FIELD OF THE INVENTION

This application relates to the field of asset tracking systems and, more particularly, to a sensor management system of a group of radio frequency (RF) sensors for asset tracking.

BACKGROUND

Building management systems encompass a wide variety of equipment that aid in monitoring and controlling building operations. Building management systems often include one or more environmental control sub-systems, such as security, fire safety, lighting, heating, ventilation, and air conditioning (“HVAC”) systems. The systems may also provide non-environmental control features for management and occupants of a building, such as indoor location tracking of assets (including occupants).

Sensor management systems may include sensors positioned throughout a structure to detect building activity, such as occupancy detection and asset tracking. Unfortunately, these sensors might be installed improperly, recorded inaccurately, or otherwise fail to operate according to specifications. For example, a technician may install a sensor improperly, interchange the locations of two or more sensors, or mislabel a floor or ceiling plan intended to reflect sensor locations. Sensors may also lack sufficient precision since different structures may have different objects and conditions. Besides, sensors may become misaligned or otherwise malfunction over time. After installation or whenever issues are observed, a technician is sent on-site at the structure to perform visual observations and manual tasks to identify problems and address them. Such solutions can be time-consuming, costly, and produce mediocre or even erroneous results. Detection of malfunctioning sensors or out of specification conditions also presents a challenge because of the sensor management system's statistical nature. The system's performance could deteriorate over time due to the sub-optimum performance of a small number of sensors without detection.

SUMMARY

In accordance with one embodiment of the disclosure, a sensor management system approach for asset tracking is provided. The method measures radio frequency (RF) loss between sensors, compares the measurement to an expected RF loss between the sensors, and determines whether the difference between the measured and expected values indicates a problem with one or more sensors. For example, the difference between the measured and expected values may indicate that a sensor is positioned improperly at its assigned location, recorded inaccurately by a corresponding area plan, or operating incorrectly. When a problem with a sensor is indicated, then there are a number of actions that may be taken to compensate for the differential and/or address issues associated with the differential.

One aspect is a sensor management system comprising a first sensor, a second sensor, and an upstream device. The first sensor is positioned at a first location and transmits a wireless signal. The second sensor is positioned at a second location within a reception range of the wireless signal, and the second sensor detects the wireless signal. The first and second locations of the first and second sensors correspond to an expected wireless signal of the first sensor. The upstream device is configured to perform an action in response to determining that a difference between the detected wireless signal and the expected wireless signal exceeds a predetermined threshold.

Another aspect is a method of a sensor management system. The first location of the first sensor and the second location of the second sensor are identified. The first and second locations of the first and second sensors correspond to an expected wireless signal of the first sensor. A wireless signal is transmitted from the first sensor. The wireless signal is detected at the second sensor, the second location being within a reception range of the wireless signal. The upstream device performs an action in response to determining that a difference between the detected wireless signal and the expected wireless signal exceeds a predetermined threshold.

Yet another aspect is a sensor management system comprising a first sensor, a second sensor, and an upstream device. The first sensor is positioned at a first location and transmits multiple wireless signals. The second sensor is positioned at a second location within a reception range of the wireless signals, and the second sensor detects some or all of the wireless signals. The upstream device is configured to perform an action in response to determining that a difference between a detected statistical feature and an expected statistical feature exceeds a predetermined threshold. The detected statistical feature is based on at least some of the wireless signals. The expected statistical feature is based on first and second locations of the first and second sensors, and the expected statistical feature is determined independent of the wireless signals.

Still another aspect is a method of a sensor management system. The first location of the first sensor and the second location of the second sensor are identified. The first and second locations of the first and second sensors correspond to an expected statistical feature of the first sensor. Multiple wireless signals are transmitted from the first sensor, and the second location is within a reception range of the wireless signals. Some or all of the wireless signals are detected at the second sensor. A detected statistical feature is determined based on at least some of wireless signals. An expected statistical feature is determined based on the first and second locations of the first and second sensors, and the expected statistical feature is determined independent of the wireless signals. The upstream device performs an action in response to determining that a difference between the detected statistical feature and the expected statistical feature exceeds a predetermined threshold.

The above described features and advantages and others will become more readily apparent to those of ordinary skill in the art by reference to the following detailed description and accompanying drawings. While it would be desirable to provide one or more of these or other advantageous features, the teachings disclosed herein extend to those embodiments that fall within the scope of the appended claims, regardless of whether they accomplish one or more of the advantages as mentioned above.

