Communications: directive radio wave systems and devices (e.g. – Return signal controls external device – Radar mounted on and controls land vehicle
Reexamination Certificate
2002-08-07
2003-12-30
Tarcza, Thomas H. (Department: 3662)
Communications: directive radio wave systems and devices (e.g.,
Return signal controls external device
Radar mounted on and controls land vehicle
C180S167000, C340S435000
Reexamination Certificate
active
06670911
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a scanning radar system that transmits radio waves while scanning the projection direction thereof, that determines the lateral position of a target based on the strength of a reflected wave returned from the target and, more particularly, to a scanning radar system that measures the lateral position of a target as well as the distance and relative velocity thereof for vehicle-to-vehicle distance control.
BACKGROUND ART
A vehicle equipped with an FM-CW radar can measure the distance and relative velocity of a target located ahead of the vehicle. If the distance, for example, to a vehicle traveling ahead is to be properly controlled based on these measured values, the lateral position of the target located ahead must be determined.
A scanning radar system, as shown in FIG.
1
(
b
), transmits a radiowave while scanning the projection direction thereof, and determines the lateral position of a target based on the direction in which the target is located, i.e., the direction in which the strength of the reflected wave from the target is the highest.
According to this method, the lateral position of the target can be determined accurately, provided that there is no displacement between the direction to which the target is located when viewed from the radar-equipped vehicle (the direction to the target) and the direction in which the target is traveling (the heading of the target).
However, if there is a displacement between the direction to the target and the heading of the target, the lateral position of the target cannot be determined accurately. For example, in the case shown in FIG.
1
(
a
) or
1
(
c
), as the power of the reflected wave is the highest at one edge of the target, the lateral position of the target cannot be estimated accurately.
DISCLOSURE OF THE INVENTION
Accordingly, it is an object of the present invention to provide a scanning radar system that can accurately determine the lateral position of a target even when the heading of the target is displaced from the direction to the target.
According to the present invention, there is provided a scanning radar system comprising: lateral position determining means for determining a lateral position X of a target, based on the strength of a reflected wave returned from the target when radio waves are projected while scanning the projection direction thereof; means for determining an angle &PSgr; between a direction to the target and a heading of the target; means for determining a correction value &Dgr;X for the lateral position based on the angle &PSgr;; and means for correcting the lateral position X by the correction value &Dgr;X.
Preferably, the angle &PSgr; determining means determines the angle &PSgr;, based on a turning radius R, a distance d to the target, and an angle &thgr; between the direction to the target and the heading of a vehicle equipped with the radar system, by calculating equation
&PSgr;=&thgr;−tan
−1
{d
cos &thgr;/(
R−d
sin &thgr;)}
REFERENCES:
patent: 5023617 (1991-06-01), Deering
patent: 5745070 (1998-04-01), Yamada
patent: 5786787 (1998-07-01), Eriksson et al.
patent: 5818355 (1998-10-01), Shirai et al.
patent: 5955967 (1999-09-01), Yamada
patent: 6269307 (2001-07-01), Shinmura et al.
patent: 0 775 919 (1997-05-01), None
patent: 0 825 454 (1998-02-01), None
patent: WO 95/34830 (1995-12-01), None
International Search Report of PCT/JP01/10918, dated Jan. 22, 2002.
Higashida Hirofumi
Kishida Masayuki
Andrea Brian
Christie Parker & Hale LLP
Fujitsu Ten Limited
Tarcza Thomas H.
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