JPH05297938A - Coordinate position estimating device for vehicle - Google Patents

Abstract

PURPOSE:To made effective use of the output of a steering sensor by securing the effective use of this output also in a vehicle guiding operation system. CONSTITUTION:The present coordinates are set by an ECU 11 in a step 101, and the pulse inputted from a distance sensor 13 is confirmed in a step 102. Then, the steering angle of a steering sensor 12 is read out in a step 103 after the input of a distance pulse signal is confirmed. A turning radius of a vehicle is calculated from the steering angle in a step 104, and a moved variable (coordinates) of the vehicle is calculated in a step 105 based on the turning radius. In a step 106, the calculated moved variable is added to the present coordinates set in the step 101. Then, the present coordinates are estimated after the vehicle moved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle coordinate position estimating device for estimating a moving coordinate of a vehicle traveling at an extremely low speed, for example, in a vehicle guidance control device.

[0002]

2. Description of the Related Art For example, various automatic guidance systems for vehicles that guide a vehicle into a predetermined garage are desired.
In such an automatic guidance system, the guidance route to the target coordinate position is calculated corresponding to the vehicle set at the predetermined coordinates, and the vehicle is guided and driven along the guidance route. To do. Therefore, in such an automatic guidance system, it is important to always recognize the coordinate position of the own vehicle, and the guidance control is executed while measuring or estimating the coordinate position of the own vehicle.

As means for estimating the coordinate position of the vehicle,
For example, a method using a magnetic sensor is known. However, in such a method using a magnetic sensor, an accurate coordinate position cannot be recognized in an environment area in which a disturbance that causes disturbance in the earth's magnetism exists.

Further, as disclosed in, for example, Japanese Unexamined Patent Publication No. 2-208512, means for using the detection signals from the wheel speed sensors set for each of the four wheels set in the vehicle has been considered.

The four wheels set on the vehicle have the property of being moved along a turning circle having the same turning center. Therefore, the moving distances of the four wheels are obtained based on the detection signals from the wheel speed sensors set for the four wheels. The turning angle of the vehicle is corrected on the basis of the difference.

The wheel speed sensor is set, for example, in the vicinity of the peripheral surface of the toothed wheel that is rotated integrally with the wheel, and corresponds to each tooth of the toothed wheel that passes closely as the wheel rotates. Pulsed signals are output. Therefore, the wheel speed sensor used here is equipped with a vehicle in which a wheel speed sensor for detecting rotation of a toothed wheel is attached to each of four wheels, specifically, an automatic brake control system and a traction control system. It was a method that was only applicable to vehicles. That is, it cannot be implemented in vehicles that are not equipped with toothed wheels that rotate with each wheel.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and means for detecting a steering angle such as a steering sensor by using a speedometer cable that is always provided in a vehicle. If is set, it can be easily implemented for ordinary vehicles, the movement coordinates can be easily estimated for the vehicle, and the vehicle can be effectively applied in an automatic guidance system, for example. An object is to provide a coordinate position estimating device.

[0008]

SUMMARY OF THE INVENTION In a vehicle coordinate position estimating device according to the present invention, a vehicle based on a distance sensor for measuring a moving distance of the vehicle from a speedometer cable and a distance pulse signal from the distance sensor. Is recognized, the steering angle detection means for detecting the steering angle of the vehicle, the turning radius calculation means for obtaining the turning radius of the vehicle based on the detected steering angle, and the distance sensor And a movement amount calculation means for calculating the movement coordinates of the vehicle based on the detection pulse signal.

[0009]

According to the coordinate position estimating apparatus for a vehicle constructed as above, the current coordinates are first set at the origin position, and the steering angle is recognized while the movement of the vehicle is confirmed by the distance sensor. Therefore, the turning radius of the vehicle is obtained from this steering angle based on predetermined map data, etc., and the current position of the vehicle is calculated based on the origin position coordinates, the turning radius, and the vehicle movement amount obtained from the information from the distance sensor. Is calculated and estimated. That is, the current coordinate position is easily estimated based on the detection signal from the speedometer cable set in a normal vehicle and the detection signal from the steering sensor. In this case, the steering angle detecting means such as the steering sensor is a component that is normally set in the automatic guidance system.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of the electronic control unit (ECU) 11 including a microcomputer and the like.
, The detection signal from the steering sensor 12 installed on the steering of the vehicle, and the distance sensor
A pulse-like movement distance signal from 13 is input.

Here, the distance sensor 13 outputs a pulse signal corresponding to the rotation of the speedometer cable which is rotated with the rotation of the wheel, for example, by counting the pulse signal. The travel distance can be calculated, and the vehicle speed is calculated by counting the pulsed signals in the specific time range.

That is, in this apparatus, the input information corresponding to the steering angle from the steering sensor 12 and the moving distance information from the distance sensor 13 are used once, for example, when the ignition key is turned on or by using sensors. The coordinate movement amount when the vehicle is moved is calculated by the internal calculation of the ECU 11 from the initial state such as when the coordinate measurement is performed, and the coordinate data in this initial state is input to the ECU 11. ing. Then, the estimated current coordinates after the calculated movement are output.

FIG. 2 shows the flow of the coordinate estimating process as described above in the ECU 11. First, in step 101, the current coordinate in the initial state is set as the initial coordinate. Here, for example, when performing automatic guidance for entering the garage, for example, a reference position setting means such as a reflecting plate is installed at the entrance of the garage, and a laser beam is scanned from the vehicle to measure the distance from the reference position setting means. Then, the azimuth angle is measured, and the coordinates based on the position of the reference position setting means are set as the initial coordinates. Further, in the case of simply calculating the movement amount of the vehicle, the initial coordinates of the X and Y coordinates (0, 0,
0) may be the initial coordinates.

In step 102, it is judged whether or not a vehicle speed pulse signal is input from the distance sensor 13. That is,
The distance sensor 13 is used to determine that the vehicle has moved.
The pulse estimation signal is input to the ECU 11 to start the coordinate estimating operation for the first time. Here, the smaller the pulse signal output from the distance sensor 13 with respect to the wheel rotation angle, the more accurate the movement amount calculation becomes. For example, the output of about 20 pulses per rotation of the speedometer cable can be obtained. Then it is effective.

In this way, after the input of the vehicle speed pulse signal is confirmed in step 102, the process proceeds to step 103. In step 103, the steering sensor is
Read the steering angle information from 12. If the steering angle is read in step 103, the turning radius of the vehicle is calculated in step 104.

As shown in FIG. 3, when the steering angle is constant, the vehicle has an Ackermann characteristic of moving along a turning circle centered on an extension of the rear wheel axle while the vehicle is traveling at an extremely low speed. Then, the amount of movement of the vehicle is calculated using the center Q of the rear wheel shaft, and the turning radius is set to the turning radius R at the center Q.

Since the distance sensor 13 is set by branching from the speedometer cable, it detects the movement amount of the wheel virtually set in the middle of the front wheels of the vehicle. Therefore, when the turning radius at the rear wheel shaft center Q is R, the turning radius Ro of the virtual wheel is given by the equation (1). In this formula, L is the vehicle wheel base.

[0018]

[Equation 1] The turning radius R of the rear wheel center Q is uniquely set by the vehicle in relation to the steering operation angle, and is specified as shown in FIG. 4, for example, in correspondence with the steering right or left steering direction. .. The relationship between the steering angle and the turning radius is stored and set as a map in the memory set in the ECU 11. The turning angle at that time is determined in step 104 according to the read angle from the steering sensor 12. The radius is read.

When the turning radius is obtained corresponding to the steering angle in this way, in step 105, the moving amount (vector) of the vehicle is calculated by the specified calculation formula based on the turning radius.

As shown in FIG. 5, the turning angle θ of the vehicle when the moving distance detected by the distance sensor 13 is D under the condition that the steering angle is set constant is given by the equation (2). Like Also, 1 obtained from the distance sensor 13
The movement of the rear wheel axis center coordinate Q by the pulse is calculated by using the distance W of the pulse output interval of the distance sensor 13 when the steering angle is constant and the circular turning having the turning angle given by the equation (3) is calculated. Can be done (movement from Q0 to Q1).

In a normal guide traveling state of a vehicle, the steering is continuously operated, and the steering angle continuously changes. However, in the pulse output interval W from the distance sensor 13, it can be approximated that the steering angle is constant and does not change while the vehicle moves through the output interval W. Therefore, even in the state where the steering angle continuously changes, Q1 → Q2 in FIG. 6 in which turning circles having different turning radii are combined for each pulse output interval W is combined.
It is possible to calculate the amount of movement for each locus of → Q3 → Q4 → ... Here, the value read in step 103 is used as the steering angle of each movement locus.

In step 106, the movement amount (vector) obtained in step 105 is added to the current coordinates set in step 101 to calculate the current coordinates after the vehicle is moved. Such calculation is executed by the ECU 11 every time a pulse signal is input to the ECU 11 from the distance sensor 13, and the current coordinates are always obtained in the process of guiding the vehicle.

In the above description, the case of extremely low speed traveling for automatic guidance or the like has been taken as an example, but the vehicle motion characteristics with a constant steering angle during high speed traveling rather than extremely low speed traveling are shown in FIG. The turning center comes to be deviated from the rear wheel side.

This turning center changes according to the vehicle speed. The turning radius and the turning center are measured from the actual vehicle in response to the changes in the vehicle speed and the steering angle, and these are measured in the ECU 11. If stored as values, the turning circles shown in FIG. 7 are added at arbitrary pulse intervals W of the distance sensor 13 as shown in FIG. 6 in response to changes in vehicle speed and steering angle. By going, it is possible to calculate the movement trajectory coordinates of the vehicle.

In such a case, the traveling speed of the vehicle is obtained by measuring the time interval of the measurement pulse from the distance sensor 13 in the ECU 11, and it is not necessary to set the vehicle speed sensor specially. Therefore, based on such vehicle motion characteristics during high-speed traveling, it can be effectively applied to, for example, autonomous traveling (IVHS) on a highway. Further, even when the vehicle is not autonomously traveling, it is possible to monitor the state in which the vehicle travels off a predetermined course.

In the above embodiment, the amount of movement (coordinates) of the vehicle is calculated based on the steering angle and the output from the distance sensor. On the contrary, the vehicle turns based on the amount of movement. It is also possible to calculate the angle.

[0027]

As described above, according to the vehicle coordinate position estimating apparatus of the present invention, if means for detecting the steering angle such as a steering sensor is set, the steering angle and the normal vehicle are set. It is possible to easily estimate the moving coordinates of the vehicle in combination with the distance sensor mechanism that is used, and it can be effectively applied to guide the vehicle according to the set guidance route in the automatic guidance device of the vehicle, for example. , Will be able to easily configure the automatic guidance system.

[Brief description of drawings]

FIG. 1 is a configuration diagram illustrating a vehicle coordinate position estimating device according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating a flow of a coordinate estimation operation performed by the ECU of this embodiment.

FIG. 3 is a diagram illustrating a turning radius at an extremely low speed.

FIG. 4 is a diagram showing an example of a map showing a relationship between a steering angle and a turning radius.

FIG. 5 is a diagram illustrating a means for obtaining a movement amount D.

FIG. 6 is a diagram illustrating a means for obtaining a movement amount when a steering angle continuously changes.

FIG. 7 is a diagram illustrating a turning radius during high-speed traveling.

[Explanation of symbols]

11 ... Electronic control unit (ECU), 12 ... Steering sensor, 13 ... Distance sensor (vehicle speed pulse sensor).

Claims (1)

[Claims] 1. A current coordinate setting means for setting current coordinates, a distance sensor for measuring a moving distance of a vehicle from a speedometer cable, and a movement of the vehicle recognized based on a detection signal from the distance sensor, Steering angle detection means for detecting the steering angle of the vehicle, turning radius calculation means for obtaining the turning radius of the vehicle based on the detected steering angle, and based on the detection signal from the distance sensor and the turning radius A movement amount calculation means for calculating the movement coordinates of the vehicle, and a coordinate position estimation device for the vehicle.