FMCW/2FD implementation for vehicle near obstacle detection system

• US 5,087,918 A
• Filed: 04/02/1990
• Issued: 02/11/1992
• Est. Priority Date: 04/02/1990
• Status: Expired due to Term

• Current Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated)
• Original Assignee: Delco Electronics Corporation (General Motors Company)
• Inventors: Ward, John L., Kebede, Kassahun, May, Phillip A.
• Primary Examiner(s): Sotomayor, John B.
• Application Number:
  US07/503,435
• Time in Patent Office: 680 Days
• Field of Search: 342/85, 342/70, 342/82, 342/130, 340/932.2, 340/435, 340/436, 340/437
• US Class Current: 342/85
• 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 13/348 using square or rectangular modulation, e.g. diplex radar for ranging over short distances
• CPC Class Codes: G01S 13/583 using transmission of continuous unmodulated waves, amplitude-, frequency-, or phase-modulated waves and based upon the Doppler effect resulting from movement of targets
• CPC Class Codes: G01S 13/931 of land vehicles
• CPC Class Codes: G01S 2013/9315 Monitoring blind spots
• CPC Class Codes: G01S 2013/9317 Driving backwards
• CPC Class Codes: G01S 2013/932 using own vehicle data, e.g. ground speed, steering wheel direction
• CPC Class Codes: G01S 2013/93271 in the front of the vehicles
• CPC Class Codes: G01S 2013/93272 in the back of the vehicles

Abstract

A vehicle near obstacle detection system includes a plurality of radio frequency heads that can transmit and receive both frequency-modulated, continuous wave and two-frequency Doppler radar signals, such that the system operates in frequency-modulated, continuous wave radar mode and in two-frequency Doppler radar mode. The radio frequency heads used for transmitting the radar signals transmit their radar signals in accordance with commands from a system controller. The radio frequency heads are provided at various locations on the vehicle, directed at points around the vehicle which cannot easily be seen by the vehicle operator. The system controller switches between the two radar modes depending on which one is more appropriate to make use of one mode'"'"'s strengths while avoiding the other mode'"'"'s weaknesses. When there is no relative movement between objects and the vehicle, the frequency-modulated, continuous wave mode is used. When there is relative movement and the accuracy warrants it, the two-frequency Doppler mode is used.

Claims

1. A vehicle near obstacle detection system, the system comprising:

a radio frequency head capable of transmitting and receiving both frequency-modulated, continuous wave radar signals and two-frequency Doppler radar signals;

signal processing means responsive to received radar signals reflected from an object for determining the range to the object;

means for sensing vehicle speed; and

means for controlling the radio frequency head to (A) transmit frequency-modulated, continuous wave radar signals when the sensed vehicle speed is zero and (B) transmit two-frequency Doppler radar signals when at least the sensed vehicle speed is greater than zero.

2. A vehicle near obstacle detection system, the system comprising:

a radio frequency head capable of transmitting and receiving both frequency-modulated, continuous wave radar signals and two-frequency Doppler radar signals;

signal processing means responsive to received radar signals reflected from an object for determining the range to the object; and

means for controlling the radio frequency head to (A) transmit frequency-modulated, continuous wave radar signals when the determined range is greater than a predetermined distance and (B) transmit two-frequency Doppler radar signals when the range is less than the predetermined distance.

3. A vehicle near obstacle detection system, the system comprising:

a radio frequency head capable of transmitting and receiving both frequency-modulated, continuous wave radar signals and two-frequency Doppler radar signals;

signal processing means responsive to received a radar signals reflected from at least one object for determining the range to a nearest object when two-frequency Doppler radar signals are transmitted and for determining the ranges to multiple objects when frequency-modulated, continuous wave radar signals are transmitted;

means for sensing vehicle speed; and

means for controlling the radio frequency head to (A) transmit frequency-modulated, continuous wave radar signals in response to predetermined conditions including (b

     1) the sensed vehicle speed is zero, (2) the determined range to the nearest object is greater than a predetermined distance and (3) radar signals are reflected from multiple objects while the radio frequency head is controlled to transmit frequency-modulated, continuous wave radar signals and (B) transmit two-frequency Doppler radar signals otherwise.

4. A method of detecting obstacles in proximity to a vehicle having a radio frequency head capable of transmitting and receiving both frequency-modulated, continuous wave radar signals and two-frequency Doppler radar signals, the method comprising the steps of:

determining the range to an object from received radar signals reflected from the object;

sensing vehicle speed; and

controlling the radio frequency head to (A) transmit frequency-modulated, continuous wave radar signals when the sensed vehicle speed is zero and (B) transmit two-frequency Doppler radar signals when at least the sensed vehicle speed is greater than zero.

5. A method of detecting obstacles in proximity to a vehicle having a radio frequency head capable of transmitting and receiving both frequency-modulated, continuous wave radar signals and two-frequency Doppler radar signals, the method comprising the steps of:

determining the range to an object from received radar signals reflected from the object; and

controlling the radio frequency head to (A) transmit frequency-modulated, continuous wave radar signals when the determined range is greater than a predetermined distance and (B) transmit two-frequency Doppler radar signals when the range is less than the predetermined distance.

6. A method of detecting obstacles in proximity to a vehicle having a radio frequency head capable of transmitting and receiving both frequency-modulated, continuous wave radar signals and two-frequency Doppler radar signals, the method comprising the steps of:

determining the range to a nearest object from received radar signals reflected from the nearest object when two-frequency Doppler radar signals are transmitted;

determining the ranges to each object from received radar signals reflected from at least one object when frequency-modulated, continuous wave radar signals are transmitted;

sensing vehicle speed; and

controlling the radio frequency head to (A) transmit frequency-modulated, continuous wave radar signals in response to any one of predetermined conditions including (1) the sensed vehicle speed is zero, (2) the determined range to the nearest object is greater than a predetermined distance and (3) radar signals are received reflected from multiple objects while the radio frequency head is controlled to transmit frequency-modulated, continuous wave radar signals and (B) transmit two-frequency Doppler radar signals otherwise.