FM-CW Radar system for use in an automotive vehicle

• US 4,348,675 A
• Filed: 07/22/1980
• Issued: 09/07/1982
• Est. Priority Date: 07/24/1979
• Status: Expired due to Term

• Current Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Original Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Inventors: Senzaki, Takaya, Murao, Eiji
• Primary Examiner(s): Tubbesing, T. H.
• Application Number:
  US06/171,149
• Time in Patent Office: 777 Days
• Field of Search: 343/7 VM, 343/14
• US Class Current: 342/71
• CPC Class Codes: G01S 13/345 using triangular modulation
• CPC Class Codes: G01S 13/931 of land vehicles
• CPC Class Codes: G01S 2013/93185 Controlling the brakes
• 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 2013/93271 in the front of the vehicles

Abstract

An FM-CW type radar system, for use in an automotive vehicle, which is specifically designed with a signal processor of relatively simple construction having an improved capability of identifying an object, particularly a plurality of objects, to be identified in suurrounding traffic or road areas. The system is particularly effective in overcoming possible error in detection of the object(s) due to reflected or scattering waves from the road surface or the like as experienced in the general radar navigation system for detecting the approaching or interfering object(s) by the provision of incessant radar monitoring along with the path of travel of the vehicle equipped with the radar system so as to eventually maintain a safe relative distance and/or velocity of that vehicle with respect to the object(s) in the surrounding traffic or road areas.

Claims

1. An FM-CW type radar system for use in an automotive vehicle for emitting a radio wave beam having the oscillating frequency thereof modulated at a given frequency, receiving reflected-to-return waves from an object or objects to be detected and determining a distance to the object by way of beat frequency signals produced from the emitting and receiving waves, which comprises:

means for dividing said beat frequency signals into a plurality of equal fractional frequency bands and detecting the thus-divided beat frequency signals;

signal processing means for operating arithmetically in a predetermined manner to provide an appropriate safe vehicle interval on each signal component of said divided frequency signals, whereby a warning or a command for actuating the brake of said vehicle is produced in accordance with said appropriate or safe vehicle interval distance;

signal extraction circuit means for selectively passing a beat frequency having a given frequency band width channel-by-channel in the beat frequency signal system thereof; and

channel selection circuit means for setting the frequency signal of each said channel at an appropriate reference level as a threshold value and offsetting each of said frequency signals set at said reference level, and thereafter optionally selecting the channel corresponding to the object to be detected in accordance with the output level of each said channel.

2. An FM-CW type radar system for use in an automotive vehicle for emitting a radio wave beam having the oscillating frequency thereof modulated at a given frequency, receiving reflected-to-return waves from an object or objects to be detected and determining a distance to the object by way of beat frequency signals produced from the emitting and receiving waves, which comprises:

means for dividing said beat frequency signals into a plurality of equal fractional frequency bands and detecting the thus-divided beat frequency signals;

signal processing means for operating arithmetically in a predetermined manner to provide an appropriate safe vehicle interval on each signal component of said divided frequency signals, whereby a warning or a command for actuating the brake of said vehicle is produced in accordance with said appropriate or safe vehicle interval distance;

multifilter means for passing said beat frequency signals through a plurality of filters having an equal frequency band and detecting said filter output signals having said equal frequency band so as to be applied as outputs therefrom;

multiplexer means for sequentially selecting the detection outputs from said multifilter means so as to be applied as outputs therefrom;

analog-digital converter means for converting said detection outputs selected by said multiplexer means to digital signals; and

arithmetic operating means for receiving said digital signals from said analog-digital converter means, selecting said filter outputs through filter gate means so as to be applied as inputs thereto and arithmetically operating to produce a warning or a command for actuating the brake of the vehicle.

3. An FM-CW type radar system according to claim 2 wherein:

said multifilter means comprises a plurality of constituent filters corresponding to said given frequency bands, a plurality of detector means for respectively detecting the outputs from said constituent filters, averaging arithmetic means for obtaining an average value of said detector outputs, and a plurality of arithmetic means for obtaining a difference between each of said detector outputs and said average value so as to be applied as outputs therefrom.