U.S. patent application number 09/795707 was filed with the patent office on 2001-09-27 for forward condition detecting apparatus for vehicles.
Invention is credited to Nishimura, Kenichi.
Application Number | 20010024171 09/795707 |
Document ID | / |
Family ID | 26586573 |
Filed Date | 2001-09-27 |
United States Patent
Application |
20010024171 |
Kind Code |
A1 |
Nishimura, Kenichi |
September 27, 2001 |
Forward condition detecting apparatus for vehicles
Abstract
A forward condition detecting apparatus for vehicles has a laser
radar device mounted on a vehicle. A front height sensor and a rear
height sensor detect a front height and a rear height of the
vehicle, respectively. An electronic control unit calculates an
angle of inclination of the vehicle relative to a reference plane
based on a difference between the detected front height and rear
height. The electronic control unit then calculates a laser beam
radiation angle based on the calculated angle of inclination. The
electronic control unit controls an angular position of the laser
radar device based on the calculated radiation angle so that the
laser beam may be maintained leveled generally in parallel with the
reference plane irrespective of the inclination of the vehicle. The
laser radar device is preferably mounted in a vehicle front
headlight unit to be driven together with a headlight lamp.
Inventors: |
Nishimura, Kenichi;
(Gifu-city, JP) |
Correspondence
Address: |
PILLSBURY WINTHROP LLP
1600 TYSONS BOULEVARD
MCLEAN
VA
22102
US
|
Family ID: |
26586573 |
Appl. No.: |
09/795707 |
Filed: |
March 1, 2001 |
Current U.S.
Class: |
342/70 ;
180/169 |
Current CPC
Class: |
G01S 17/88 20130101;
B60Q 1/0023 20130101; G01S 7/4813 20130101; B60Q 2300/132 20130101;
B60Q 1/115 20130101; G01S 7/4972 20130101; G01S 7/4817
20130101 |
Class at
Publication: |
342/70 ;
180/169 |
International
Class: |
G01S 013/00; B62D
001/24 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 2, 2000 |
JP |
2000-56579 |
Mar 21, 2000 |
JP |
2000-78433 |
Claims
What is claimed is:
1. A forward condition detecting apparatus for vehicles comprising:
parameter detecting means for detecting a parameter variable with
inclination of a vehicle; angle calculating means for calculating
an angle of inclination of the vehicle relative to a reference
plane based on the detected parameter; forward condition detecting
means movably installed on the vehicle for detecting forward
condition of the vehicle; and control means for controlling an
angle of the forward condition detecting means based on the
calculated angle of inclination of the vehicle.
2. The forward condition detecting apparatus as in claim 1, wherein
the parameter detecting means includes a vehicle height sensor
which detects a height of the vehicle.
3. The forward condition detecting apparatus as in claim 1, wherein
the forward condition detecting means includes a laser radar device
installed on a front bumper of the vehicle.
4. The forward condition detecting apparatus as in claim 1, wherein
the control means compensates for a change of the angle of the
forward condition detecting means caused by a change in the angle
of inclination of the vehicle.
5. The forward condition detecting apparatus as in claim 1,
wherein: the parameter detecting means detects a front height and a
rear height of the vehicle; and the angle calculating means
calculates the angle of inclination of the vehicle based on a
difference between the front height and the rear height.
6. The forward condition detecting apparatus as in claim 1, wherein
the forward condition detecting means includes a laser radar device
installed within a headlight unit of the vehicle.
7. The forward condition detecting apparatus as in claim 6, wherein
the laser radar device is coupled with a headlight lamp of the
headlight unit to be moved together with the head lamp by the
control means.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is based on and incorporates herein by
reference Japanese Patent Applications No. 2000-56579 filed Mar. 2,
2000 and 2000-78433 filed Mar. 21, 2000.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention relates to an apparatus for vehicles for
detecting forward condition such as information existing ahead of a
vehicle and related to safety drive.
[0004] 2. Related Art
[0005] Laser radar devices are proposed to detect vehicle forward
condition such as road conditions, preceding vehicles and the like.
The laser radar device is generally installed on a front bumper of
a vehicle. The laser radar device radiates a laser beam forward in
a predetermined angle relative to the reference plane such as the
ground plane as long as the vehicle posture is stable, for
instance, when the vehicle is at rest or in a cruising condition.
As a result, the laser radar device is enabled to receive a
reflected beam from a front object and detect the front object as
the forward condition based on the received beam.
[0006] The laser beam is radiated in the more upward direction than
in the predetermined angle direction, when the vehicle is loaded
with heavy stuff at the rear side or the vehicle is accelerated.
The laser beam is radiated in the more downward direction than in
the predetermined angle direction, when the vehicle is decelerated.
In those instances, the forward condition detecting operation will
be affected by the vehicle posture.
SUMMARY OF THE INVENTION
[0007] It is therefore an object of the present invention to
provide a forward condition detecting apparatus which is capable of
detecting forward condition without being affected by changes in
vehicle drive condition or loading.
[0008] It is another object of the present invention to provide a
forward condition detecting apparatus which is simple in
construction and is capable of being driven together with a front
headlight lamp.
[0009] A forward condition detecting apparatus for vehicles has a
laser radar device which detects forward condition of a vehicle. An
electronic control unit calculates an angle of inclination of the
vehicle. The electronic control unit then calculates a radiation
angle based on the calculated angle of inclination. The electronic
control controls an angular position of the laser radar device
based on the calculated radiation angle so that a laser beam may be
maintained radiated generally in parallel with the reference plane
irrespective of the inclination of the vehicle. The angle of
inclination of the vehicle is calculated based on a difference
between a front height and a rear height of the vehicle.
[0010] Preferably, the laser radar device is provided in a front
headlight unit and driven together with a front headlight lamp in
response to the calculated angle of inclination.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The above and other objects, features and advantages of the
present invention will become more apparent from the following
detailed description made with reference to the accompanying
drawings. In the drawings:
[0012] FIG. 1 is a schematic view showing a forward condition
detecting apparatus according to a first embodiment of the present
invention;
[0013] FIG. 2 is a sectional view of a laser radar device mounted
in a front bumper of a vehicle in the first embodiment;
[0014] FIG. 3 is a flow diagram showing a radiation angle control
process executed in the first embodiment;
[0015] FIGS. 4A and 4B are schematic views showing operation modes
of the first embodiment;
[0016] FIGS. 5A and 5B are schematic views of the laser radar
device used in the first embodiment;
[0017] FIGS. 6A and 6B are schematic views of a laser radar device
required when no automatic leveling operation is attained in the
first embodiment; and
[0018] FIGS. 7A and 7B are a front view and a side view of a laser
radar device mounted in a headlight unit of a vehicle according to
a second embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0019] The present invention will be described in detail with
reference to various embodiments, in which the same reference
numerals are used to designate the same or similar parts.
[0020] (First Embodiment)
[0021] Referring first to FIG. 1, a front height sensor 11F and a
rear height sensor 11R are attached to a front wheel-side
suspension and a rear wheel-side suspension of a vehicle,
respectively. The front suspension is provided between a vehicle
chassis and a front axle of either right or left side, and the rear
suspension is provided between the vehicle chassis and a rear axle
of either right or left side. The front height sensor 11F detects a
relative distance between the vehicle chassis and the front axle,
and the rear height sensor 11R detects a relative distance between
the vehicle chassis and the rear axle. The detected distances
indicate a front height HF and a rear height HR of the vehicle,
respectively. Output signals of the height sensors 11F and 11R are
input to an electronic control unit (ECU) 20 together with other
sensor output signals, so that a laser radar device 30 installed in
a front bumper 15 below a headlight unit 10 is controlled
electronically through an actuator 35 from time to time.
[0022] The ECU 20 includes a central processing unit (CPU) 21, a
read-only memory (ROM) 22 for storing a control program and control
constants, a random access memory (RAM) 23 for storing various
data, a backup RAM 24, an input/output circuit 25, and a bus 26
connecting those circuits. The ECU 20 thus operate as a logical
arithmetic unit which controls the laser beam radiation angle
radiated from the laser radar device 30.
[0023] As shown in FIG. 2, the laser radar device 30 is constructed
with a housing 31, a fixed support 33, a movable link 34 and the
actuator 35 such as a stepper motor. The housing 31 accommodates
therein a laser beam generator (not shown) and a reflected beam
receiver (not shown). The fixed support 33 supports the housing 31
swingably in an arrow direction. The movable link 34 connects the
housing 31 with the actuator 35, so that the housing 31 swings in
correspondence with horizontal movement of the link 34 when the
link 34 is driven by the actuator 35. The laser radar device 30 is
designed in such a manner that the laser beam is radiated at a
predetermined angle relative to a reference plane (e.g., ground
plane) assuming that only a driver is in the vehicle. That is, the
laser beam is radiated normally with the predetermined angle being
0.degree., in parallel with the ground plane.
[0024] The ECU 20, particularly the CPU 21 executes a control
process as shown in FIG. 3 based on a control program stored in the
ROM 22. This control process may be executed every predetermined
time interval.
[0025] Specifically, the CPU 21 reads in the front height HF and
the rear height HR detected by the front height sensor 11F and the
rear height sensor 11R, respectively, at step 101. The CPU 21 then
calculates the pitch angle .theta.p (.degree.) as follows relative
to the predetermined reference plane (ground plane) by using the
detected heights HF and HR and assuming a wheel base between the
front axle and the rear axle is Lw. The pitch angle .theta.p
indicates inclination of the vehicle in the vehicle travel
direction.
.theta.p=tan.sup.-1{(HF-HR)/Lw}
[0026] The CPU 21 calculates a radiation angle .theta.T at step 103
based on the calculated inclination angle .theta.p so that the
laser beam radiation angle is maintained in parallel with the
ground plane. That is, the radiation angle .theta.T is calculated
as .theta.T -.theta.p. This angle .theta.T is a corrective value by
which the radiation angle caused by the vehicle inclination
(.theta.p) is corrected to the predetermined angle (0.degree.). The
CPU 21 then drives at step 104 the actuator 35 through the I/O
circuit 25 based on the calculated value .theta.T so that the laser
beam may be maintained radiated at the predetermined angle relative
the ground plane.
[0027] In operation of the first embodiment, as shown in FIG. 4A,
the laser beam radiation is automatically corrected to the
generally horizontal direction (solid line) from the upward-headed
direction (dotted line) even when the vehicle front side is raised
due to vehicle acceleration or heavy loading at the rear of the
vehicle. Further, as shown in FIG. 4B, the laser beam radiation is
automatically corrected to the generally horizontal direction
(solid line) from the downward-headed direction (dotted line) even
when the vehicle rear side is raised due to vehicle deceleration.
Thus, according to the first embodiment, the laser radar device 30
is automatically leveled in such a manner the laser beam radiation
angle can be maintained at a fixed angle irrespective of changes in
the vehicle posture so that any front condition existing ahead of
the vehicle can be detected accurately.
[0028] In the first embodiment, the laser beam radiation angle may
be calculated by using only one of the front height HF or the rear
height HR. It may also be calculated by detecting acceleration and
deceleration of a vehicle. Further, the laser beam radiation angle
may be corrected by filtering processing such as a moving average
processing, which correspond to vehicle stop, cruising and
acceleration/deceleration conditions, by detecting a vehicle speed
and acceleration/deceleration magnitude.
[0029] The laser radar device 30 is comprised of, as shown in FIGS.
5A, 5B, 6A and 6B, a laser beam generator 301a, a polygon mirror
301b and a drive motor 301c, which form a laser beam radiator 301
in the known manner. Other components such as a laser beam receiver
(not shown) are not shown in the figures. The polygon mirror 301b,
which reflects the laser beam from the laser generator 301a
frontward when rotated by the drive motor 301c, has a plurality of
inclined surfaces around its axis of rotation. The surfaces are
inclined by predetermined angles .theta.i against the horizontal
plane, respectively. The angles .theta.i are different from each
other, so that the reflected laser beams are directed up and down
in each rotation of the polygon mirror 301b.
[0030] The inclination of the vehicle (pitch angle .theta.p) is
normally considered to vary in the range of +3.degree. and
-3.degree. from the horizontal plane. If the laser radar device 30
is fixed to the vehicle chassis such as a front bumper and no
automatic leveling is provided for the laser radar device 30, the
polygon mirror 301b is required to have eight inclined surfaces
(numbered from 1 to 8 in FIG. 6B) to cover the above variation in
the pitch angle .theta.p.
[0031] According to the first embodiment, however, the laser radar
device 30 is automatically leveled, thus minimizing the range of
variations in the angle of radiation of the laser beam, which the
laser radar device 30 is required to cover. Thus, the number of
surfaces of the polygon mirror 301b can be reduced to four
(numbered from 1 to 4) as shown in FIG. 5B. As a result, the
polygon mirror 301b can be sized small and the laser beam generator
301a can be positioned close to the polygon mirror 301b, thus
enabling use of a compact-sized laser radar device.
[0032] (Second Embodiment)
[0033] In a second embodiment, as shown in FIGS. 7A and 7B, the
laser radar device 30 is mounted in the headlight unit 10 which is
disposed right above the front bumper 15 (FIG. 1).
[0034] Specifically, the front headlight unit 10 has a cover lens
10a at the front side and a housing 12, which jointly define a
closed chamber therein. In the chamber, a headlight lamp (not
shown) is fixed to a reflector 13, and the reflector 3 is fixed to
a board 17. A design panel 16 is attached to the housing 12 at a
position ahead of the reflector 13. The board 17 is attached to a
support member 36 at a top side end thereof and to the movable link
34 at a bottom side end thereof. The laser radar device 30
comprising the laser beam radiator 301 and a laser beam receiver
302 is fixedly attached to the board 17. The movable link 34 is
coupled to the actuator 35 so that the bottom side of the board 17
is moved by the actuator 35 pivotally around its top side supported
by the support member 36. As a result, the angles of radiation of
the laser beam from the laser beam radiator 301 and the headlight
from the reflector 17 are regulated simultaneously in response to
the inclination of a vehicle by the ECU 20 in the same manner as in
the first embodiment. The laser beam radiator 301 and the laser
beam receiver 302 may be provided at separate locations on the
board 17 or the reflector 13.
[0035] According to the second embodiment, the laser radar device
30 can be protected from dust and water by the cover lens 10a in
addition to the automatic leveling of the angle of laser beam
radiation. Further, the radiation angle of both headlight and laser
beam can be automatically regulated by one actuator 35.
[0036] The present invention should not be limited to the disclosed
embodiments and modifications, but may be implemented in many other
ways without departing from the spirit of the invention.
* * * * *