Occupancy Sensor Voltage Divider Battery Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing occupancy-based lighting control systems face high energy consumption and reduced battery lifetime due to frequent state reports from multiple sensors, leading to increased power usage and potential wrong detections from changing battery voltage, which affects sensitivity and accuracy.
Innovation Solution
Implementing a system where only the 'occupied' state is periodically transmitted, reducing radio on-time and energy consumption, and using a sleep mode for sensors with a signal conditioning circuit that maintains a constant detection window by dynamically adjusting the voltage divider resistances to counteract battery voltage drops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple occupancy sensors periodically report their detected occupancy state to the actuated device, then the actuated device can accurately determine occupancy status, but energy consumption of the sensor increases significantly
Solution Approach 1:
The patent implements periodic occupancy sensing and reporting, where sensors wake up at intervals to detect occupancy status and transmit data only when changes are detected. This periodic operation allows the radio to remain off most of the time, dramatically reducing energy consumption while maintaining reliable occupancy detection through regular status checks.
Solution Approach 2:
The patent extracts and transmits only the essential information (occupancy status changes) rather than continuous data streams. By taking out only the critical state changes and transmitting them periodically, the system maintains detection reliability while minimizing radio transmission time and associated energy consumption.
2Measurement precision
If sensors transmit status reports frequently to ensure accurate occupancy detection, then occupancy detection accuracy is maintained, but battery lifetime is reduced
Solution Approach 1:
The system uses periodic sensing intervals where the sensor wakes up, checks for occupancy changes, and transmits only if the state has changed. This periodic approach extends battery lifetime by keeping the radio off during intervals while maintaining detection precision through regular status verification at each wake cycle.
Solution Approach 2:
The sensor autonomously determines when transmission is necessary based on detected occupancy changes. By self-managing the transmission schedule based on actual occupancy events rather than fixed intervals, the system extends battery life by avoiding unnecessary transmissions while ensuring accurate occupancy detection when changes occur.
3Ease of operation
If the radio is switched on continuously to listen to wireless traffic and synchronize state reports, then coordination between multiple sensors is achieved, but power consumption increases strongly
Solution Approach 1:
The radio operates periodically rather than continuously, waking up at scheduled intervals to listen for wireless traffic and synchronize with other sensors. This periodic operation achieves the necessary coordination and synchronization while dramatically reducing power consumption compared to continuous radio operation.
Solution Approach 2:
The system maintains continuous occupancy monitoring capability through periodic radio wake-ups that ensure sensors remain synchronized with the network and each other. By keeping the radio off between wake-ups, the system achieves continuous useful action for occupancy detection while minimizing energy consumption during the non-active periods.
4Loss of energy
If battery voltage decreases over lifetime, then energy is conserved, but sensor sensitivity increases causing wrong detections
Solution Approach 1:
The system dynamically adjusts the detection threshold parameter based on the current battery voltage level. As battery voltage decreases over lifetime, the threshold is automatically adjusted to compensate for the resulting sensitivity changes, preventing wrong detections while maintaining energy-efficient operation with the declining voltage source.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly reduces power consumption, extends battery life, and maintains accurate occupancy detection by minimizing radio usage and stabilizing signal sensitivity despite battery voltage changes.
Implementation Method 1
In the case of battery-powered occupancy sensors using a PIR (Passive Infra Red) sensor or probe
Implementation Method 2
a voltage divider which defines at least one comparison value against which the signal produced by the occupancy sensor or probe is compared
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An occupancy sensor (S) includes: - a sensing probe (101) to detect occupancy (P) of a space monitored by the sensor (S) and produce a corresponding sensing signal, - a comparator (104) including a voltage divider (RA, RB, R1, R2, R3, RC) defining a comparison value (A, B) against which the sensing signal is compared to detect occupancy, and - a voltage sensing means (105) to sense a feed voltage (Vbattery) applied to the sensor (S), wherein changes in the feed voltage (Vbattery) to the sensor induce a change in the comparison value (A, B). The voltage divider (RA, RB, R1, R2, R3, RC) includes one or more resistors (R1, R2, R3) selectively switcheable (Q1, Q2, Q3) to counter changes induced in said comparison value (A, B) by changes in the feed voltage (Vbattery) ° For instance, the voltage divider (RA, RB, R1, R2, R3, RC) may define a comparison window for the sensing signal with a width between an upper threshold (A) and a lower threshold (B), and may include one or more resistors (R1, R2, R3) selectively switcheable (Q1, Q2, Q3) to counter changes in the width of the comparison window (A, B) induced by changes in the feed voltage ( Vbattery) °