Active near-field object sensor and method employing object classification techniques
First Claim
1. A sensor means for detecting the presence of an object within an area located at a close range, the sensor comprising:
- means for emitting an output of pulsed, coherent radiation toward a fixed area a known distance from the emitting means;
means for receiving a portion of the returning pulsed energy reflected from the area;
means for determining a time of flight change for pulses between the emitting and receiving means caused by the presence of an object in the area;
means for receiving an input from the time of flight determining means and for providing an output indicating whether the object meets one of a plurality of classification criteria; and
means for determining a timing error caused by amplitude variations in the returning reflected energy and providing a range correction responsive thereto.
5 Assignments
0 Petitions
Accused Products
Abstract
The sensor includes a range finder having means for emitting a directional output of pulsed energy toward a fixed area, and includes a transmitter section which divides pulsed energy into divergent beams, which are then received as reflective energy in a receiver section. The receiver alternately selects between outputs of two detectors receiving reflections from the beam and provide inputs for purposes of determining time of flight, and for measuring the time interval between interceptions of the two divergent beams for a given object. The sensor also receives inputs indicating the time that each pulse is emitted and the selected outputs from the detector to indicate when returning energy is received from the corresponding pulse to determine the elapsed time between the two.
58 Citations
31 Claims
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1. A sensor means for detecting the presence of an object within an area located at a close range, the sensor comprising:
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means for emitting an output of pulsed, coherent radiation toward a fixed area a known distance from the emitting means; means for receiving a portion of the returning pulsed energy reflected from the area; means for determining a time of flight change for pulses between the emitting and receiving means caused by the presence of an object in the area; means for receiving an input from the time of flight determining means and for providing an output indicating whether the object meets one of a plurality of classification criteria; and means for determining a timing error caused by amplitude variations in the returning reflected energy and providing a range correction responsive thereto. - View Dependent Claims (31)
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2. A sensor means for detecting the presence of an object within an area located at a close range, the sensor comprising:
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means for emitting an output of pulsed, coherent radiation toward a fixed area a known distance from the emitting means; means for receiving a portion of the returning pulsed energy reflected from the area; means for determining a time of flight change for pulses between the emitting and receiving means caused by the presence of an object in the area; means for receiving an input from the time of flight determining means and for providing an output indicating whether the object meets one of a plurality of classification criteria; and means for dividing the pulsed energy output of the emitting means into two diverging directional beams. - View Dependent Claims (23)
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3. A sensor means for detecting the presence of an object within an area located at a close range, the sensor comprising:
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means for emitting an output of pulsed, coherent radiation toward a fixed area a known distance from the emitting means; means for receiving a portion of the returning pulsed energy reflected from the area; means for determining a time of flight change for pulses between the emitting and receiving means caused by the presence of an object in the area; means for receiving an input from the time of flight determining means and for providing an output indicating whether the object meets one of a plurality of classification criteria; and means for alternately selecting between outputs of the two detectors for providing an input to the time of flight determining means.
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4. A sensor for detecting the presence of a vehicle within close range and suitable for controlling traffic signals or measuring traffic speed, census or flow, the sensor comprising:
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means for emitting a directional output of pulsed energy toward a fixed area a known distance from the emitting means; means for receiving a portion of returning pulsed energy reflected from the area; means for determining a time-of-flight change for pulses between the emitting and receiving means caused by the presence of a vehicle in the area; and means including a peak return signal level detector for determining a timing error caused by amplitude variations in the returning reflected energy and providing a range correction responsive thereto. - View Dependent Claims (5, 6, 7, 8, 9, 10, 11, 12)
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13. A sensor, comprising:
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means for emitting a pulse of coherent infrared radiation; means for dividing the pulse into two diverging directional beams and directing the two beams toward an area which is a distance from the sensor; two detectors, each receiving returning energy from reflections of the two beams; means for receiving a signal from the emitting means indicating that a pulse has been emitted and for receiving an input from a selected one of the detectors for indicating when returning energy is received from the corresponding beams, and for then generating an output representative of the elapsed time between the signal and the input; and means for receiving and determining from the elapsed time output whether an object is present between the sensor and the area. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22)
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24. A sensor for providing outputs useful in detecting objects and for measuring object size, census or speed, the sensor comprising:
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a compact enclosure having an optically transmissive window; a transmitter section, a receiver section, a signal processing section and a power supply; the transmitter section having; a laser diode for emitting coherent infrared radiation through the windows, means for alternately energizing the diode for a predetermined time and at a predetermined rate so that the diode emits pulses of coherent radiation having a known pulse width and repetition rate, and a prism between the diode and the window for dividing the pulsed output of the laser diode into two diverging directional beams at a predetermined angle through the window; the receiver section having; two photo detectors for receiving returning pulsed energy from one of the two transmitter beams and providing inputs representative of the time when the returned energy for each beam is received and a signal level for the returned energy of each beam, an optical filter between the window and the photo detectors for restricting ambient light from the detectors, and a focusing lens between the window and the photo detectors for focusing incident returning pulsed energy for the beams within the predetermined angle into the two photo detectors; and the signal processing section having; means for receiving an input from the transmitter section indicating the time that each pulse is emitted, means for receiving the inputs from the receiver section representative of the time when returned energy for each beam is received and the signal level for the returned energy of each beam, and means for generating an output representative of the elapsed time between the transmitter section input and the returned energy time input from the receiver section, and means for providing an output indicating the presence of an object dependent upon either an elapsed time determination indicating the presence of an object, or a signal level input from the receiver section below a predetermined threshold. - View Dependent Claims (25, 26, 27)
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28. A method for providing outputs representative of the presence of a vehicle within a close range and suitable for controlling traffic signals or measuring traffic speed, flow or census, the method comprising the steps of:
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emitting a directional output of pulsed energy toward a fixed area which is a known distance away; receiving a portion of returning pulsed energy reflected from the area; determining time-of-flight changes between the emitting and receiving steps caused by the presence of a vehicle located in the area; and detecting a peak return signal level and a timing error caused by amplitude variations in the returning pulsed energy. - View Dependent Claims (29, 30)
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Specification