Radar system and direction detecting method

• US 8,390,509 B2
• Filed: 01/26/2011
• Issued: 03/05/2013
• Est. Priority Date: 01/27/2010
• Status: Active Grant

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Asanuma, Hisateru, Sakaguchi, Masahiro, Kawasaki, Tomoya, Iyoda, Motomi
• Primary Examiner(s): Keith, Jack W
• Assistant Examiner(s): BYTHROW, PETER M
• Application Number:
  US13/574,449
• Publication Number:
  US 20120306685A1
• Time in Patent Office: 769 Days
• Field of Search: 342 70- 72, 342/147, 342149-152
• US Class Current: 342/149
• CPC Class Codes: G01S 13/345 using triangular modulation
• CPC Class Codes: G01S 13/931 of land vehicles
• CPC Class Codes: G01S 2013/93271 in the front of the vehicles
• CPC Class Codes: G01S 7/354 Extracting wanted echo-signals Doppler systems G01S13/50

Abstract

A reflected wave that a transmitted wave is reflected by targets including a stationary target and a moving target is received as receiving signals of at least two reception antennas. A phase difference between beat signals at respective peak frequencies, generated from a transmitting signal and the receiving signals, is calculated. Directions of the targets are calculated in such a manner that the calculated phase difference of the targets is stored in a storage area in advance, it is predicted whether peak frequencies of the plurality of targets overlap each other, a predicted phase difference of the stationary target at the time when the peak frequencies overlap each other is calculated on the basis of the stored phase difference, and a predicted phase difference of the moving target is calculated on the basis of the calculated phase difference and the predicted phase difference of the stationary target.

Claims

1. A radar system comprising:

a transmission antenna;

at least two reception antennas;

a transmitting unit that transmits a frequency-modulated transmitting signal as a transmitted wave transmitted via the transmission antenna;

a receiving unit that receives reflected waves that are the transmitted waves reflected by targets including a stationary target and a moving target and that are received via the at least two reception antennas as receiving signals of the respective reception antennas;

a direction calculating unit that calculates a phase difference between beat signals at respective peak frequencies to calculate directions of the targets on the basis of the calculated phase difference, wherein the beat signals are generated from the transmitting signal and the receiving signals of the respective reception antennas;

a storage unit that stores the phase difference, calculated by the direction calculating unit, in a storage area;

a prediction unit that predicts whether peak frequencies of the plurality of targets overlap each other on the basis of predicted information, which includes direction information about the directions of the targets, calculated by the direction calculating unit, and which predicts a variation in the peak frequency of each of the beat signals; and

a predicted phase difference calculating unit that calculates a predicted phase difference of the stationary target at the time when the peak frequencies overlap each other on the basis of the phase difference stored in the storage area, and that calculates a predicted phase difference of the moving target on the basis of the phase difference calculated by the direction calculating unit and the predicted phase difference of the stationary target, wherein

when the prediction unit predicts that the peak frequencies overlap each other, the direction calculating unit calculates the direction of the moving target on the basis of the predicted phase difference of the moving target, calculated by the predicted phase difference calculating unit.

2. The radar system according to claim 1, wherein the predicted phase difference calculating unit calculates the phase difference of the stationary target at the time when the peak frequencies overlap each other as the predicted phase difference of the stationary target on the basis of the phase difference stored in the storage area, and calculates the phase difference of the moving target as the predicted phase difference of the moving target from a difference between the phase difference calculated by the direction calculating unit and the predicted phase difference of the stationary target.

3. The radar system according to claim 1, further comprising:

a determining unit that determines whether a difference between the predicted phase difference of the stationary target, calculated by the predicted phase difference calculating unit, and the phase difference calculated by the direction calculating unit falls within a predetermined range, wherein

when the determining unit determines that the difference between the predicted phase difference of the stationary target and the phase difference calculated by the direction calculating unit does not fall within the predetermined range, the predicted phase difference calculating unit calculates the predicted phase difference of the moving target on the basis of the phase difference calculated by the direction calculating unit and the predicted phase difference of the stationary target.

5. The radar system according to claim 2, further comprising:

a determining unit that determines whether a difference between the predicted phase difference of the stationary target, calculated by the predicted phase difference calculating unit, and the phase difference calculated by the direction calculating unit falls within a predetermined range, wherein

when the determining unit determines that the difference between the predicted phase difference of the stationary target and the phase difference calculated by the direction calculating unit does not fall within the predetermined range, the predicted phase difference calculating unit calculates the predicted phase difference of the moving target on the basis of the phase difference calculated by the direction calculating unit and the predicted phase difference of the stationary target.

4. A target direction calculation method comprising:

transmitting a frequency-modulated transmitting signal as a transmitted wave transmitted via a transmission antenna;

receiving reflected waves that are the transmitted waves reflected by targets including a Stationary target and a moving target and that are received via at least two reception antennas as receiving signals of the respective reception antennas;

calculating a phase difference between beat signals at respective peak frequencies to calculate directions of the targets on the basis of the calculated phase difference, wherein the beat signals are generated from the transmitting signal and the receiving signals of the respective reception antennas;

storing the calculated phase difference in a storage area;

predicting whether peak frequencies of the plurality of targets overlap each other on the basis of predicted information, which includes direction information about the calculated directions of the targets and which predicts a variation in the peak frequency of each of the beat signals; and

calculating a predicted phase difference of the stationary target at the time when the peak frequencies overlap each other on the basis of the phase difference stored in the storage area, and calculating a predicted phase difference of the moving target on the basis of the calculated phase difference and the predicted phase difference of the stationary target, wherein

when it is predicted that the peak frequencies overlap each other, the direction of the moving target is calculated on the basis of the calculated predicted phase difference of the moving target.