Obstacle detection system for a vehicle

• US 6,281,786 B1
• Filed: 04/19/1999
• Issued: 08/28/2001
• Est. Priority Date: 04/20/1998
• Status: Expired due to Term

• Current Assignee: Panasonic Electric Works Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Asahi Matsushita Electric Works Ltd. (Panasonic Holdings Corporation)
• Inventors: Azuma, Naoya, Adachi, Kenichi
• Primary Examiner(s): SWARTHOUT, BRENT
• Application Number:
  US09/293,961
• Time in Patent Office: 862 Days
• Field of Search: 340/903, 340/435, 340/943, 340/904, 340/460, 342/70, 342/85, 342/87, 342/99, 367/99, 367/909
• US Class Current: 340/435
• CPC Class Codes: G01S 13/34 using transmission of continuous, frequency-modulated waves while heterodyning the received signal, or a signal derived therefrom, with a locally-generated signal related to the contemporaneously transmitted signal
• CPC Class Codes: G01S 13/862 Combination of radar systems with sonar systems
• CPC Class Codes: G01S 13/931 of land vehicles
• CPC Class Codes: G01S 15/86 Combinations of sonar systems with lidar systems; Combinations of sonar systems with systems not using wave reflection
• CPC Class Codes: G01S 15/931 of land vehicles
• CPC Class Codes: G01S 2013/932 using own vehicle data, e.g. ground speed, steering wheel direction
• CPC Class Codes: G01S 2013/9324 Alternative operation using ultrasonic waves
• CPC Class Codes: G01S 2013/93271 in the front of the vehicles
• CPC Class Codes: G01S 2013/93272 in the back of the vehicles
• CPC Class Codes: G01S 2013/93274 on the side of the vehicles
• CPC Class Codes: Y10S 367/909 Collision avoidance

Abstract

An obstacle detection system for a vehicle which is capable of detecting nearby and remote objects successfully by use of a combination of an electromagnetic wave sensors and ultrasonic wave sensors. The system of the present invention includes a plurality of ultrasonic wave sensors each transmitting an ultrasonic wave around the vehicle and receives a reflected wave thereof for detection of nearby obstacles around the vehicle, and an electromagnetic waver sensor which transmits an electromagnetic wave in a forward direction of the vehicle and receives a reflected electromagnetic wave thereof for detection of a remote obstacle. The system includes a vehicle speed sensor is provided for sensing a speed of the vehicle. A detection unit detects a presence of the nearby obstacle based upon the reflected ultrasonic wave when the vehicle speed equals to a predetermined reference speed or less, and detects a position of the remote obstacle relative to the vehicle only based upon the reflected electromagnetic wave when the vehicle speed exceeds the reference speed. The detection unit issues a nearby signal upon detection of the nearby obstacle and issues a remote signal when the position of the remote obstacle is within a predetermined long distance from the vehicle. A warning unit gives warnings respectively in response to the nearby and remote signals.

Claims

1. An obstacle detection system for a vehicle comprising:

a plurality of ultrasonic wave sensors each of which transmits an ultrasonic wave around the vehicle and receives a reflected ultrasonic wave for detecting a nearby obstacle around the vehicle;

an electromagnetic wave sensor which transmits an electromagnetic wave in a forward direction of the vehicle and receives a reflected electromagnetic wave for detecting a remote obstacle at a distance remote from the vehicle;

a vehicle speed sensor for sensing a speed of the vehicle and providing a speed output;

a detection unit which detects a presence of the nearby obstacle based upon said reflected ultrasonic wave and a presence of the remote obstacle based upon said reflected electromagnetic wave when said speed output is not more than a predetermined reference speed and detects a position of the remote obstacle relative to the vehicle only based upon said reflected electromagnetic wave when said speed output exceeds the predetermined reference speed, said detection unit issuing a nearby signal when said nearby obstacle is detected and issuing a remote signal when the position of said remote obstacle is within a predetermined distance of the vehicle; and

a warning unit which provide warnings in response to each of said nearby and remote signals.

2. The system as set forth in claim 1, wherein

said detection unit is configured to shorten said predetermined distance by narrowing a detection range for detection of said remote obstacle as said speed output is lowered.

3. The system as set forth in claim 1, further including

a direction sensor which provides a steering wheel angle of said vehicle, said electromagnetic wave sensor varying a wave transmission direction dependent upon said steering wheel angle.

4. The system as set forth in claim 1, further including

a rear electromagnetic wave sensor unit which, when the vehicle is in one of a reverse drive condition and a condition whereby the vehicle speed exceeds a predetermined speed, transmits an electromagnetic wave in a rearward direction of the vehicle and receives a reflected electromagnetic wave for detecting a remote obstacle behind the vehicle;

said detection unit processing the reflected electromagnetic wave from said rear electromagnetic wave sensor to detect a relative position of the remote obstacle behind the vehicle and to recognize the remote obstacle as another vehicle approaching from behind when the position of the remote obstacle is determined to come closer to the vehicle and issue a catching-up signal indicative of the presence of the another vehicle, and

said warning unit generates a warning in response to said catching-up signal.

5. The system as set forth in claim 1, wherein

said warning unit comprises a buzzer generating an intermittent buzzing sound, wherein at least one of an interval of the buzzing sound and a frequency of the buzzing sound varies according to the detection of the nearby and remote obstacles.

6. The system as set forth in claim 1, wherein

said warning unit comprises a voice speaker which generates a voice message upon detection of the nearby and remote obstacles.

7. The obstacle detection system according to claim 1, further comprising a control unit that activates different ones of said plurality of ultrasonic sensors depending upon a direction of movement of the vehicle.