magnetic sensor Cn and executes a marker detection process or the like. The detection results of the magnetic marker 10 calculated by the detection processing circuit 110 are all input to the control unit 12 including the measured lateral displacement amount. The sensor unit 11 can execute the marker detection process at a cycle of 3 kHz.

Here, the configuration of the magnetic sensor Cn will be described. In this example, as shown in FIG. 4, a one-chip MI sensor in which the MI element 21 and the drive circuit are integrated is adopted as the magnetic sensor Cn. The MI element 21 is an element including an amorphous wire 211 made of a CoFeSiB-based alloy and having substantially zero magnetostriction, and a pickup coil 213 wound around the amorphous wire 211. The magnetic sensor Cn detects the magnetism acting on the amorphous wire 211 by measuring the voltage generated in the pickup coil 213 when a pulse current is applied to the amorphous wire 211. The MI element 21 has a detection sensitivity in the axial direction of the amorphous wire 211 which is a magnetic sensor. In each magnetic sensor Cn of the sensor unit 11 of this example, the amorphous wire 211 is arranged in the vertical direction.

The drive circuit is an electronic circuit including a pulse circuit 23 that supplies a pulse current to the amorphous wire 211 and a signal processing circuit 25 that samples and outputs the voltage generated by the pickup coil 213 at a predetermined timing. The pulse circuit 23 is a circuit including a pulse generator 231 that generates a pulse signal that is a source of a pulse current. The signal processing circuit 25 is a circuit that takes out the induced voltage of the pickup coil 213 via the synchronous detection 251 that is opened and closed in conjunction with the pulse signal, and amplifies it at a predetermined amplification factor by the amplifier 253. The signal amplified by the signal processing circuit 25 is output to the outside as a sensor signal.

The magnetic sensor Cn is a highly sensitive sensor having a magnetic flux density measurement range of ± 0.6 millitesla and a magnetic flux resolution within the measurement range of 0.02 microtesla. Such high sensitivity is realized by the MI element 21 that utilizes the MI effect that the impedance of the amorphous wire 211 changes sensitively according to the external magnetic field. Further, this magnetic sensor Cn is capable of high-speed sampling in a cycle of 3 kHz, and is also compatible with high-speed running of vehicles. In this example, the period of magnetic measurement by the sensor unit 11 is set to 3 kHz, and the sensor unit 11 inputs a sensor signal to the control unit 12 every time the magnetic measurement is performed.

Table 2 shows a part of the specifications of the magnetic sensor Cn.

As described above, the magnetic marker 10 acts on magnetism having a magnetic flux density of 8 μT (8 × ^10-6 T) or more in a range of 100 to 250 mm assumed as the mounting height of the magnetic sensor Cn. If the magnetic marker 10 acts on magnetism having a magnetic flux density of 8 μT or more, it can be detected with high certainty using a magnetic sensor Cn having a magnetic flux resolution of 0.02 μT.

Next, the control unit 12 (FIGS. 1 to 3) is a unit that controls the sensor unit 11 and estimates the traveling direction of the vehicle 5 by using the detection result of the sensor unit 11. The estimation result of the traveling direction of the vehicle 5 by the control unit 12 is input to a vehicle ECU (not shown) and used for various vehicle controls for enhancing running safety such as throttle control, brake control, and torque control of each wheel.

The control unit 12 is a unit including a CPU for executing various calculations and an electronic board (not shown) on which memory elements such as ROM and RAM are mounted. The control unit 12 controls the operation of the sensor unit 11 and estimates the traveling direction of the vehicle 5 by using the change in the amount of lateral displacement of the vehicle 5 with respect to the magnetic marker 10 laid along the lane 100.

The control unit 12 has the following functions as each means.
(A) Period setting means: When the sensor unit 11 detects the first magnetic marker 10, it predicts the time when the second magnetic marker 10 can be detected, and detects the time period including the time when the second magnetic marker 10 can be detected. Means to set as a period.
(B) Lateral displacement amount difference means: A means for calculating the difference in lateral displacement amount with respect to two magnetic markers 10 laid along the lane 100.
(C) Course estimation means: The course deviation angle, which is the deviation of the traveling direction of the vehicle 5 with respect to the lane direction, is specified from the difference in the amount of lateral deviation with respect to the two magnetic markers 10, and the traveling direction of the vehicle 5 is estimated accordingly.

Next, (1) a marker detection process for each sensor unit 11 to detect the magnetic marker 10, (2) a flow of the overall operation of the vehicle system 1, and (3) a course estimation process will be described.
(1) Marker detection process The sensor unit 11 executes a marker detection process at a cycle of 3 kHz under the control of the control unit 12. The sensor unit 11 samples the magnetic measurement values represented by the sensor signals of the 15 magnetic sensors Cn for each execution cycle (p1 to p7) of the marker detection process to obtain a magnetic distribution in the vehicle width direction (see FIG. 5). ). As shown in the figure, the peak value of the magnetic distribution in the vehicle width direction becomes the maximum when passing through the magnetic marker 10 (period of p4 in FIG. 5).

When the vehicle 5 travels along the lane 100 (FIG. 1) on which the magnetic marker 10 is laid, each time the peak value of the magnetic distribution in the vehicle width direction passes through the magnetic marker 10 as shown in FIG. Becomes larger. In the marker detection process, the threshold value determination regarding this peak value is executed, and it is determined that the magnetic marker 10 is detected when the threshold value is equal to or higher than a predetermined threshold value.

When the sensor unit 11 having a function as a lateral displacement amount measuring means detects the magnetic marker 10, the position of the peak value in the vehicle width direction in the magnetic distribution in the vehicle width direction, which is the distribution of the magnetic measurement values of the magnetic sensor Cn. To identify. By using the position of the peak value in the vehicle width direction, the amount of lateral displacement of the vehicle 5 with respect to the magnetic marker 10 can be calculated. In the vehicle 5, since the sensor unit 11 is attached so that the central magnetic sensor C8 is located on the center line of the vehicle 5, the deviation of the position of the above peak value in the vehicle width direction with respect to the magnetic sensor C8 is the magnetic marker 10. It is the amount of lateral displacement of the vehicle 5 with respect to. It is preferable to make the positive and negative of the lateral displacement amount different depending on which of the left and right peak values is located with respect to the position of the magnetic sensor C8.

In particular, as shown in FIG. 7, the sensor unit 11 of this example executes a curve approximation (quadratic approximation) for the magnetic distribution in the vehicle width direction, which is the distribution of the magnetic measurement values of the magnetic sensor Cn, and obtains the peak value of the approximate curve. The position in the vehicle width direction is specified. If the approximate curve is used, the position of the peak value can be specified with an accuracy finer than the interval between the 15 magnetic sensors, and the amount of lateral displacement of the vehicle 5 with respect to the magnetic marker 10 can be measured with high accuracy.

(2) Overall Operation of Vehicle System 1 The overall operation of the vehicle system 1 will be described with reference to the flow chart of FIG. 8 mainly with the control unit 12 as the main body.
The control unit 12 causes the sensor unit 11 to repeatedly execute the above marker detection process until the magnetic marker 10 is detected (S101, first detection step → S102: NO). When the control unit 12 receives an input from the sensor unit 11 that the magnetic marker 10 has been detected (S102: YES), the control unit 12 sets a detection period, which is a time period for causing the sensor unit 11 to execute a new marker detection process. (S103, period setting step).

Specifically, as shown in FIG. 9, the control unit 12 first has a marker span S (see FIG. 1. laying interval of the magnetic marker 10) based on the vehicle speed (vehicle speed) V (m / sec) measured by the vehicle speed sensor. In this example, the required time δta obtained by dividing 2 m) is added to the time t1 when the sensor unit 11 detects the first magnetic marker 10. By adding the required time δta to the time t1 in this way, the time t2 at the time when the sensor unit 11 can detect the new magnetic marker 10 can be predicted. Then, the control unit 12 starts at the time (t2-δtb) obtained by subtracting the section time δtb obtained by dividing the reference distance (for example, 0.2 (m)) by the vehicle speed V (m / sec) from the time t2, and sets the section time. The time interval (t2 + δtb) obtained by adding δtb to the time t2 is set as the detection period. The reference distance may be appropriately changed in consideration of the detection range of the sensor unit 11 and the like.

The control unit 12 causes the sensor unit 11 to repeatedly execute the marker detection process within the detection period (FIG. 9) set in step S103 above (S104: NO → S114, second detection step). The content of this marker detection process is the same as the marker detection process of the first magnetic marker 10 in step S101.

If the sensor unit 11 can detect the second magnetic marker 10 during the detection period (FIG. 9) (S104: YES → S105: YES), the control unit 12 will be described next for estimating the traveling direction of the vehicle 5. The course estimation process is executed (S106). On the other hand, when the sensor unit 11 was able to detect the first magnetic marker 10 (S102: YES), but could not detect the second magnetic marker 10 during the above detection period (FIG. 9) (S102: YES). S104: YES → S105: NO), the control unit 12 returns to the marker detection process (S101) for detecting the first magnetic marker 10 and repeatedly executes the above series of processes.

(3) Course estimation process The course estimation process (step S106 in FIG. 8) executed by the control unit 12 is the amount of strike-slip measured when the sensor unit 11 passes through the two magnetic markers 10 as shown in FIG. This process includes a step of calculating the difference (S201) and a step of calculating the course deviation angle Rf which is a deviation in the traveling direction with respect to the line segment direction connecting the positions of the two magnetic markers 10 (S202). Since the two magnetic markers 10 are laid in the center of the lane 100 so as to be along the lane direction which is the path direction of the lane 100, the above line segment direction represents the lane direction.

In step S201, as shown in FIG. 11, when the vehicle 5 passes through the magnetic marker 10 twice, the lateral displacement amount Of1 measured for the first magnetic marker 10 and the lateral displacement measured for the second magnetic marker 10 The difference Ofd between the quantity Of2 and Of2 is calculated by the following equation. In the case of the figure, since the positive and negative values of Of1 and Of2 are different, the absolute value of Ofd exceeds the absolute value of Of1 and Of2 according to the difference.

In step S202, as shown in FIG. 12, the course deviation, which is the angle (deviation of the angle in the turning direction) formed by the traveling direction Dir of the vehicle 5 with respect to the line segment direction Mx (corresponding to the lane direction) connecting the positions of the two magnetic markers 10. Calculate the angle Rf. This course deviation angle Rf is calculated by the following equation including the difference Ofd of the lateral deviation amount and the marker span S.

For example, when the vehicle 5 is traveling along the lane (FIG. 12), the course deviation angle Rf, which is the angle formed by the traveling direction Dir of the vehicle 5 with respect to the line segment direction Mx connecting the positions of the two magnetic markers, is zero. It becomes. On the other hand, when the vehicle traverses the lane (FIG. 13), the traveling direction Dir of the vehicle 5 deviates from the line segment direction Mx, and the course deviation angle Rf becomes large. Further, when the vehicle 5 is traveling along the curved road (FIG. 14), the line segment direction Mx connecting the positions of the two magnetic markers coincides with the tangential direction of the lane which is the curved road, and this line. The course deviation angle Rf, which is the “made angle” of the traveling direction Dir of the vehicle 5 with respect to the minute direction Mx, becomes zero. On the other hand, when the vehicle is oblique in a curved lane (FIG. 15), the deviation of the traveling direction Dir of the vehicle 5 with respect to the tangential direction of the curved lane becomes large, and the course deviation angle Rf becomes large.

As described above, the vehicle system 1 of this example estimates the traveling direction of the vehicle 5 by using the difference in the amount of lateral displacement with respect to the two magnetic markers 10. The path deviation angle Rf, which is the traveling direction of the vehicle 5 estimated by the vehicle system 1, is not an absolute direction, but a "tidal angle" with respect to the line segment direction Mx connecting the positions of the two magnetic markers 10. Since the line segment direction Mx is a direction that can be a reference defined by the two magnetic markers 10 fixed to the road surface 100S, the angular deviation of the vehicle traveling direction with respect to the line segment direction Mx is the traveling of the vehicle 5. It can be an index that accurately indicates the direction.

In the vehicle system 1, the difference Offd of the amount of lateral displacement with respect to the two magnetic markers 10 is used, and the calculated path deviation angle Rf is obtained as the deviation. Instead of or in addition to this, the amount of deviation in the lateral direction with respect to the above-mentioned line segment direction Mx predicted when traveling a predetermined distance, for example, 2 m forward or 10 m forward, may be obtained as a deviation. ..

In this example, among the magnetic markers 10 laid every 2 m, the traveling direction Dir of the vehicle 5 is estimated by using the two magnetic markers 10 that are adjacent to each other in the immediate vicinity. For example, since the distance traveled by a vehicle at 100 km / h in 1 second is 27.7 m, the passing time of 2 m is 0.07 seconds, which is less than 0.1 seconds. Considering the reaction time of the steering operation, the passing time may be 0.2 to 0.3 seconds. In this case, every other 4 m interval and every two 6 m intervals are adjacent to each other 2 It is also possible to estimate the traveling direction Dir by using the combination of the two magnetic markers 10. For magnetic markers 10 arranged at relatively close intervals such as 1 m interval and 2 m interval, a combination of two magnetic markers 10 having a wider interval is used as the speed increases, and two magnetisms having a narrower interval as the speed decreases. It is also possible to use a combination of markers 10. Alternatively, on a road such as an expressway, the interval between the magnetic markers 10 may be set relatively wide, and on a general road, the interval between the magnetic markers 10 may be set relatively narrow. Further, in this example, the magnetic markers 10 are arranged at intervals of 2 m so that the traveling direction can be estimated for all the magnetic markers 10. Instead of this, for example, on a road where magnetic markers 10 are arranged at intervals of 10 to 20 m for lane departure or automatic driving, for estimating the traveling direction of a specific magnetic marker 10 such as every two or every other. It is also possible to additionally arrange the magnetic markers 10 of the above side by side.

In this example, after detecting the first magnetic marker 10, the detection period for trying to detect the second magnetic marker 10 is set. This detection period is not an essential configuration and may be omitted. Alternatively, it is also possible to always try to detect the magnetic marker 10 without setting the detection period. In this case, if the time when the second magnetic marker 10 is detected is not included in the period corresponding to the above detection period with reference to the detection time of the first magnetic marker 10, it is an erroneous detection. It is also good to make a reliability judgment that there is a possibility.

It is also possible to calculate the strike-slip amount Rf for each of the two adjacent magnetic markers 10 among the three or more magnetic markers 10 and to calculate the average value of the plurality of strike-slip amounts Rf. In this way, in estimating the deviation in the traveling direction of the vehicle, a configuration using three or more magnetic markers 10 may be adopted.

In addition to the geomagnetism, the sensor unit 11 has common noise, which is magnetic noise that is almost uniform to each magnetic sensor Cn due to a large magnetic source such as an iron bridge or another vehicle. Is working. Such common noise is likely to act uniformly and close to each magnetic sensor Cn of the sensor unit 11. Therefore, it is also possible to detect the magnetic marker 10 by using the difference value of the magnetic measurement values of the magnetic sensors Cn arranged in the vehicle width direction. With this difference value representing the magnetic gradient in the vehicle width direction, common noise acting uniformly close to each magnetic sensor Cn can be effectively suppressed.

In this example, the magnetic sensor Cn having sensitivity in the vertical direction is adopted, but it may be a magnetic sensor having sensitivity in the traveling direction or a magnetic sensor having sensitivity in the vehicle width direction. Further, for example, a magnetic sensor having sensitivity in two axial directions of the vehicle width direction and the traveling direction or two axial directions of the traveling direction and the vertical direction may be adopted. For example, three axes of the vehicle width direction, the traveling direction and the vertical direction may be adopted. A magnetic sensor having sensitivity in the direction may be adopted. By using magnetic sensors having sensitivities in a plurality of axial directions, it is possible to measure the magnitude of magnetism as well as the direction of action of magnetism and generate a magnetic vector. It is also possible to distinguish between the magnetism of the magnetic marker 10 and the disturbance magnetism by using the difference between the magnetic vectors and the rate of change in the traveling direction of the difference.

(Example 2)
This example is an example of calculating the course deviation angle Rf by using the sensor units 11 provided in front of and behind the vehicle 5 based on the vehicle system 1 of the first embodiment. This content will be described with reference to FIG.

In the vehicle 5, the sensor units 11 are arranged at intervals of 4 m. The distance of 4 m between the front and rear sensor units 11 is the same as the distance of 4 m between every other two magnetic markers 10 (referred to as marker span S1). According to the sensor units 11 arranged at intervals of 4 m, two magnetic markers 10 adjacent to each other with one magnetic marker 10 in between can be detected at substantially the same timing.

As shown in FIG. 16, when the amount of lateral displacement measured by the front sensor unit 11 is Of1 and the amount of lateral displacement measured by the rear sensor unit is Of2, and the difference between the two is Ofd, the lateral displacement angle Rf is calculated by the following equation. It can be calculated.

The sensor unit 11 may be additionally arranged at the center of the sensor units 11 before and after the interval of 4 m. In this case, magnetic markers adjacent to each other at intervals of 2 m at least one of the combination of the front sensor unit 11 and the center sensor unit and the combination of the rear sensor unit 11 and the center sensor unit. 10 can be detected at the same timing and the amount of strike-slip can be measured. Depending on the speed, it is also possible to switch between using two magnetic markers 10 at 2 m intervals and using two magnetic markers 10 at 4 m intervals.
The other configurations and effects are the same as in Example 1.

(Example 3)
This example is an example in which a function of estimating the road structure is added based on the vehicle system 1 of the first embodiment. This content will be described with reference to FIGS. 17 to 19.

This example is an example of estimating a two-dimensional road structure by using the path deviation angle Rf in an image 551 captured by an in-vehicle camera installed so that the optical axis coincides with the central axis of the vehicle 5. ..
For example, when the vehicle 5 travels along a straight road, in the road structure in the captured image 551 acquired by the in-vehicle camera, as shown in FIG. 17, the lane, the road, the left and right lane marks, the guardrail, and the like disappear at a distance. Vp is located in the center of the screen.

On the other hand, when the vehicle 5 travels diagonally so as to deviate to the right with respect to the straight road, the vanishing point Vp at which the lane or the like disappears is located shifted to the left side of the screen as shown in FIG. The amount of deviation of the vanishing point Vp at this time is an amount determined by the ratio of the path deviation angle Rf to the angle of view of the in-vehicle camera. For example, if the ratio of the path deviation angle Rf to the horizontal angle of view of the vehicle-mounted camera is 1/2, the deviation amount of the vanishing point Vp is half the screen width. For example, when the position of the vanishing point Vp when the path deviation angle Rf = 0 is the center of the screen as shown in FIG. 17, if the ratio of the path deviation angle Rf is 1/2, the vanishing point Vp is the screen width. It is located at the edge of the screen, off the center of 1/2. Further, if the ratio of the path deviation angle Rf to the horizontal angle of view of the vehicle-mounted camera is 1/4, the deviation amount of the vanishing point Vp from the center of the screen is 1/4 of the screen width.

In this way, if the traveling direction of the vehicle such as the course deviation angle Rf can be estimated, the position of the vanishing point Vp in the captured image 551 can be estimated, and the road structure in the captured image 551 can be grasped. If the position of the vanishing point Vp at which the lane or the like disappears is known, the lane region or the roadside region in the captured image 551 can be estimated. If it is possible to estimate such a region, image recognition can be performed efficiently. For example, if the lane area can be estimated, the process for recognizing the lane mark that divides the lane can be efficiently performed, false detection can be suppressed, and the recognition rate can be improved. Further, for example, if the roadside area can be estimated, the recognition rate of signs, signals, etc. installed on the roadside can be improved.

It is also good to estimate the three-dimensional road structure. For example, if the vehicle 5 is equipped with a sensor for measuring the steering angle, the course Es of the vehicle 5 can be predicted by using the steering angle as shown in FIG. At this time, if the course deviation angle Rf is zero, the area A along the predicted course Es can be estimated as the lane area. Furthermore, if map information that the road is a two-way road with one lane on each side can be obtained from a map database or the like, for example, in the case of left-hand traffic, the area B on the right side of the area A can be estimated as the area of the oncoming lane, and the left side of the area A. Region C can be estimated as a roadside region. For example, in the case of recognizing a roadside object such as a sign or a guardrail by image recognition by an in-vehicle camera or an active sensor such as a laser radar, the efficiency can be improved by performing the processing mainly in the area C. Further, for example, in a system that automatically switches to a low beam when passing an oncoming vehicle, it is possible to suppress a malfunction due to light such as a street light by capturing the oncoming vehicle with the area B as the main target.

Also, for example, if map information that the road is a four-lane road with two lanes on each side can be obtained from a map database or the like, and information that the lane in which the vehicle is running is a lane closer to the center can be obtained from the infrastructure side, the area C can be run in parallel. It can be estimated as the area of the lane. As a method of providing information from the infrastructure side, for example, there is a method of providing lane information by making the polarity of the magnetic marker 10 different for each lane.
The other configurations and effects are the same as in Example 1.

(Example 4)
This example is an example in which a lane deviation warning function is added to the vehicle system 1 of the first embodiment.
This content will be described with reference to FIG.
In FIG. 20, the vehicle 5 (vehicle width Wc) on the lane 100 in which the lane width is Wr and the magnetic markers 10 are arranged along the center has a speed V (m / sec) and a lane deviation angle Rf. An example shows a traveling situation in which 100 is skewed. It should be noted that the figure is a view that gives a bird's-eye view of the plane on which the vehicle 5 travels, the vehicle width direction is defined in the horizontal direction, and the forward direction is defined in the vertical direction. Further, in the figure, only the second magnetic marker 10 is shown in the figure, and the illustration of the magnetic marker 10 including the first one is omitted.

The deviation warning when the amount of lateral displacement when passing through the second magnetic marker 10 is Of2 and the path deviation angle estimated at this time is Rf will be described. This deviation alarm is an alarm by a control unit having a function as a predicting means for predicting the following deviation time and an alarm means for issuing a deviation alarm.

For the procedure for calculating the deviation time, which is the time until the vehicle 5 deviates from the lane 100 when the vehicle 5 traveling in the lane 100 is oblique and the course deviation angle is Rf, the following equations 3 to 6 are used. It will be explained with reference to it.

First, in FIG. 20, the distance D1 from the center of the lane 100 represented by the alternate long and short dash line to the side end of the vehicle 5 can be calculated by the following equation.

Then, the distance D2 between the boundary (for example, the lane mark) 100E of the lane on the side where the vehicle 5 is oblique and the side surface of the vehicle 5 becomes as follows.

On the other hand, of the speed V (m / sec) of the vehicle 5, the speed component Vx (m / sec) in the vehicle width direction is as follows.

Therefore, when the vehicle 5 travels at a speed V (m / sec) while maintaining the course deviation angle Rf, the time Tr of the following equation required to reach the boundary 100E of the lane 100 may be calculated as the deviation time.

If this deviation time Tr is used, a highly accurate deviation warning can be executed. For example, if the deviation time Tr is 20 seconds or more, no alarm is issued, if the deviation time Tr is 10 to 20 seconds, a gentle alarm is issued, and if the deviation time Tr is 10 seconds or less, caution is given. It is also possible to issue an alarm to urge or an alarm to announce an emergency. The deviation time threshold can be changed as appropriate.

Instead of the deviation time, it is also possible to calculate the deviation distance, which is the predicted distance traveled before departing from the lane, and issue a deviation warning according to the magnitude of the deviation distance. The deviation distance can be calculated by multiplying the deviation time Tr by the speed component (V × cosRf) in the lane direction.
The other configurations and effects are the same as in Example 1.

(Example 5)
This example is an example in which the deviation of the traveling direction of the vehicle with respect to the route direction of the traveling path of the vehicle can be estimated based on the vehicle system of the first embodiment.
There is an error in the laying position of the magnetic marker on the travel path, and the line segment direction connecting the positions of the adjacent magnetic markers does not always match the path direction of the travel path. Attempting to improve this matching accuracy may result in an increase in the laying cost of the magnetic marker. Therefore, there is a demand for a technique for accurately estimating the deviation of the traveling direction of the vehicle with respect to the route direction of the traveling road while allowing an error of the laying position of the magnetic marker to some extent.

The vehicle system of this example is an example in which the above-mentioned technology is realized by being configured so as to be able to acquire information that can identify the deviation in the above-mentioned line segment direction with respect to the route direction of the traveling path.
In the first embodiment, the strike-slip angle Rf representing the first deviation of the traveling direction of the vehicle with respect to the line segment direction is estimated. In this example, a second deviation in the line segment direction with respect to the route direction of the travel path is specified, and based on the second deviation and the first deviation described above, the traveling direction of the vehicle with respect to the route direction of the travel path. It is possible to estimate the third deviation of.

As a configuration for specifying the deviation (second deviation) in the line segment direction with respect to the route direction of the travel path, for example, there is the following configuration.
(1) A map database is provided to store map information including information on the deviation of each magnetic marker in the vehicle width direction from the center of the traveling route, and the detected deviation information of the magnetic marker is acquired from the map database to obtain the information on the deviation of the detected magnetic marker. A configuration that specifies the deviation (second deviation) in the line segment direction connecting the positions of the two magnetic markers with respect to the path direction.

(2) In addition to the information on the absolute position of the center of the travel path, a map database that stores map information including the information on the absolute position of the magnetic marker is provided, and the route direction of the travel route is obtained from the information on the absolute position of the center of the travel route. And specify the direction of the line segment connecting the positions of the magnetic markers from the information on the absolute positions of the magnetic markers. Then, a configuration for specifying the deviation (second deviation) in the line segment direction connecting the positions of the magnetic markers with respect to the path direction of the traveling path.

In any of the above configurations, the map database may be a map database stored in a storage medium mounted on the vehicle, and is stored in a storage medium of a server device that can be connected via the Internet or the like. It may be a map database.

A wireless communication RF-ID tag that operates by receiving power supply from the outside and can output information wirelessly is attached to a magnetic marker, and a receiving means for receiving the above-mentioned deviation information transmitted by the RF-ID tag is provided on the vehicle side. It is also good to provide it in. Information on the absolute position of the center of the travel path and information on the absolute position of the magnetic marker may be transmitted from the RF-ID tag.
Other configurations and effects are the same as in Example 1.

(Example 6)
This example is an example of a system capable of specifying the absolute position of the vehicle at the time when the deviation in the traveling direction of the vehicle is estimated based on the vehicle system of the first embodiment.
In the vehicle system of this example, information representing the absolute position of the magnetic marker can be acquired from the map database, and the absolute position of the vehicle can be specified from the detected absolute position of the magnetic marker. The map database may be a map database stored in a storage medium mounted on a vehicle, or may be a map database stored in a storage medium of a server device that can be connected via the Internet or the like.

If the absolute position of the vehicle can be specified, for example, the shape of the traveling road in front of the vehicle can be grasped by referring to a database that stores map information capable of specifying the route direction of the traveling route. Then, by comparing the shape of the traveling path ahead and the deviation of the estimated traveling direction of the vehicle, it is possible to estimate the degree of danger or the like with respect to the estimated traveling direction of the vehicle. For example, when a vehicle traveling in the right lane reaches a position in front of the left curve, if the deviation in the traveling direction of the vehicle is toward the right, it can be estimated that the risk is high.
The other configurations and effects are the same as in Example 1.

Although specific examples of the present invention have been described in detail as in the examples, these specific examples merely disclose an example of the technology included in the claims. Needless to say, the scope of claims should not be construed in a limited manner depending on the composition and numerical values of specific examples. The scope of claims includes technologies that are variously modified, modified, or appropriately combined with the above specific examples by utilizing publicly known technologies and knowledge of those skilled in the art.

1 Vehicle system 10 Magnetic marker 100 lanes 11 Sensor unit (lateral displacement measuring means)
110 Detection processing circuit 12 Control unit (course estimation means)
21 MI element 5 vehicle

Claims (9)

A lateral displacement amount measuring means for measuring the lateral displacement amount, which is a positional deviation of the vehicle in the vehicle width direction with respect to the magnetic marker,
A course that estimates the deviation of the vehicle's traveling direction with respect to the line segment direction connecting the positions of the two magnetic markers by using the difference in the amount of lateral displacement of the two magnetic markers arranged at intervals on the road surface on which the vehicle travels. Equipped with an estimation means,
When the amount of lateral displacement of the two magnetic markers is measured by one lateral displacement amount measuring means in time with respect to the movement of the vehicle, the course estimating means is used for one of the two magnetic markers. A vehicle system that estimates the deviation in the traveling direction by using the difference between the measured lateral displacement amount and the lateral displacement amount measured for the other of the two magnetic markers. In claim 1, information that can specify the deviation of the line segment direction with respect to the route direction of the traveling path on which the vehicle travels is acquired, and the deviation of the line segment direction with respect to the route direction specified by using this information and the said. A vehicle system that estimates the deviation of the traveling direction of the vehicle with respect to the line segment direction and the deviation of the traveling direction of the vehicle with respect to the route direction of the traveling path based on the deviation. The vehicle system according to claim 1 or 2, wherein the two magnetic markers are arranged along a route direction of a traveling path on which a vehicle travels. In any one of claims 1 to 3, the magnetic marker is arranged along a lane which is a division in which the vehicle travels.
Depending on the prediction means for predicting at least one of the time and distance until the vehicle deviates from the lane using the strike-slip amount, the deviation and the vehicle speed, and the time or distance predicted by the prediction means. A vehicle system equipped with an alarm means for issuing an alarm. In any one of claims 1 to 4, the magnetic marker is arranged along a lane which is a division in which the vehicle travels.
A vehicle system including a means for estimating a three-dimensional road structure based on the own vehicle by using the amount of strike-slip and the deviation. The vehicle system for specifying the absolute position of the vehicle at the time when the deviation in the traveling direction of the vehicle is estimated by acquiring the absolute position of the magnetic marker in any one of claims 1 to 5. A method for estimating the course of a vehicle, which comprises a lateral slip amount measuring means for measuring a lateral displacement amount which is a positional deviation of the vehicle in the vehicle width direction with respect to magnetic markers arranged at intervals on the road surface on which the vehicle travels.
Processing to measure the amount of lateral displacement of two magnetic markers arranged at intervals on the road surface on which the vehicle travels, and
It includes a process of estimating the deviation of the traveling direction of the vehicle with respect to the line segment direction connecting the positions of the two magnetic markers by using the difference of the amount of lateral displacement with respect to the two magnetic markers.
When the amount of lateral displacement of the two magnetic markers is measured by one lateral displacement amount measuring means according to the movement of the vehicle in time, the amount of lateral displacement measured for one of the two magnetic markers and the amount of lateral displacement. A course estimation method for estimating the deviation in the traveling direction by using the difference between the lateral displacement amount measured for the other of the two magnetic markers and the lateral deviation amount. In claim 7, the information capable of specifying the deviation of the line segment direction with respect to the route direction of the traveling path on which the vehicle travels is acquired, and the deviation of the line segment direction with respect to the route direction specified by using this information and the said. A course estimation method for estimating the deviation of the traveling direction of the vehicle with respect to the route direction of the traveling path based on the deviation of the traveling direction of the vehicle with respect to the line segment direction. The course estimation method according to claim 7 or 8, wherein the two magnetic markers are arranged along the path direction of the travel path on which the vehicle travels.

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