Communications: directive radio wave systems and devices (e.g. – Return signal controls external device – Radar mounted on and controls land vehicle
Reexamination Certificate
2000-03-20
2002-07-02
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
C342S173000
Reexamination Certificate
active
06414623
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a radar system, and more particularly to a radar system which is mounted on a vehicle and which can detect degradation of the sensitivity of a radar apparatus.
2. Description of the Related Art
A radar system mounted on a vehicle has conventionally come into a practical use for the purpose of detection of any obstacle to prevent the vehicle from colliding with the obstacle around the vehicle in running in a narrow alley or putting the vehicle in a garage. Also, in recent years, a radar system has been developed to catch a detection object in a relatively long distance from the vehicle at a high speed in a high precision as a warning apparatus to prevent the vehicle from colliding with a preceding vehicle or as an Adaptive Cruise Control (ACC) to control the vehicle to run while keeping a distance to the preceding vehicle constant.
Here, a radar apparatus of the above radar system mounted on the vehicle is generally installed in a bumper section of the vehicle or a front grill in a front portion of the vehicle. Therefore, it is easy for snow to accrete on a radome of the radar apparatus in case of snowfall. Also, when snow containing much water accretes, the transmission loss of radar wave becomes large. Therefore, the detection sensitivity of the radar system reduces uniformly over all the azimuth directions, so that the distance measuring range of a detection object becomes short.
For this reason, in Japanese Laid Open Utility Model Application (JP-U-Showa 60-173084: a first conventional example), a temperature sensor and a water sensor are provided for the radome of the radar apparatus. An electric current is supplied to a resistor, which is provided for the radome, based on the detection results of the sensors to melt snow and ice. In this way, the sensitivity degradation of the radar system due to snow or ice is prevented.
Also, in Japanese Laid Open Patent Application (JP-A-Heisei 6-59024: a second conventional example), a plurality of electrodes are provided on the whole surface of a radome of a radar apparatus. A voltage or current between these electrodes is detected. In this way, ice formation or adhesion of muddy water on the radome surface is detected.
However, in the radar systems of the first and second conventional examples, the structure of the radome or the radar system becomes complicated to increase the cost of the radar system.
Also, the degree of the sensitivity degradation of the radar system depends on a quality of snow accretion on the radome. Also, even if the accreted snow is melt into water with the heat by a heater provided for the radome or the radiation heat from an engine once,the water sometimes froze again during the running of the vehicle. In this way, the accretion situation of snow and ice changes dependent on the running state of the vehicle. It is difficult to prevent the sensitivity degradation of the radar system due to snowfall by only the measure based on the surface temperature of the radome and the local wetting situation.
In conjunction with the above description, an FM radar apparatus is described in Japanese Laid Open Patent Application (JP-A-Heisei 10-282229). In this reference, a transmission FM signal and a reception FM signal are mixed to obtain a beat signal (
10
a
). A low frequency component of the beat signal (
10
a
) is filtered by a low pass filter (
12
), A/D converted by a converter (
13
), and then is subjected to a fast Fourier transformation (FFT) by an FFT converter (
14
) to produce a detection signal. A control unit (
15
) compares the detection signal and a corresponding stored signal to detect contamination of a radome (
8
). The control unit (
15
) increases a frequency change quantity of a FM signal per a unit time on the detection of the contamination. Thus, the contamination of the radome is detected without providing any sensor to the radome.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide a radar system which can estimate existence or non-existence of accretion of snow or ice.
Another object of the present invention is to provide a radar system which can estimate a melting state of an accreted snow or ice.
Still another object of the present invention is to provide a radar system which can estimate the sensitivity degradation of a radar apparatus.
Yet still another aspect of the present invention is to provide a radar system in which the accreted snow or ice can be removed when the sensitivity degradation of a radar apparatus is estimated.
It is an object of the present invention to provide a radar system in which the sensitivity degradation of the radar system can be prevented with a simple structure.
Another object of the present invention is to provide a method of keeping the sensitivity of a radar apparatus in the above radar systems.
In order to achieve an aspect of the present invention, a radar system mounted on a vehicle includes a radar apparatus, a radome provided for the radar apparatus, a front wiper, a wiper operation detector detecting an operation of the front wiper, a temperature detector detecting temperature outside of the vehicle, and a processing unit. The processing unit estimates whether sensitivity degradation of the radar apparatus is caused, based on the detecting result of the wiper operation detector and the detecting result of the temperature detector.
Here, the radar system mounted on a vehicle may further include an output unit. At this time, the processing unit notifies that the sensitivity degradation of the radar apparatus is caused, to, a driver via the output unit based on the estimating result.
Also, the radar system mounted on a vehicle may further include a radome heater provided for the radome, and a radome heater control circuit controlling the radome heater to be turned on in response to a heater control signal. At this time, the processing unit outputs the heater control signal to the radome heater control circuit when it is estimated that the sensitivity degradation of the radar apparatus is caused.
Also, the radar system mounted on a vehicle may further include a radome wiper provided for the radome, and a radome wiper control circuit controlling the radome wiper to be turned on in response to a wiper control signal. At this time, the processing unit outputs the wiper control signal to the radome wiper control circuit when it is estimated that the sensitivity degradation of the radar apparatus is caused.
Also, the processing unit may include a first counter, a first estimating section, a second estimating section. The first estimating section estimates whether snow falls, based on the detecting result of the wiper operation detector and the detecting result of the temperature detector, and increments the first counter when it is estimated that the snow falls. The second estimating section estimates whether the sensitivity degradation of the radar apparatus is caused, based on a value of the first counter. In this case, the processing unit further include a second counter. At this time, the first estimating section estimates whether sleet falls, based on the detecting result of the wiper operation detector and the detecting result of the temperature detector, and increments the second counter when it is estimated that the sleet falls. The second estimating section estimates whether the sensitivity degradation of the radar apparatus is caused, based on the first counter value and a value of the second counter. Also, in this case, the first estimating section estimates whether rain falls, based on the detecting result of the wiper operation detector and the detecting result of the temperature detector. Also, the first estimating section decrements the first and second counters by first and second values, respectively, and also increments the second counter by a third value, when it is estimated that the rain falls. The second estimating section estimates whether the sensitivity degradation of the radar apparatus is caused, based on the first c
Blackman William D.
Carrier Joseph P.
Carrier Blackman & Associates P.C.
Honda Giken Kogyo Kabushiki Kaisha
Lobo Ian J.
LandOfFree
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