TECHNICAL FIELD

The present invention relates to a radar apparatus and a target detection method for detecting a target in the periphery, and more particularly, to a technique of recognizing the type of a specific target.

BACKGROUND ART

Intelligent Transport Systems (ITS) for solving problems related to road traffic using information and communication technology are being developed. In this field, techniques for detecting a surrounding environment (such as a vehicle, a pedestrian, an obstacle in the periphery) of a vehicle by a sensor, and for performing a safety support operation (for example, alert, brake control or the like) for avoiding or reducing a risk on the basis of a detection result have been put to practical use, for example.

As one such sensor, there is known a radar apparatus (a so-called millimeter wave radar) that uses millimeter waves having wavelengths of 1 to 10 mm (frequencies: 30 to 300 GHz). Since a millimeter wave radar uses radio waves, a certain level of sensitivity can advantageously be maintained even in bad weather such as rain or fog. In recent years, a high-resolution millimeter wave radar that uses millimeter waves in a wide band of 79 GHz band (77 to 81 GHz) has been put to practical use.

A frequency modulated-continuous wave (FMCW) method is widely used by vehicle-mounted radar apparatuses. According to the FMCW method, a continuous frequency-modulated wave (millimeter wave) is transmitted, and a reflected wave that is reflected from a target object (hereinafter referred to as “target”) is received. The position (distance and azimuth) or the relative velocity of the target is then detected on the basis of a frequency difference between transmission/reception signals.

Furthermore, information obtained by the radar apparatus can be used to determine a still object, detect an attachment angle of the radar apparatus, detect a movement direction of a target (such as a preceding vehicle) or determine the type of the target (for example, Patent Literatures (hereinafter, abbreviated as PTLs) 1 to 5). PTL 5 discloses identification of a two-wheeler using an image taken by a camera and information obtained by the radar apparatus.

CITATION LIST

Patent Literature

PTL 1

Japanese Patent No. 4992367

PTL 2

Japanese Patent Application Laid-Open No. 2014-153256

PTL 3

Japanese Patent Application Laid-Open No. 2009-211212

PTL 4

Japanese Patent Application Laid-Open No. 2007-139650

PTL 5

Japanese Patent No. 5959581

SUMMARY OF INVENTION

Technical Problem

However, because it is difficult to highly accurately recognize the type of a target only by the radar apparatus, identification of a two-wheeler by a conventional method is premised on use of an image taken by a camera.

An object of the present invention is to provide a radar apparatus and a target detection method by which the type of a specific target (particularly, a two-wheeler) can be highly accurately recognized by the radar apparatus alone.

Solution to Problem

A radar apparatus according to one aspect of the present invention includes:

a transmitting section that transmits a transmission wave that is based on a transmission signal toward a target;

a receiving section that receives a reflected wave generated when the transmission wave is reflected on the target, and generates a reception signal; and

a target detecting section that acquires information about the target on a basis of the transmission signal and the reception signal, in which:

the target detection section calculates relative velocities of a plurality of detected points on a same target, and

the target detection section determines a type of the target on a basis of spread of the relative velocities.

A target detection method according to one aspect of the present invention is a method of detecting a target using a radar apparatus, the target detection method including:

a first step of transmitting a transmission wave that is based on a transmission signal toward a target;

a second step of receiving a reflected wave generated when the transmission wave is reflected on the target, and generating a reception signal; and

a third step of acquiring information about the target on a basis of the transmission signal and the reception signal, in which

in the third step:relative velocities of a plurality of detected points on a same target are calculated, anda type of the target is determined on a basis of spread of the relative velocities.

Advantageous Effects of Invention

According to the present invention, the type of a specific target may be highly accurately recognized by the radar apparatus alone.

