Communications: directive radio wave systems and devices (e.g. – Testing or calibrating of radar system – By monitoring
Reexamination Certificate
2000-02-18
2001-08-21
Gregory, Bernarr E. (Department: 3662)
Communications: directive radio wave systems and devices (e.g.,
Testing or calibrating of radar system
By monitoring
C342S070000, C342S071000, C342S072000, C342S165000, C342S175000, C342S195000, C702S183000, C180S167000, C180S169000
Reexamination Certificate
active
06278399
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a vehicular radar apparatus comprising a malfunction detecting device and a method for detecting a malfunction of the radar apparatus.
2. Description of Related Art
Vehicular radar apparatuses for detecting relatively approximate and immobile obstacles, such as trolley poles and concrete fences, in order to prevent vehicles (for example, automobiles) from colliding with the obstacles for example while parking the vehicle in a garage, have been conventionally implemented. Furthermore, in recent years, in addition to the radar apparatus for the detection of immobile obstacles as described above, research and development have been carried out for implementing a radar apparatus for the acquisition of moving objects over relatively long distances at high accuracy and at high speed. Such a radar apparatus can be used, for example, as an alarm system for preventing colliding with or rear-ending another car while driving, or an adaptive cruse control (ACC) used for auto cruising.
U.S. Pat. No. RE 36,095 which belongs to the assignee of the present application discloses a multi-beam radar apparatus which uses a high frequency beam in the millimeter waveband as a radar wave. This multi-beam radar apparatus comprises a plurality of transmitter receivers for radiating and receiving radar beams so that the radar beams spatially overlap with each other, and it is possible to improve the accuracy of detection by optimizing the combination of the transmitter and receivers.
European Patent Application No. EP0840140A1 filed by the assignee of the present application discloses a scanning beam radar apparatus which uses a high frequency beam in the millimeter waveband as a radar wave. In this scanning beam radar apparatus, a primary transmitter radiates a high frequency beam, and the beam is scanned by a rotating reflector. The scanned beam is converged by a dielectric lens in order to decrease the scanning angle of the beam, and is radiated toward the running direction of the vehicle.
However, in the above multi-beam radar apparatus, each of the transmitter receivers has an inherent detection area, and the position of a detected object, that is, the direction with respect to a vehicle and the distance between the object and the vehicle, is calculated by collating a plurality of data from the selected transmitter receivers. Therefore, when a malfunction or a sensitivity degradation due to deterioration occur in any one of the selected transmitter receivers, it becomes necessary to detect which receiver has a malfunction or a sensitivity degradation.
In contrast, in the case where the above scanning beam radar apparatus uses only one transmitter receiver, when a sensitivity degradation occurs in the transmitter receiver, it becomes necessary to compensate the sensitivity in all directions.
Also, in the above conventional radar apparatuses, in order to check the radar sensitivity, it is necessary to transport a vehicle comprising a radar apparatus to a predetermined position in a testing station where a reference object is provided and to activate the radar apparatus to measure its receiving sensitivity with respect to the reference object. Therefore, a periodic check of the conventional apparatus requires a laborious process and a high costs. Furthermore, in the conventional radar apparatuses, it is difficult to check the radar sensitivity at an arbitrary time other than the periodic checks.
Additionally, because the conventional radar apparatus is generally installed at the front or rear end of a vehicle, such as in a bumper or in a front grille, it is susceptible to the adverse effects of rain, snow, wind, dust, and mud. In particular, the radar sensitivity decreases when snow or mud is thickly attached to the radar apparatus. Accordingly, some countermeasure for preventing such effects is necessary. Furthermore, in the case of installing the radar apparatus in the vicinity of the engine compartment, it is necessary to improve the heat resistance of the radar apparatus, which increases the manufacturing costs of the radar apparatus.
SUMMARY OF THE INVENTION
The objective of the present invention is to provide a radar apparatus and a malfunction detection method in which it is possible to check the sensitivity of the radar apparatus under normal conditions of a vehicle without transporting the vehicle to a testing station, and to improving the sensitivity of the radar apparatus without requiring high cost.
Another object of the present invention is to prevent deposition of snow, mud, etc. on a passage of a radar beam and prevent errors in locating objects or deterioration of the sensitivity of the radar apparatus.
In order to achieve the above objectives, the radar apparatus of the present invention comprises:
a beam transmitter for radiating a radar beam as a transmitted signal;
a beam receiver for receiving a signal reflected by an object in an area irradiated by the radar beam;
a processor for calculating the position of the object from the transmitted signal and the reflected signal; and
a malfunction detecting device for detecting a malfunction of the radar apparatus;
wherein at least one of the area irradiated by the beam transmitter and a receiving area of the beam receiver overlaps with an area over which a wiping member of a windshield wiper device, and the malfunction detecting device estimates that the radar apparatus is malfunctioning if a wiper passing signal to be detected does not appear in an output signal of the processor when the wiper device is activated.
According to this radar apparatus, because the wiping member intermittently crosses at least one of the radiated radar beam or the returning radar beam while the wiper device is activated, the radar beam is intermittently reflected, diffused, or absorbed by the wiping member. Therefore, in the receiving signals received by the radar apparatus, wiper passing signals having a characteristic waveform appear in synchronization with the movement of the wiper member. The malfunction detecting device estimates that the radar apparatus has an abnormality, such as a malfunction or deterioration of the sensitivity, if the wiper passing signal to be detected does not appear in an output signal of the processor when the wiper device is activated.
Therefore, in this radar apparatus, without transporting the vehicle to a special testing station, and regardless of the circumstances such as road conditions or state of the vehicle, it is possible to inspect the radar apparatus at a desirable time and place, for example, at the same time as a start-up inspection or during driving. The inspection can be performed intermittently or continuously while the wiper device is activated. Furthermore, the inspection can be automatically started by a driver's operation for activating the wiper device, and periodic inspections can surely be performed without requiring additional operations by the driver.
In addition, because the wiping member moves in front of at least one of the beam transmitter and beam receiver, it is possible to wipe off rain, snow, dust, mad, which may interrupt radar beams. Therefore, deterioration of the sensitivity of the radar apparatus can thereby be prevented or diminished, and reliability of the radar apparatus is improved.
This radar apparatus may comprise a wiper movement detecting device for detecting whether the wiper device is activated. In this case, the malfunction detecting device can estimate that the radar apparatus is malfunctioning if a wiper passing signal to be detected does not appear in an output signal of the processor while the wiper movement detecting device detects that the wiper device is activated.
The beam transmitter and the beam receiver may be assembled into a radar module to be installed on an inner surface of a windshield of the vehicle.
In this case, because the radar module is positioned in a cabin of the vehicle and is protected by the windshield, it is possible to diminish the requirements for the radar a
Armstrong Westerman Hattori McLeland & Naughton LLP
Gregory Bernarr E.
Honda Giken Kogyo Kabushiki Kaisha
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