Portable Sensor Association Using Motion and Signal Strength
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Solution Overview
Problem
Existing building management systems require manual user intervention to associate portable sensor devices with control devices when moving to a new room, and the limited energy storage of portable sensor devices necessitates power conservation.
Innovation Solution
A method and system where a portable sensor device automatically associates with a stationary control device by changing transmission frequencies based on movement detection and signal strength, allowing for energy-efficient communication and eliminating the need for manual intervention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If the portable sensor device transmits signals frequently to track movement and enable automatic association, then the automation and tracking capability is improved, but the energy consumption increases
Solution Approach 1:
The portable sensor device dynamically adjusts its transmission frequency based on its operational state. When movement is detected, the device switches to a second mode with higher transmission frequency (second frequency) to enable tracking and automatic association. When stationary, it switches to a first mode with lower transmission frequency to conserve energy. This dynamic adaptation resolves the contradiction between automation and energy consumption.
Solution Approach 2:
The system changes the transmission frequency parameter according to the device's movement state. In the first mode, signals are transmitted at a lower frequency to save battery power. Upon detecting movement, the system transitions to the second mode where signals are transmitted at a higher frequency, enabling the control devices to track the portable sensor's location and perform automatic association without manual intervention.
2Measurement precision
If the portable sensor device remains in high-frequency transmission mode to ensure accurate tracking and association, then the tracking precision is improved, but the battery life decreases
Solution Approach 1:
The transmission frequency is made dynamic rather than static. The device automatically switches between low-frequency mode (first mode) when stationary to extend battery life, and high-frequency mode (second mode) when movement is detected to ensure accurate tracking. This dynamic approach ensures tracking precision is maintained only when necessary, optimizing battery life.
Solution Approach 2:
The system uses periodic transmission with varying periods based on operational mode. In the first mode, transmissions occur at longer intervals to conserve energy. When movement is detected and the device switches to the second mode, transmissions occur at shorter intervals to maintain precise tracking during the movement event, after which it returns to the longer interval pattern.
Data Source
AI summary
There is provided a building management system and a method for associating a portable sensor device with a stationary control device in such a system. Upon detection of a movement of the portable sensor device, the portable sensor device starts to transmit signals more frequently to the stationary control devices. It is determined that the movement of the portable sensor device has stopped if the signal strength of the transmitted signals received at the stationary control devices is essentially constant during a time window. In response to such a determination, the portable sensor device is associated with the stationary control device having the highest received signal strength and the portable sensor device returns to an energy-saving mode.