OBJECT DETECTION APPARATUS AND OBJECT DETECTION SYSTEM

• US 20160238700A1
• Filed: 09/03/2014
• Published: 08/18/2016
• Est. Priority Date: 09/17/2013
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Matsuura, Mitsuyasu, Akiyama, Keiko
• Granted Patent: US 9,880,273 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B60W 30/08 Active safety systems predicting or avoiding probable or impending collision or attempting to minimise its consequences
• CPC Class Codes: B60W 40/02 related to ambient conditions
• CPC Class Codes: G01S 15/04 Systems determining presence of a target
• CPC Class Codes: G01S 15/876 Combination of several spaced transmitters or receivers of known location for determining the position of a transponder or a reflector G01S15/872 takes precedence
• CPC Class Codes: G01S 15/931 of land vehicles
• CPC Class Codes: G01S 2007/52012 involving a reference ground return
• CPC Class Codes: G01S 2013/932 using own vehicle data, e.g. ground speed, steering wheel direction
• CPC Class Codes: G01S 7/52001 Auxiliary means for detecting or identifying sonar signals or the like, e.g. sonar jamming signals
• CPC Class Codes: G01S 7/52004 Means for monitoring or calibrating short-range imaging G01S7/5205
• CPC Class Codes: G01S 7/5276 using analogue techniques
• CPC Class Codes: G01S 7/539 using analysis of echo signal for target characterisation; Target signature; Target cross-section
• CPC Class Codes: G01V 1/001 Acoustic presence detection
• CPC Class Codes: G01V 3/12 operating with electromagnetic waves operating with millimetre waves G01V8/005

Abstract

An object detection apparatus mounted to a vehicle includes a transmitter, a receiver, a filter, a threshold calculator, and an object determinator. The transmitter transmits a probe wave in pulse form. The receiver receives a reflected wave of the probe wave. The filter passes, among the received reflected wave, only frequencies that are at least smaller than a pulse frequency of the probe wave. Based on an output of the filter, the threshold calculator calculates an objection determination threshold for determining presence and absence of an object. The object determinator determines the presence and absence of the object by using the objection determination threshold calculated by the threshold calculator.

Claims

1. An object detection apparatus mounted to a vehicle, comprising:

a transmitter that transmits a probe wave in pulse form;

a receiver that receives a reflected wave of the probe wave;

a filter that passes, among the received reflected wave, only frequencies that are at least smaller than a pulse frequency of the probe wave;

a threshold calculator that, based on an output of the filter, calculates an objection determination threshold for determining presence and absence of an object; and

an object determinator that determines the presence and absence of the object by using the objection determination threshold calculated by the threshold calculator.

2. The object detection apparatus according to claim 1, wherein

the filter passes only frequencies smaller than or equal to one third of the pulse frequency of the probe wave.

3. The object detection apparatus according to claim 1, wherein

the filter includes:

a down sampling part that performs down sampling in which the frequencies of the reflected wave received by the receiver are decreased to at least smaller than or equal to the pulse frequency of the probe wave; and

a moving average part that performs moving average of successive outputs of the down sampling part.

4. The object detection apparatus according to claim 1, wherein

the threshold calculator calculates the objection determination threshold by adding a predetermined reference value to the output of the filter.

5. The object detection apparatus according to claim 4, wherein

the reference value is a dark noise level of the output of the filter, the dark noise level being a noise level obtained when the probe wave is not transmitted by the transmitter.

6. The object detection apparatus according to claim 4, further comprising:

an operation controller that controls an operation of the filter, wherein

when a speed of the vehicle is larger than or equal to a predetermined speed, the operation controller prohibits the filter from operating and the threshold calculator calculates, as the object determination threshold, the reference value to which the output of the filter is not added.

7. The object detection apparatus according to claim 4, further comprising:

a noise superimposition determinator that, when a difference between the outout of the filter and the reference value is larger than a pre-designated value, determines that a noise larger than or equal to a preset value is superimposed.

8. The object detection apparatus according to claim 1,

wherein the probe wave is ultrasonic wave,

the object detection apparatus further comprising

an operation controller that controls an operation of the filter,

wherein when the transmitter transmits the probe wave, the operation controller causes the filter to operate after elapse of a reverberation time of the transmission of the probe wave.

9. An object detection system comprising:

a plurality of the object detection apparatuses recited in claim 1 and mounted to a single vehicle.

10. The object detection system according to claim 9, further comprising:

a comparator that makes a comparison between the outputs of the filters of the plurality of object detection apparatuses; and

a determinator that

determines a road surface reflection noise when a difference between the outputs, which is obtained from the comparison of the comparator, is within a predetermined range, and

determines a foreign noise other than the road surface reflection noise when the difference between the outputs, which is obtained from the comparison of the comparator, is out of the predetermined range.

11. The object detection system according to claim 10, further comprising:

a notifier that notifies that the object detection apparatus is unusable due to the foreign noise when the foreign noise is determined a plurality of times in row by the determinator, wherein the plurality of times is predetermined.