Passive Infrared Sensor Arrays for Accurate Visitor Distance Detection
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Solution Overview
Problem
Existing security devices, such as video doorbells, struggle to accurately determine the distance of a visitor from the device using motion sensors, leading to unwanted notifications when pedestrians are detected on sidewalks rather than at the entrance.
Innovation Solution
Utilizing multiple passive infrared sensors with overlapping or non-overlapping fields of view, aligned vertically, to generate signal ratios that allow for precise distance determination based on the relative output values from each sensor, enabling targeted motion alerts and image generation only when the visitor is within a specific threshold distance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a single motion sensor with wide field-of-view is used to detect visitors, then the detection coverage is improved, but the distance determination accuracy deteriorates causing unwanted notifications from distant pedestrians
Solution Approach 1:
The patent divides the detection space into multiple zones by using multiple passive infrared sensors positioned at different locations and orientations. Each sensor covers a specific angular range, and by segmenting the field-of-view into discrete sensor coverage areas, the system can determine which sensor detected the motion and calculate distance based on the sensor's angular position. This segmentation resolves the contradiction by maintaining wide overall coverage while enabling precise distance measurement through zone identification.
2Measurement precision
If multiple passive infrared sensors with different fields-of-view are used, then the distance determination precision is improved, but the device complexity increases
Solution Approach 1:
The patent resolves the complexity issue by transitioning from a single-sensor approach to a multi-sensor angular arrangement. Instead of using a single complex sensor, the system employs multiple simpler passive infrared sensors positioned at different angles. The distance determination is achieved by identifying which sensor detects the motion and using the known angular position of that sensor, thereby solving the distance measurement problem through spatial dimensionality rather than through complex single-sensor processing.
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
Enhances the accuracy of distance detection, allowing security devices to differentiate between visitors at the entrance and pedestrians at a distance, thereby reducing unnecessary alerts and improving user experience.
Implementation Method 1
a first passive infrared sensor and a second passive infrared sensor of an electronic device may be configured to provide a first field of view and a second field of view, respectively
Data Source
AI summary
This disclosure describes, in part, techniques for using multiple passive infrared sensors to determine a distance to an object. For instance, an electronic device may include a first passive infrared sensor including a first FOV that extends a first distance from the electronic device and a second passive infrared sensor including a second FOV that extends a second distance from the electronic device further than the first distance. The electronic device may generate first sensor data using the first passive infrared sensor and second sensor data using the second passive infrared sensor. The electronic device may then determine a first amplitude associated with the first sensor data and a second amplitude associated with the second sensor data and determine a ratio between the amplitudes. After the ratio is determined, the electronic device may determine a distance associated with the ratio, generate image data based on the distance, and send the image data to computing device(s).