Communications: directive radio wave systems and devices (e.g. – Return signal controls external device – Radar mounted on and controls land vehicle
Reexamination Certificate
1999-11-05
2001-07-10
Lobo, Ian J. (Department: 3662)
Communications: directive radio wave systems and devices (e.g.,
Return signal controls external device
Radar mounted on and controls land vehicle
C340S903000, C701S096000, C342S071000
Reexamination Certificate
active
06259395
ABSTRACT:
BACKGROUND OF THE INVENTION
a) Field of the Invention
The present invention relates to a relative velocity detecting apparatus for an automotive vehicle applicable to an automatic vehicular velocity control system which follows up a preceding vehicle which is running ahead of the vehicle on the same traffic lane if the preceding vehicle appears in a forward detection zone of the vehicle.
b) Description of the Related Art
A Japanese Patent Application First Publication No. Heisei 6-187599 published on Jul. 8, 1994 exemplifies a previously proposed automotive vehicular radar apparatus which determines an inter-vehicle distance from a preceding vehicle to the vehicle using a laser beam radar unit as an inter-vehicle distance sensor.
In the previously proposed relative velocity detecting apparatus, the relative velocity vrn is calculated using a digital differentiation calculation according to the following equation (1) on the basis of inter-vehicle distance detection data dfn-
1
and dfn through a predetermined filtering:
vrn=
(
dfn
-
1
-
dfn
)/0.1
[m/S]
(1).
In the equation (1), 0.1 means a sampling time in seconds.
SUMMARY OF THE INVENTION
However, according to the calculation method of the relative velocity value is not robust to (i.e., easily influenced by or susceptible to) a noise mixed into an inter-vehicle detection signal.
A Japanese Patent Application First Publication No. Heisei 11-59222 published on Mar. 2, 1999 (which corresponds to a U.S. Pat. No. 5,959,572 and corresponds to a British Patent No. GB 2 324 283 B published on Aug. 18, 1999) exemplifies a previously proposed automatic vehicular velocity control system in which the relative velocity is calculated by performing a band pass filtering for the inter-vehicle detection data lr(t). That is to say, the relative velocity vr(t) is calculated according to the following equation using the inter-vehicle distance value lr(t).
vr
(
t
)=&ohgr;
n
2
·S·lr
(
t
)/(
S
2
+2·&zgr;·&ohgr;
n S+&ohgr;n
2
) (2).
In the equation (2), S denotes a differential operator. The above equation (2) is expressed as a product of a low pass filter &ohgr;n
2
/(S
2
+2·&zgr;·&ohgr;nS+&ohgr;n
2
) and a high pass filter of the differetiator of S. The low pass filter eliminates a noise component having a high frequency mixed within the inter-vehicle distance detection value and the differentiator of S calculates the relative velocity vr(t) from the differentiation of the inter-vehicle distance lr(t).
In the previously proposed automatic vehicular velocity control system, no consideration has been given to initial values of the inter-vehicle distance and the relative velocity of the preceding vehicle to the vehicle.
It is an object of the present invention to provide an improved relative velocity detecting apparatus for an automotive vehicle which can accurately detect the relative velocity of the preceding vehicle to the vehicle immediately after an inter-vehicle distance detector sensor has recognized that a preceding vehicle appears in a forward detection zone of the vehicle. The preceding vehicle described above is, for example, another vehicle which has interrupted the forward detection zone of the inter-vehicle distance sensor of the vehicle from another traffic lane and which is running ahead of the vehicle on the same traffic lane of the vehicle, which is present in the forward detection zone when the vehicle is changed to another traffic lane, or which has appeared in the forward detection zone when the vehicle is in a forward run.
The above-described object can be achieved by providing a relative velocity detecting apparatus for an automotive vehicle, comprising: an inter-vehicle distance detector, disposed on the vehicle so as to be oriented toward a forward detection zone of the vehicle to detect an inter-vehicle distance to a preceding vehicle which is running ahead of the vehicle, to recognize whether the preceding vehicle has entered the forward detection zone and to derive the inter-vehicle distance value lrn (n=
1, 2, - - - ,
n) whenever a predetermined period of time has passed when recognizing that the preceding vehicle has entered the forward detection zone; a relative velocity calculator to perform a band pass filter calculation for the inter-vehicle distance value lrn, the band pass filter being expressed as: CF
0
·S/(S
2
+CF
1
·S+CF
0
), wherein CF
0
and CF
1
denote constants and S denotes a differential operator, and to calculate a relative velocity value vr of the preceding vehicle to the vehicle according to the above equation; and an initial value setting section to set a first initial value lr
0
of the inter-vehicle distance value and a second initial value vr
0
of the relative velocity value in the band pass filter calculation by the relative velocity calculator during a run of the vehicle.
The above-described object can also be achieved by providing a relative velocity detecting apparatus for an automotive vehicle, comprising: an inter-vehicle distance detector, disposed on the vehicle so as to be oriented toward a forward detection zone of the vehicle to detect an inter-vehicle distance to a preceding vehicle which is running ahead of the vehicle, to recognize whether the preceding vehicle has entered the forward detection zone and to derive the inter-vehicle distance value lrn (n=
1, 2, - - - ,
n) whenever a predetermined period of time has passed when recognizing that the preceding vehicle has entered the forward detection zone; a relative velocity calculator to perform a band pass filter calculation for the inter-vehicle distance value lrn, the band pass filter being expressed as: CF
0
·S/(S
2
+CF
1
·S+CF
0
), wherein CF
0
and CF
1
denote constants and S denotes a differential operator, and to calculate a relative velocity value vr of the preceding vehicle to the vehicle according to the above equation; and an initial value setting section to change a first initial value lr
0
of the inter-vehicle distance value from null and to change a second initial value vr
0
of the relative velocity value from null in the band pass filter calculation by the relative velocity calculator.
REFERENCES:
patent: 4628317 (1986-12-01), Nishikawa et al.
patent: 5162794 (1992-11-01), Seith
patent: 5710565 (1998-01-01), Shirai et al.
patent: 5959572 (1999-09-01), Higashimata et al.
patent: 6175799 (2001-01-01), Tsutsumi et al.
patent: 6188950 (2001-02-01), Tsutsumi et al.
patent: 2 324 283 (1998-10-01), None
patent: 6-187599 (1994-07-01), None
Adachi Kazutaka
Hashizume Takenori
Iwamoto Hideo
Foley & Lardner
Lobo Ian J.
Nissan Motor Co,. Ltd.
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