Occupant counting device

Abstract

The invention relates to an occupant counting device. A sensor may be configured to determine the number of people who have entered or exited a space. The sensor may include a pyroelectric infrared (PIR) detection circuit capable of generating different output signal patterns in response to a person entering or exiting the space. The sensor may determine whether a person has entered or exited the space based on the output signal pattern. The sensor may include a thermopile array, a radar detection circuit, or a visible light sensing circuit. The thermopile array, radar detection circuit, or visible light sensing circuit can detect the location and / or movement of a person within an area monitored by the sensor and determine whether the person has entered or exited the space based on the detected movement. An occupant count of the space may then be determined by the sensor or by a system controller accordingly.

Description

[0001] This application is a divisional application of the patent application for invention titled "Occupant Counting Device" with the application date of August 23, 2019, application number 201980065749.5.

[0002] Cross - reference to related applications

[0003] This application claims the benefit of U.S. Provisional Patent Application No. 62 / 722,555, filed on August 24, 2018, and U.S. Provisional Patent Application No. 62 / 783,525, filed on December 21, 2018. The disclosures of the above - mentioned applications are hereby incorporated by reference in their entirety. Background Art

[0004] To manage a user environment such as a residential or office building, it may be desirable to have the ability to estimate the number of people occupying the user environment at a given time. Knowing the number of people in the environment can improve occupant - driven control measures such as energy control, air quality control, room allocation, and / or scheduling. Existing occupant counting methods and devices have poor accuracy and / or high cost, and often result in privacy issues. Summary of the Invention

[0005] A sensor device for determining a count of occupants (e.g., occupant count) in a space is described herein. The sensor device is mounted near the space to detect movement (e.g., movement of an occupant) adjacent to the device. For example, the sensor device can be mounted in a doorway and / or entrance of the space to detect occupants entering and / or exiting the space.

[0006] A control circuit can maintain the occupant count of the space by incrementing the count when it is determined that a person has entered the space and decrementing the count when it is determined that a person has exited the space. The sensor device can also include a communication circuit that can be used to send a signal (e.g., a digital message) indicating the occupant count. The signal can be sent to a system controller or another device having similar occupant - counting capabilities. The sensor device can reset the occupant count to zero after sending the signal, for example, to prevent the propagation of any mis - counts. The system controller can be configured to receive occupant count data (e.g., entry / exit count data) from the sensor device and maintain the occupant count of the space. For example, the system controller can be configured to receive occupant count data from multiple sensor devices and maintain the total occupant count of the space.

[0007] The system controller can also be configured to obtain information about the occupancy status of a space from an occupancy sensor. The system controller can compare the occupant count reported by the sensor device with the occupancy status indicated by the occupancy sensor and resolve any mismatch between the two pieces of information. For example, if the occupant count reported by the sensor device is greater than zero, but the occupancy sensor indicates that the space is unoccupied, the system controller can reset the occupant count to zero.

[0008] The sensor device can include a detection circuit (such as a pyroelectric infrared (PIR) detection circuit) and a control circuit. The PIR detection circuit can include a plurality of PIR elements connected in an anti-series configuration. The PIR elements can respond to the movement of a person in the detection area, and the PIR detection circuit can generate an output signal having different patterns corresponding to different movement directions. The control circuit can collect a plurality of samples from the output of the PIR detection circuit in response to the detected movement of the person. From the plurality of samples, the control circuit can identify a first sample and a second sample having opposite polarities and amplitudes above a certain threshold. Based on the pattern exhibited by the plurality of samples, such as the order in which the first sample signal and the second sample signal are generated, the control circuit can determine whether the person has entered the space or has exited the space.

[0009] The sensor device can include a thermopile array (e.g., a plurality of thermosensitive elements arranged in an N×N array). The thermosensitive elements can respond to thermal energy in a two-dimensional area and can generate a signal representing a thermal map or a two-dimensional (2D) thermal image of the area. The control circuit can receive the signal from the thermopile array, determine the position of the energy-emitting object in the 2D area by processing the signal, and further determine the movement of the energy-emitting object through multiple zones of the area. Based on these movements, the control circuit can determine whether the energy-emitting object has entered the space or has left the area. The sensor device can include a radar sensing circuit, a visible light sensing circuit, and / or a time-of-flight sensing circuit (e.g., instead of or in addition to the thermopile array). The radar sensing circuit, the visible light sensing circuit, and / or the time-of-flight sensing circuit can function in a manner similar to the thermopile array at least in terms of having the ability to determine the position and / or movement of an object in the area monitored by the radar sensing circuit, the visible light sensing circuit, or the time-of-flight sensing circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 is a schematic diagram of an exemplary load control system including one or more occupant counting devices and an occupancy sensor.

[0011] Figure 2 is a perspective view of an exemplary occupant counting sensor as described herein.

[0012] Figure 3Ais a block diagram of an exemplary occupant counting sensor as described herein.

[0013] Figure 3B Shows an exemplary waveform of the output signal of an exemplary occupant counting sensor when a person enters and exits a space monitored by the occupant counting sensor.

[0014] Figure 4 is a flowchart of an exemplary occupant counting program.

[0015] Figure 5 is an example diagram showing an occupant counting sensor configured to detect an occupant in a space based on the movement of the occupant in a two-dimensional area.

[0016] Figure 6 is as Figure 5 described in the block diagram of an exemplary occupant counting sensor.

[0017] Figure 7A is an exemplary state diagram for determining the movement of an occupant when the occupant enters the space.

[0018] Figure 7B is an exemplary state diagram for determining the movement of an occupant when the occupant leaves the space.

[0019] Figure 8 is a communication sequence diagram depicting an exemplary message flow in a system including two occupant counting sensors and a system controller.

[0020] Figure 9 is a flowchart of an example program for resetting the occupant counting sensor.

[0021] Figure 10 is a flowchart of an exemplary occupant counting receiving program.

[0022] Figure 11 is an exemplary block diagram of a system controller configured to receive occupant counting information sent by an occupant counting sensor. Detailed Description

[0023] Figure 1FIG. 0 is a schematic diagram of an exemplary load control system 100 for controlling the amount of electrical power delivered from an alternating current (AC) power source (not shown) to one or more electrical loads. The load control system 100 may be installed in a room 102 of a building. The load control system 100 may include a plurality of control devices configured to communicate with each other via wireless signals (e.g., radio frequency (RF) signals 108). Alternatively or additionally, the load control system 100 may include a wired digital communication link coupled to one or more of the control devices to provide communication between the load control devices. The control devices of the load control system 100 may include a plurality of control source devices (e.g., input devices operable to send digital messages in response to user input, occupancy / vacancy status, changes in measured light intensity, etc.) and a plurality of control target devices (e.g., load control devices operable to receive digital messages and control corresponding electrical loads in response to the received digital messages). A single control device of the load control system 100 may operate as both a control source device and a control target device.

[0024] The control source devices may be configured to send digital messages directly to the control target devices. Additionally, the load control system 100 may include a system controller 110 (e.g., a central processor or a load controller) operable to communicate digital messages to and from the control devices (e.g., control source devices and / or control target devices). For example, the system controller 110 may be configured to receive digital messages from the control source devices and, in response to the digital messages received from the control source devices, send digital messages to the control target devices. The control source devices, the control target devices, and the system controller 110 may be configured to use a proprietary RF protocol (such as, protocol) to send and receive the RF signals 108. Other RF protocols may also be used to send the RF signals 108, such as standard protocols (e.g., one of WIFI, ZIGBEE, Z-WAVE, KNX-RF, ENOCEAN RADIO protocols), or different proprietary protocols.

[0025] The load control system 100 can include one or more load control devices, such as a dimmer switch 120 for controlling a lighting load 122. The dimmer switch 120 can be adapted to be wall-mounted in a standard electrical wall box. The dimmer switch 120 can include a tabletop or plug-in load control device. The dimmer switch 120 can include a toggle actuator (e.g., a button) and an intensity adjustment actuator (e.g., a rocker switch). Actuation of the toggle actuator (e.g., continuous actuation) can toggle (e.g., turn off and on) the lighting load 122. Actuation of the upper or lower part of the intensity adjustment actuator can correspondingly increase or decrease the amount of electrical power delivered to the lighting load 122, and thus increase or decrease the intensity of the receptive lighting load within a range from a minimum intensity (e.g., about 1%) to a maximum intensity (e.g., about 100%). The dimmer switch 120 can include a plurality of visual indicators (e.g., light-emitting diodes (LEDs)), which can be arranged in a linear array and lit to provide feedback on the intensity of the lighting load 122. Examples of wall-mounted dimmer switches are described in more detail in U.S. Patent No. 5,248,919, titled "LIGHTING CONTROL DEVICE," issued on September 28, 1993, and U.S. Patent No. 9,676,696, titled "WIRELESS LOAD CONTROL DEVICE," issued on June 13, 2017. The entire disclosures of the above patents are incorporated herein by reference.

[0026] The dimmer switch 120 can be configured to wirelessly receive digital messages (e.g., from the system controller 110) via an RF signal 108 and control the lighting load 122 in response to the received digital messages. Examples of dimmer switches operable to send and receive digital messages are described in more detail in co-owned U.S. Patent Application Publication No. 2009 / 0206983, titled "COMMUNICATION PROTOCOL FOR A RADIO-FREQUENCY LOAD CONTROL SYSTEM," published on August 20, 2009. The entire disclosure of the above U.S. patent application publication is incorporated herein by reference.

[0027] The load control system 100 may include one or more remotely located load control devices, such as a light-emitting diode (LED) driver 130 for driving an LED light source 132 (e.g., an LED light engine). For example, the LED driver 130 may be remotely located within or adjacent to a luminaire of the LED light source 132. The LED driver 130 may be configured to receive a digital message via an RF signal 108 (e.g., from the system controller 110) and control the LED light source 132 in response to the received digital message. The LED driver 130 may be configured to adjust the color temperature of the LED light source 132 in response to the received digital message. Examples of LED drivers configured to control the color temperature of an LED light source are described in more detail in commonly assigned U.S. Patent No. 9,538,603, titled "SYSTEMS AND METHODS FOR CONTROLLING COLOR TEMPERATURE," issued on January 3, 2017, the entire disclosure of which is incorporated herein by reference. The load control system 100 may also include other types of remotely located load control devices, such as an electronic dimming ballast for driving a fluorescent lamp.

[0028] A load control system 100 may include one or more daylight control devices, such as motorized window treatments 150 (such as motorized cellular shades), for controlling the amount of daylight entering a room 102. Each motorized window treatment 150 may include a window treatment fabric 152 suspended from a top rail 154 in front of a corresponding window 104. Each motorized window treatment 150 may also include a motor drive unit (not shown) located inside the top rail 154 for raising and lowering the window treatment fabric 152 to control the amount of daylight entering the room 102. The motor drive unit of the motorized window treatment 150 may be configured to receive digital messages via an RF signal 108 (e.g., from a system controller 110) and adjust the position of the corresponding window treatment fabric 152 in response to the received digital messages. The load control system 100 may include other types of daylight control devices, such as, cellular shades, curtains, roman shades, venetian blinds, persian blinds, pleated blinds, tension roller shade systems, electrochromic or smart windows, and / or other suitable daylight control devices. Examples of battery-powered motorized window treatments are described in more detail in U.S. Patent No. 8,950,461, titled "Motorized Window Treatment," issued on February 10, 2015, and U.S. Patent No. 9,488,000, titled "Integrated Accessible Battery Compartment for Motorized Window Treatment," issued on November 8, 2016, the entire disclosures of which are incorporated herein by reference.

[0029] The load control system 100 may include one or more temperature control devices, e.g., a thermostat 160 for controlling the room temperature in room 102. The thermostat 160 may be coupled to a heating, ventilation, and air conditioning (HVAC) system 162 via a control link (e.g., an analog control link or a wired digital communication link). The thermostat 160 may be configured to wirelessly communicate digital messages with a controller of the HVAC system 162. The thermostat 160 may include a temperature sensor for measuring the room temperature in room 102 and may control the HVAC system 162 to adjust the temperature in the room to a set point temperature. The load control system 100 may include one or more wireless temperature sensors (not shown) located in room 102 for measuring the room temperature. The HVAC system 162 may be configured to turn on and off a compressor for cooling room 102 and turn on and off a heat source for heating the room in response to control signals received from the thermostat 160. The HVAC system 162 may be configured to turn on and off a fan of the HVAC system in response to control signals received from the thermostat 160. The thermostat 160 and / or the HVAC system 162 may be configured to control one or more controllable dampers to control the air flow in room 102. The thermostat 160 may be configured to receive digital messages via an RF signal 108 (e.g., from a system controller 110) and adjust heating, ventilation, and cooling in response to the received digital messages.

[0030] The load control system 100 may include one or more other types of load control devices, such as: a screw-in lamp fixture including a dimmer circuit and an incandescent or halogen lamp; a screw-in lamp fixture including a ballast and a compact fluorescent lamp; a screw-in lamp fixture including an LED driver and an LED light source; an electronic switch, a controllable circuit breaker, or other switching devices for turning on and off an electrical appliance; a plug-in load control device, a controllable electrical outlet, or a controllable power strip for controlling one or more plug-in loads; a motor control unit for controlling a motor load such as a ceiling fan or an exhaust fan; a drive unit for controlling an electric window covering or a projection screen; electric interior or exterior blinds; a thermostat for a heating and / or cooling system; a temperature control device for controlling the set temperature of an HVAC system; an air conditioner; a compressor; an electric baseboard heater controller; a controllable damper; a variable air volume controller; a fresh air intake controller; a ventilation controller; a hydraulic valve for a radiator and a radiant heating system; a humidity control unit; a humidifier; a dehumidifier; a water heater; a boiler controller; a pool pump; a refrigerator; a freezer; a television or a computer monitor; a camera; an audio system or an amplifier; an elevator; a power supply; a generator; a charger such as an electric vehicle charger; and an alternative energy controller.

[0031] The load control system 100 may include one or more input devices, such as, for example, a remote control device 170, an occupancy sensor 180, or an occupant counting device (e.g., an occupant counting sensor 190). The input device may be a fixed or a movable input device. The system controller 110 may be configured to send one or more digital messages to load control devices (such as, for example, a dimmer switch 120, an LED driver 130, motorized window treatments 150, and / or a thermostat 160) in response to digital messages received from the remote control device 170, the occupancy sensor 180, and / or the occupant counting sensor 190. The remote control device 170, the occupancy sensor 180, and / or the occupant counting sensor 190 may be configured to send digital messages directly to the system controller 110, the dimmer switch 120, the LED driver 130, the motorized window treatments 150, and / or the thermostat 160.

[0032] The remote control device 170 may be configured to send a digital message to the system controller 110 (e.g., directly to the system controller) via an RF signal 108 in response to actuation of one or more buttons of the remote control device. For example, the remote control device 170 may be battery powered.

[0033] The occupancy sensor 180 may be configured to detect occupancy and vacancy conditions in a room 102. The occupancy sensor 180 may be an infrared sensor (e.g., a passive infrared sensor). The occupancy sensor 180 may be removably mounted to a ceiling or a wall. Although Figure 1 only one occupancy sensor is shown, those skilled in the art will recognize that the load control system 100 may include more than one spaced-apart occupancy sensor for detecting occupancy conditions in different areas of the room 102. The occupancy sensor 180 may include an internal detector, such as a pyroelectric infrared (PIR) detector, an ultrasonic detector, a microwave detector, or any combination thereof. For example, the internal PIR detector may be housed in a housing that includes a lens (e.g., an outwardly domed lens) disposed in a front surface of the housing. The internal PIR detector is operable to receive energy (e.g., infrared energy) emitted from an occupant in the space via the lens, thereby sensing the occupancy condition in the space. The occupancy sensor 180 is operable to process the output of the PIR detector to determine, for example, whether an occupancy condition or a vacancy condition is currently present in the room 102 by comparing the output of the internal detector to a predetermined occupancy voltage threshold.

[0034] The occupancy sensor 180 can send a digital message to the system controller 110 via an RF signal 108 (e.g., using the proprietary protocol described herein) in response to detecting an occupied or unoccupied condition. The system controller 110 can be configured to send commands to the corresponding load control devices to turn on or off the corresponding lighting loads (e.g., lighting load 122 and / or LED light source 132) in response to receiving an occupancy command or a vacancy command, respectively. The system controller 110 can be configured to adjust the occupant count submitted by the occupant count sensor 190 based on the occupied or unoccupied condition detected by the occupancy sensor 180 (e.g., correct its accuracy) (e.g., as will be described in more detail below). Examples of RF load control systems with occupancy and vacancy sensors are described in more detail in the following patents: U.S. Patent No. 8,009,042, co-assigned, titled "RADIO-FREQUENCY LIGHTING CONTROL SYSTEM WITH OCCUPANCY SENSING," issued September 3, 2008; U.S. Patent No. 8,199,010, titled "METHOD AND APPARATUS FOR CONFIGURING A WIRELESS SENSOR," issued June 12, 2012; and U.S. Patent No. 8,228,184, titled "BATTERY-POWERED OCCUPANCY SENSOR," issued July 24, 2012, the entire disclosures of which are incorporated herein by reference.

[0035] The occupancy sensor 180 can additionally or alternatively include visible light sensing circuitry, such as a camera and / or image processing circuitry. The camera can be pointed into the room 102 and can be configured to record an image of the room 102. The occupancy sensor 180 can be configured to detect an occupied condition and an unoccupied condition using the recorded image of the image. Examples of sensors including visible light sensing circuitry are described in more detail in U.S. Patent Application Publication No. 2017 / 0171941, co-assigned, published June 15, 2017, and U.S. Patent Application Publication No. 2018 / 0168019, published June 14, 2018, both titled "LOAD CONTROL SYSTEM HAVING A VISIBLE LIGHT SENSOR," the entire disclosures of which are incorporated herein by reference.

[0036] The load control system 100 may include other types of input devices, such as temperature sensors, humidity sensors, radiometers, overcast sensors, shadow sensors, pressure sensors, smoke detectors, carbon monoxide detectors, carbon dioxide detectors, air quality sensors, motion sensors, security sensors, proximity sensors, fixture sensors, zoning sensors, keypads, multi-zone control units, slider control units, kinetic or solar remote control devices, key fobs, cell phones, smart phones, tablet computers, personal digital assistants, personal computers, laptop computers, clocks, audio-visual control devices, security devices, power monitoring devices (e.g., power meters, energy meters, utility sub-meters, utility rate meters, etc.), central control transmitters, residential, commercial or industrial controllers, and / or any combination thereof.

[0037] The system controller 110 may be coupled to a network, such as a wireless or wired local area network (LAN), for example, for accessing the Internet. The system controller 110 may be wirelessly connected to the network, for example, using Wi-Fi technology. The system controller 110 may be coupled to the network via a network communication bus (e.g., an Ethernet communication link). The system controller 110 may be configured to communicate with one or more network devices (e.g., the mobile device 140, such as a personal computing device and / or a wearable wireless device) via the network. The mobile device 140 may be located on the occupant 142 (e.g., may be attached to the occupant's body or clothing or may be held by the occupant). The mobile device 140 may be characterized by a unique identifier that uniquely identifies the mobile device 140 and thus the occupant 142 (e.g., a serial number or address stored in a memory). Examples of personal computing devices may include smart phones (e.g., smart phones, smart phones or smart phones), laptop computers, and / or tablet devices (e.g., handheld computing devices). Examples of wearable wireless devices may include activity tracking devices (such as devices, devices, and / or Sony devices), smart watches, smart clothing (e.g., smart wearables, etc.), and / or smart glasses (such as Google glasses). Additionally, the system controller 110 may be configured to communicate with one or more other control systems (e.g., building management systems, security systems, etc.) via the network.

[0038] The mobile device 140 can be configured to send digital messages to the system controller 110, for example, in one or more Internet protocol packets. For example, the mobile device 140 can be configured to send digital messages to the system controller 110 via a LAN and / or via the Internet. The mobile device 140 can be configured to send digital messages to an external service (e.g., If ThisThen That service), and the digital messages can then be received by the system controller 110. The mobile device 140 can send and receive RF signals 109 via a Wi-Fi communication link, a Wi-MAX communication link, a Bluetooth communication link, a near field communication (NFC) link, a cellular communication link, a television white space (TVWS) communication link, or any combination thereof. Alternatively or additionally, the mobile device 190 can be configured to send RF signals according to a proprietary protocol. The load control system 100 can include other types of network devices coupled to the network, such as a desktop personal computer, a Wi-Fi- or wireless communication-enabled television, or any other suitable Internet protocol-enabled device. Examples of load control systems operable to communicate with mobile and / or network devices on a network are described in more detail in co-owned U.S. Patent Application Publication No. 2013 / 0030589, titled "LOAD CONTROL DEVICE HAVING INTERNET CONNECTIVITY," published on January 31, 2013, the entire disclosure of which is incorporated herein by reference.

[0039] The system controller 110 can be configured to determine the location of the mobile device 140 and / or the occupant 142. The system controller 110 can be configured to control (e.g., automatically control) load control devices (e.g., the dimmer switch 120, the LED driver 130, the motorized window covering 150, and / or the temperature control device 160) in response to determining the location of the mobile device 140 and / or the occupant 142. One or more of the control devices of the load control system 100 can send beacon signals, e.g., RF beacon signals sent using short-range and / or low-power RF technologies such as Bluetooth technology. The load control system 100 can also include at least one beacon transmitting device 144 for sending beacon signals. The mobile device 140 can be configured to receive beacon signals when located near a control device that is currently sending a beacon signal. The beacon signal can include a unique identifier that identifies the location of the load control device that sent the beacon signal. Since short-range and / or low-power technologies can be used to send the beacon signal, the unique identifier can indicate the approximate location of the mobile device 140. The mobile device 140 can be configured to send the unique identifier to the system controller 110, and the system controller 110 can be configured to determine the location of the mobile device 140 using the unique identifier (e.g., using data stored in memory or retrieved via the Internet). An example of a load control system for controlling one or more electrical loads in response to the location of a mobile device and / or an occupant within a building is described in more detail in co-pending U.S. Patent Application Publication No. 2016 / 0056629, titled "Load Control System Responsive to Location of an Occupant and Mobile Devices," filed on February 25, 2016, the entire disclosure of which is incorporated herein by reference.

[0040] The operation of the load control system 100 can be programmed and configured using, for example, the mobile device 140 or other network devices (e.g., when the mobile device is a personal computing device). The mobile device 140 can execute graphical user interface (GUI) configuration software for allowing a user to program how the load control system 100 will operate. For example, the configuration software can run as a PC application or a web interface. The configuration software and / or the system controller 110 (e.g., via instructions from the configuration software) can generate a load control database that defines the operation of the load control system 100. For example, the load control database can include information about the operation settings of different load control devices of the load control system (e.g., dimmer switches 120, LED drivers 130, motorized window treatments 150, and / or thermostats 160). The load control database can include information about the associations between load control devices and input devices (e.g., remote control devices 170, occupancy sensors 180, occupant count sensors 190, etc.). The load control database can include information about how load control devices respond to inputs received from input devices. Examples of configuration procedures for load control systems are described in more detail in the following patents: U.S. Patent No. 7,391,297, co-assigned, titled "HANDHELD PROGRAMMER FOR A LIGHTING CONTROL SYSTEM," issued June 24, 2008; U.S. Patent Application Publication No. 2008 / 0092075, titled "METHOD OF BUILDING A DATABASE OF A LIGHTING CONTROL SYSTEM," published April 17, 2008; and U.S. Patent Application Publication No. 2014 / 0265568, titled "COMMISSIONING LOAD CONTROL SYSTEMS," published September 18, 2014, the entire contents of the above patents are incorporated herein by reference.

[0041] The occupant counting sensor 190 may be able to detect when a person enters or exits the room 102. The occupant counting sensor 190 may include a plurality of PIR elements (e.g., two PIR detectors). These elements may include a pyroelectric material sensitive to heat (e.g., infrared radiation). The elements may be arranged in an anti-series connection such that the response (e.g., output voltage) of each PIR element to a heat source (e.g., a person entering or exiting the room 102) has an opposite polarity, e.g., to eliminate parasitic noise. Additionally, the anti-series connection enables identification of which individual PIR element first generates a response (e.g., first detects a change in infrared energy). These characteristics of the PIR elements may be used to determine the direction of movement associated with a person and, in turn, determine whether the person has entered or exited the room 102. For example, when a person enters the room 102, his / her movement may be detected as movement in one direction. When a person exits the room, his / her movement may be determined to be in the opposite direction. Based on the movement (and thus the entry / exit status of the person), the occupant counting sensor 190 may be configured to determine the occupant count and / or change in occupant count of the room 102 by incrementing the occupant count when a person enters the room and decrementing the occupant count when a person leaves the room.

[0042] The occupant counting sensor 190 may be mounted and oriented to detect an energy (e.g., IR energy) emitter moving through the doorway. As Figure 1 shown, the occupant counting sensor 190 may be mounted on the corner (e.g., upper corner) of the doorway 106 leading to the room 102, but other mounting locations are possible. For example, the occupant counting sensor 190 may be mounted on the lower corner of the doorway 106, the middle side of the doorway, the left or right side of the doorway, and / or the inside or outside of the doorway. Additionally, the occupant counting sensor 190 may be mounted to the doorframe around the door, inside the doorframe, and / or otherwise mounted to the structure around the door to appropriately detect an occupant moving through the doorway 106. Additionally, multiple occupant counting sensors may be mounted to various locations on the doorway 106 to improve the accuracy of detecting a person entering or exiting the room 102.

[0043] The occupant counting sensor 190 may include a focusing device (such as a lens (e.g., a Fresnel lens)), which may be configured to focus IR energy from an occupant onto the PIR element. The lens may be used for a variety of purposes, including, for example, enhancing the accuracy of motion detection of the occupant counting sensor 190 and / or extending its detection range. For example, a Fresnel lens may capture more IR radiation and focus it onto a small spot (e.g., at the PIR element inside the occupant counting sensor 190), thereby extending the detection range of the occupant counting sensor 190. When the IR source moves, the focus may move across the PIR element of the occupant counting sensor 190 and may expose a set of PIR elements of the occupant counting sensor 190 to the focus at one time, thereby triggering the generation of a patterned output signal as described herein.

[0044] As Figure 1 shown, a first PIR element among the PIR elements of the occupant counting sensor 190 may detect movement in a first region 192, and a second PIR element among the PIR elements may detect movement in a second region 194. For example, the occupant counting sensor 190 may be positioned and / or oriented such that when an occupant enters and / or exits the room 102 through the doorway 106, the first region 192 and the second region 194 pass through the occupant's chest. When the occupant moves into the room, the first PIR element among the PIR elements may detect movement in the first region 192 before the second PIR element among the PIR elements detects movement in the second region 194. The output signal generated by the PIR element may indicate movement in a specific direction. For example, if the output includes a positive peak followed by a negative peak, the occupant counting sensor 190 may determine that a person has entered the room 102. If the output includes a negative peak followed by a positive peak, the occupant counting sensor 190 may determine that a person has left the room 102. It should be noted that the corresponding patterns for entry / exit determination may vary based on the mounting orientation of the occupant counting sensor.

[0045] The occupant counting sensor 190 may include a switch (not shown), which may be manipulated to inform the occupant counting sensor 190 about the mounting orientation (e.g., whether the occupant counting sensor is mounted on the left or right side of the doorway 106 and / or the inside or outside of the doorway). Based on the orientation, the occupant counting sensor 190 may know which specific output signal pattern corresponds to which direction of movement. For example, when the occupant counting sensor 190 is mounted in a first orientation, the sensor may associate a positive-negative peak signal pattern with a person entering the room 102. When the occupant counting sensor 190 is mounted in a second orientation, the sensor may associate a positive-negative peak signal pattern with a person leaving the room 102.

[0046] The occupant counting sensor 190 may include other types of detection circuits. For example, the occupant counting sensor 190 may include a thermopile array (such as an N×N array of thermal response elements) configured to generate a two-dimensional thermal image of the covered area of the room 102. The occupant counting sensor 190 may include a radar sensing device that uses a transmit antenna array (e.g., a phased array) and / or a receive antenna array (e.g., a phased array) to record a radar image of the entry location. The occupant counting sensor 190 may include a visible light sensing device that uses a camera pointed at the entry location of the room 102 to record an image of the entry location. The occupant counting sensor 190 may include a time-of-flight sensing circuit capable of providing a three-dimensional image of the area of the room 102. The images generated by these detection circuits may be processed to determine the position and / or movement of the occupants in the area of the room 102 in order to determine whether an occupant has entered or exited the room 102. For example, using the thermal map (e.g., 2D thermal image) generated by the thermopile array, the control circuit of the occupant counting sensor 190 may track the movement of the occupant through multiple zones (e.g., near the doorway) of the covered area so that the control circuit can determine whether the occupant is entering or leaving the room 102 based on the pattern and / or direction of the movement. Examples of image-based detection circuits will be described in more detail below.

[0047] In response to determining the occupant count of the room 102 or detecting a change in the occupant count, the occupant counting sensor 190 may send one or more digital messages to the system controller 110 via the RF signal 108 (e.g., using the proprietary protocol described herein). The digital message may indicate the occupant count or a change thereof. For example, the occupant counting sensor 190 may be a one-way transmitter (e.g., may not be configured to receive digital messages) and may be configured to send (e.g., periodically send) a sensor occupant count indicating the change in the occupant count since the last transmission of the occupant counting sensor 190. The occupant counting sensor 190 may be configured to reset the occupant count stored in the memory at the occupant counting sensor after the occupant counting sensor sends a change in the occupant count. For example, the sensor occupant count may be positive or negative based on how many occupants have entered or exited the room 102 since the last reset of the occupant count. The system controller 110 may be configured to maintain the occupant count of the room 102 (e.g., the room occupant count). For example, whenever the system controller 110 receives a sensor occupant count from the occupant counting sensor 190, the system controller 110 may add the sensor occupant count (e.g., indicating the change in the occupant count detected by the particular occupant counting sensor) to the room occupant count.

[0048] Based on the room occupant count, the system controller 110 can also be configured to determine the occupied status and / or the vacant status of the room. For example, when the room occupant count is greater than zero, the system controller 110 can determine that the room 102 is occupied, and when the room occupant count reaches zero, the system controller 110 can determine that the room 102 is vacant.

[0049] The system controller 110 can be configured to process digital messages and take various actions based on the digital messages and / or other information collected from the load control system 100. For example, the system controller 110 can determine a mismatch between the room occupant count determined from the sensor occupant count received in the digital message and the occupancy status reported by the occupancy sensor 180. For example, an exemplary mismatch may occur when the room occupant count of the room 102 determined by the system controller 110 is greater than zero while the occupancy sensor 180 indicates that the room is unoccupied. The system controller 110 can be configured to resolve such a mismatch, for example, by resetting the room occupant count maintained by the system controller to zero. Additionally, if the system controller 110 determines that the occupant count is less than zero based on digital messages sent by the first occupant count sensor and the second occupant count sensor, the system controller 110 can reset the occupant count of the room 102 to zero.

[0050] The system controller 110 can be configured to collect and / or store room occupant count data over time (e.g., for multiple time periods) and thus maintain a history (e.g., a historical view) of the occupancy status of the room and / or the occupant count. The history can include multiple data points, each corresponding to the room occupants during a specific time period. The system controller 110 can also be configured to correct the history of the occupancy status and / or the occupant count of the room 102 in response to resolving a mismatch between the room occupant count determined from the sensor occupant count received in the digital message and the occupancy status reported by the occupancy sensor 180. For example, if the room occupant count of the room 102 determined by the system controller 110 is greater than zero while the occupancy sensor 180 indicates that the room is unoccupied, the system controller 110 can reset the room occupant count to zero and update the history of the occupancy status and / or the occupant count of the room (e.g., reset one or more data points corresponding to the room occupant count during various time periods in the history to zero).

[0051] In an example, the system controller 110 can be configured to receive occupant count information from more than one occupant count sensor associated with the room. For example, in addition to the occupant count sensor 190, Figure 1The load control system 100 therein may also include one or more additional occupant counting sensors installed at one or more other doorways adjacent to the room 102. These additional occupant counting sensors may be configured to operate similarly to the occupant counting sensor 190 and may provide additional information for determining the number of occupants in the room 102. For example, a first occupant counting sensor may be installed near the entrance of the room 102, and a second occupant counting sensor may be installed near the exit of the room. Both sensors are capable of determining the number of people passing through the respective doorways over a period of time and reporting that information to the system controller 110.

[0052] The system controller 110 may be configured to receive messages sent by the first occupant counting sensor and the second occupant counting sensor and aggregate the occupant counts (or changes thereof) indicated in those messages. For example, if the first occupant counting sensor indicates that three people entered the room 102 during the period, and the second occupant counting sensor indicates that two people left the room 102 during the same period, the system controller 110 may determine that the number of people occupying the room 102 is one.

[0053] As described above, the system controller 110 is capable of resolving mismatches between the information reported by the occupant counting sensors and the information collected from other devices in the load control system 100. Using the example provided above, if the system controller 110 determines that there is one occupant in the room 102 based on the digital messages sent by the first occupant counting sensor and the second occupant counting sensor, and determines that the room is unoccupied according to the occupancy sensor 180, the system controller 110 may reset the occupant count of the room 102 to zero.

[0054] The occupant counting sensor 190 may be a two-way wireless device and may be configured to, for example, send digital messages to the system controller 110 and receive digital messages from the system controller 110. The occupant counting sensor 190 may be configured to maintain a room occupant count (e.g., in addition to or instead of determining the sensor occupant count). For example, the occupant counting sensor 190 may be configured to periodically send the room occupant count (e.g., which indicates to the system controller 110 the number of occupants currently in the room). When the occupant counting sensor 190 is configured to maintain a room occupant count, the system controller may resolve mismatches between the information reported by the occupant counting sensor and the information collected from other devices in the load control system 100. For example, if the system controller 110 determines that there is one occupant in the room 102 and determines that the room is unoccupied according to the occupancy sensor 180, the system controller 110 may send a digital message to the occupant counting sensor 190 to reset the occupant count of the room 102 to zero.

[0055] The occupant counting sensor 190 can be configured to perform some or all of the functions of the system controller 110. For example, the occupant counting sensor 190 may be able to receive information (e.g., digital messages) regarding the occupant count (or its change) or occupancy status of the room 102 from other occupant counting sensors and / or from the occupancy sensor 180. The occupant counting sensor 190 can be configured to process the received information in combination with the occupant count determined by the occupant counting sensor 190 itself, and derive a cumulative count of the number of occupants in the room 102. Similar to the system controller 110, the occupant counting sensor 190 may be able to resolve mismatches between the various information received or derived by the occupant counting sensor 190.

[0056] Figure 2 is an enlarged perspective view of an exemplary occupant counting sensor 200 (e.g., Figure 1 the occupant counting sensor 190). The occupant counting sensor 200 can include a housing 202 for accommodating the circuitry of the occupant counting sensor. The circuitry of the occupant counting sensor 200 can include a plurality of PIR elements (e.g., two PIR elements) that are capable of detecting energy (e.g., IR energy) from an energy emitter (e.g., an occupant) in a space. The PIR elements can be arranged and / or oriented to detect the movement of an energy emitter in front of the occupant counting sensor 200 (e.g., to detect a person entering or exiting the room).

[0057] The occupant counting sensor 200 can include a focusing device (such as a Fresnel lens 204) that is configured to capture the energy of an energy emitter moving in front of the lens and focus the captured radiation onto a small spot at the PIR element, thereby enhancing the detection range and / or accuracy of the occupant counting sensor 200. The occupant counting sensor 200 can be mounted adjacent to the doorway of a user space (e.g., Figure 1 the room 102 shown). For example, the occupant counting sensor 200 can be mounted at a corner (e.g., an upper corner) of the doorway and oriented to face the opposite corner of the doorway. The orientation of the occupant counting sensor 200 can be indicated (e.g., signaled) via an orientation actuator 206 of the occupant counting sensor. For example, setting the orientation actuator 206 to a first position can indicate to the occupant counting sensor 200 that the Fresnel lens 204 is mounted at the upper left corner of the doorway (e.g., on the inside of the doorway) and is pointing in the lower right direction, while setting the orientation actuator 206 to a second position can indicate to the occupant counting sensor 200 that the Fresnel lens 204 is mounted at the upper right corner of the doorway (e.g., on the inside of the doorway) and is pointing in the lower left direction.

[0058] Figure 3Ais an exemplary occupant counting sensor 300 (e.g., Figure 1 the occupant counting sensor 190 and / or Figure 2 the occupant counting sensor 200). The occupant counting sensor 200 may include a detection circuit 310 configured to detect an occupant in a space (e.g., an occupant entering and / or exiting the space). For example, the detection circuit 310 may include a pyroelectric infrared (PIR) detector circuit 312 and an amplifier circuit 314. The PIR detection circuit 312 may include a plurality of PIR elements (e.g., two PIR elements) that are capable of detecting energy (e.g., IR energy) from an energy emitter (e.g., an occupant) in the space and generating a PIR voltage V PIR . The occupant counting sensor 300 may include a focusing device (e.g., Figure 2 the Fresnel lens 204 shown in PIR ) configured to capture the energy of an energy emitter moving in front of the lens and focus the captured radiation onto the PIR elements of the PIR detector circuit 312. The amplifier circuit 314 may be coupled to the output of the PIR detector circuit 312 to receive the PIR voltage V DETECT . The amplifier circuit 314 may be configured to generate a detection voltage V

[0059] DETECT which may indicate the movement of the energy emitter through the doorway (e.g., to detect an occupant entering or exiting a room). DETECT PIR The occupant counting sensor 300 may include a control circuit 315 configured to receive the detection voltage V

[0060] from the detection circuit 310 for detecting occupants entering and exiting the room. The control circuit 315 may include, for example, a microprocessor, a programmable logic device (PLD), a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), or any suitable processing device. The control circuit 315 may be configured to determine an occupant count of the people who have entered or exited the room based on the detection voltage V PIRamplitude. Due to the anti - series connection of the PIR elements, when each of the individual PIR elements is exposed to IR energy, the PIR detector circuit 312 can generate responses of opposite polarities (e.g., peaks and / or pulses). This makes it possible to identify which individual PIR element first detects motion (e.g., a change in infrared energy). The characteristics of the PIR elements of the PIR detector circuit 312 can be used to determine the direction of movement of the occupant in front of the occupant counting sensor 300 and, in turn, determine whether the occupant has entered or exited the room. For example, if the detection voltage V generated by the detection circuit 310 DETECT includes a first peak amplitude of positive polarity followed by a second peak amplitude of negative polarity, the control circuit 315 can determine that the occupant has passed through the doorway in the first direction (e.g., entered the room). If the detection voltage V generated by the detection circuit 310 DETECT includes a first peak amplitude of negative polarity followed by a second peak amplitude of positive polarity, the control circuit 315 can determine that the occupant has passed through the doorway in the second direction (e.g., exited the room).

[0061] Figure 3B shows an exemplary waveform of the signal of the detection voltage V generated by the detection circuit 310 DETECT . The amplifier circuit 314 can add a DC offset to the PIR voltage V PIR , such that the detection voltage V DETECT is centered around a mid - point voltage, such as half of the supply voltage V CC (e.g., V cc / 2), as shown in Figure 3A . When one of the PIR elements of the PIR detector circuit 312 is exposed to a change in IR energy and subsequently another of the PIR elements is exposed to a change in IR energy, the detection circuit 310 can generate a signal (e.g., an entry signal or an exit signal). For example, when an IR radiator moves across the occupant counting sensor, the first PIR element among the PIR elements may be exposed to a change in IR energy caused by the movement of the radiator, and then the second PIR element among the PIR elements may be exposed to a change in IR energy. Thus, the output of the PIR detection circuit can exhibit a specific pattern corresponding to the movement of the radiator.

[0062] As shown in Figure 3B , a first signal (e.g., an entry signal) can be generated when an occupant enters the space monitored by the occupant counting sensor 300. Such a first signal can reach a maximum peak (e.g., a positive peak) amplitude V 1a at a first time point t MAX1 (e.g., when the first PIR element among the PIR elements is exposed to IR energy), and then at a second time point t 2areaches a minimum peak (e.g., a negative peak) amplitude V at a location (e.g., when the second PIR element in the PIR element is exposed to IR energy). MIN1 . When the occupant leaves the space monitored by the occupant counting sensor, the same characteristic of the PIR element may cause a second signal (e.g., an exit signal) to be generated. As Figure 3B shown in, the second signal may reach a minimum peak (e.g., a negative peak) amplitude at a first time point t 1b at a location (e.g., when the second PIR element in the PIR element is exposed to IR energy), and then reach a maximum peak (e.g., a positive peak) amplitude at a second time point t 2b at a location (e.g., when the first PIR element in the PIR element is exposed to IR energy).

[0063] A specific signal (e.g., a signal pattern) (e.g., a detection voltage V DETECT corresponding to the entry or exit of an occupant into or out of a room that may be generated by the detector circuit 310) may depend on the orientation of the occupant counting sensor 300. For example, if the occupant counting sensor 300 is positioned adjacent to the upper right corner of the interior door of a room, a signal (e.g., an entry signal) with a maximum peak (e.g., a positive peak) followed by a minimum peak (e.g., a negative peak) may indicate that the occupant has entered the room, while a signal with a minimum peak followed by a maximum peak (e.g., an entry signal) may indicate that the occupant has exited the room. If the occupant counting sensor 300 is positioned adjacent to the upper left corner of the interior door of a room, a signal with a minimum peak followed by a maximum peak (e.g., an entry signal) may indicate that the occupant has entered the room, while a signal with a minimum peak followed by a maximum peak (e.g., an entry signal) may indicate that the occupant has exited the room.

[0064] The occupant counting sensor 300 may include an orientation switch 316 that can respond to an orientation actuator (e.g., Figure 2 the orientation actuator 206 of the occupant counting sensor 200 shown in). The control circuit 314 may obtain information about the installation orientation of the occupant counting sensor 300 via the orientation switch 316. For example, the orientation switch 316 may be set in response to the actuation of the orientation actuator during the configuration of the occupant counting sensor 300. For example, the control circuit 315 may be configured to map different output signal patterns of the PIR detector circuit 310 to a determination of the entry or exit of an occupant into or out of a room. As explained herein, such signal patterns of the detection voltage V DETECT may include a positive peak followed by a negative peak or a negative peak followed by a positive peak.

[0065] The control circuit 315 can maintain (e.g., determine and / or update) an occupant count for a room. In response to detecting motion, the control circuit 315 can obtain multiple samples of the detection voltage V received from the detection circuit 310 (e.g., over a sampling time period) and determine whether a mapped signal pattern can be identified. If it is determined that the mapped signal pattern has occurred, the control circuit 315 can increase or decrease the occupant count accordingly. If the occupant count is greater than zero, the control circuit 315 can additionally infer that the room is occupied. When the occupant count drops to zero, the control circuit 315 can additionally infer that the room has become unoccupied. DETECT The control circuit 315 can be configured to store the occupant count and / or the occupancy state in the memory 318 of the occupant count sensor 300. The memory 318 can be implemented as an external integrated circuit (IC) coupled to the control circuit 315 or as an internal circuit of the control circuit 315. The control circuit 315 can be configured to save different occupant counts associated with different time periods in the memory 318, such that a historical view of the occupancy status of the room (e.g., using history) can be derived.

[0066] The occupant count sensor 300 can include a communication circuit 320 configured to send and / or receive digital messages via a communication link using a communication protocol. For example, the communication link can include a wireless communication link, and the communication circuit 320 can include an RF transceiver coupled to an antenna. The communication link can include a wired digital communication link, and the communication circuit 320 can include a wired communication circuit. The communication protocol can include a proprietary protocol, e.g., the ClearConnect protocol. The control circuit 315 can be configured to send and / or receive digital messages via the communication link during normal operation of the occupant count sensor 300. For example, the control circuit 315 can be configured to send an indication of the determined occupant count (or a change thereof) for the room to a system controller (e.g.,

[0067] system controller 110). The control circuit 315 is also capable of receiving an indication of the occupant count (or a change thereof) for the room determined by another occupant count sensor (e.g., an occupant count sensor installed at a different doorway of the room). In the latter case, as described herein, the occupant count sensor 300 can perform some or all of the functions of the system controller. Figure 1 The occupant count sensor 300 can include a power supply 322 for generating a DC supply voltage V

[0068] CC ​, to supply power to the control circuit 315, the memory 318, the communication circuit 320, and other low-voltage circuits of the occupant counting sensor 300. The power supply 322 may include a power supply configured to receive an external supply voltage from an external power source (e.g., an AC mains voltage power source and / or an external DC power supply). Additionally, the power supply 322 may include a battery for powering the circuits of the occupant counting sensor 300.

[0069] Figure 4 is a simplified flowchart of an exemplary occupant counting program 400. At 410, the occupant counting program 400 may be executed (e.g., periodically) by the control circuit of the occupant counting sensor (e.g., the control circuit 315 of the occupant counting sensor 300). At 412, the control circuit may determine, for example, based on a detection signal generated by a detection circuit (e.g., the detection circuit 310), whether motion has been detected in the vicinity of the occupant counting sensor (e.g., if any of the PIR elements detect a change in IR energy). For example, at 412, the control circuit may compare the amplitude of the detection signal with a motion threshold to determine whether motion has been detected. If motion is detected at 412 (e.g., the amplitude of the detection signal is greater than the motion threshold), then at 414 the control circuit may begin sampling the output of the detection circuit for a period of time and / or until a plurality of samples (e.g., n samples of the output voltage) have been collected / stored. The duration of the sampling period and / or the number of samples to be collected may be preconfigured and stored in the memory of the occupant counting sensor.

[0070] At 416, the control circuit may determine (e.g., identify) the maximum amplitude (e.g., the peak voltage with positive polarity) and the minimum amplitude (e.g., the peak voltage with negative polarity) of the collected samples. At 418, the control circuit may determine, based on the maximum and minimum amplitudes of the sample signal, whether the collected samples represent a valid signal generated in response to an occupant entering or exiting the space monitored by the occupant counting sensor. The control circuit may make this determination by checking whether the maximum and minimum amplitudes of the samples have opposite polarities and / or whether the corresponding absolute values of the maximum and minimum amplitudes exceed corresponding maximum and minimum thresholds (e.g., preconfigured thresholds V TH-MAX and V TH-MIN , as Figure 3B shown). The absolute values of the thresholds V TH-MAX and V TH-MIN may be the same or may be different from each other. Consecutive output signals (such as those generated in response to an occupant stopping at a doorway and / or a continuous stream of people passing through the sensor-equipped doorway (e.g., a conga line)) may not exhibit the above pattern and may therefore not generate a response from the control circuit.

[0071] If the control circuit determines that the collected sample represents a valid signal associated with an occupant entering or exiting the space (e.g., the maximum and minimum amplitudes of the sample have opposite polarities (e.g., bipolar), and the absolute values of the maximum and minimum amplitudes exceed the absolute values of the corresponding thresholds), then at 420 the control circuit can also determine whether the pattern reflected in the collected sample corresponds to an occupant entering the space or an occupant exiting the space. As described herein, the corresponding patterns associated with an occupant entering and exiting the space can be determined based on the mounting orientation of the occupant counting sensor, which can be indicated to the control circuit via a switching device (e.g., orientation switch 206). Also as described herein, the patterns associated with an occupant entering and exiting the space can include a peak positive voltage followed by a peak negative voltage, a peak negative voltage followed by a peak positive voltage, and / or vice versa.

[0072] If the pattern of the collected sample indicates that an occupant has entered the space, then at 422 the control circuit can increment the occupant count (e.g., the sensor occupant count) by 1. Otherwise, at 424, the control circuit can decrement the occupant count by 1. After adjusting the occupant count, at 426 the control circuit can wait for a blanking period (e.g., having a configurable duration), and then at 428 check again whether another motion has been detected in the vicinity of the occupant counting sensor. The blanking period may prevent the control circuit from responding to any residual peaks of the signal generated by the detection circuit due to an occupant entering or exiting the room. If there is motion at 428, the control circuit can repeat the actions described above. If there is no motion at 428, then at 430, the control circuit can enter the sleep mode for a preconfigured period of time, or until the control circuit is notified that motion has been detected in its vicinity. Then at 432 the control circuit can exit program 400.

[0073] When at 412 the control circuit determines that no motion has been detected, the control circuit can also enter the sleep mode at 430.

[0074] Figure 5 An exemplary occupant counting sensor 500 is shown (e.g., Figure 1The occupant counting sensor 190), which is configured to detect the entry or exit of an occupant (e.g., a person and / or an energy emitter) into or out of a space (e.g., a room). The occupant counting sensor 500 can be installed near the doorway 502 of the space and thus has a view of the doorway 502. For example, the occupant counting sensor 500 can be placed near the upper side of the doorway 502 (e.g., the upper center section of the doorway), the upper corner or lower corner of the doorway 502, the middle side section of the doorway 502, the left or right side of the doorway 502, and / or the inner or outer side of the doorway 502. The occupant counting sensor 500 can be installed on the doorframe 504 around the doorway 502, inside the doorframe 504, and / or otherwise installed on the structure around the doorframe 504 to appropriately detect occupants moving through the doorway 502. Additionally, although Figure 5 only one occupant counting sensor is shown, multiple such sensors can be installed at various positions near the doorway 502 to improve the accuracy of detecting people entering or exiting the space.

[0075] The occupant counting sensor 500 can include a detection circuit (not shown), which is configured to detect one or more occupants (e.g., energy emitters) in a coverage area (e.g., the area near the doorway 502) and generate one or more signals indicating the position of the one or more occupants in the coverage area. The detection circuit can be configured to generate an occupant map, e.g., a two-dimensional (2D) map or image indicating the position of the occupants. The occupant map can also include a three-dimensional (3D) map or image. For example, the detection circuit can include a thermopile array, such as an N×N array of thermal response elements. The detection circuit can include a microbolometer array (e.g., an N×N array of thermal response elements) or another suitable type of thermal sensing camera or detector. The thermal response elements can be sensitive to the thermal energy level at various points in the coverage area 501 and can operate to convert the thermal energy into an electrical signal indicating the thermal energy level in the coverage area. Thus, the output of the thermopile array can represent an occupant map (e.g., a 2D thermal image or thermogram) of the coverage area 501, where each thermal response element of the thermopile array corresponds to a pixel in the thermogram. When a heat-emitting object (e.g., a person or an occupant) moves into and out of the coverage area 501 and / or moves through the coverage area 501, the output of the thermopile array (e.g., the 2D thermal image) can indicate the change (or no change) in the thermal energy level at various points in the coverage area. Thus, the output can be used to determine the position of the heat-emitting object in the coverage area 501. The detection circuit can also include a radar sensing circuit, a visible light sensing circuit (e.g., a camera), and / or a time-of-flight sensing circuit (e.g., as will be described in more detail below).

[0076] The occupant counting sensor 500 may also include a control circuit (not shown) coupled to the detection circuit (e.g., a thermopile array) and configured to receive an output signal of the detection circuit (e.g., an occupant map). The control circuit may include, for example, a microprocessor, a programmable logic device (PLD), a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), or any suitable processing device. The control circuit may be configured to process the output signal of the detection circuit (e.g., an occupant map) and determine the location and / or movement of a person in the coverage area 501 based on the processed output signal. For example, the occupant map may be used to monitor the coverage area 501 near a doorway 502. The coverage area 501 may include multiple zones. A first zone (e.g., Figure 5 Zone A 508 shown in FIG. 504 may correspond to an area outside of doorway 502 (eg, outside of a space or room), a second zone (eg, Figure 5 Zone B 510 shown in FIG. 5 ) may correspond to all or a portion of doorway 502, and a third zone (e.g., Figure 5 Zone C 512 shown in the figure may correspond to an area on the inside of the doorway 502 (e.g., the interior of a space or room). The control circuit may detect the position and / or movement of a person relative to the multiple zones 508-512 in response to receiving an output signal from the detection circuit (e.g., an occupant map), and determine whether the person has entered or exited the space based on the detected position and / or movement of the person. For example, if the control circuit determines that a person has moved through multiple zones in a first order (e.g., from zone A 508 through zone B 510 to zone C 512) based on the output signal of the detection circuit (e.g., an occupant map), the control circuit may also determine that the person has entered the space. Similarly, if the control circuit determines that a person has moved through multiple zones in a second order (e.g., from zone C 512 through zone B 510 to zone A 508) based on the output signal of the detection circuit (e.g., an occupant map), the control circuit may also determine that the person has left the space.

[0077] The control circuitry may determine an occupant count of the space in response to determining that a person has entered or exited the space. For example, the control circuitry may increase the occupant count of the space based on a determination that a person has entered the space, and may decrease the occupant count based on a determination that a person has left the space.

[0078] The occupant count sensor 500 can be configured to send one or more digital messages to a system controller (e.g., system controller 110) via an RF signal (e.g., using the proprietary protocol described herein) in response to determining an occupant count of a space. The digital messages can indicate the occupant count or a change thereof. For example, the occupant count sensor 500 can be a one-way transmitter (e.g., may not be configured to receive digital messages) and can be configured to periodically send a sensor occupant count indicating a change in the number of occupants since the last transmission from the occupant count sensor 500. The occupant count sensor 500 can be configured to reset the occupant count stored in a memory at the occupant count sensor after the occupant count sensor sends a change in the occupant count. For example, the sensor occupant count can be positive or negative based on how many occupants have entered or exited the space since the last reset of the occupant count. The system controller can be configured to maintain a central occupant count for the space. For example, the system controller can add the sensor occupant count (e.g., indicating a change in the occupant count of the space) to the central occupant count in response to receiving the sensor occupant count from the occupant count sensor 500.

[0079] The occupant count sensor 500 can include a switch (not shown) that can be manipulated to notify the occupant count sensor 500 about the installed orientation and / or location (e.g., whether the occupant count sensor is installed at the center of the doorway 502, on the left or right side of the doorway 502, and / or inside or outside of the doorway 502). Based on the orientation, the occupant count sensor 500 can know which particular output signal corresponds to which direction of movement. For example, when the occupant count sensor 500 is installed in a first orientation, the sensor can associate a first output signal pattern with people entering through the doorway 502. When the occupant count sensor 500 is installed in a second orientation, the sensor can associate a second output signal pattern with people leaving through the doorway 502.

[0080] Figure 6 is an exemplary block diagram of an exemplary occupant count sensor 600 (e.g., Figure 5 the occupant count sensor 500). The occupant count sensor 600 can include a detection circuit 610 and a control circuit 615. The detection circuit 610 can be configured to generate an occupant map, e.g., a two-dimensional (2D) map or image indicating the positions of occupants. The occupant map can also include a three-dimensional (3D) map or image. For example, the detection circuit 610 can include a thermopile array 612 (e.g., N×N thermally responsive elements, where N can be equal to 8). These thermally responsive elements may be capable of detecting from a coverage area (e.g., Figure 5Thermal energy (e.g., heat) generated by an energy emitter (e.g., an occupant) in the covered area 501 shown and generates one or more signals representing an occupant map (e.g., a 2D thermal image or heat map) of the area. Each thermal response element may correspond to a pixel in the occupant map (e.g., a 2D thermal image), and the signal generated by the thermal response element may represent the thermal energy level at the corresponding point in the covered area. Thus, the output of the detection circuit 610 can be used to determine the position of the occupant (e.g., the energy emitter) in the covered area (e.g., because the thermal energy level at the energy emitter position may be different from the thermal energy levels at other positions in the covered area).

[0081] The control circuit 615 may be configured to receive the signal generated by the detection circuit 610 and determine the X-Y coordinates of the occupant (e.g., the energy emitter) in the occupant map (e.g., a 2D thermal image) or the area covered by the detection circuit 610. The control circuit 615 may include an occupant map processing unit 630 (e.g., a software module for processing the occupant map), an occupant tracking filter 632 (e.g., a software module implementing a Kalman tracking filter), and / or a control unit 634 (e.g., a control software module). The control circuit 615 may include a microprocessor, a programmable logic device (PLD), a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), or any suitable processing device that may be configured to perform the functions of the occupant map processing unit 630, the occupant tracking filter 632, and / or the control unit 634. Although shown as including all three of the occupant map processing unit 630, the occupant tracking filter 632, and / or the control unit 634, the control circuit may also include a subset of these components.

[0082] The occupant map processing unit 630 may be configured to receive the input from the detection circuit 610 and output the occupant map or the preliminary coordinates of the occupant in the area covered by the occupant counting sensor 600. The input received from the detection circuit 610 may represent, for example, a plurality of pixels (e.g., a 2D thermal image) of the occupant map of the covered area, and the occupant map processing unit 630 may identify which one or more pixels of the occupant map represent the occupant (e.g., the energy emitter) (e.g., are covered by it). For example, the identification may be performed by comparing the thermal energy level at each pixel of the 2D thermal image generated by the detection circuit 610 with a predetermined threshold, and if the thermal energy level at the pixel exceeds the predetermined threshold, determining that the pixel is covered by the energy emitter.

[0083] When identifying one or more pixels of an occupant map representing an occupant, the occupant map processing unit 630 may also determine the X-Y coordinates of the occupant. For example, if the occupant occupies only one of the pixels of the occupant map, the occupant map processing unit 630 may determine the X-Y coordinates of the occupant based on the position of the pixel in the occupant map. If the energy emitter occupies multiple pixels of the occupant map, the occupant map processing unit 630 may determine the X-Y coordinates of the occupant based on the centroid of the multiple pixels (e.g., based on the central pixel among the multiple pixels).

[0084] The X-Y coordinates determined by the occupant map processing unit 630 may deviate from the actual coordinates of the occupant in the occupant map or the coverage area covered by the detection circuit 610 (e.g., due to errors introduced when measuring the thermal energy level). By further processing the X-Y coordinates determined by the occupant map processing unit 630 using a filter (e.g., the occupant tracking filter 632) and obtaining improved X-Y coordinates of the occupant at the output of the filter, such deviations can be reduced or eliminated.

[0085] The X-Y coordinates of the occupant (e.g., the improved X-Y coordinates) may be provided to the control unit 634 and used to determine the movement of the occupant in the area covered by the detection circuit 610. As described herein, the coverage area of the detection circuit 610 may include multiple zones (e.g., Figure 5 the zones 508-512 shown in ). These zones may correspond to areas near, for example, the entrance or exit of the space. Thus, by tracking the movement of the occupant in these areas, the control unit 634 can determine whether the occupant has entered or exited the space. For example, the control unit 634 may use a state machine to track the occupant moving through the zones of the coverage area. The control unit 634 may be configured to track multiple occupants within the coverage area. For example, the control unit 634 may use a separate state machine for each occupant among the multiple occupants in the coverage area.

[0086] When tracking an occupant entering the space, the control unit 634 may initially determine, based on the X-Y coordinates of the occupant, that the occupant has entered a first zone (e.g., Figure 5 zone A 508 shown in ) near the entrance or exit of the space (e.g., just outside). In response to detecting the occupant in the zone, the control unit 634 may assign an identifier (e.g., a tracking number) to the occupant. Subsequently, the control unit 634 may determine that the occupant has moved from the first zone through a second zone (e.g., Figure 5 zone B 510 shown in ) into a third zone (e.g., Figure 5Zone C (510) shown therein. In response to detecting that an occupant enters the first zone, moves through the zones, and exits the last zone, the control unit 634 may determine that the occupant has entered the space.

[0087] Similarly, after initially detecting an occupant, the control unit 634 may later determine, based on the X-Y coordinates of the occupant and the identifier assigned to the occupant, that the occupant has moved from the third zone through the second zone and into the first zone. In such a case, the control unit 634 may determine that the occupant has left the space and may disassociate the occupant from the identifier assigned to the occupant.

[0088] In some instances, the control unit 634 may lose track of an occupant or determine that the tracked occupant has shown a lack of movement (e.g., no movement for a preconfigured duration). In response, the control unit 634 may mark the occupant as a stationary occupant (e.g., in a stationary state) and may disassociate the occupant from the identifier previously assigned to the occupant. Subsequently, if the control unit 634 detects the occupant again (e.g., when the occupant enters Zone A, Zone B, or Zone C), or if the control unit 634 determines that the occupant has resumed movement, the control unit 634 may assign a new identifier to the occupant and begin tracking the occupant again.

[0089] The occupant counting sensor 600 may more accurately detect when an occupant enters or leaves the space by tracking the movement of the occupant through multiple zones of a two-dimensional area and determining, based on the tracked movement, whether the occupant has entered or exited the space. Using these techniques, the occupant counting sensor 600 may avoid incorrectly determining the entry or exit status of an occupant relative to a particular space. For example, if an occupant lingers at the doorway of the space (e.g., if the occupant enters Figure 5 Zone B shown therein but does not leave), the control unit 634 may not make a determination regarding the entry or exit status of the occupant until further movement of the occupant is detected (e.g., until the occupant moves into Figure 5 Zone A or Zone C shown therein).

[0090] The control unit 634 may maintain an occupant count for the space that the control unit is configured to monitor. If the control unit 634 determines that an occupant has entered the space, the control circuit 634 may increment the occupant count accordingly. If the control unit 634 determines that an occupant has left the space, the control circuit 634 may decrement the occupant count accordingly. If the occupant count is greater than zero, the control unit 614 may additionally infer that the space is occupied. When the occupant count drops to zero, the control unit 634 may infer that the space has become unoccupied.

[0091] The occupant counting sensor 600 may include an orientation switch 616. The orientation switch 616 can be manipulated to inform the occupant counting sensor 600 about the orientation of installation (e.g., whether the occupant counting sensor is installed at the center of the doorway 502, on the left or right side of the doorway 502, and / or on the inner or outer side of the doorway 502). Based on the orientation, the occupant counting sensor 600 can know how to interpret the signals (e.g., 2D thermal images) received from the detection circuit 610 in order to determine the position (e.g., X-Y coordinates) and / or movement of the occupant.

[0092] The occupant counting sensor 600 may include a memory 618, which is configured to store the X-Y coordinates of the occupants provided by the occupant mapping processing unit 630 and / or the occupant tracking filter 632. As described herein, the memory 618 may also be configured to store information about one or more zones of the coverage area (e.g., boundary information). The memory 618 may also be configured to store the identifier of the occupant (e.g., tracking number) and the state of the state machine (e.g., which zone(s) of the coverage area the occupant is in) and / or the X-Y coordinates associated with the tracking number. As described herein, the control unit 634 may use the stored information to track the movement of the occupant and / or determine the entry / exit state of the occupant. When the occupant exits the coverage area, the tracking number and the associated state machine state (e.g., X-Y coordinates) may be deleted from the memory 618. The memory 618 may also be configured to store the occupant count and / or the occupancy status of the space. For example, the control unit 634 may be configured to save different occupant counts associated with different time periods in the memory 618, such that a historical view of the occupancy condition of the space (e.g., usage history) can be derived. In addition, the operating parameters of the occupant counting sensor 600 may also be stored in the memory 618. For example, the control unit 634 may be configured to store in the memory 618 the threshold used to determine whether a pixel in the occupant map corresponds to an occupant. The memory 618 may be implemented as an external integrated circuit (IC) coupled to the control circuit 615 or as an internal circuit of the control circuit 615.

[0093] The occupant counting sensor 600 may include a communication circuit 620 configured to send and / or receive digital messages via a communication link using a communication protocol. For example, the communication link may include a wireless communication link, and the communication circuit 620 may include an RF transceiver coupled to an antenna. The communication link may include a wired digital communication link, and the communication circuit 620 may include a wired communication circuit. The communication protocol may include a proprietary protocol, such as, for example, the ClearConnect protocol. The control circuit 615 may be configured to send and / or receive digital messages via the communication link during normal operation of the occupant counting sensor 600. For example, the control circuit 615 may be configured to use the communication circuit 620 to send an indication of a determined occupant count (or a change thereof) of a space to a system controller (e.g., Figure 1 system controller 110). The control circuit 615 is also capable of receiving an indication of the occupant count (or a change thereof) of the space determined by another occupant counting sensor (e.g., an occupant counting sensor installed at a different doorway of the space). In the latter case, as described herein, the occupant counting sensor 600 may perform some or all of the functions of the system controller.

[0094] The occupant counting sensor 600 may include a power supply 622 for generating a DC supply voltage V CC to power the detection circuit 610, the control circuit 615, the memory 618, the communication circuit 620, and other low-voltage circuits of the occupant counting sensor 600. The power supply 622 may include a power supply configured to receive an external supply voltage from an external power source (e.g., an AC mains voltage power source and / or an external DC power supply). Additionally, the power supply 622 may include a battery for powering the circuits of the occupant counting sensor 600.

[0095] The detection circuit 610 may also include a radar sensing circuit, a visible light sensing circuit, and / or a time-of-flight sensing circuit. For example, when the detection circuit 610 includes a radar sensing circuit, the occupant mapping processing unit 630 of the control circuit 615 may include a radar detection software module. The radar sensing circuit may include: a transmit antenna array (e.g., a phased array) coupled to the control circuit 615 (e.g., the radar detection software module) via a radar transmitter circuit; and / or a receive antenna array (e.g., a phased array) coupled to the control circuit 615 (e.g., the radar detection software module) via a radar receiver circuit. Additionally, when the detection circuit 610 includes a visible light sensing circuit, the occupant mapping processing unit 620 of the control circuit 615 may include an image processing software module. The visible light sensing circuit may include a camera configured to record an image of the space, and the image of the space may be received by the image processing software module of the control circuit 615.

[0096] Figure 7A An example state diagram in which an occupant counting sensor (e.g., Figure 5 occupant counting sensor 500 and / or Figure 6 occupant counting sensor 600) can be used to determine the movement of an occupant (e.g., an energy emitter) when the occupant enters a space (e.g., a room). The occupant counting sensor can use a separate state machine to track each occupant in the coverage area. The occupant counting sensor can be in an idle state before detecting an occupant that may enter the space (e.g., when there are no occupants in the coverage area). An occupant can enter a first zone (e.g., zone A) of the area monitored by the occupant counting sensor. Such entry can be detected by the occupant counting sensor (e.g., as described herein), and the occupant counting sensor can assign an identifier (e.g., a tracking number) to the detected occupant. The occupant counting sensor can save the identifier, the state of the state machine (e.g., the zone of the coverage area where the occupant is located), and / or the location of the occupant (e.g., X-Y coordinates) in the memory of the occupant counting sensor (e.g., memory 618). When the occupant moves from the first zone to a second zone (e.g., zone B), the occupant counting sensor can track (e.g., record) the movement (e.g., using occupant tracking filter 632) based, for example, on the updated coordinates of the occupant and / or the identifier assigned to the occupant. When the occupant moves from the second zone to a third zone (e.g., zone C), the occupant counting sensor can similarly track the movement of the occupant. When the occupant exits the third zone, the occupant detection sensor may no longer detect the occupant in the coverage area. In response to detecting the movement of the occupant through the first zone, the second zone, and the third zone (e.g., in that particular order) and then exiting the third zone, the occupant counting sensor can determine that the occupant has entered the space. Thus, the occupant counting sensor can increment the occupant count for the space to reflect that an occupant has entered the space. The occupant counting sensor can then disassociate the occupant from the identifier previously assigned to the occupant (e.g., the occupant counting sensor can destroy the identifier assigned to the occupant) and eliminate the instance of the state machine. The occupant counting sensor can then re-enter the idle state.

[0097] When in any one of the first, second, or third zones, an occupant may become stationary (e.g., exhibit lack of movement and / or linger at a doorway) or undetectable (e.g., the occupant has exited the coverage area monitored by the occupant counting sensor). In those cases, the occupant counting sensor may consider the occupant to have entered a paused or stationary state, and thus, the occupant counting sensor may disassociate the occupant from the identifier previously assigned to the occupant (e.g., the occupant counting sensor may destroy the identifier assigned to the occupant), and eliminate the instance of the state machine. Additionally, the occupant counting sensor may determine that the occupant has moved backward, e.g., from the third zone to the second zone, or from the second zone to the first zone.

[0098] Figure 7B is an exemplary state diagram of how an occupant counting sensor (e.g., Figure 5 occupant counting sensor 500 and / or Figure 6 occupant counting sensor 600) can be used to determine the movement of an occupant when the occupant exits a space (e.g., a room). The occupant counting sensor may use a separate state machine to track each occupant in the coverage area. As described above, the occupant counting sensor may be in an idle state before detecting an occupant who may enter the space. An occupant may be detected by an occupant counting sensor in the third zone (e.g., zone C). In response to the detection, the occupant counting sensor may assign an identifier to the occupant. The occupant counting sensor may save the identifier, the state of the state machine (e.g., the zone of the coverage area), and / or the location of the occupant (e.g., X-Y coordinates) of the occupant in the memory of the occupant counting sensor (e.g., memory 618). When the occupant moves from the third zone to the second zone (e.g., zone B), the occupant counting sensor may track (e.g., record) the movement (e.g., using occupant tracking filter 632) based on, for example, the updated coordinates of the occupant and / or the identifier assigned to the occupant. When the occupant moves from the second zone to the first zone (e.g., zone A), the occupant counting sensor may similarly track the movement of the occupant. When the occupant exits the first zone, the occupant detection sensor may no longer detect the occupant in the coverage area. In response to detecting the movement of the occupant through the third, second, and first zones (e.g., in that particular order) and then exiting the first zone, the occupant counting sensor may determine that the occupant has left the space. Thus, the occupant counting sensor may decrement the occupant count maintained for the space. The occupant counting sensor may then disassociate the occupant from the identifier previously assigned to the occupant (e.g., the occupant counting sensor may destroy the identifier assigned to the occupant), and eliminate the instance of the state machine. The occupant counting sensor may then re-enter the idle state.

[0099] When in any one of the first zone, the second zone, or the third zone, an occupant may become stationary (e.g., exhibit lack of movement and / or linger at a doorway) or undetectable (e.g., the occupant has exited the coverage area monitored by the occupant counting sensor). In that case, the occupant counting sensor may consider the occupant to have entered a paused state or a stationary state, and thus, the occupant counting sensor may invalidate the identifier assigned to the occupant and eliminate the instance of the state machine. Additionally, the occupant counting sensor may determine that the occupant has moved backward, e.g., from the first zone to the second zone, or from the second zone to the third zone.

[0100] Although described herein as including a thermopile array, the occupant counting sensor (e.g., occupant counting sensor 500 or occupant counting sensor 600) may alternatively or additionally include radar sensing circuitry. Such radar sensing circuitry may in turn include: a radar detection processor; a transmit antenna array (e.g., a phased array) coupled to the radar detection processor (e.g., via radar transmitter circuitry); and / or a receive antenna array (e.g., a phased array) coupled to the radar detection processor (e.g., via radar receiver circuitry). The radar sensing circuitry may be implemented using modulated continuous wave radar technology or other types of radar technology, e.g., pulsed radar, continuous wave radar, side aperture radar, phased array radar, monostatic radar, multistatic radar, etc. The radar detection processor may be configured to transmit radar signals (e.g., chirps) via the transmit antenna array and receive reflected signals via the receive antenna array. The radar signals may be frequency-modulated continuous waveform (FMCW) that increases in frequency over a period of time. The radar sensing circuitry may be configured to process the reflected signals (e.g., compared to the transmitted radar signals) to determine the Doppler shift of the reflected signals and data about the occupant in space, such as the distance to the occupant, the direction of movement of the occupant, and / or the acceleration of the occupant.

[0101] The radar detection processor can be configured to use a transmit antenna array and a receive antenna array to measure the angles at which a moving object (e.g., an occupant) can be detected. The radar detection processor can be configured to measure various detection angles and determine data about the moving object at each detection angle. The radar detection processor can transmit radar signals at each detection angle and receive the reflected signals for processing. The radar detection processor can be configured to construct a map of the moving object in the area monitored by the radar sensing circuit (e.g., a two-dimensional or three-dimensional map) based on the data about the moving object determined at each detection angle. At least in terms of how the map can be used to determine the position (e.g., X-Y coordinates) of the moving object in the map or the area covered by the map, the map can be constructed in a manner similar to the heat map or 2D thermal image described in connection with the thermopile array. Such a map can be used to determine the entry / exit status of the moving object and / or the number of occupants in the monitored area. Thus, the techniques described above regarding tracking a moving object through multiple zones to determine the entry, exit, or pause status of the moving object (e.g., as shown in Figure 7A and Figure 7B ) can be equivalently applied to an occupant counting sensor including a radar sensing circuit. For example, when the occupant counting sensor includes a radar sensing circuit, the occupant tracking filter can be implemented as an extended Kalman tracking filter.

[0102] The occupant counting sensors described herein (e.g., occupant counting sensor 500 or occupant counting sensor 600) can include a visible light sensing device that uses a camera pointed at an area of interest in space to record an image of the area. These images can contain information about one or more characteristics of the area (such as the movement of objects in the area). The images can be processed (e.g., similar to the heat map of the 2D thermal image described above) to determine the occupancy status and / or occupant count of the area. Thus, the techniques described above regarding tracking a moving object through multiple zones to determine the entry, exit, or pause status of the moving object (e.g., as shown in Figure 7A and Figure 7B ) can be equivalently applied to an occupant counting sensor including a visible light sensing device. Examples of visible light sensing devices are described in more detail in U.S. Patent Application Publication No. 2017 / 0171941, published on June 15, 2017, and U.S. Patent Application Publication No. 2018 / 0168019, published on June 14, 2018, both of which are entitled "Load Control System Having a Visible Light Sensor" and are commonly assigned, and the entire disclosures of the above U.S. patent application publications are incorporated herein by reference.

[0103] In addition, the occupant counting sensors described herein (e.g., occupant counting sensor 500 or occupant counting sensor 600) may include time-of-flight sensing circuitry. In addition to providing X-Y coordinates, the time-of-flight sensing circuitry may also provide the Z coordinate of an occupant in the coverage area (e.g., the Z coordinate may indicate the distance from the occupant counting sensor to the occupant). The X-Y-Z coordinates of an occupant may indicate the position of the occupant in the coverage area and may thus be used to track the movement of the occupant in a manner similar to that described herein. Thus, the techniques described above regarding tracking a moving object through multiple zones to determine the entry, exit, or pause state of the moving object (e.g., as shown in Figure 7A and Figure 7B ) may equivalently apply to occupant counting sensors that include time-of-flight sensing circuitry.

[0104] The accuracy of the occupant counting sensors described herein may be affected by many factors. For example, multiple people walking side by side through a doorway, passing through a doorway closely behind each other, or standing in a doorway may confuse the occupant counting sensor. The occupant counting sensor may also suffer from malfunction interference caused by one or more components of the occupant counting sensor. To prevent and / or reduce the effects of these factors over time, e.g., to prevent any incorrect counts from persisting or propagating to different time periods, the occupant counting sensor may be configured to periodically reset its occupant counter.

[0105] In an example, the occupant counting sensor may be configured to reset the occupant count (e.g., the sensor occupant count) maintained by the sensor when sending the count to another device (e.g., to a system controller), when storing the count in memory, etc. For example, the system controller may maintain a room occupant count in response to receiving the sensor occupant count from the occupant counting sensor.

[0106] Resetting the occupant count may allow the occupant counting sensor to effectively report only changes in the number of occupants in the space. To illustrate, the occupant counting sensor may mis-count that five people entered a room when in fact only four people entered that room. By being able to reset the occupant count to zero and effectively only determine / report changes in the number of occupants in the room, after one or more factors causing an incorrect count are removed or corrected, the occupant counting sensor will still be able to correctly determine / report the number of people leaving the room.

[0107] As described herein, an occupant counting sensor (e.g., occupant counting sensor 190, occupant counting sensor 200, occupant counting sensor 300, occupant counting sensor 500, and / or occupant counting sensor 600) can report an occupant count or a change thereof to another device. Such other devices can be a system controller (e.g., system controller 110), another occupant counting sensor (e.g., which performs some or all of the functions of the system controller), etc. The receiving device can be configured to maintain an occupant count (e.g., room occupant count) for one or more user spaces and adjust these counts based on the information received from the sending sensor.

[0108] Figure 8 is a communication sequence diagram depicting an exemplary message flow (e.g., a digital message flow) in system 800, which includes two occupant counting sensors 810, 812 (e.g., occupant counting sensors 190, 300, 500, 600) and a system controller (e.g., system controller 110). For example, the occupant counting sensors 810, 812 can be installed at different doorways and / or entrances of a room to detect occupants entering and / or exiting the room. The system controller 814 can maintain a room occupant count in response to the two occupant counting sensors 810, 812. The occupant counting sensors 810, 812 can each send (e.g., periodically send) a corresponding sensor occupant count to the system controller 814, where the corresponding sensor occupant count can indicate a change in the room occupant count since the last time the sensor occupant count was sent.

[0109] For example, at 820 the first occupant counting sensor 810 can detect an occupant entering the room and at 822 can send a sensor occupant count of positive 1 to the system controller 814. At 824 the first occupant counting sensor 810 can zero its sensor occupant count (e.g., after sending the sensor occupant count at 822). After receiving the sensor occupant count sent at 822, at 826 the system controller 814 can increment the room occupant count by 1. At 828 and at 830 the second occupant counting sensor 812 can detect an occupant entering the room. At 832 the second occupant counting sensor 812 can send a sensor occupant count of positive 2 to the system controller 814 and at 834 can zero its sensor occupant count. After receiving the sensor occupant count sent at 832, at 836 the system controller 814 can increment the room occupant count by 2.

[0110] At 838, the first occupant count sensor 810 can detect an occupant exiting the room, at 840 detect an occupant entering the room, and at 842 detect an occupant exiting the room. At 844, the first occupant count sensor 810 can send a sensor occupant count of negative one and, at 846, zero out its occupant count. After receiving the sensor occupant count sent at 844, at 848 the system controller 814 can subtract one from the room occupant count. At 850 and 852, the second occupant count sensor 812 can detect an occupant entering the room and, at 854, detect an occupant exiting the room. At 856, the second occupant count sensor 812 can send a sensor occupant count of positive one and, at 858, zero out its occupant count. After receiving the sensor occupant count sent at 856, at 860 the system controller 814 can increment the room occupant count by one.

[0111] Figure 9 A flowchart of an example program 900 for sending and resetting a sensor occupant count at an occupant count sensor is shown. At 910, program 900 can be executed (e.g., periodically) by a control circuit of the occupant count sensor (e.g., control circuit 315 of occupant count sensor 300 and / or control circuit 615 of occupant count sensor 600). At 912, before exiting program 900, the control circuit can send the occupant count maintained by the occupant count sensor to another device (e.g., a system controller, another occupant count sensor, another device of a load control system to which the sensor belongs, etc.). After sending, at 914 the control circuit can reset the occupant count to zero so that the occupant count can be restarted.

[0112] Figure 10 A flowchart of an exemplary occupant count receiving program 1000 is shown. At 1010, the exemplary receiving program 1000 can be executed by a receiving device (such as a system controller (e.g., system controller 110), a control circuit of another occupant count sensor (e.g., control circuit 315 of occupant count sensor 300 and / or control circuit 615 of occupant count sensor 600), etc.). At 1012, the receiving device can receive occupant count information (e.g., a sensor occupant count) related to the number of people occupying a particular user space or a change thereof from an occupant count sensor (such as occupant count sensor 200 or occupant count sensor 600). The occupant count information can be included in one or more digital messages and sent to the receiving device via a wired or wireless communication link, e.g., as described herein.

[0113] The receiving device can maintain the overall occupant count of the user space (e.g., room occupant count), and can additionally maintain historical room occupant data of the user space. The historical room occupant data can include, for example, corresponding room occupant counts associated with various time points (e.g., various time periods). In response to receiving occupant count information from the occupant count sensor, at 1014, the receiving device can adjust the total occupant counter of the user space based on the received information. For example, when a positive occupant count is received from the occupant count sensor, the receiving device can increase the total occupant count, and when a negative occupant count is received from the occupant count sensor, the receiving device can decrease the total occupant count. When the occupant count from the occupant count sensor is zero, the receiving device can also maintain the total occupant counter.

[0114] The receiving device may be able to correct any incorrect counts of the occupants based on other information obtained by the receiving device. For example, at 1015, the receiving device can determine whether the room occupant count is less than zero. If the determination at 1015 is that the room occupant count is less than zero, the receiving device can determine that there is an error in the count and can correct the error. For example, at 1020, the receiving device can update the historical room occupant count data of the user space by adding the value of the incorrect count to each relevant data point (e.g., each occupant count associated with a corresponding time period). Additionally, at 1022, the receiving device can zero out the total occupant counter by resetting it to zero. The receiving device can then exit program 1000 at 1024.

[0115] At 1016, the receiving device can determine whether the user space is occupied based on the information received from the occupancy sensor (e.g., occupancy sensor 180) installed in the user space. If it is determined at 1016 that the user space is not occupied, but it is determined at 1018 that the total occupant counter of the user space is greater than zero, the receiving device can determine that there is an error in the count and can correct the error. For example, at 1020, the receiving device can update the historical room occupant count data of the user space by subtracting the value of the incorrect count from each relevant data point (e.g., each occupant count associated with a corresponding time period). Additionally, at 1022, the receiving device can zero out the total occupant counter by resetting it to zero. The receiving device can then exit program 1000 at 1024.

[0116] If it is determined at 1016 that the user space is occupied and it is determined at 1018 that the total occupant counter for the user space is greater than zero, the receiving device may determine that the count is not in error and may exit program 1000 at 1024. Also, once it is determined at 1012 that no occupant count has been received, the receiving device may also exit program 1000.

[0117] As described herein, the receiving device may be configured to receive occupant count information from more than one occupant count sensor (e.g., when the user space has multiple doorways, each doorway is monitored by a sensor). In those cases, the receiving device may be able to integrate the occupant count information received from multiple sensors and accordingly adjust the total occupant counter for the user space.

[0118] Figure 11 is a block diagram showing an example system controller 1100 (such as system controller 111 described herein) that may be configured to execute program 1000. System controller 1100 may include control circuitry 1102 for controlling the functions of system controller 1100, the functions including executing program 1000. Control circuitry 1102 may include one or more general-purpose processors, dedicated processors, conventional processors, digital signal processors (DSPs), microprocessors, integrated circuits, programmable logic devices (PLDs), application-specific integrated circuits (ASICs), etc. Control circuitry 1102 may perform signal encoding, data processing, image processing, power control, input / output processing, or any other function enabling system controller 1100 to perform the functions described herein. Control circuitry 1102 may store information in and / or retrieve information from memory 1104. Memory 1104 may include non-removable memory and / or removable memory. Non-removable memory may include random access memory (RAM), read-only memory (ROM), a hard disk, or any other type of non-removable memory. Removable memory may include a subscriber identity module (SIM) card, a memory stick, a memory card, or any other type of removable memory.

[0119] The system controller 1100 may include a communication circuit 1106 for transmitting and / or receiving information. The communication circuit 1106 may perform wireless and / or wired communication. The system controller 1100 may also or alternatively include a communication circuit 1108 for transmitting and / or receiving information. The communication circuit 1108 may perform wireless and / or wired communication. The communication circuits 1106 and 1108 may communicate with the control circuit 1102. The communication circuits 1106 and 1108 may include an RF transceiver or other communication modules capable of performing wireless communication via an antenna. The communication circuit 1106 and the communication circuit 1108 may be capable of performing communication via the same communication channel or different communication channels. For example, the communication circuit 1106 may be capable of communicating via a wireless communication channel (e.g., Near Field Communication (NFC), Thread, cellular, etc.) (e.g., with a network device, via a network, etc.), and the communication circuit 1108 may be capable of communicating via another wireless communication channel (e.g., or a proprietary communication channel such as CLEAR CONNECT TM )(e.g., with a control device and / or other devices in a load control system).

[0120] The control circuit 1102 may communicate with an LED indicator 1112 for providing an indication to a user. The control circuit 1102 may communicate with an actuator 1114 (e.g., one or more buttons), which may be actuated by the user to convey a user selection to the control circuit 1102. For example, the actuator 1114 may be actuated to place the control circuit 1102 in an association mode and / or convey an association message from the system controller 1100.

[0121] Each of the modules within the system controller 1100 may be powered by a power supply 1116. For example, the power supply 1116 may include an AC power supply or a DC power supply. The power supply 1116 may generate a supply voltage V CC to power the modules within the system controller 1100.

[0122] Although the features and elements are described herein in specific combinations, each feature or element can be used alone or in any combination with other features and elements. For example, the functions described herein can be described as being performed by a control device such as a remote control device or a lighting device, but can similarly be performed by a hub device or a network device. The methods described herein can be implemented in a computer program, software, or firmware contained in a computer-readable medium executed by a computer or a processor. Examples of computer-readable media include electronic signals (sent via a wired or wireless connection) and computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, read-only memory (ROM), random access memory (RAM), removable disks, and optical media such as CD-ROM disks and digital versatile disks (DVDs).

Claims

1. A system controller configured to determine an occupant count of a space, the system controller comprising: a communication circuit configured to receive one or more first messages from a first sensor, the one or more first messages indicating a number of people entering or leaving the space; and a control circuit configured to: determine the occupant count of the space based on the one or more first messages, wherein the control circuit is configured to determine that the occupant count of the space has increased if the one or more first messages indicate that the number of people in the space has increased; and wherein the control circuit is configured to determine that the occupant count of the space has decreased if the one or more first messages indicate that the number of people in the space has decreased; determine whether the space is occupied based on an indication provided by a second sensor; and reset the occupant count of the space to zero based on a situation where the indication provided by the second sensor indicates that the space is not occupied and the occupant count of the space determined according to the one or more first messages is greater than zero.

2. The system controller according to claim 1, wherein the indication is obtained via the communication circuit in one or more second messages received from the second sensor.

3. The system controller according to claim 1, wherein the control circuit is further configured to maintain historical data including a plurality of data points, each data point indicating the occupant count of the space during various time periods.

4. The system controller according to claim 3, wherein the control circuit is further configured to adjust the historical data by resetting at least one data point in the historical data when a value of at least one data point in the historical data is greater than zero and the indication provided by the second sensor indicates that the space is not occupied.

5. The system controller according to claim 3, wherein the control circuit is further configured to determine that there is an error in the determination of the occupant count based on a situation where the occupant count of the space determined according to the one or more first messages is less than zero.

6. The system controller according to claim 5, wherein the control circuit is further configured to adjust the historical data by adding a value associated with the error to at least one data point of the historical data based on determining that there is an error in the determination of the occupant count.

7. The system controller according to claim 5, wherein the control circuit is further configured to reset the occupant count of the space to zero based on determining that there is an error in the determination of the occupant count.

8. The system controller according to claim 3, wherein the control circuit is further configured to determine that there is an error in the determination of the occupant count based on a situation where the indication provided by the second sensor indicates that the space is not occupied and the occupant count of the space determined based on the one or more first messages is greater than zero.

9. The system controller according to claim 8, wherein the control circuit is further configured to adjust the historical data by subtracting a value associated with the error from at least one data point of the historical data based on determining that there is an error in the determination of the occupant count.

10. The system controller according to claim 1, wherein the control circuit is further configured to: Based on an indication provided by the second sensor indicating that the space is occupied and the occupant count of the space determined based on the one or more first messages being greater than zero, determine that there is no error in the determination of the occupant count; and Based on determining that there is no error in the determination of the occupant count, maintain the occupant count.

11. A method for determining an occupant count of a space, the method comprises: Receiving one or more first messages that indicate the number of people entering or leaving the space; and Determining the occupant count of the space based on the one or more first messages, wherein determining the occupant count of the space includes determining that the occupant count of the space has increased if the one or more first messages indicate that the number of people in the space has increased; or determining the occupant count of the space includes determining that the occupant count of the space has decreased if the one or more first messages indicate that the number of people in the space has decreased; Based on the indication, determining whether the space is occupied; and Based on the indication indicating that the space is not occupied and the occupant count of the space determined according to the one or more first messages being greater than zero, resetting the occupant count of the space to zero.

12. The method according to claim 11, further comprises: Maintaining historical data including a plurality of data points, each data point indicating the occupant count of the space during various time periods; and When the value of at least one data point in the historical data is greater than zero and the indication indicates that the space is not occupied, adjusting the historical data by resetting the data point.

13. The method according to claim 11, further comprises: Based on the occupant count of the space determined according to the one or more first messages being less than zero, determining that there is an error in the determination of the occupant count; and Based on determining that there is an error in the determination of the occupant count, resetting the occupant count of the space to zero.

14. The method according to claim 11, further comprises: Maintaining historical data including a plurality of data points, each data point indicating the occupant count of the space during various time periods; Based on the indication indicating that the space is not occupied and the occupant count of the space determined according to the one or more first messages being greater than zero, determining that there is an error in the determination of the occupant count; and Based on determining that there is an error in the determination of the occupant count, adjusting the historical data by subtracting a value associated with the error from at least one data point of the historical data.

15. The method according to claim 11, further comprises: Based on the indication indicating that the space is occupied and the occupant count of the space determined according to the one or more first messages being greater than zero, determining that there is no error in the determination of the occupant count; and Based on determining that there is no error in the determination of the occupant count, maintaining the occupant count.

16. At least one computer-readable medium comprising instructions that, when executed by at least one control circuit, cause the at least one control circuit to: Receive one or more first messages, the one or more first messages indicating the number of people entering or leaving the space; and Determine an occupant count for the space based on the one or more first messages, wherein the instructions that, when executed by the at least one control circuit, cause the control circuit to determine the occupant count for the space include instructions that, when executed by the at least one control circuit, cause the at least one control circuit to perform the following operations: If the one or more first messages indicate that the number of people in the space has increased, determine that the occupant count for the space has increased; or if the one or more first messages indicate that the number of people in the space has decreased, determine that the occupant count for the space has decreased; Determine whether the space is occupied based on the indication; And Based on the indication that the space is not occupied and the occupant count for the space determined according to the one or more first messages is greater than zero, reset the occupant count for the space to zero.

17. The at least one computer-readable medium according to claim 16, wherein the instructions, when executed by the at least one control circuit, cause the at least one control circuit to: Maintain historical data including a plurality of data points, each data point indicating the occupant count for the space during various time periods; and When the value of at least one data point in the historical data is greater than zero and the indication indicates that the space is not occupied, adjust the historical data by resetting the data point.

18. The at least one computer-readable medium according to claim 16, wherein the instructions, when executed by the at least one control circuit, cause the at least one control circuit to: Based on the case that the occupant count for the space determined according to the one or more first messages is less than zero, determine that there is an error in the determination of the occupant count; and Based on determining that there is an error in the determination of the occupant count, reset the occupant count for the space to zero.

19. The at least one computer-readable medium according to claim 16, wherein the instructions, when executed by the at least one control circuit, cause the at least one control circuit to: Maintain historical data including a plurality of data points, each data point indicating the occupant count for the space during various time periods; Based on the indication that the space is not occupied and the occupant count for the space determined according to the one or more first messages is greater than zero, determine that there is an error in the determination of the occupant count; And Based on determining that there is an error in the determination of the occupant count, adjust the historical data by subtracting the value associated with the error from at least one data point of the historical data.

20. The at least one computer-readable medium according to claim 16, wherein the instructions, when executed by the at least one control circuit, cause the at least one control circuit to: In the case that it is indicated based on the indication that the space is occupied and the occupant count of the space determined based on the one or more first messages is greater than zero, determine that there is no error in the determination of the occupant count; and Based on determining that there is no error in the determination of the occupant count, maintain the occupant count.

21. An apparatus configured to detect occupants entering or exiting a space, the apparatus comprising: a detection circuit configured to detect the occupants in a coverage area of the space, generate one or more signals indicating positions of the occupants in the coverage area, and generate an occupant map indicating positions of the occupants; and a control circuit including a tracking filter, wherein the control circuit is configured to: receive the one or more signals from the detection circuit; determine initial coordinates of the occupants in the occupant map based on the one or more signals received from the detection circuit; use the tracking filter to adjust the initial coordinates to determine the positions of the occupants in the occupant map; determine movement of the occupants through a plurality of zones within the coverage area; and judge whether the occupants are entering or leaving the space based on the movement of the occupants through the plurality of zones within the coverage area.

22. The apparatus according to claim 21, wherein the tracking filter includes a Kalman tracking filter.

23. The apparatus according to claim 21, wherein the detection circuit includes a thermopile array having a plurality of thermosensitive elements.

24. The apparatus according to claim 23, wherein the one or more signals generated by the detection circuit include a two-dimensional (2D) thermal image of the coverage area, and wherein the positions of the occupants in the coverage area are indicated in the thermal image.

25. The apparatus according to claim 21, wherein the detection circuit includes a visible light sensing circuit having a camera.

26. The apparatus according to claim 25, wherein the one or more signals generated by the detection circuit include a two-dimensional (2D) image of the coverage area, and wherein the positions of the occupants in the coverage area are indicated in the image.

27. The apparatus according to claim 21, wherein the detection circuit includes a radar sensing circuit.

28. The apparatus according to claim 27, wherein the one or more signals generated by the detection circuit include a two-dimensional (2D) occupant map of the coverage area, and wherein the positions of the occupants in the coverage area are indicated in the occupant map.

29. The apparatus according to claim 21, wherein the control circuit is configured to determine that the occupants have entered the space in response to determining that the occupants have moved through the plurality of zones in a first order.

30. The apparatus according to claim 29, wherein the control circuit is configured to determine that the occupants have exited the space in response to determining that the occupants have moved through the plurality of zones in a second order.

31. The device according to claim 30, wherein the plurality of zones includes a first zone, a second zone, and a third zone, the first zone includes an area outside the entry position of the space, the second zone includes the entry position, the third zone includes an area inside the entry position, the control circuit is configured to determine that the occupant has entered the space in response to determining that the occupant has moved from the first zone through the second zone to the third zone, and the control circuit is further configured to determine that the occupant has exited the space in response to determining that the occupant has moved from the third zone through the second zone to the first zone.

32. The device according to claim 21, wherein the control circuit is further configured to determine that the occupant has entered an idle state based on the lack of movement of the occupant or in response to the loss of detection of the occupant.

33. The device according to claim 32, wherein the control circuit is configured to determine that the occupant has entered the idle state based on the lack of movement of the occupant during a preconfigured time period.

34. The device according to claim 33, wherein the control circuit is configured to assign an identifier to the occupant in response to detecting that the occupant has entered one of the plurality of zones from the idle state, and the control circuit is further configured to use the identifier to track the movement of the occupant through the plurality of zones.

35. The device according to claim 34, wherein the control circuit is configured to disassociate the occupant from the identifier in response to detecting that the occupant has moved from one of the plurality of zones to the idle state.

36. The device according to claim 21, wherein the control circuit is further configured to maintain an occupant count of the space, the control circuit is configured to increment the occupant count in response to determining that the occupant has entered the space, and to decrement the occupant count in response to determining that the occupant has exited the space.

37. The device according to claim 36, further comprising a communication circuit, wherein the control circuit is configured to send a message indicating the occupant count via the communication circuit.

38. The device according to claim 37, wherein the control circuit is further configured to reset the occupant count to zero after the message is sent.

39. The device according to claim 37, wherein the message is sent to a controller external to the device.

40. The device according to claim 36, further comprising a communication circuit, the communication circuit being configured to receive a signal indicating the occupancy status of the space from an occupancy sensor.

41. The device according to claim 40, wherein the control circuit is further configured to set the occupant count to zero when the signal received from the occupancy sensor indicates that the space is unoccupied.

42. The device according to claim 36, wherein the control circuit is further configured to maintain historical data indicating the respective occupant counts of the space during various time periods.

43. A device configured to detect an occupant entering or exiting a space, the device comprising: a detection circuit configured to detect the occupant in a coverage area of the space and generate one or more signals indicative of a position of the occupant in the coverage area; and a control circuit configured to: receive the one or more signals from the detection circuit; determine a movement of the occupant through a plurality of zones of the coverage area based on the one or more signals, wherein the plurality of zones includes a first zone, a second zone, and a third zone, the first zone including an area outside the space and adjacent to an entry position of the space, the second zone including an area at the entry position, and the third zone including an area inside the space and adjacent to the entry position; determine that the occupant has entered the space in response to determining that the occupant has moved from the first zone through the second zone to the third zone; and determine that the occupant has exited the space in response to determining that the occupant has moved from the third zone through the second zone to the first zone.

44. The device of claim 43, wherein the detection circuit is configured to generate an occupant map indicative of the position of the occupant relative to the plurality of zones.

45. The device of claim 44, wherein the control circuit is configured to determine the position of the occupant relative to the plurality of zones based on coordinates of the occupant in the occupant map.

46. The device of claim 45, wherein the control circuit includes a Kalman tracking filter, and the control circuit is configured to use the Kalman tracking filter to determine the coordinates of the occupant.

47. The device of claim 46, wherein the control circuit is configured to determine preliminary coordinates of the occupant in the occupant map based on the one or more signals received from the detection circuit and use the Kalman tracking filter to adjust the preliminary coordinates.

48. The device of claim 43, wherein the detection circuit includes a thermopile array having a plurality of thermosensitive elements.

49. The device of claim 48, wherein the one or more signals generated by the detection circuit include a two-dimensional (2D) thermal image of the coverage area, and wherein the position of the occupant in the coverage area is indicated in the thermal image.

50. The device of claim 43, wherein the detection circuit includes a visible light sensing circuit having a camera.

51. The device of claim 50, wherein the one or more signals generated by the detection circuit include a two-dimensional (2D) image of the coverage area, and wherein the position of the occupant in the coverage area is indicated in the image.

52. The device of claim 43, wherein the detection circuit includes a radar sensing circuit.

53. The apparatus according to claim 52, wherein the one or more signals generated by the detection circuit include a two-dimensional (2D) occupant map of the coverage area, and wherein the position of the occupant in the coverage area relative to the plurality of zones is indicated in the occupant map.

54. The apparatus according to claim 43, wherein the control circuit is further configured to determine that the occupant has entered an idle state based on a lack of movement of the occupant or in response to a loss of detection of the occupant.

55. The apparatus according to claim 54, wherein the control circuit is configured to determine that the occupant has entered the idle state based on a lack of movement of the occupant during a preconfigured time period.

56. The apparatus according to claim 55, wherein the control circuit is configured to assign an identifier to the occupant in response to detecting that the occupant has entered one of the plurality of zones from the idle state, and the control circuit is further configured to use the identifier to track the movement of the occupant through the plurality of zones.

57. The apparatus according to claim 56, wherein the control circuit is configured to disassociate the occupant from the identifier in response to detecting that the occupant has moved from one of the plurality of zones to the idle state.

58. The apparatus according to claim 43, wherein the control circuit is further configured to maintain an occupant count for the space, and the control circuit is configured to increment the occupant count in response to determining that the occupant has entered the space and to decrement the occupant count in response to determining that the occupant has exited the space.

59. The apparatus according to claim 58, further comprising a communication circuit, wherein the control circuit is configured to send a message indicating the occupant count via the communication circuit.

60. The apparatus according to claim 59, wherein the control circuit is further configured to reset the occupant count to zero after the message is sent.

61. The apparatus according to claim 58, further comprising a communication circuit configured to receive a signal indicating the occupancy status of the space from an occupancy sensor; wherein the control circuit is further configured to set the occupant count to zero when the signal received from the occupancy sensor indicates that the space is unoccupied.

62. The apparatus according to claim 58, wherein the control circuit is further configured to maintain historical data indicating the respective occupant counts of the space during various time periods.

63. An apparatus configured to detect a person entering or exiting a space, the apparatus comprising: a detection circuit including at least two pyroelectric infrared (PIR) elements connected in an anti-series configuration, the detection circuit being configured to generate a detection signal in response to detecting a person entering or exiting the space; and a control circuit configured to: collect a plurality of samples of the detection signal generated by the detection circuit; Identify a first peak sample of a first polarity and a second peak sample of a second polarity in the plurality of samples, the first polarity and the second polarity being opposite to each other; And Determine whether a person has entered or exited the space based on the order in which the detection circuit generates the first peak sample and the second peak sample, wherein if the first peak sample is generated before the second peak sample, it is determined that the person has entered the space, and wherein if the second peak sample is generated before the first peak sample, it is determined that the person has exited the space.

64. The apparatus according to claim 63, wherein the first polarity is one of a positive polarity or a negative polarity, and the second polarity is the other of the positive polarity or the negative polarity.

65. The apparatus according to claim 64, wherein the control circuit is configured to identify the first peak sample including the control circuit being configured to determine that the amplitude of the first peak sample is higher than a first threshold, and wherein the control circuit is configured to identify the second peak sample including the control circuit being configured to determine that the amplitude of the second peak sample is higher than a second threshold.

66. The apparatus according to claim 65, wherein the absolute value of the first threshold is different from the absolute value of the second threshold.

67. The apparatus according to claim 63, wherein the control circuit is configured to start collecting the plurality of samples in response to determining that motion has been detected by the detection circuit.

68. The apparatus according to claim 67, wherein the control circuit is configured to determine that motion has been detected by the detection circuit in response to determining that the amplitude of a detection signal generated by the detection circuit exceeds a threshold.

69. The apparatus according to claim 63, wherein the control circuit is configured to collect the plurality of samples within a sampling period.

70. The apparatus according to claim 69, wherein the duration of the sampling period is predetermined.

71. The apparatus according to claim 69, wherein the control circuit is configured to collect a predetermined number of detection signals within the sampling period.

72. The apparatus according to claim 69, wherein when determining whether the person has entered or exited the space, the control circuit is configured to pause collecting the detection signals generated by the detection circuit during a second time period.

73. The apparatus according to claim 72, wherein after the second time period, the control circuit is configured to determine whether the detection circuit has detected motion, and if no motion is detected, enter a sleep mode.

74. The apparatus according to claim 63, wherein the apparatus is configured to be installed adjacent to a doorway of the space.

75. The apparatus according to claim 74, wherein the apparatus is configured to be installed in an upper corner of the doorway.

76. The apparatus according to claim 63, further comprising a switch that can be manipulated to indicate the installation orientation of the apparatus; Wherein when the switch is in the first position, the control circuit is configured to determine that the person has entered the space if the first peak sample is generated before the second peak sample, and to determine that the person has exited the space if the second peak sample is generated before the first peak sample; and Wherein when the switch is in the second position, the control circuit is configured to determine that the person has entered the space if the second peak sample is generated before the first peak sample, and to determine that the person has exited the space if the first peak sample is generated before the second peak sample.

77. The apparatus according to claim 63, wherein the control circuit is further configured to determine a count of the number of occupants in the space, the control circuit being configured to increment the count in response to determining that the person has entered the space and to decrement the count in response to determining that the person has exited the space.

78. The apparatus according to claim 77, further comprising a communication circuit, wherein the control circuit is configured to send a message via the communication circuit indicating the count of the number of occupants in the space.

79. The apparatus according to claim 78, wherein the control circuit is further configured to reset the count of the number of occupants in the space to zero after the message is sent.

80. The apparatus according to claim 78, wherein the message is sent to a controller external to the apparatus.

81. The apparatus according to claim 77, further comprising a communication circuit, the communication circuit being configured to receive an indication from an occupancy sensor indicating the occupancy status of the space.

82. The apparatus according to claim 81, wherein the control circuit is further configured to set the count of the number of occupants to zero when the indication received from the occupancy sensor indicates that the space is unoccupied.

83. The apparatus according to claim 82, wherein the control circuit is further configured to maintain historical data including a plurality of data points, each data point indicating the count of the number of occupants in the space during a corresponding time period.

84. The apparatus according to claim 83, wherein the control circuit is configured to adjust the historical data by resetting at least one of the data points of the historical data to zero when the data point has a value greater than zero and the indication received from the occupancy sensor indicates that the space is unoccupied.

85. The apparatus according to claim 77, further comprising a communication circuit, the communication circuit being configured to receive a signal from a second device, the signal indicating the number of people who have entered or exited the space.

86. The apparatus according to claim 85, wherein the control circuit is further configured to add or subtract the number of people from the count of the number of occupants determined by the control circuit.

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