Communications: directive radio wave systems and devices (e.g. – Return signal controls external device – Radar mounted on and controls land vehicle
Reexamination Certificate
2000-02-23
2002-04-09
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
C342S165000, C702S183000
Reexamination Certificate
active
06369747
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a radar apparatus utilized as a vehicle radar system or the like, and more specifically relates to an abnormality detection method for detecting an abnormality of a radar apparatus, and a radar apparatus using this abnormality detection method.
This application is based on Japanese Patent Application No. Hei 11-046055, the contents of which are incorporated herein by reference.
2. Description of the Related Art
A vehicle radar apparatus has heretofore been made practicable for obstacle detection, detecting an object within a relatively short distance so that, for example, at the time of putting a vehicle into a garage, the vehicle does not collide against an obstacle such as a telegraph pole, a block wall or the like. Moreover, research for making practicable a radar apparatus, which intercepts a target object at a relatively long distance at a high speed and at high accuracy, has been recently promoted as an alarm system for preventing a rear-end collision with a vehicle driving ahead, or a collision at the time of driving a vehicle, other than prevention of a collision against the above described stationary obstacles, or as an adaptive cruise control system (ACC) at the time of so-called auto-cruise.
For example, in the U.S. Pat. No. RE 36,095 by the present applicant, is proposed a multi-beam radar apparatus which uses a high frequency beam in a millimeter-wave band as a transmit-beam. In this publication there is disclosed a radar apparatus which improves the detection accuracy by radiating spatially overlapping beams, using a plurality of transmitter-receiver devices, and changing the combination of the transmitter-receiver devices.
Moreover, in the publication EP 0840140A1 by the present applicant, is proposed a scan beam radar apparatus which uses a high radio frequency in a millimeter-wave band as a transmit-beam. In this publication there is disclosed a method of scanning the radio frequency radiated from a primary radiator by means of a rotating reflective body and converging the reflected beam by a dielectric lens to reduce a spread angle, to thereby radiate the reflective beam in the vehicle driving direction.
However, for example, with the multi-beam radar apparatus, the detection area has an intrinsic detection area defined for each combination of respective transmitter-receiver devices, and the position of a target object. That is, an azimuth angle and a distance with respect to a vehicle are calculated by synthesizing the received data observed for each combination of these transmitter-receiver devices. Therefore, if any one of the plurality of transmitter devices or receiver devices breaks down or deteriorates to impair the sensitivity, the radar apparatus must accurately measure the sensitivity and must appropriately judge the abnormality.
Moreover, for example, with the aforesaid scan beam radar apparatus, a transmitter-receiver circuit normally adopts a pair construction, hence the azimuth error as in the multi-beam radar apparatus is not likely to occur due to deterioration of the transmission circuit or the reception circuit. On the other hand however, the detection sensitivity deteriorates evenly over all directions.
Therefore, it has heretofore been necessary to regularly measure the sensitivity of the radar apparatus and confirm that there is no abnormality therein, such- as sensitivity deterioration or the like. This sensitivity measurement however, has been performed by transporting a vehicle mounted with the radar apparatus to a test environment where a reference target is installed, transmitting and receiving a beam to/from the reference target in a state that the vehicle is halted at a predetermined test position, and measuring the reception level. Hence there is a problem that much time and man-hours are required. Moreover, the sensitivity may be impaired due to some reason, and a partial breakdown may be caused in a constituent circuit during the regular check.
Therefore, there has been devised a method for predicting the sensitivity of a radar apparatus from the detection number for the target objects which are detected for a predetermined period of time, for the purpose of detecting abnormalities in a vehicle mounted condition. With this method however, there is a problem in that the abnormality judgement varies widely according to individual conditions such as vehicle travelling state and the road environment for travelling, such that when the target object is not detected within the predetermined period of time, the estimation is not possible (or erroneous judgement is caused). Hence, a radar apparatus has been desired which can measure the sensitivity and judge the abnormality during travelling, without being affected by such individual conditions.
SUMMARY OF THE INVENTION
The present invention has been completed under such a background, and it is an object of the present invention to provide a radar apparatus which detects and judges abnormality of the radar apparatus in the normally used state of a vehicle, without transporting the vehicle to a special environment, and avoids various problems, even if a sensitivity drop or a breakdown of the transmitter-receiver devices occurs.
To solve the above described problems, with the present invention, with a radar apparatus used mounted on a vehicle and having: a beam transmission device (for example, the transmission section
30
in embodiments) for radiating a beam as a transmission signal; a beam reception device (for example, the reception section
40
in the embodiments) for receiving a signal reflected from a target object which is within a radiation range of the radiated beam; and a processing unit (for example, the detection/control section
50
in the embodiments) for detecting the position of a target object from the transmission signal and the reception signal. The processing unit has a roadbed reflection analysis device (for example, the roadbed reflection analysis circuit
51
b
in the embodiments) for analyzing from among the reception signals, a roadbed reflection signal reflected from a roadbed, and incorporates an abnormality judging device (for example, the abnormality judging circuit
51
c
in the embodiments) for judging an abnormality of the beam transmission device or the beam reception device, based on the analysis results of the roadbed reflection analysis device.
With the above described construction, the processing unit has a roadbed reflection analysis device for analyzing from among the reception signals being received, a roadbed reflection signal reflected from a roadbed, and the abnormality judging device judges that the beam transmission device or the beam reception device is abnormal, when a reflection signal is not detected from the roadbed by the roadbed reflection analysis device. Hence, abnormality in the radar apparatus can be detected and judged during travelling, without transporting and setting a vehicle in a special measurement environment to measure the sensitivity, and without depending upon the road environment, such as the presence or absence of a target object normally serving as a target of the radar apparatus.
Moreover, with the radar apparatus wherein the processing unit detects the position of the target object by using the transmission signal and the reception signal and performing frequency conversion processing, the processing unit comprises a signal separation device (for example, the signal separation circuit
51
a
in the embodiment) for separating a low-intensity spectrum signal not higher than a previously set predetermined intensity level, from among the received spectrum signals which have been frequency-conversion processed by the processing unit. The roadbed reflection analysis device preferably analyzes the separated low-intensity spectrum signal as the roadbed reflection signal.
With such a radar apparatus, the reflection signal from the target object normally serving as a target of the radar apparatus is comprehended as a spectrum signal having a
Armstrong Westerman & Hattori, LLP.
Honda Giken Kogyo Kabushiki Kaisha
Lobo Ian J.
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