Sensor Arrangement Combining Doppler Radar and Vibration Sensor
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Solution Overview
Problem
Doppler radar sensors are prone to false triggering due to external causes like environmental vibrations and noise, making it difficult to accurately distinguish human motion from repetitive or constant noise, leading to unnecessary activation of associated luminaires.
Innovation Solution
A sensor arrangement that combines a motion sensor, such as a doppler radar sensor, with a vibration sensor like an accelerometer and optionally a microphone or acoustic sensor, to filter out false triggers by using acceleration and sound patterns to determine if the motion is human-related, with a processor calculating radar acceleration and applying threshold values to validate motion detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a doppler radar sensor is used to detect motion, then motion detection capability is improved, but false triggering due to environmental vibrations and noise increases
Solution Approach 1:
The patent combines a doppler radar motion sensor with a vibration sensor (accelerometer) into a single sensor arrangement. The vibration sensor detects environmental vibrations and noise, allowing the system to distinguish between motion caused by environmental factors and motion caused by human presence. This merging of sensors resolves the contradiction by maintaining motion detection accuracy while reducing false triggering through cross-validation of sensor data.
Solution Approach 2:
The vibration sensor acts as an intermediary that mediates between the doppler radar sensor and the control system. By detecting environmental vibrations separately, the vibration sensor provides information that helps interpret radar signals more accurately, preventing false triggering while preserving genuine motion detection capability.
2Ease of operation
If the sensor is mounted to a suspended ceiling, then installation flexibility is improved, but sensitivity to environmental vibrations increases
Solution Approach 1:
The vibration sensor serves as an intermediary that specifically detects vibrations transmitted through the suspended ceiling mounting. This allows the system to recognize when vibrations are caused by the mounting structure rather than human motion, thereby maintaining installation flexibility while compensating for increased vibration sensitivity.
Solution Approach 2:
The patent converts the harmful effect of vibration sensitivity into a beneficial feature by using the vibration sensor to detect environmental vibrations. These previously problematic vibrations are now used as additional information to filter false triggers, transforming the mounting-related vibration issue into a useful diagnostic signal.
3Measurement precision
If motion detection threshold is lowered to detect subtle human motion, then detection sensitivity is improved, but susceptibility to environmental noise increases
Solution Approach 1:
The patent merges data from the doppler radar sensor and vibration sensor to establish a more robust detection threshold. By analyzing both motion signals and vibration signals together, the system can lower the motion detection threshold to capture subtle human movements while using vibration data to filter out environmental noise that would otherwise trigger false positives.
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 configuration significantly reduces false triggering, ensuring that luminaires are only activated by human presence, saving energy and accurately differentiating human motion from environmental noise and vibrations.
Implementation Method 1
continuous wave (CW) doppler radar motion sensors which emit a continuous wave carrier and mix the transmitted radio frequency (RF) with the return echoes to produce a difference frequency equal to the Doppler shift produced by a moving target
Implementation Method 2
the vibration sensor is an accelerometer configured to detect an acceleration of the sensor arrangement
Data Source
AI summary
The invention relates to a sensor arrangement (101) configured to detect a motion of an object. The sensor arrangement (101) comprises a motion sensor (101a) configured to detect data about the motion of the object; a vibration sensor (101b) configured to detect a vibration of the sensor arrangement (101), wherein if the vibration is lower than a threshold value, then an output signal of the sensor arrangement (101) signaling the motion of the object is output.