Compound Sensor System for Low Power User Presence Detection
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Solution Overview
Problem
Traditional proximity sensors consume excessive power, making them unsuitable for battery-powered systems that require long battery life, such as those used in consumer and industrial electronics.
Innovation Solution
A compound sensor system comprising a low power coarse detection sensor and a high power fine detection sensor, where the high power sensor operates in a sleep mode until activated by the low power sensor to confirm user presence or absence, reducing overall power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional proximity sensors are used for continuous monitoring, then detection accuracy is maintained, but power consumption exceeds acceptable levels for battery-powered systems
Solution Approach 1:
The system dynamically adjusts the operating state of the second sensor between sleep mode and active mode based on detection needs. The sensor transitions from a low-power state to a high-precision detection state only when required, optimizing the balance between power consumption and detection accuracy throughout operation.
Solution Approach 2:
The system implements periodic monitoring where the first sensor continuously operates at low power to detect potential user presence, and the second sensor is activated periodically only when the first sensor indicates a likelihood of user presence. This periodic activation pattern significantly reduces overall power consumption while maintaining detection accuracy.
2Reliability
If a single high power sensor operates continuously, then user presence detection is accurate, but battery life is reduced to a few months
Solution Approach 1:
The detection function is segmented into two parts: the first sensor performs continuous coarse detection to monitor for user presence, while the second sensor performs periodic fine detection only when needed. This segmentation allows the system to maintain reliable detection overall while dramatically reducing the time the high-power sensor is active, extending battery life to over a year.
Solution Approach 2:
The first sensor acts as an intermediary that filters when the second sensor needs to activate. Instead of the second sensor operating continuously or being triggered by every minor detection, the first sensor serves as a gatekeeper that only triggers the high-power sensor when there is a genuine likelihood of user presence, optimizing battery life while maintaining detection reliability.
3Speed
If the second sensor remains in active mode, then immediate user detection is possible, but power consumption increases beyond acceptable limits
Solution Approach 1:
The first sensor performs preliminary continuous monitoring to detect potential user presence before activating the second sensor. This preliminary action ensures that when the user actually arrives, the system can respond quickly by having the second sensor activate immediately upon detection by the first sensor, while avoiding unnecessary activation during false positives.
Data Source
AI summary
A compound sensor system includes a first sensor, a second sensor, a memory that stores a module, and a processor coupled to the first sensor, the second sensor, and the memory. The first sensor is configured to detect a parameter that indicates a likelihood of having a user enter or leave a target area, and, in response, send a first command signal to the processor. The processor is configured to receive the first command signal from the first sensor and send a second command signal to the second sensor based on receiving the first command signal. The second sensor is configured to operate at a sleep mode and switch to an active mode upon receiving the second command signal, and during the active mode the second sensor is configured to determine if the user enters or leaves the target area.