JPH10213446A - Vehicle traveling system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To calibrate the neutral point of a steering angle sensor during traveling a vehicle. SOLUTION: An object recognizing device 9 judges the road shape based on the data of a range R and a direction θ of an object outputted from a laser distance measuring device 1. For example, the road shape is judged based on the arrangement of road-side delineators D, the track of a traveling vehicle 27 and the coordinates of two preceding traveling vehicles 28 and 29 traveling on the other lanes. Then, when a road 25 is judged to be the straight line, a neutral-point correcting device 12 of the steering angle sensor corrects the neutral point of a steering angle sensor 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a vehicle traveling system. In particular, calibrate the neutral point of the steering angle sensor (calibrat
The present invention relates to a vehicle traveling system having a function of performing ionization.

[0002]

2. Description of the Related Art For example, a steering mechanism for steering rear wheels is mounted, and a four-wheel drive capable of steering all four wheels is provided.
In a vehicle equipped with an S (4 Weels Steering) control system, a steering angle sensor is provided to detect a wheel direction (steering angle) of a rear wheel. The steering angle of the rear wheels is controlled.

[0003] In such a steering angle sensor, it is necessary to detect the steering angle of the wheel based on the direction (neutral point) when the vehicle is going straight and the vehicle is going straight. Therefore, generally, the vehicle is shipped from the factory with the neutral point of the output of the steering angle sensor adjusted.

However, in the method of adjusting the neutral point of the steering angle sensor at the time of shipment from the factory, the adjustment accuracy of the neutral point of the steering angle sensor must be coarse. Further, the neutral point of the steering angle sensor may be shifted by hitting a tire running on a road against a curb or the like, or the neutral point of the steering angle sensor may be shifted due to aging.

For this reason, conventionally, especially when the accuracy of the neutral point of the steering angle sensor is required, the ABS (An
tilock Brake System) Using the wheel speed sensor used in the system, etc., determines the straight ahead of the vehicle based on the difference between the left and right wheel speeds, detects that the wheels are facing straight, and outputs the steering angle sensor at that time Is set to the neutral point.

[0006]

As described above, in the method of correcting the neutral point of the steering angle sensor based on the wheel speed difference detected by the wheel speed sensor, an ABS system or the like is mounted and the wheel speed sensor is used from the beginning. It is limited to the vehicle to which it is attached, and has a drawback of narrowing its application range. Alternatively, it is necessary to attach a wheel speed sensor only to detect the neutral point of the steering angle sensor, and there is a disadvantage that the cost for calibrating the neutral point of the steering angle sensor is expensive.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned drawbacks of the prior art, and has as its object the purpose of the present invention is to provide a low-cost, wide-ranging application, and a neutral point of the steering angle sensor based on the road shape. To provide a vehicle traveling system having a function of calibrating the vehicle.

[0008]

DISCLOSURE OF THE INVENTION A vehicle traveling system according to the present invention includes a means for determining a road shape, a steering angle sensor, and a means for calibrating a neutral point of the steering angle sensor. It is characterized in that the neutral point of the steering angle sensor is calibrated based on the determination result by the shape determining means.

More specifically, in the vehicle traveling system of the present invention, when the road shape determining means determines that the road shape is straight, the neutral point calibrating means calibrates the neutral point of the steering angle sensor. . That is, since it is determined that the wheels of the vehicle traveling on the straight road are pointing in a straight direction, the neutral point of the steering angle sensor is corrected by calibrating the neutral point of the steering angle sensor at that time. Can be calibrated.

Further, according to the method of calibrating the neutral point of the steering angle sensor based on the road shape, a laser distance measuring device can be used as the road shape determining means. For example,
The road shape is determined by detecting the roadside sign of the road with the laser distance measuring device, the road shape is determined from the trajectory by detecting the preceding vehicle with the laser distance measuring device, and the preceding vehicle is determined with the laser distance measuring device. It is possible to detect and determine the road shape from the coordinates.

A laser distance measuring apparatus is used in a vehicle traveling system having a function of following a constant distance between vehicles.
It is more widely used than a wheel speed sensor such as a BS system. Therefore, if the laser range finder can judge the road shape and calibrate the neutral point of the steering angle sensor, the application of the steering angle sensor with the neutral point correction function can be broadened, and the steering angle can be accurately detected. The vehicle traveling system capable of performing the above can be widely spread.

Further, in the case of a vehicle already equipped with a laser distance measuring device, the neutral point of the steering angle sensor can be calibrated simply by adding or changing the algorithm processing inside the laser distance measuring device. The neutral point can be calibrated without being raised. Further, even when the vehicle is additionally equipped with a laser distance measuring device, the cost can be reduced as compared with the case where the wheel speed sensor is additionally equipped.

[0013]

FIG. 1 is a block diagram showing the configuration of a vehicle traveling system according to one embodiment of the present invention. Reference numeral 1 denotes a laser distance measuring device, which is mounted on the front of the vehicle, for example, above a bumper. The laser distance measuring device 1 includes a semiconductor laser element (LD) 2 and a semiconductor laser element driving circuit (LD driving circuit) for driving the semiconductor laser element 2.
And a light scanning unit (scanner) 4 for scanning a laser pulse L emitted from the semiconductor laser element 2 in a detection area. The semiconductor laser device drive circuit 3 causes the semiconductor laser device 2 to emit pulses in synchronization with the light emission timing signal a output from the control circuit 5. A laser pulse L emitted from the semiconductor laser element 2 is reflected by a mirror surface of an optical scanning unit 4 composed of a polygon mirror rotated by a servomotor or a vibration plate rotated by a piezoelectric vibrator, and scans a predetermined detection area. You.

Here, the light projecting operation in the laser distance measuring device 1 will be specifically described with reference to FIG. The semiconductor laser element 2 includes a control circuit 5 and a semiconductor laser element driving circuit 3
As a result, light is emitted every 5 μsec. On the other hand, the optical scanning device 4
Scans the laser pulse L with a period of 50 msec over a measurement range of 200 mrad. Laser pulse L is 2
Since light is emitted every 5 μsec, 50 msec
The semiconductor laser element 2 emits 2000 times during
A distance measurement of 00 samples is performed. Of the 2000 samples in one scan, 1600 samples from 201 to 1800 are used for distance measurement, and distance measurement is not performed in the end point areas (samples 1 to 200 and samples 1801 to 2000). 1600 samples (201st to 1800th samples) used for distance measurement are divided into 80 regions (80 directions) every 20 samples.

The scanning direction detecting device 6 in FIG. 1 detects the scanning direction (light emitting direction) of the laser pulse L by the optical scanning section 4 in synchronization with the light emission timing signal a. The scanning direction of the laser pulse L detected is transmitted to the control circuit 5 as scanning direction information b. The end point area serves as a reference for detecting a scanning direction.

The laser distance measuring device 1 further includes a light receiving section including a light receiving element 7 such as a photodiode (PD) and a light receiving circuit 8. Laser pulse L emitted from semiconductor laser element 2 and scanned by optical scanning section 4
Is projected forward and is reflected by objects such as vehicles ahead and roadside delinators (reflective road boundary signs),
The light returns to the laser distance measuring device 1 and is received by the light receiving element 7. The light receiving element 7 outputs a light receiving signal c according to the light receiving intensity. The light receiving signal c output from the light receiving element 7 is amplified by the light receiving circuit 8, and the light receiving signal c corresponding to the light receiving level of the light receiving element 7 is output from the light receiving circuit 8 to the control circuit 5.

The control circuit 5 compares the light receiving signal c output from the light receiving circuit 8 with a certain threshold value, and if the light receiving signal c output from the light receiving circuit 8 is equal to or more than the certain threshold value, the light receiving element 7 It is determined that has received the laser pulse L. Then, the distance to the target is calculated from the propagation delay time from the emission of the laser pulse L to the reception thereof. At this time, the control circuit 5 controls the light receiving signal c in each of the 80 regions divided every 20 samples shown in FIG.
The distance R to the object is obtained for each region. At the same time, the direction θ of the object is determined from the scanning direction information b at that time. The control circuit 5 transmits the obtained data of the distance R and the direction θ of the target object to the target object recognition device 9.

The vehicle speed sensor 10 outputs a pulse signal d corresponding to the speed of the vehicle. The vehicle speed calculation device 11 calculates the vehicle speed based on the pulse signal d, and uses the calculated vehicle speed data e as the object recognition device 9. Output to

The object recognizing device 9 extracts road information from a target object by a roadside delineator or the like, and determines whether or not the traveling road is a straight road. If it is determined that the traveling road is a straight road, it is determined that the vehicle is traveling in a state where the wheels of the host vehicle are straight, and the determination result is output to the neutral point correction device 12 of the steering angle sensor. .

The steering angle sensor 13 outputs a pulse signal f in accordance with a change in the steering angle, and the steering angle calculator 14 calculates the steering angle based on the pulse signal f, and outputs the calculated steering angle data g. It outputs to the neutral point correction device 12 of the steering angle sensor.

When the neutral point correcting device 12 of the steering angle sensor receives from the object recognizing device 9 the result of the determination that the traveling road is a straight road, it reads the output from the steering angle calculating device 14 and outputs the output. Does not indicate the neutral point, the neutral point correction signal h is output to the steering angle sensor 13 to correct the neutral point of the steering angle sensor 13.

The object recognition device 9 and the vehicle speed calculation device 1
1. The neutral point correction device 12, the steering angle calculation device 14, etc. of the steering angle sensor may be configured by an electric circuit,
It may be constituted by a microcomputer (CPU) and software.

FIG. 3 is a block diagram showing the configuration of the object recognition device 9 in detail. In particular, the configuration for determining the road shape based on the outputs R and θ from the laser distance measuring device 1 is shown. First, the coordinate system conversion device 16 converts data (polar coordinate system data) on the distance R and the direction θ to the object calculated by the control circuit 5 into X, Y coordinate data (Cartesian coordinate system data), and converts the data into 80 directions. The X and Y coordinate data of each area are stored in the memory 15 together with the received light amount data (received light signal c). Note that the X coordinate axis (X direction) is the direction in which the host vehicle travels straight, and the Y coordinate axis (Y direction) is the direction orthogonal to the host vehicle's straight travel direction, that is, the width direction of the host vehicle.

Next, the ranging data grouping device 17
Extracts individual objects by grouping the distance measurement data based on the X, Y coordinate data (hereinafter, referred to as distance measurement data) of each of the 80 azimuth regions converted into the X, Y coordinate data. Do. Here, the grouping of the distance measurement data means, as shown in FIGS. 4A and 4B, the distance measurement data of an adjacent area among the individual distance measurement data α ₁ , α ₂ ,. The objects that approach each other are collected, and the distance measurement data β ₁ (= α _{1 to} α ₃ ) and β ₂ grouped for each object
(= Α _{4 to} α ₈ ), β ₃ (α ₉ , α ₁₀ ,...),..., And each of the grouped ranging data corresponds to one target object in the subsequent processing. Is treated as data By grouping the distance measurement data for each area in this way, the distance from the laser distance measuring device 1 to each object and the width of the object are calculated for each object. The grouped distance measurement data or the distance and width of the object are stored in the memory 15.

The time-series associating device 18 associates the grouped data obtained at the time of the previous scan (or at the time of the last scan) with the grouped data obtained at the time of the current scan, and is specified by the grouped data. The relative speed of the object to be calculated is calculated. More specifically, as shown in FIG. 5A, the time-series associating device 18 determines the position of the grouped data obtained in the previous scan (前 回 in FIG. 5).
The window (movable range) W is set for each grouped data based on P _-1 ) and the relative speed V _-1 at the time of the previous scan.

The window W is a range in which the object can be moved (the corresponding grouped data can appear) between the time of the previous scan and the time of the current scan, and is a range of the grouped data obtained in the previous scan. Based on the position P _-1 and the relative speed V _-1 , the grouping data is set within a certain range around a position Ps (indicated by a hatched circle in FIG. 5A) Ps at which the grouped data is expected to appear during the current scan You.

Thereafter, as shown in FIG. 5B, it is checked in which window W the current grouping data is located, and the previous grouping data contained in the same window W is compared with the current grouping data. associate a group of data (i.e., regarded as the position data for the same object), and calculates the relative velocity V ₀ which said object. That is, the position of the grouped data at the time of the current scan that is contained in the window W (indicated by a circle in FIG. 5B) P
_The relative speed V ₀ is obtained from ₀ and the position P _{- 1} of the grouping data at the time of the previous scan.

Next, the object attribute determining device 19 includes the ranging data grouping device 17 and the time-series associating device 1.
8 based on the width and relative speed V _{0 of} the target object determined by E.g. 8, the vehicle speed data e of the own vehicle from the vehicle speed calculation device 11, and the like, to determine the attribute of the target object present at the position indicated by each distance measurement data. I do. Here, the attribute of the object refers to the type of the object (for example, a vehicle, a motorcycle, a person, a signboard, a roadside delineator, etc.) and the state of the object (for example, moving, stopping, and the like).

When the attribute of each object is determined by the attribute determining device 19 for the object, the road shape estimating device 20 based on the roadside delineator determines the distance measurement data of the roadside delineator from the distance measurement data. And data having an attribute with a high received light intensity). Then, as shown in FIG. 6, the road shape estimating device 20 based on the roadside delineator determines whether the distance measurement data of each roadside delineator D belongs to the left or right roadside, and further determines the distance of the roadside delineator D divided into left and right. The data (Xn, Yn) based on the nearest roadside delineator D and the data (Xr, Yr) based on the farthest roadside delineator D are selected. Next, the road shape estimating device 20 based on the roadside delineator determines whether it is better to calculate the road shape using the distance measurement data of the left or right roadside delineator D based on the past data, and determines the roadside on the determined side. Delineator D
It is determined whether the shape of the traveling road 25 is a curve (the radius of curvature R of the road is not substantially zero) or a straight line (the radius of curvature of the road R is substantially zero) using the distance measurement data.

The shape of the road 25 on which the vehicle 26 is traveling is
Using the distance measurement data of the roadside deriniator D,
It is determined by the equation and the equation.

[0031]

(Equation 1)

Here, Xr and Yr are relative distances (distance measurement data) in the X and Y directions of the roadside delineator D farthest from the detection area, and Xn and Yn are the X directions and the distances of the nearest roadside delinator D. This is a relative distance (distance measurement data) in the Y direction. Further, X ₀ and Y ₀ shown by the formulas and the formulas
Are relative coordinates of the center of curvature (center of curvature) O of the road 25. Further, R shown in the equation is a radius of curvature of the road.

If the curvature radius R of the road 25 calculated by the formula is equal to or smaller than a small predetermined value, the road shape estimating device 20 based on the roadside delineator determines that the road is a straight road, and if the curvature radius R is larger than the small predetermined value. For example, it is determined that the road is a curved road.

Next, if the road shape determined by the roadside delineator is determined to be a straight road, and if the determination continues for a certain period of time, for example, 1 second or more, the host vehicle 26 travels on the straight road 25. It is determined that the steering angle sensor 13 is present, and the result of the determination is output to the neutral point correction device 12 of the steering angle sensor to correct the neutral point of the steering angle sensor 13.

Therefore, in the vehicle traveling system of the present invention, the neutral point correction of the steering angle sensor is constantly performed while the vehicle is traveling, and the steering angle sensor can be maintained with high accuracy.

(Second Embodiment) Next, a vehicle traveling system according to another embodiment of the present invention will be described. This vehicle traveling system detects the trajectory of a vehicle traveling ahead, recognizes the shape of the road from the trajectory of the vehicle, and corrects the neutral point of the steering angle sensor when determining that the road is straight. Features. Correspondingly, in the object recognition device 21 according to this embodiment, as shown in FIG. 7, the road shape estimating device is not a roadside delineator, but a road shape estimating device 22 based on the trajectory of the vehicle. I have.

The road shape estimating device 2 based on the trajectory of the vehicle
2 extracts distance measurement data of the preceding vehicle based on the attribute of each object determined by the attribute determining device 19 of the object.
Further, from the distance measurement data of the preceding vehicle, the distance measurement data of the preceding vehicle 27 having a large relative speed (for example, 10 km / h or more) is selected, and the distance measurement data of the preceding vehicle 27 is divided into two points at time intervals. Sampling at When the distance difference of the distance measurement data in the Y-axis direction of the preceding vehicle 27 becomes a certain distance (for example, 15 m or more), the shape of the road 25 is calculated based on the following equation.

[0038]

(Equation 2)

Here, as shown in FIG. 8, X ₂ and Y
_2, X and Y directions relative distance when located farthest out of the distance data of the preceding vehicle 27 of interest, X ₁ and Y ₁ is the distance data of the preceding vehicle 27 of interest Is the relative distance in the X and Y directions when it is located closest. Further, X ₀ and Y ₀ shown in the formulas and the formulas are relative coordinates of the center of curvature (curvature center) O of the road 25. R in the equation is the radius of curvature of the road 25. In order to simplify the calculation, the relative distance Y ₀ of the center of the curvature in the Y-axis direction may be treated as Y ₀ = 0.

If the curvature radius R of the road calculated by the formula is smaller than a predetermined small value, the road shape estimating device 22 based on the trajectory of the vehicle determines that the road is a straight road, and the curvature radius R is larger than the predetermined small value. For example, it is determined that the road is a curved road.

Next, it is determined that the shape of the road 25 determined based on the trajectory of the preceding vehicle 27 is a straight road,
If the determination is continued for a certain period of time, for example, 1 second or more, it is determined that the vehicle 26 is traveling on the straight road 25, and the determination result is output to the neutral point correction device 12 of the steering angle sensor. The neutral point of the steering angle sensor 13 is corrected.

(Third Embodiment) Next, a vehicle traveling system according to still another embodiment of the present invention will be described. This vehicle traveling system detects the relative position of two vehicles traveling in another lane, recognizes the shape of the road from the coordinates of the two vehicles, and detects a steering angle when the road is determined to be straight. Is characterized in that the neutral point is corrected. Correspondingly, in the object recognition device 23 according to this embodiment,
As shown in FIG. 9, the road shape estimating device uses a road shape estimating device 24 using two vehicles instead of a roadside delineator or the like.

The road shape estimating device 2 using the two vehicles
4 extracts the distance measurement data of the vehicle based on the attributes of each object determined by the object attribute determining device 19. Further, the distance measurement data of the preceding vehicle traveling in another lane is selected from the distance measurement data of the vehicle. Next, it is determined which of the left lane and the right other lane is to be used to calculate the road shape using the distance measurement data of the preceding vehicle traveling on the lane, and the other lane on the determined side is traveled. The distance measurement data (X ₄ , Y ₄ ) of the farthest preceding vehicle 29 and the distance measurement data (X ₃ , Y ₃ ) of the closest preceding vehicle 28 are selected from the preceding vehicles. Then, using the distance measurement data, the shape of the road 25 is calculated based on the following formula, formula, and formula.

[0044]

(Equation 3)

Here, as shown in FIG. 10, X ₄ and Y ₄
Preceding vehicle is X and Y directions relative distance of the preceding vehicle 29 which is located farthest preceding vehicle out traveling on the other lane (distance data), X ₃ and Y _3, which runs the other lane The relative distance (distance measurement data) in the X direction and the Y direction of the preceding vehicle 28 located closest to the preceding vehicle. Also,
X ₀ and Y ₀ shown by the formulas and the formulas are relative coordinates of the center of curvature (center of curvature) O of the road 25. In addition, R
Is the radius of curvature of the road 25. In order to simplify the calculation, the relative distance Y ₀ of the center of the curvature in the Y-axis direction is Y ₀ = 0.
It may be treated as.

If the curvature radius R of the road 25 calculated by the equation is equal to or smaller than a small predetermined value, the road shape estimating device 24 of the two vehicles determines that the road is a straight road, and the curvature radius R becomes smaller than the small predetermined value. Is larger, it is determined that the road is a curved road.

If the shape of the road 25 determined based on the two preceding vehicles 28 and 29 is determined to be a straight road, and the determination has been continued for a certain period of time, for example, 1 second or more, the own vehicle 26 determines that the vehicle is traveling on a straight road 25, outputs the result of the determination to the neutral point correction device 12 of the steering angle sensor, and corrects the neutral point of the steering angle sensor 13.

In this embodiment, the reason why the distance measurement data of two vehicles traveling in other lanes is used is that it is difficult to measure the distance to the preceding vehicle ahead on a straight road or the like. is there. Of course, the road shape may be estimated based on the distance measurement data of two or more vehicles, and the road shape may be estimated based on the coordinates (relative position) of the preceding vehicle and the own vehicle.

In each of the above embodiments, a road shape estimating device using a roadside delineator that determines a road shape by detecting a roadside delineator, and a vehicle trajectory that determines a road shape by detecting a vehicle trajectory are described. Although the object shape recognition device provided with the road shape estimation device by two vehicles and the road shape estimation device by two vehicles which determines the road shape from the coordinates of two vehicles traveling in the other lane has been described as separate embodiments, Two or more types of road shape estimation devices may be provided in the object recognition device, and the road shape determination means may be switched and used depending on the situation.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a vehicle traveling system according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a state in which a laser pulse is emitted from a laser distance measuring device used in the above vehicle traveling system.

FIG. 3 is a block diagram showing a configuration of an object recognition device in the vehicle traveling system according to the first embodiment;

FIG. 4 is a diagram illustrating a process in a distance measurement data grouping device that forms the object recognition device according to the first embodiment.

FIGS. 5A and 5B are views for explaining processing in a time-series association device that constitutes the object recognition device according to the first embodiment;

FIG. 6 is an operation explanatory view of the embodiment.

FIG. 7 is a block diagram illustrating a configuration of an object recognition device in a vehicle traveling system according to a second embodiment of the present invention.

FIG. 8 is an operation explanatory view of the embodiment.

FIG. 9 is a block diagram illustrating a configuration of an object recognition device in a vehicle traveling system according to a third embodiment of the present invention.

FIG. 10 is an operation explanatory view of the embodiment.

[Explanation of symbols]

 L Laser pulse 1 Laser distance measuring device 9, 21, 23 Object recognition device 12 Neutral point correction device for steering angle sensor 13 Steering angle sensor 20 Road shape estimating device using roadside delineator 22 Road shape estimating device using vehicle trajectory 24 2 Road Shape Estimation System Using Different Vehicles

Claims (6)

[Claims] A means for determining a road shape; a steering angle sensor; and a means for calibrating a neutral point of the steering angle sensor. The neutral point calibrating means is based on a determination result by the road shape determining means. A vehicle neutralization system for calibrating the neutral point of the steering angle sensor. 2. The neutral point calibration unit according to claim 1, wherein the neutral point calibration unit calibrates the neutral point of the steering angle sensor when the road shape determination unit determines that the road shape is a straight line. A vehicle traveling system as described. 3. The vehicle traveling system according to claim 1, wherein said road shape determining means determines the road shape from the distance measurement data using a laser distance measuring device. 4. The vehicle travel system according to claim 3, wherein said road shape determining means determines a road shape based on a roadside sign of the road detected by the laser distance measuring device. 5. The vehicle traveling system according to claim 3, wherein said road shape determining means determines a road shape based on a trajectory of a preceding vehicle detected by a laser distance measuring device. 6. The vehicle traveling system according to claim 3, wherein said road shape determining means determines a road shape based on coordinates of a preceding vehicle detected by a laser distance measuring device.