Luminaire Motion Detector Signal Processing for Hum Noise Cancellation
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Solution Overview
Problem
Existing motion detection systems are prone to false positives due to hum noise, require separate vibration sensors, and can be inoperable during persistent hum, and only detect mechanical vibrations, failing to account for electrical hum noise.
Innovation Solution
A luminaire with a motion detector that processes motion signals to cancel components corresponding to motions with opposite directions, eliminating hum noise without a separate vibration sensor, using a processor system to analyze motion components and determine motion based on energy thresholds in frequency bins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a separate vibration sensor is added to detect vibrations, then the ability to distinguish between motion and vibration improves, but device complexity and cost increase
Solution Approach 1:
The patent extracts and removes the vibration sensing functionality from a separate sensor and integrates it into the motion sensor's signal processing. By processing the motion sensor signal to identify and eliminate vibration components, the system achieves vibration discrimination without requiring a separate vibration sensor, thus reducing device complexity while maintaining measurement precision.
Solution Approach 2:
The patent replaces the mechanical approach of using a separate vibration sensor with a signal processing approach. Instead of mechanically sensing vibrations separately, the system uses digital signal processing to extract and eliminate vibration components from the motion sensor signal, substituting a mechanical sensing system with an electronic signal processing system.
2Reliability
If the motion sensor threshold is set high to avoid false positives from hum noise, then reliability improves, but the system becomes inoperable during persistent hum
Solution Approach 1:
The patent applies preliminary anti-action by proactively identifying and eliminating vibration components from the motion sensor signal before making motion detection decisions. By pre-processing the signal to remove vibration-related components, the system prevents false positives without needing to set high thresholds that would cause operational failure during persistent hum.
Solution Approach 2:
The patent converts the harmful effect of vibration and hum noise into a beneficial filtering mechanism. By processing the motion sensor signal to identify vibration components and eliminating them, the system uses the presence of noise to improve its own performance, converting what would be a source of false positives into a means of enhancing detection accuracy.
3Speed
If the motion sensor detects only mechanical vibrations, then the response to mechanical motion is fast, but electrical hum noise from power supplies causes false detections
Solution Approach 1:
The patent replaces reliance on mechanical vibration detection with a signal processing approach that analyzes the frequency content of the motion sensor output. By transforming the signal into the frequency domain and identifying vibration components, the system can distinguish between mechanical motion and electrical hum noise, eliminating false detections from power supply interference while maintaining fast response.
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 solution reduces false positives, eliminates the need for separate vibration sensors, and effectively detects motion by distinguishing between hum noise and true motion, even in the presence of electrical hum sources, ensuring reliable lighting control and occupancy detection.
Implementation Method 1
The motion sensing unit is a microwave (RF) Doppler sensor that senses motion using a Doppler effect using microwave (RF)
Data Source
AI summary
Some embodiments are directed to a motion detector (100) configured to signal-process a motion signal to obtain multiple motion components, a motion component being correlated with a direction and velocity of a motion in the environment, cancel in motion components, two motion components that correspond to motions with opposite directions, and detect motion in the environment from the motion components that are not cancelled.