Acoustic sensor system for vehicle detection and multi-lane highway monitoring
First Claim
1. A motor vehicle detection system for providing automatic multiple lane position determination, multiple lane traffic monitoring, significant reduction of false detections due to out of lane sound sources, individual vehicle speed measurement, and individual vehicle type classification, said system comprising:
- A. a plurality of electro-acoustic sensors arranged in an array according to a prescribed spacing for converting impinging acoustic signals from motor vehicles into individual electrical signals at the electro-acoustic sensor outputs;
B. means to coherently scale and combine said individual electrical signals at said electro-acoustic sensor output for creating a plurality of coherent stave signals;
C. means to perform signal frequency band discrimination, digital sampling, and Fourier transformation of said coherent stave signals for creating a plurality of frequency decomposed stave signals;
D. means responsive to said frequency decomposed stave signals to automatically and adaptively perform spatial discrimination for creating a plurality of directional signals, each representing a single acoustic signal or a collection of acoustic signals originating within each said active traveled lane;
E. means responsive to said coherent directional signals for creating a plurality of vehicle presence signals and for directly measuring individual vehicle speed and for determining individual vehicle type classification;
F. means responsive to said vehicle presence signals and responsive to said individual vehicle speed measurements and responsive to said individual vehicle type classification for creating a transportation system signal and information message interface.
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Accused Products
Abstract
A novel multi-lane traffic monitoring system is based on detecting the acoustic signals motor vehicles create and radiate during operation. The system comprises an array of electro-acoustic sensors for converting impinging acoustic wavefronts to analog electrical signals; a circuit to acquire, perform signal frequency component discrimination, and digitize the electrical signals at the electro-acoustic sensor array output; a circuit to perform effective spatial discrimination in the up/down road direction and in the cross-road direction in real time; a circuit to perform vehicle detection for individual lanes and to estimate or measure pertinent parameters associated with each vehicle detection from each traveled lane; and a circuit to compute for each lane, pertinent traffic flow parameters from vehicle parameters for the purpose of providing a transportation system interface. In accordance with another embodiment, a circuit is provided to automatically scan for acoustic sources in the cross-road direction and to automatically identify each highway lane direction relative to the physical electro-acoustic sensor array orientation. In accordance with still another embodiment, a circuit is provided via signal frequency component discrimination and signal processing to create, from a single physical sensor, two vehicle detection zones within each highway lane, wherein a smaller detection zone is located inside a larger detection zone. A circuit is also provided to measure the time between initial vehicle detection in the larger (outer) detection zone and initial vehicle detection in the smaller (inner) detection zone, wherein vehicle speed is determined from the initial detection time difference. In accordance with yet another embodiment, a circuit is provided to measure the relative position of the sound radiated from each of a vehicle'"'"'s tires and determine vehicle type classification associated with each vehicle detection and with each measured vehicle speed.
79 Citations
14 Claims
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1. A motor vehicle detection system for providing automatic multiple lane position determination, multiple lane traffic monitoring, significant reduction of false detections due to out of lane sound sources, individual vehicle speed measurement, and individual vehicle type classification, said system comprising:
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A. a plurality of electro-acoustic sensors arranged in an array according to a prescribed spacing for converting impinging acoustic signals from motor vehicles into individual electrical signals at the electro-acoustic sensor outputs; B. means to coherently scale and combine said individual electrical signals at said electro-acoustic sensor output for creating a plurality of coherent stave signals; C. means to perform signal frequency band discrimination, digital sampling, and Fourier transformation of said coherent stave signals for creating a plurality of frequency decomposed stave signals; D. means responsive to said frequency decomposed stave signals to automatically and adaptively perform spatial discrimination for creating a plurality of directional signals, each representing a single acoustic signal or a collection of acoustic signals originating within each said active traveled lane; E. means responsive to said coherent directional signals for creating a plurality of vehicle presence signals and for directly measuring individual vehicle speed and for determining individual vehicle type classification; F. means responsive to said vehicle presence signals and responsive to said individual vehicle speed measurements and responsive to said individual vehicle type classification for creating a transportation system signal and information message interface. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. An automatic highway lane position determining system for measuring the acoustic energy levels in all cross-road directions and from said acoustic energy levels automatically identifying each and every active traveled lane, said system comprising:
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A. an input port for connection to a source of frequency decomposed signals from a plurality of electro-acoustic sensors in a periodically scanned format; B. means responsive to said frequency decomposed signals for creating a beam power response function for all cross road direction angles and for creating a plurality of valid lane direction angles and valid lane separation angles; C. an output port for application of said lane direction angles and said lane separation direction angles to a processor, indicator, or visual display. - View Dependent Claims (11, 12)
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13. A system for measuring individual vehicle speed using a single directional passive acoustic sensor mounted above the highway and pointed toward the lanes carrying said vehicles, said system comprises:
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A. a plurality of electro-acoustic sensors arranged in an array according to a prescribed spacing for converting impinging acoustic signals from said motor vehicles into individual electrical signals at said electro-acoustic sensor outputs; B. means to scale and combine said electrical signals at said electro-acoustic sensor output for creating a plurality of directional signals each representing a single acoustic signal or a collection of acoustic signals originating within each active traveled lane; C. an above the road mounting structure for mounting said electro-acoustic sensor array near lanes carrying said vehicles whose speed is to be measured; D. means responsive to said directional signals to perform frequency band discrimination and signal envelop detection for creating a lower band power signal and for creating an upper band power signal; E. means to perform threshold comparisons for measuring the time difference between initial threshold crossings corresponding to said lower band power signal and said upper band power signal; F. means to compute said individual vehicle speed by dividing a prescribed detection zone size difference by said threshold crossings time difference. - View Dependent Claims (14)
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Specification