Systems and methods for detection of occupancy using radio waves

Patent metadata

Field	Value
Publication number	US-10620307-B2
Application number	US-201615343843-A
Country	US
Kind code	B2
Filing date	Nov 4, 2016
Priority date	Nov 4, 2015
Publication date	Apr 14, 2020
Grant date	Apr 14, 2020

Abstract

Systems and methods are disclosed for detecting a presence of a person in an area of coverage using radar. A transmitter can transmit radio signals in a first direction in an area of coverage defined by a wall and a floor. A receiver can receive the transmitted radio signals reflected back from the area of coverage. A signal conditioning circuit can process the received radio signals. One or more hardware processors can be programmed to analyze the processed radio signals and detect a presence of a person in the area of coverage based on the analysis. The analysis of the processed signals can be performed in both time and frequency domain. In addition to radar, an input from an infrared sensor can also be used in conjunction with radar based detection.

First claim

What is claimed is:

1. A sensor configured to detect a presence of a person in an area of coverage using wireless network compatible radio signals and control a building element, said sensor secured to a wall or ceiling, the sensor comprising:
a mounting board configured to secure a transmitter, said transmitter configured to transmit wireless network compatible radio signals in the area of coverage, said mounting board positioned at an angle with respect to the wall, wherein the angle is greater than 0, thereby tilting the transmitter and the transmission of the radio signals away from an axis that is normal to a surface of the wall or ceiling;
a receiver configured to receive the transmitted radio signals that are reflected back from the area of coverage, demodulate the reflected radio signals, and output a baseband signal that includes a Doppler shift from the radio signal;
a signal conditioning circuit including an analog filter configured to remove noise in the baseband signal;
a digitizing circuit configured to digitize the analog filtered baseband signal; and
one or more hardware processors configured to:
filter the digitized baseband signal to remove frequency components in the baseband signal that are not in a frequency of interest, said frequency of interest including a range of frequencies corresponding to heartbeat or respiration of humans and their harmonics;
determine, in time domain, a moving average of an amplitude in the filtered signal over a time window;
compare the moving average to a first threshold;
detect a presence of a person in the area of coverage based on the comparison;
control the building element based on the detection of the presence of the person, wherein the building element comprises a lighting system or a HVAC system.

2. The sensor of claim 1 , wherein the one or more hardware processors are further configured to:
extract a first rate of a physiological parameter from a first frequency range of a frequency transform of the digitally filtered signal;
wherein the control of the building element is further based on the extracted first rate of the physiological parameter.

3. The sensor of claim 2 , wherein the one or more hardware processors are further configured to:
determine a ratio in a time period that the moving average is greater than the first threshold; and
wherein the control of the building element is further based on the determined ratio.

4. The sensor of claim 2 , wherein the one or more hardware processors are further configured to:
extract a second rate of a physiological parameter from a second frequency range of the frequency transform of the digitally filtered signal, the second frequency range corresponding to a harmonic of the first frequency range;
wherein the control of the building element is further based on the extracted second rate.

5. The sensor of claim 1 , wherein the one or more hardware processors are further configured to:
receive an indication from an infrared sensor; and
control the transmitter based on the received indication from the infrared sensor.

6. The sensor of claim 1 , wherein the angle is substantially 45 degrees.

7. The sensor of claim 1 , further comprising an antenna.

8. The sensor of claim 7 , wherein the antenna is shared by the transmitter and the receiver.

9. The sensor of claim 7 , wherein the mounting board is secured to a sensor chassis.

10. The sensor of claim 1 , wherein the transmission is not in a plane parallel to the floor.

11. The sensor of claim 1 , wherein the transmission is not substantially perpendicular to a surface parallel to the wall or ceiling.

12. The sensor of claim 1 , further comprising an infrared sensor configured to detect motion.

13. A method for detecting a presence of a person in an area of coverage using wireless network radio signals and controlling a building element, said sensor secured to a wall or ceiling, the method comprising:
transmitting a wireless network radio signals in an area of coverage, wherein the transmission of the radio signals is fixed at an angle away from an axis that is normal to a surface of the wall or ceiling;
receiving the transmitted radio signals that are reflected back from the area of coverage;
demodulating the reflected radio signals;
outputting a baseband signal that includes a Doppler shift from the radio signal;
filtering noise from the baseband signal;
digitizing the filtered baseband signal;
filtering the digitized baseband signal to remove frequency components in the baseband signal that are not in the frequency of interest, said frequency of interest including a range of frequencies corresponding to heartbeat or respiration of humans and their harmonics;
extracting a time domain feature from the filtered digitized signal;
extracting frequency domain features from the filtered digitized signal, said frequency domain features comprise a first peak in a first frequency range corresponding to a physiological rate and a second peak in a second frequency range corresponding to a harmonic of the physiological rate;
detecting a presence of a person in an area of coverage based on the extracted time domain feature and the frequency domain features; and
controlling the building element based on the detection of the presence of the person, wherein the building element comprises a lighting system or a HVAC system.

14. The method of claim 13 , wherein the time domain feature comprises an average measurement of an amplitude of the signal.

15. The sensor of claim 1 , wherein the wireless network compatible radio signals comprise a wireless personal area network or a wireless local area network generated from a system on a chip.

16. The sensor of claim 4 , wherein the one or more hardware processors are further configured to determine a ratio of a first power in the first frequency range to a second power in the second frequency range, and wherein the control of the building element is further based on the determined ratio.

17. The method of claim 13 , wherein the wireless network compatible radio signals comprise a wireless personal area network or a wireless local area network generated from a system on a chip.

Assignees

• Univ Hawaii

Inventors

• Yavari Ehsan
• Gao Xiaomeng
• Boric-Lubecke Olga
• Song Chenyan
• Nuti Pooja
• Yamada Shuhei

Classifications

• G01S13/86

  Combinations of radar systems with non-radar systems, e.g. sonar, direction finder · CPC title

• G01S13/56 Primary

  for presence detection {(presence detection using near field arrangements G01V3/00, e.g. G01V3/08, G01V3/12; burglar, theft or intruder alarms with electrical actuation G08B13/22 - G08B13/26)} · CPC title