System for detecting and determining range of target vehicle

• US 5,227,784 A
• Filed: 12/05/1991
• Issued: 07/13/1993
• Est. Priority Date: 12/10/1990
• Status: Expired due to Term

• Current Assignee: Mazda Motor Corporation
• Original Assignee: Mazda Motor Corporation
• Inventors: Sasaki, Hideyuki, Masamori, Ichiro
• Primary Examiner(s): Crosland, Donnie L.
• Application Number:
  US07/801,580
• Time in Patent Office: 586 Days
• Field of Search: 340/903, 340/901, 340/904, 340/435, 340/436, 340/902, 340/555-557, 180/167, 342/27, 342/44, 342/47, 342/48, 342/53, 342/54, 342/56, 342/61, 342/70, 342/81, 342/96
• US Class Current: 340/903
• CPC Class Codes: G01S 17/14 wherein a voltage or current pulse is initiated and terminated in accordance with the pulse transmission and echo reception respectively, e.g. using counters
• CPC Class Codes: G01S 17/34 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 17/66 Tracking systems using electromagnetic waves other than radio waves
• CPC Class Codes: G01S 17/931 of land vehicles

Abstract

A target detecting and range determining system for an automobile detects a distance between two vehicles travelling in front of and behind each other and includes a range detector using a range determining signal directed toward and reflected by a target vehicle. The system also includes a controller for controlling the range detector so that it receives a proper reflection of the range determining signal when a primary vehicle changes its travelling direction relative to the target vehicle.

Claims

1. A target detecting and range determining system for an automotive vehicle for determining a distance between two vehicles travelling in front of and behind one another, said target detecting and range determining system comprising:

signal transmitting means for transmitting a range determining signal toward a target vehicle travelling ahead of a primary vehicle equipped with the target detecting and range determining system;

signal receiving means for receiving a reflected range determining signal reflected from said target vehicle so as to detect a distance of said primary vehicle from said target vehicle in accordance with at least a time from transmission of said range determining signal to reception of said reflected range determining signal; and

control means for controlling said signal receiving means so that it receives said reflected range determining signal while the vehicle changes its direction of travel relative to said target vehicle, said control means comprising signal identification means for generating an identification signal having a distinct frequency which is different from that of said range determining signal, and changing means for causing said signal transmitting means to modulate the frequency of said range determining signal from one to another when said signal receiving means receives a reflection of said range determining signal containing an identification signal having another frequency, different from said distinct frequency, thereby picking up a range determining signal having the other frequency.

2. A target detecting and range determining system as recited in claim 1, wherein said control means comprises relative direction detecting means for detecting a relative direction of travel between said primary vehicle and said target vehicle to provide a direction signal representative of a change in the relative direction of travel based on a change of the reflected range determining signal, and drive means for turning said signal transmitting means and said signal receiving means together with respect to a direction in which said vehicle is travelling according to said direction signal, thereby continuously tracking said target vehicle.

3. A target detecting and range determining system for an automotive vehicle for determining a distance between two vehicles, said target detecting and range determining system comprising:

range determining means for transmitting and directing a range determining signal, at different ranging frequencies, toward a target vehicle and receiving, as a distance signal, a reflected range determining signal from the target vehicle to detect a distance between a primary vehicle, equipped with the target detecting and range determining system, and the target vehicle in accordance with a time from transmission of said range determining signal to reception of said reflected range determining signal and a phase difference between said range determining signal and said reflected range determining signal;

identification means for generating a target identification signal, having a target identification frequency which is different from a frequency of said range determining signal and superimposed on said range determining signal prior to transmission, and detecting identification signals, different in frequency from said target identification signal, from said reflected range determining signal to provide a control signal; and

control means for varying said range determining signal from one ranging frequency to another ranging frequency when said control signal is present so as to find a distance between said primary vehicle and said target vehicle based on the reflected range determining signal having the other ranging frequency.

4. A target detecting and range determining system as recited in claim 3, wherein said range determining means comprises filtering means for permitting reflected range determining signals having the one ranging frequency only as a distance signal to filter therethrough when said control signal is not provided and reflected range determining signals having the other ranging frequency only as a distance signal to filter therethrough when said control signal is provided.

5. A target detecting and range determining system as recited in claim 3, wherein said range determining means comprises an oscillator for frequency modulating said range determining signal when said control signal is present.