PRESENCE DETECTION SYSTEM, PRESENCE DETECTION METHOD, AND PROGRAM

• US 20140015706A1
• Filed: 04/04/2011
• Published: 01/16/2014
• Est. Priority Date: 04/04/2011
• Status: Active Grant

• Current Assignee: Mitsubishi Electric Corporation
• Original Assignee: Mitsubishi Electric Corporation
• Inventors: Ishihara, Masahiro, Koizumi, Yoshiaki
• Granted Patent: US 9,383,438 B2
• Time in Patent Office: Days
• US Class Current: 342/27
• CPC Class Codes: G01S 13/003 Bistatic radar systems; Multistatic radar systems
• CPC Class Codes: G01S 13/04 Systems determining presence of a target based on relative movement of target G01S13/56
• CPC Class Codes: G01V 8/20 using multiple transmitters or receivers
• CPC Class Codes: G08B 21/22 responsive to presence or absence of persons

Abstract

A presence detection system is equipped with a transmitter that transmits a multipath wireless signal and a receiver that detects the presence of a person by receiving the transmitted wireless signal, within a prescribed space. On the basis of the reception level for a wireless signal received intermittently at the beginning of a first interval, the receiver determines whether there has been a change in the present/absent state of a person. When it is determined that there has been a change in the present/absent state of a person, the receiver determines whether a person is present/absent on the basis of variation in the reception level for a wireless signal received at the beginning of a second interval, which is shorter than the first interval.

Claims

1. A presence detection system comprising a transmitter that transmits wireless signals and a receiver that receives the transmitted wireless signals;

wherein the receiver comprises;

a first determiner that determines whether or not there has been a change in the reception level of the wireless signals received intermittently at the beginning of a first interval; and

a second determiner that determines the presence/absence of a person on the basis of the reception level of the wireless signals received multiple times at the beginning of a second interval shorter than the first interval, when it is determined by the first determiner that the reception level of the wireless signals has changed.

2. The presence detection system according to claim 1, wherein the transmitter is a transmitter used in a prescribed wireless communication service for transmitting the wireless signals with a constant transmission power, set within a prescribed space.

3. The presence detection system according to claim 1, wherein:

the transmitter;

switches the transmission interval of the wireless signals from the first interval to the second interval upon a request to increase transmission frequency from the receiver; and

the receiver transmits a request to increase the transmission frequency to the transmitter when it is determined by the first determiner that there has been a change in the present/absent state of a person.

4. The presence detection system according to claim 1, wherein the first determiner determines whether or not data relating to the reception level of the wireless signals is contained within a fluctuation range of the reception level when no person is present, and determines whether or not there has been a change in the reception level based on the determined result.

5. The presence detection system according to claim 4, further comprising an adjuster that adjusts the fluctuation range, on the basis of reception levels of wireless signals measured in the past.

6. The presence detection system according to claim 4, wherein the first determiner determines whether or not the average value of the reception levels of wireless signals received multiple times is contained within the fluctuation range and determines whether or not there has been a change in the reception level based on the determined result.

7. The presence detection system according to claim 4, wherein the first determiner compares, of the reception levels of wireless signals received multiple times, the number of instances contained within the fluctuation range with the number of instances not contained within the fluctuation range, and determines whether or not there has been a change in the reception level based on the result of the comparison.

8. The presence detection system according to claim 1, wherein the second determiner compares the standard deviation of the reception levels of the wireless signals received multiple times with a threshold value, and determines the present/absent state of a person based on the result of the comparison.

9. The presence detection system according to claim 8, further comprising an adjuster that adjusts the threshold value on the basis of the reception levels of wireless signals measured in the past.

10. A presence detection method that uses a system comprising a transmitter for transmitting wireless signals and a receiver for of receiving the transmitted wireless signals, this method comprising:

a first determination procedure for determining whether or not there has been a change in the reception level of the wireless signals received intermittently at the beginning of a first interval by the receiver; and

a second determination procedure for determining the presence/absence of a person on the basis of the reception level of the wireless signals received multiple times at the beginning of a second interval shorter than the first interval by the receiver, when it is determined in the first determination procedure that the reception level of the wireless signals has changed.

11. A non-transitory computer-readable recording medium having stored thereof a program for causing a computer that controls a receiver for receiving wireless signals transmitted, to function as:

a first determiner for determining whether or not there has been a change in the reception level of the wireless signals received at the beginning of a first interval by the receiver; and

a second determiner for determining the presence/absence of a person on the basis of in the reception level of the wireless signals received multiple times at the beginning of a second interval shorter than the first interval by the receiver, when it is determined by the first determiner that the reception level of the wireless signals has changed.