Patent Description:
Wireless tracking devices are employed to track locations and conditions of various assets. Such wireless tracking devices are often mounted on the assets or placed in the vicinity of the assets. As the assets are transported or are exposed to changing environment, the wireless tracking devices detect the location and/or sense changing conditions of the assets. Then, the wireless tracking devices send wireless messages indicating the locations and/or other environment parameters of the assets to a remote monitoring station. Based on the collected information, the remote monitoring station may prompt actions such as sending reports to customers, taking remedial actions to prevent deterioration of the assets, and initiating retrieval of stolen assets.

Generally, a wireless tracking device includes various components and sensors enclosed in a casing. The casing provides robust protection against dirt or other contaminants as well as external forces. The wireless tracking device may include various components such as temperature sensors, humidity sensors, light sensors, accelerometers, gyroscopes, magnetometers, controllers, GPS modules and wireless communication modules. These components or modules may consume power during their operations. Some wireless tracking devices include sensors to accommodate diverse applications whereas other wireless tracking devices are equipped with fewer types of sensors selected for specific applications.

To provide power to these components and modules, a wireless tracking device includes a restricted power source such as batteries or solar cells. In many cases, the wireless tracking devices operate in environments where access to other power sources is unavailable. The wireless tracking devices often rely on the restricted power source for their operations. Hence, to increase the operable time of a wireless tracking device, it is necessary to reduce the power consumption of its components. <CIT> relates to a power-saving position tracking device which includes a central processing unit; a short-distance wireless communication unit, for establishing a wireless connection with a short-distance wireless transceiver to perform a position tracking; a GPS receiving unit, for receiving a satellite signal for performing a position tracking and outputting position information; a mobile communication unit, for transmitting the position information to a remote control center.

According to aspects of the present invention, there are provided a method, a device and a computer-readable storage medium as set forth in the appended claims. Other features of the invention will be apparent from the dependent claims, the attached drawings and the description which follows. Embodiments relate to a wireless tracking device that operates in at least two modes of operation to reduce power consumption. In a hibernation mode, the wireless tracking device turns off the components consuming a large amount of power to preserve power. The wireless tracking device may be intermittently placed in an active mode where components consuming a large amount of power are turned on. When an event is detected, the wireless tracking device switches from the hibernation mode to the active mode to track locations or detect changes in its environment. The wireless tracking device may revert back to the hibernation mode if no further events are detected or a preset time is elapsed.

The features and advantages described in the specification are not all inclusive and, in particular, many additional features and advantages will be apparent to one of ordinary skill in the art in view of the drawings, specification, and claims. Moreover, it should be noted that the language used in the specification has been principally selected for readability and instructional purposes.

Embodiments described herein provide a wireless tracking device operating in at least two modes to reduce power consumption and extend the operable time of the wireless tracking device. In an active mode, the wireless tracking device activates a communication module for communicating with a remote device via wireless connection or other components that consume a large amount of power. In a hibernation mode, the components or modules in the wireless tracking device are shut down to reduce power consumption. The wireless tracking device may switch from the hibernation mode to the active mode selectively when a predetermine event is detected.

<FIG> is a diagram illustrating a wireless tracking device <NUM> in a moving vehicle <NUM>. The wireless tracking device <NUM> may be located in a cargo <NUM> being transported by the vehicle <NUM>. In this example, the wireless tracking device <NUM> tracks its location using a Global Positioning System (GPS) module that detects signals from satellites <NUM>. The wireless tracking device <NUM> inside cargoes <NUM> also communicates with a remote monitoring station <NUM> over a wireless communication channel <NUM>.

The vehicle <NUM> may carry multiple units of cargoes <NUM> where each unit is equipped with a wireless tracking device <NUM>. Each cargo <NUM> may be destined to a different target location. As a cargo <NUM> is transported, a wireless tracking device <NUM> attached to the cargo <NUM> tracks the location of the cargo <NUM> and environmental conditions surrounding the cargo <NUM>. Then, the location and other environment information are transmitted to a remote monitoring station <NUM> in a wireless message.

The environment conditions detected by the wireless tracking device <NUM> may include, but are not limited to, temperature, humidity, light, sound, vibration, tilt, shock, certain types of chemical compounds, pressure, magnetic field, smoke, and movements. The wireless tracking device <NUM> may be configured to detect some or all of these environment conditions.

The use of wireless tracking device <NUM> is not limited to moving cargoes <NUM>. The wireless tracking device <NUM> may be used for an object that remains stationary. In such case, the wireless tracking device <NUM> is used primarily for detecting environmental conditions surrounding the wireless tracking device <NUM>. Further, the vehicle <NUM> is merely an example of a mode of transport. The wireless tracking device <NUM> and the cargo <NUM> may be transported using other modes of transport such as vessels, trains or airplanes. Cargo <NUM> may be any asset transported in commerce, including among other
things, envelopes, parcels, express packages, boxes, palettes, containers, crates, and specialty goods and materials.

The wireless tracking device <NUM> operates in two distinct modes: an active mode and a hibernation mode. In the active mode, most or all of the components in the wireless tracking device <NUM> are activated. The activated components include high power consumption components such as a wireless communication module. In the hibernation mode, a fewer number of components or modules in the wireless tracking device <NUM> are activated. Other components or modules are turned off to preserve power. The wireless tracking device <NUM> switches between the active mode and the hibernation mode in response to detecting or in anticipation of an event.

<FIG> is a block diagram illustrating the wireless tracking device <NUM>, according to one embodiment. The wireless tracking device <NUM> includes, among other components, at least one controller such as high power system controller <NUM> or a low power system controller <NUM>, a Global Positioning System (GPS) module <NUM>, a wireless communication module <NUM>, and at least one sensor <NUM> through <NUM>. The wireless tracking device <NUM> may also include a power manager <NUM>, a restricted power source <NUM>, and other components not illustrated in <FIG> such as an input module or speakers.

The wireless tracking device <NUM> of <FIG> has a dual processor structure including two controllers: the high power system controller <NUM> and the low power system controller <NUM>. By using the two controllers, the power consumption is reduced in the hibernation mode while obtaining high computing capacity during the active mode. When the wireless tracking device <NUM> is placed in the active mode, the high power system controller <NUM> becomes active and performs power intensive operations. Such power intensive operations include, for example, determining the location of the wireless tracking device <NUM> using the GPS module <NUM> and communicating wirelessly with the remote monitoring station <NUM> via the wireless communication module <NUM>. During the hibernation mode, the wireless tracking device <NUM>, the GPS module <NUM> and the wireless communication module <NUM> may be disabled to reduce power consumption.

In one embodiment, the low power system controller <NUM> is embodied as ATMEGA <NUM>-bit microcontroller (available from Atmel Corporation of San Jose, California), Energy Micro Gecko micro controller (available from Energy Micro AS of Oslo, Norway) or SAM3 (available from Atmel Corporation of San Jose, California). Examples of the high power system controllers <NUM> include the Marvell PXA series, ARM11, Cortex-A series, or TI DSPs.

In one embodiment, the high power system controller <NUM> controls the operation of the GPS module <NUM> and the wireless communication module <NUM>. When the high power system controller <NUM> is turned off, the GPS module <NUM> and the wireless communication module <NUM> are also deactivated to reduce power consumption.

The low power system controller <NUM> remains active in both the active mode and the hibernation mode. The low power system controller <NUM> determines whether to place the wireless tracking device <NUM> in the active mode or the hibernation mode, as described below in detail with reference to <FIG>. In one embodiment, the low power system controller <NUM> is connected to low-power consumption components such as sensors <NUM> through <NUM>. The low power system controller <NUM> continues to receive sensor signals <NUM> through <NUM> even in the hibernation mode to avoid losing meaningful sensor data. However, the sampling rate and the sensitivity of the sensor signals <NUM> through <NUM> may be reduced in the hibernation mode to reduce power consumption.

The low power system controller <NUM> sends commands to the power manager <NUM> to turn on or off power provided to the high power system controller <NUM>. When the low power system controller <NUM> issues a command indicating that the wireless tracking device <NUM> should be placed in the hibernation mode, the power manager <NUM> turns off power to the high power system controller <NUM>.

The power manager <NUM> is connected to the power source <NUM>. The power source <NUM> may be a restricted power source such as a battery or solar cells. In one embodiment, the power source <NUM> includes a charge circuit. The charger circuit receives charging electric current via port <NUM> to charge the battery.

The GPS module <NUM> may include an antenna and a signal processing unit for receiving GPS signals. The GPS module <NUM> operates under the command of the high power system controller <NUM> to identify the current location of the wireless tracking device <NUM>. In one embodiment, the GPS module <NUM> embodies A-GPS (Assisted GPS) which improves the startup performance or TTFF (Time To First Fix) by utilizing data received via the wireless communication module <NUM>. For this purpose, the GPS module <NUM> receives ephemeris data from a remote server via the wireless communication module <NUM>.

The wireless communication module <NUM> includes a transceiver for sending or receiving data to or from the remote monitoring station <NUM>. The wireless communication module <NUM> may establish communicating using various communication protocols such as GSM, WiFi, Bluetooth, Zigbee, UMTS/HSxPA, 3GPP Long Term Evolution (LTE) and WiMAX.

The sensors <NUM> through <NUM> detect various physical properties or conditions and send the sensor signals <NUM> through <NUM> to the low power system controller <NUM>. The sensors in the wireless tracking device <NUM> include, for example, an accelerometer <NUM>, a light sensor <NUM>, a temperature sensor <NUM> and a humidity sensor <NUM>. The wireless tracking device <NUM> may include other types of sensors to detect different physical properties or conditions.

The high power system controller <NUM> and the low power system controller <NUM> communicate over a data bridge <NUM>. The high power system controller <NUM> may receive the sensor data from the low power system controller <NUM>, compiles the sensor data into a message, and sends the message to the remote monitoring station <NUM> via the wireless communication module <NUM>. On the other hand, the low power system controller <NUM> receives location information (based on the GPS module <NUM>) from the high power system controller <NUM> or any data (e.g., control commands) received from the remote monitoring station <NUM> via the data bridge <NUM>.

The high power system controller <NUM> and the low power system controller <NUM> include computer readable storage medium <NUM> and computer readable storage medium <NUM>, respectively. The computer readable storage medium <NUM> stores instructions for execution by the high power system controller <NUM>. The computer readable storage medium <NUM> stores instructions for execution by the low power system controller <NUM>. In one embodiment, the computer readable storage media <NUM>, <NUM> are embodied as a non-volatile memory device (e.g., EEPROM (Electrically Erasable Programmable Read-Only Memory) or a flash memory), a volatile memory device (e.g., Random Access Memory (RAM)) or a combination of both.

The embodiment of <FIG> is merely illustrative. Wireless tracking devices of different configuration may also be used. For example, a single processor architecture including only a single controller may be used. In the single processor architecture, all the components and sensors are connected and controlled by the single controller. In one embodiment, the single controller may operate in two modes: an active mode with a higher processing capacity, and a hibernation mode with reduced power consumption. In yet another embodiment, the high power system controller <NUM> and the low power system controller <NUM> could also be implemented in a multi core configuration or via virtualization with a single core.

<FIG> is a diagram illustrating a method of placing the wireless tracking device <NUM> in the active mode or the hibernation mode, according to one embodiment. The low power system controller <NUM> receives <NUM> the sensor signals <NUM> through <NUM> from the sensors <NUM> through <NUM> or the location of the wireless tracking device <NUM> from the GPS module <NUM>. For this purpose, the low power system controller <NUM> stores instructions for switching power modes in the computer readable storage medium <NUM>.

Then, the low power system controller <NUM> determines <NUM> if one or more of predetermined events are detected to place the wireless tracking device <NUM> in the active mode. Various types of events may be used for switching the modes. The wireless tracking device <NUM> is placed in the active mode when events of interest to a user are likely to occur or continue whereas the wireless tracking device <NUM> is placed in the hibernation mode when the events of interest are unlikely to occur or continue.

If one or more of predetermined events are detected, the low power system controller <NUM> places or maintains <NUM> the wireless tracking device <NUM> in the active mode. In one embodiment, the predetermined events include detection of movement of the wireless tracking device <NUM> by the accelerometer sensor or the speed of the wireless tracking device <NUM> above a threshold. While the wireless tracking device <NUM> is in the active mode, the low power system controller <NUM> may monitor changes in the location based on GPS signals from the current active mode session to determine the speed of the wireless tracking device <NUM>. Alternatively, the low power system controller <NUM> may compare the location of the wireless tracking device <NUM> with the location of the wireless tracking device <NUM> in the previous active mode session to determine the speed of the wireless tracking device <NUM>.

In one embodiment, the wireless tracking device <NUM> is placed or maintained <NUM> in the active mode when external events are detected via the sensors <NUM> through <NUM>. The external events refer to events occurring outside the wireless tracking device <NUM> and may include, for example, (i) a motion of the wireless tracking device <NUM> (as detected by the accelerometer <NUM>), (ii) changes from indoor to outdoor or vice versa (as detected by the light sensor <NUM>), (iii) changes in temperature (as detected by the temperature sensor <NUM>), (iv) changes in the humidity (as detected by the humidity sensor <NUM>), and (v) detection of certain chemical compounds or smoke. If such external events are detected, events of interest are likely to ensue or continue. Hence, the wireless tracking device <NUM> is maintained in the active mode to capture data associated with the external events.

In one embodiment, the event may be passing of time or a signal from a timer indicating a predetermined time. The low power system controller <NUM> may periodically switch the wireless tracking device <NUM> to the active mode. The low power system controller <NUM> switches to the active mode more often or stays in the active mode for a longer time when the accelerometer <NUM> sends a signal <NUM> indicating the movement of the wireless tracking device <NUM>. The wireless tracking device <NUM> is more likely to experience significant changes in the environment when the wireless tracking device <NUM> is being transported. Hence, the wireless tracking device <NUM> is placed in the active mode to send more frequent updates to the remote monitoring station <NUM>. The low power system controller <NUM> may switch back to the hibernation mode if a certain amount of time is elapsed.

If no significant events are detected for a predetermined amount of time, the low power system controller <NUM> places or maintains <NUM> the wireless tracking device <NUM> in the hibernation mode. The wireless tracking device <NUM> is unlikely to encounter significant changes when predetermined events are not detected. Hence, the low power system controller <NUM> places the wireless tracking device <NUM> in the hibernation mode to preserve power.

After placing or maintaining <NUM>, <NUM> the wireless tracking device <NUM> in the active mode or the hibernation mode, the process returns to receiving <NUM> the sensor signals or locations.

In one embodiment, more significant events in the sensor signals or more drastic changes in locations are needed to switch the wireless tracking device <NUM> from the hibernation mode to the active mode compared to the events for maintaining the wireless tracking device <NUM> in the active mode. The sensitivity of sensors (e.g., the accelerometer <NUM>) is lowered in the hibernation mode to avoid the wireless tracking device <NUM> from waking up to the active mode due to minor variances in the sensor signals.

In contrast, if the wireless tracking device <NUM> is currently in the active mode, the sensitivity of the sensors is increased. The fact that the wireless tracking device <NUM> is currently in the active mode indicates that the wireless tracking device <NUM> is likely to experience other significant events. By adjusting the sensitivity to sensor signals and location changes based on the mode of the wireless tracking device <NUM>, the wireless tracking device <NUM> may be prevented from waking up due to insignificant events while retaining the chance of detecting significant events.

The wireless tracking device <NUM> may move through a geographic region where wireless communication is not available or where reception of the wireless communication is poor. In one embodiment, such geographic region may be established as a goefence in which the wireless tracking device <NUM> does not attempt to communicate with the remote monitoring station <NUM>. A geofence herein refers to a geographical area artificially defined for one purpose or the other. By avoiding communication in the geofenced area, power consumption associated with attempting to communicate with the remote monitoring station <NUM> in a poor reception area can be avoided. In addition, this feature may be used to satisfy certain regulatory requirements about RF transmissions in particular areas.

<FIG> is a diagram illustrating a geofence <NUM> associated with wireless communication of the wireless tracking device <NUM> where wireless communication is unavailable or the signal reception is poor. Within the geofence <NUM>, the wireless tracking device <NUM> does not attempt to communicate with the remote monitoring station <NUM>. Data collected for events while the wireless tracking device <NUM> remains in the geofence <NUM> are stored and then transmitted to the remote monitoring station <NUM> when the wireless tracking device <NUM> leaves the geofence <NUM>. In <FIG>, region <NUM> represents an area where the wireless communication of the wireless tracking device <NUM> is available with good reception.

In the example of <FIG>, the wireless tracking device <NUM> moves from point X to point Z. While the wireless tracking device <NUM> is in the region <NUM> and distanced away from the geofence <NUM> (represented by line X-Y), the wireless tracking device <NUM> switches to the active mode at a first frequency (i.e. sampling interval). As the wireless tracking device <NUM> approaches the geofence <NUM> (represented by line Y-Z), the wireless tracking device <NUM> switches to the active mode at a second frequency higher than the first frequency (i.e., the wireless tracking device <NUM> is placed in the active mode more often). For example, the wireless tracking device <NUM> may switch from the hibernation mode to the active mode every <NUM> minutes when the wireless tracking device <NUM> is traveling from point X to point Y. The same wireless tracking device <NUM> may switch from the hibernation mode to the active mode every <NUM> minutes when the wireless tracking device <NUM> is traveling from point Y to point Z.

In one embodiment, the wireless tracking device <NUM> gradually switches to active mode with increasing frequency or stays in the active mode for a longer time as the wireless tracking device <NUM> approaches the geofence <NUM>.

<FIG> is a flowchart illustrating the process of switching between the active mode and the hibernation mode when the geofence <NUM> is implemented. First, the wireless tracking device <NUM> switches <NUM> to the active mode. In the active mode, the low power system controller <NUM> determines <NUM> the location, the moving direction and the speed of the wireless tracking device <NUM>. Based on the location, the moving direction and the speed of the wireless tracking device <NUM>, the wireless tracking device <NUM> computes <NUM> the estimated time that the wireless tracking device <NUM> will arrive at the region of the geofence <NUM>.

Based on the estimated time of arrival at the region of the geofence <NUM>, the interval for switching to the active mode is determined <NUM>. After any process in the current active mode is finished or preset time for staying in the active mode is elapsed, the wireless tracking device <NUM> switches <NUM> to the hibernation mode.

Then the wireless tracking device <NUM> determines <NUM> whether it is time to switch to the active mode based on the computed interval. If it is time to switch to the active mode, the process proceeds to switch <NUM> the wireless tracking device <NUM> to the active mode and repeats the subsequent steps. If it is not yet time to switch to the active mode, the wireless tracking device <NUM> remains <NUM> in the hibernation mode.

Claim 1:
A method of operating a wireless tracking device (<NUM>) comprising a locating device (<NUM>), at least one sensor (<NUM>) and a communication module (<NUM>), the method comprising:
determining, by the locating device (<NUM>), a geographic location of the wireless tracking device (<NUM>);
generating, by the at least one sensor (<NUM>), a sensor signal (<NUM>), the sensor signal (<NUM>) representing a condition or a property associated with the wireless tracking device (<NUM>);
generating a message indicating the geographic location and the condition or the property associated with the wireless tracking device (<NUM>),
placing the wireless tracking device (<NUM>) in a hibernation mode,
lowering a sensitivity for detecting an event by the at least one sensor (<NUM>) to a first sensitivity while the wireless tracking device (<NUM>) is in the hibernation mode, and
switching the wireless tracking device (<NUM>) to an active mode in response to receiving, from the at least one sensor (<NUM>), a sensor signal (<NUM>) indicating a change exceeding the first sensitivity corresponding to a first external event, wherein the active mode consumes more power than the hibernation mode; and
sending, by the communication module (<NUM>), the message via a wireless network, wherein the communication module (<NUM>) is configured to operate in the active mode but not in the hibernation mode.