Dual mode system for detecting occupancy of a room

Abstract

A method and system improve on the accuracy of and power consumption of occupancy detection systems. Embodiments may provide a dual mode system that includes a passive infrared sensor with low power consumption and a RADAR-based sensor with higher power consumption that is only powered when the system determines a room is occupied with the passive sensor and no new movement is detected after a threshold duration.

What is claimed is: 
     
         1 . A method for detecting occupancy in a room, comprising:
 operating an infrared sensor to detect a presence of a person in the room, wherein the operation of the infrared sensor draws a first power level from a battery;   receiving, by a processor, a signal from the infrared sensor detecting movement in the room;   determining, by the processor, whether a first threshold duration has passed since a most recent signal from the infrared sensor detecting movement in the room has been received;   triggering, by the processor, operation of a RADAR based sensor based on the first threshold duration having passed since the most recent signal from the infrared sensor detecting movement in the room was received, wherein operation of the RADAR based sensor draws a second power level from the battery that is substantially higher than the first power level;   determining, by the processor, whether the RADAR based sensor detects a presence of one or more persons in the room or an absence of persons in the room;   in response to the RADAR based sensor detecting the presence of one or more persons in the room or the absence of persons in the room, changing operation of the RADAR based sensor into a sleep mode, wherein the sleep mode draws less power than the first power level and substantially less power than the second power level; and   operating the infrared sensor again to detect movement in the room, drawing the first power level from the battery.   
     
     
         2 . The method of  claim 1 , wherein the operation of the RADAR based sensor is for a second threshold duration before the change to the sleep mode. 
     
     
         3 . The method of  claim 1 , wherein operation of the infrared sensor remains active during operation of the RADAR based sensor. 
     
     
         4 . The method of  claim 1 , wherein the operation of the infrared sensor is for more than one minute and the operation of the RADAR based sensor is for one minute or less than one minute. 
     
     
         5 . The method of  claim 1 , further comprising placing the processor into the sleep mode in response to the RADAR based sensor detecting the absence of persons in the room. 
     
     
         6 . The method of  claim 5 , further comprising waking the processor up from the sleep mode in the event the infrared sensor detects movement.