Communications: directive radio wave systems and devices (e.g. – Return signal controls external device – Radar mounted on and controls land vehicle
Reexamination Certificate
1999-09-07
2001-03-06
Sotomayor, John B. (Department: 3662)
Communications: directive radio wave systems and devices (e.g.,
Return signal controls external device
Radar mounted on and controls land vehicle
C342S071000, C342S072000, C342S114000, C342S115000
Reexamination Certificate
active
06198426
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method and an apparatus for detecting road circumstances around a traveling vehicle and a recording medium for storing a related software program. The present invention is applicable to a vehicle follow-up system or a distance warning system based on a radar system.
In a conventional vehicle follow-up control, a same lane judgement is performed to check whether the preceding vehicle is traveling on the same traffic lane as that of a traveling vehicle mounting a radar system (hereinafter referred to as system's vehicle).
For example, it is possible to use information obtainable from the steering sensor and the yaw rate sensor in judging whether the traffic lane is a straight lane or a curved lane. An estimated road shape or configuration will be obtained from this judgement. The same lane judgement is performed based on such an estimated road by checking whether the preceding vehicle and the system's vehicle exist on the same traffic lane of this estimated road.
However, the curvature of a traveling road changes flexibly or randomly. A straight road may suddenly change to a curved road or vice versa. In such a case, it is difficult to accurately obtain the estimated road. This leads to an error in the same lane judgement. In other words, the information obtainable from the steering sensor and the yaw rate sensor is limited to present conditions of the system's vehicle and therefore cannot predict the future behavior of the system's vehicle.
To solve such a problem, Unexamined Japanese Patent Publication No. 6-195600 discloses a laser radar system and proposes a method of estimating the road configuration based on the positional relationship between the traveling vehicle and reflectors provided along a road edge.
However, this conventional system has the following problems:
{circle around (1)} There are many roads along which no reflectors are provided. Thus, the usability of the above conventional system is limited to specific or high-grade roads.
{circle around (2)} In general, many of highway roads are designed to have a clothoid curve whose curvature changes continuously or momentarily. Thus, an error will be caused if the same lane judgement is made based on only one curvature value.
{circle around (3)} Furthermore, the laser-based radar technology cannot be simply applied to a radio wave type radar due to difference in their resolutions. In general, the radio wave type radar is inferior to the laser type radar in azimuth detecting capability. The level of reflected radar wave varies greatly depending on the angle between the emitted radar wave and a target object. Furthermore, the radio wave type radar is subjected to a multipath phenomenon caused by multiple reflections of radio wave.
SUMMARY OF THE INVENTION
In view of the foregoing problems in the prior art, the present invention has an object to provide a method and an apparatus for accurately detecting road circumstances around a traveling vehicle and a recording medium for storing a related software program.
In order to accomplish this and other related objects, the present invention provides a first road circumstance detecting apparatus comprising a radar system mounted on a traveling vehicle for emitting radar wave toward a presently measurable stationary object group existing in front of the radar system and for measuring the momentary position of the presently measurable stationary object group based on reflection of the radar wave. A memory means is provided for storing measured position data of the presently measurable stationary object group existing in front of the radar system. An estimating means is provided for estimating the present position of a previously recognized stationary object group based on the measured position data of the previously recognized stationary object group stored in the memory means and the movement of the traveling vehicle during a past time. And, a detecting means is provided for detecting a clearance between the traveling vehicle and a stationary object group positioned adjacent to the traveling vehicle along a road edge based on the present position data of the previously recognized stationary object group estimated by the estimating means.
Preferably, the clearance detection is performed by using the present position data of a previously recognized stationary object group existing within a predetermined region with respect to the traveling vehicle.
In this case, the predetermined region has a longitudinal size longer than a longitudinal length of the traveling vehicle. The longitudinal size of the predetermined region is substantially equal to two times the longitudinal length of the traveling vehicle.
Preferably, the stationary object group positioned adjacent to the traveling vehicle along the road edge is separated into right and left groups to detect a clearance between the traveling vehicle and each of the right and left groups.
Furthermore, the present invention provides a second road circumstance detecting apparatus comprising a radar system mounted on a traveling vehicle for emitting radar wave toward a presently measurable stationary object group existing in front of the radar system and for measuring the momentary position of the presently measurable stationary object group based on reflection of the radar wave. The second road circumstance detecting apparatus comprises a memory means for storing measured position data of the presently measurable stationary object group existing in front of the radar system, an estimating means for estimating the present position of a previously recognized stationary object group based on the measured position data of the previously recognized stationary object group stored in the memory means and the movement of the traveling vehicle during a past time, and a detecting means for detecting a clearance between a preceding vehicle and a stationary object group positioned adjacent to the preceding vehicle along a road edge based on the present position data of the previously recognized stationary object group estimated by the estimating means and position data of the preceding vehicle.
Preferably, a first selecting means is provided for selecting a previously recognized stationary object group existing within a predetermined region with respect to the preceding vehicle, and the clearance detection is performed by using the present position data of the previously recognized stationary object group selected by the first selecting means.
In this case, the predetermined region has a longitudinal size longer than a longitudinal length of the preceding vehicle. The longitudinal size of the predetermined region is substantially equal to two times the longitudinal length of the preceding vehicle.
Preferably, a second selecting means is provided for selecting a presently measurable stationary object group existing within a predetermined region with respect to the preceding vehicle, and the clearance detection is performed by using the position data of the presently measurable stationary object group selected by the second selecting means.
And, the stationary object group positioned adjacent to the preceding vehicle along the road edge is separated into right and left groups to detect a clearance between the preceding vehicle and each of the right and left groups.
It is also preferably that an estimated traffic lane of a traveling road is corrected based on the clearance obtained by the detecting means.
The present invention provides a third road circumstance detecting apparatus including all of characteristic features of the above-described first and second road circumstance detecting apparatus. The third road circumstance detecting apparatus further comprises a same lane judging means for judging whether the traveling vehicle and the preceding vehicle are traveling on a same traffic lane based on at least one of the detected clearances detected by the first detecting means and the second detecting means.
In this same lane judgement, the clearance between the trav
Kumon Hiroaki
Tamatsu Yukimasa
Denso Corporation
Pillsbury Madison & Sutro LLP
Sotomayor John B.
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