Radar apparatus

• US 6,348,889 B1
• Filed: 08/04/2000
• Issued: 02/19/2002
• Est. Priority Date: 08/04/1999
• Status: Expired due to Fees

• Current Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Original Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Inventors: Sawamoto, Kiichirou, Ashihara, Jun
• Primary Examiner(s): Sotomayor, John B.
• Application Number:
  US09/632,460
• Time in Patent Office: 564 Days
• Field of Search: 342/70, 342/71, 342/72, 342/85, 342/89, 342/91, 342/173, 342/174, 342/195
• US Class Current: 342/70
• CPC Class Codes: G01S 13/931 of land vehicles
• CPC Class Codes: G01S 17/931 of land vehicles
• CPC Class Codes: G01S 2013/932 using own vehicle data, e.g. ground speed, steering wheel direction
• CPC Class Codes: G01S 2013/9325 for inter-vehicle distance regulation, e.g. navigating in platoons
• CPC Class Codes: G01S 7/4004 of parts of a radar system
• CPC Class Codes: G01S 7/4039 of sensor or antenna obstruction, e.g. dirt- or ice-coating
• CPC Class Codes: G01S 7/4047 Heated dielectric lens, e.g. by heated wire
• CPC Class Codes: G01S 7/4056 specially adapted to FMCW
• CPC Class Codes: G01S 7/4091 during normal radar operation
• CPC Class Codes: G01S 7/497 Means for monitoring or calibrating

Abstract

A vehicular radar apparatus comprising a radar beam transmission device and a reception device, and a processing unit for detecting the position of a target object from transmission signals and reception signals. The processing unit has a preceding vehicle judgment circuit for judging if a vehicle travelling in front of a subject vehicle in the same direction is the same vehicle as previously detected or not, and a signal strength comparing device for comparing the signal strength of a current reception signal reflected from the preceding vehicle, with a signal strength of a reception signal reflected from the preceding vehicle a predetermined comparison reference time prior, to thereby calculate a change amount in signal strength. When the change amount calculated by the signal strength comparing device drops beyond a previously set threshold value and it is judged by the preceding vehicle judgment device that the preceding vehicle is the same vehicle, it is judged that the detection sensitivity of the radar apparatus has dropped.

Claims

1. A radar apparatus for being mounted on a subject vehicle comprising:

a beam transmission means for radiating a radar beam as a transmission signal;

a beam reception means for receiving a reception signal reflected from a target object which is within a radiation range of said radiated radar beam; and

a processing unit for detecting a position of a target object from said transmission signal and said received reception signal, said processing unit comprising;

a preceding vehicle judgement means for judging if a preceding vehicle travelling in front of the subject vehicle in approximately a same direction as the subject vehicle is same vehicle as previously detected, and

a signal strength comparing means for comparing the signal strength of a reception signal reflected from said preceding vehicle, with a signal strength of a reception signal reflected from said preceding vehicle a comparison reference time prior, to thereby calculate a change amount in signal strength, and

when said change amount calculated by said signal strength comparing means drops beyond a previously set threshold value and it is judged by said preceding vehicle judgement means that said preceding vehicle is the same vehicle, said processing unit diagnoses that detection sensitivity of the radar apparatus has dropped.

2. A radar apparatus according to claim 1, wherein said processing unit further comprises a distance change calculating means for calculating a change amount of relative distance between said preceding vehicle and said subject vehicle,

and comparison of said reception signal is made when said calculated change amount of the relative distance is below a previously set change amount.

3. A radar apparatus according to claim 1, wherein said processing unit further comprises a distance change calculating means for calculating a change amount of relative distance between said preceding vehicle and said subject vehicle,

and said comparison reference time is changed based on to said calculated change amount of the relative distance.

4. A processing unit according to claim 1, wherein said comparison reference time is changed based on said calculated change amount of the relative distance.

5. A processing unit for a vehicular radar apparatus having means for radiating a radar beam as a transmission signal and means for receiving a reception signal reflected from a target object which is within a radiation range of said radiated radar beam, said processing unit determining a position of a target object from said transmission signal and said received reception signal and comprising:

means for judging if a preceding vehicle travelling in front of a subject vehicle on which the radar apparatus is mounted, in approximately a same direction as the subject vehicle is a same vehicle as previously detected, and

a signal strength comparing means for comparing the signal strength of a reception signal reflected from said preceding vehicle, with a signal strength of a reception signal reflected from said preceding vehicle in a prior reference time, to thereby calculate a change amount in signal strength, and

when said change amount calculated by said signal strength comparing means drops below a preset threshold value and it is judged by said preceding vehicle judgement means that said preceding vehicle is the same vehicle, said processing unit diagnoses that detection sensitivity of the radar apparatus has dropped.

6. A processing unit according to claim 5, further comprising a distance change calculating means for calculating a change amount of relative distance between said preceding vehicle and said subject vehicle, and

said signal strength comparing means performs said comparison when the calculated change amount of relative distance is below a preset value.

7. A processing unit according to claim 5, further comprising a distance change calculating means for calculating a change amount of relative distance between said preceding vehicle and said subject vehicle, and

said comparison reference time is changed based on said calculated change amount of the relative distance.

8. A processing unit according to claim 6, wherein said comparison reference time is changed based on said calculated change amount of the relative distance.