Apparatus for calculating deflection of central axis of an...

Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Indication or control of braking – acceleration – or deceleration

Reexamination Certificate

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C701S301000, C342S070000

Reexamination Certificate

active

06246949

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus for calculating how much a central axis of an obstacle detecting apparatus for a vehicle deflects from the centerline of the vehicle along a longitudinal direction, in which the obstacle detecting apparatus is mounted on the vehicle and serves to radiate a transmission wave over a given angular range from a given central axis to the width direction of the vehicle for detecting a distance to and an angle of an obstacle in response to a reflected wave from the obstacle. The invention also relates to a deflection of central axis correcting apparatus for correcting the deflection of central axis of the obstacle detecting apparatus. Further, the invention relates to an inter-vehicle distance control system for controlling a distance between a system vehicle equipped with the system and a vehicle ahead of the system vehicle on the basis of the central axis of the obstacle detecting apparatus the deflection of which has been corrected.
2. Description of the Related Art
An obstacle detecting apparatus is designed to be mounted on a vehicle and to serve to radiate a transmission wave, such as an optical wave or an electromagnetic wave, over a forward detection zone defined by a given angle to the width direction of the vehicle for detecting a distance to and an angle of an obstacle such as a preceding vehicle on the basis of a reflected wave from the obstacle. This type of obstacle detecting apparatus is used in an inter-vehicle distance control system for detecting a preceding vehicle ahead of a system vehicle equipped with the system and holding a distance between the vehicles at a constant value, or in a warning control system for issuing an alarm when the system vehicle moves into proximity to an obstacle.
Such an obstacle detecting apparatus must be mounted on a vehicle such that the central axis of the apparatus is exactly in line with the centerline of the vehicle along the longitudinal direction. If the control axis deviates from the center line, an error in detecting an angle of the obstacle appears. In this case, the obstacle detecting apparatus may recognize a vehicle traveling along an adjacent lane as the preceding vehicle, or it may recognize the preceding vehicle as an object other than the preceding vehicle.
However, a highly accurate adjustment is required to put the central axis of the obstacle detecting apparatus exactly in line with the centerline of the vehicle along the longitudinal direction, and therefore a problem arises because this installation takes a significant amount of time.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an improved apparatus for calculating a deflection of central axis of an obstacle detecting apparatus relative to a vehicle equipped with the system and, to facilitate correction of central axis of the obstacle detecting apparatus.
In order to achieve the above object, a first aspect of the present invention provides a deflection of central axis calculating apparatus which is used for an obstacle detecting apparatus mounted on a vehicle, the obstacle detecting apparatus serving to radiate a transmission wave over a given angular range along a central axis thereof for detecting a distance to and an angle of an obstacle, and which comprises, as shown in
FIG. 15A
, object recognizing means for determining whether the obstacle is a stationary object or a moving object on the basis of the distance to and angle of the obstacle detected by the obstacle detecting apparatus; speed calculating means for calculating a vector representing a speed of the obstacle relative to the vehicle; and first deflection calculating means, when a target obstacle is selected from among obstacles detected by the obstacle detecting apparatus under conditions that the target obstacle has been recognized as a moving object by the object recognizing means and the relative speed thereof calculated by the speed calculating means falls within a given range, which calculates the deflection of central axis of the obstacle detecting apparatus relative to the vehicle on the basis of the angle of the target obstacle.
In the deflection of central axis calculating apparatus according to the first aspect of the present invention, the speed calculating means calculates a speed vector of the obstacle relative to the vehicle on the basis of changes in the distance to and angle of the obstacle detected by the obstacle detecting apparatus. The first deflection calculating means calculates a deflection of central axis of the obstacle detecting apparatus relative to the vehicle on the basis of the angle of the target obstacle detected by the obstacle detecting apparatus. As previously described, the target obstacle is selected from among obstacles detected by the obstacle detecting apparatus under conditions that the target obstacle has been recognized as a moving object by the object recognizing means and the components of the vector representing the speed of the target obstacle relative to the vehicle and calculated by the speed calculating means falls within the given range.
In most cases the obstacle recognized as a moving object by the object recognizing means is a preceding vehicle. In the case where a subject vehicle equipped with the obstacle detecting apparatus maintains a constant distance to a preceding vehicle ahead of the subject vehicle, when the subject vehicle and the preceding vehicle travel together along a straight section of a road, the relative position between both vehicles hardly changes. In this case, the preceding vehicle is detected straight ahead of the subject vehicle. Therefore, the first deflection calculating means calculates the deflection of central axis of the obstacle detecting apparatus on the basis of the angle of the target obstacle detected by the object detecting apparatus as long as the target obstacle is estimated to be the preceding vehicle. For example, if the detected angle of the target obstacle is directed to the forward direction of the subject vehicle, the central axis of the obstacle detecting apparatus is regarded as not deflecting, so that the deflection value becomes zero. On the other hand, if the angle deviates from the forward direction of the subject vehicle, the central axis is regarded as deflecting by an angle represented by the deviation.
The deflection of central axis calculating apparatus is able to calculate the deflection of central axis of the obstacle detecting apparatus relative to the subject vehicle and to facilitate correction of the central axis of the obstacle detecting apparatus. Specifically, in the deflection of central axis calculating apparatus according to the first aspect of the present invention, the deflection of central axis of the obstacle detecting apparatus relative to the subject vehicle is calculated from only data related to the target obstacle (preceding vehicle), which is selected from among obstacles detected by the obstacle detecting apparatus under conditions that the preceding vehicle has a vector of a relative speed the components of which fall within the given range, so that other data related to moving objects other than the preceding vehicle and data representing the preceding vehicle during cornering, can be eliminated properly, thereby improving the accuracy in calculating the deflection.
The given range may be defined for one of the components of the vector representing the speed of the target obstacle relative to the subject vehicle, for each of the components, or for a norm.
A second aspect of the present invention provides a deflection of central axis calculating apparatus which is used for an obstacle detecting apparatus mounted on a vehicle, the obstacle detecting apparatus serving to radiate a transmission wave over a given angular range along a central axis thereof for detecting a distance to and an angle of an obstacle, and which comprises, as shown in
FIG. 15B
, object recognizing means for determining whether the obstacle is a stationary object o

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