Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Automatic route guidance vehicle
Reexamination Certificate
2000-03-28
2002-01-01
Cuchlinski, Jr., William A. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Automatic route guidance vehicle
C180S167000, C180S168000
Reexamination Certificate
active
06336064
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a magnetic apparatus for detecting a position of a vehicle that calculates a lateral deviating distance of a vehicle from the centerline on the road by detecting a magnetic field generated from magnetic markers located on the centerline of the road.
BACKGROUND OF THE INVENTION
An automatic driving system has been researched by various approaches. The principles for these approaches are to detect a cable with current by a pickup coil, to analyze a figure by camera, to use radiowaves, to use an ultrasonic device, to detect magnetic tape by a magnetic sensor and so on. However, these methods, except magnetic methods, are difficult to apply to vehicles running on the road in bad weather (rain, snow, mist and so on). The magnetic methods in which linearly arrayed sensors detect a magnetic line is usually adopted to an automatic driving system used in a plant, but it is difficult for arrayed sensors to apply to guiding vehicles on roads because of high speed and vertical oscillation.
U.S. Pat. No. 5,347,456 discloses a magnetic guiding method for vehicles. According to this method, a magnetic sensor set on a vehicle detects both vertical component and transverse component of a magnetic field and then a lateral deviating distance is calculated from this data accompanied with the correction of the vertical oscillation of the vehicle.
However, the vertical component of the magnetic field considerably decreases when the magnetic sensor is set at a height of more than about 20 cm to 25 cm. So the detectable range of the lateral deviating distance is very narrow at about 20 cm to 25 cm. Therefore it is noted that the magnetic guiding system does not operate when a vehicle does not enter into the area within about 20 cm to 25 cm from the center of the road.
As usual a vehicle is correctly guided within about 20 cm to 25 cm from the centerline of the road. But the problem remains that the vehicle deviates from the centerline over 25 cm and becomes out of control when the vehicle is running through bridges or tunnels because they are made of reinforced concrete that generate the magnetic field. The external magnetic field is locally as strong as the magnetic field generated from magnetic markers. Here the word ‘external’ means ‘except things by magnetic markers’.
For example, the vehicle is running 20 cm distant from the centerline to the right. In this situation the magnetic sensor of the vehicle detects the right directed component of the magnetic field generated from magnetic markers located in the centerline. If the left directed component of the external magnetic field is larger than the right directed component of the magnetic field generated from markers, the computer misjudges that the vehicle is running on the left side of the lane. From this misjudgment the computer guides the vehicle toward the right.
The magnetic markers are set along the centerline at the interval of 2 m. However there is the case that the vehicle deviates at distance of about 25 cm from the centerline while it goes about 1 m. In this undesirable case, the guiding system easily becomes out of control. Here the maximum of steering angle of 5 degrees, the vehicle width of 1.7 m and the lane width of 3.5 m are assumed.
The maximum of the distance between the magnetic marker and the magnetic sensor is 0.9 m in these above assumptions. If the magnetic guiding system has the detectable range of about 1 m, the magnetic sensor can detect the magnetic marker always when the vehicle is on the lane. That means that the system certainly and correctly guides the vehicle toward the centerline. But the above-mentioned system has the detectable range of only about 25 cm. The range is insufficient.
Moreover in running on a curve, a lateral deviating distance varies at the point of every magnetic marker. It is necessary to detect the deviating distance from the centerline while a vehicle goes 2 m. And the above-mentioned system uses so complex method to calculate the position of vehicle that the system needs long time to identify the position of the vehicle.
It is desirable that the interval of magnetic markers is shorter than 2 m. In order to solve this problem, the new magnetic guiding system is expected. It must be able to easily detect the lateral deviating distance with high accuracy in spite of the interval of 2 m for markers.
This invention is made in order to solve the above problem. The subject of this invention is to provide the magnetic apparatus for detecting position of vehicle that can detect the lateral deviating distance from centerline with wide detectable range, high accuracy and short response time.
SUMMARY OF THE INVENTION
Disclosure of the Invention
To solve this problem, the inventors found out a new method to enhance the ability of the sensor for keeping a position of a vehicle on the centerline and to extend the detectable range of the sensor for the lateral deviating distance from 25 cm to 1 m. The detectable range becomes 4 times larger. The method is characterized by detecting the longitudinal component of the magnetic field. The longitudinal component means along the lane. Moreover it is favorable to detect three components of the magnetic field. Three components are the longitudinal component, the vertical component and the transverse component. In this method, when the lateral deviating distance between the sensor and the marker becomes over 25 cm because of the misjudgment brought by external magnetic field, the system certainly and correctly guides the vehicle toward the centerline and recovers the vehicle at the center position of the lane.
The Following are Details of this Invention.
A magnetic apparatus for detecting position of the vehicle detects a lateral deviating distance between the vehicle and the centerline (correctly between the magnetic sensor and magnetic markers) using the measured value for the longitudinal component of the magnetic field.
As after mentioned the appreciative magnetic apparatus for detecting position of the vehicle comes true by this system. This apparatus can detect accurately the lateral deviating distance with wide detectable range compared to the conventional apparatus that detects not the longitudinal component but the other components of the magnetic field.
The magnetic apparatus for detecting a position of a vehicle is characterized by detecting the lateral deviating distance using the largest variation of the longitudinal component of the magnetic field.
Here, the largest variation is the difference between the maximum output signal and the minimum output signal of the magnetic sensor that detects the longitudinal component of the magnetic field. The largest variation is dependent on the lateral deviating distance.
This method makes it possible to detect accurately the lateral deviating distance.
The magnetic apparatus for detecting a position of a vehicle is characterized by detecting the lateral deviating distance using Lx. Here, Lx is defined as the distance obtained by multiplying a vehicle's speed together with the period from the minus peak time to the plus peak time of a Bx output signal. The plus or minus peak time means the time to get the maximum or minimum output signal of the magnetic sensor respectively. Lx is dependent on the lateral deviating distance. This method makes it possible to detect accurately the lateral deviating distance.
The magnetic apparatus for detecting a position of a vehicle is characterized by detecting the lateral deviating distance using three components of the magnetic field. The above three components are detected by the vertical magnetic sensor, the transverse magnetic sensor and the longitudinal magnetic sensor. This method makes it possible to detect more accurately the lateral deviating distance, when the lateral deviating distance is small. In other words, the vertical magnetic sensor detects the component normal to the lane plane, and the transverse magnetic sensor detects the component parallel to right-and-left direction of the vehicle.
The magnetic ap
Eiji Kako
Fujii Hideki
Honkura Yoshinobu
Watarai Aki
Aichi Steel Works Ltd.
Cuchlinski Jr. William A.
Marc-Coleman Marthe Y.
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