Patent•
Inductive loop vehicle detector
23 Jan 1975-
TL;DR: In this paper, an inductive loop is used to detect vehicles in the immediate vicinity of the loop, where the vehicle's presence is dependent on whether or not the vehicle is over the loop.
Abstract: Apparatus for use in combination with an inductive loop for detecting metal objects, e.g. vehicles, in the immediate vicinity of said loop. The loop may, for example, be a coil of wire buried in a roadway in a plane parallel to the roadway surface. Oscillator circuitry is operatively connected to the loop with the frequency of oscillation being determined by the loop inductance, which in turn is dependent on whether or not the vehicle is over the loop. The loop frequency is monitored by digital circuitry including a loop counter which counts loop oscillator cycles and a duration counter which measures the time duration of a fixed number of loop oscillator cycles. The measured time duration is compared with an adaptable reference duration to ascertain whether the loop oscillator frequency has increased or decreased. The presence of a vehicle over the loop decreases loop inductance, increases loop frequency, and thus reduces the measured time duration of a fixed number of loop cycles. A reduction in the measured time duration by an amount greater than a preselected threshold value produces an output signal or "call" to indicate the vehicle's presence.
Citations
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Patent•
29 Aug 2012
TL;DR: In this paper, a control and management system for defined areas, employs a card reader, vehicle sensing loop detectors and electric eyes, entrance door sensors and operators, truck securement devices, cameras, a control system with memory, and a wireless connection or internet/intranet connection, is provided to produce event log documentation.
Abstract: A control and management system for defined areas, employs a card reader, vehicle sensing loop detectors and electric eyes, entrance door sensors and operators, truck securement devices, cameras, a control system with memory, and a wireless connection or internet/intranet connection, is provided to produce event log documentation. The event information is readily accessible by management or supervisory personnel, to see all of the recorded information concerning a specified event. Thus, an event can be readily reconstructed after the fact, using all available sensors and other information relevant to a manager or supervisor. An alert can be issued whenever an abnormal or unauthorized event occurs during operations. A QR code reader can be provided which communicates with the system to enable a person carrying the cell phone to scan QR codes at specified locations or on specified items or vehicles.
106 citations
TL;DR: A novel inductive loop sensor that can detect vehicles under a heterogeneous and less-lane-disciplined traffic and thus can be used to support a traffic control management system in optimizing the best use of existing roads is presented.
Abstract: This paper presents a novel inductive loop sensor that can detect vehicles under a heterogeneous and less-lane-disciplined traffic and thus can be used to support a traffic control management system in optimizing the best use of existing roads. The loop sensor proposed in this paper detects large (e.g., bus) as well as small (e.g., bicycle) vehicles occupying any available space in the roadway, which is the main requirement for sensing heterogeneous and lane-less traffic. To accomplish the sensing of large as well as small vehicles, a multiple loop system with a new inductive loop sensor structure is proposed. The proposed sensor structure not only senses and segregates the vehicle type as bicycle, motor cycle, scooter, car, and bus but also enables accurate counting of the number of vehicles even in a mixed traffic flow condition. A prototype of the multiple loop sensing system has been developed and tested. Field tests indicate that the prototype successfully detected all types of vehicles and counted, correctly, the number of each type of vehicles. Thus, the suitability of the proposed sensor system for any type of traffic has been established.
92 citations
Patent•
16 Jun 2004
TL;DR: In this article, a door system includes an antenna-based proximity sensor with a releasable electrical connector that enables the sensor to function with a breakaway feature of the door.
Abstract: A door system includes an antenna-based proximity sensor with a releasable electrical connector that enables the sensor to function with a breakaway feature of the door. The sensor includes a signal generator and a door-mounted antenna for sensing a body or an obstruction near the door. The signal generator (or oscillator) can be installed at various locations between a power source and the antenna. In some cases, the wiring between the antenna and the power source includes a rotatable feature to accommodate the rotation of a drum that carries a wrap-up, pliable door panel. The rotatable feature may be a rotatable electrical connector, or it may be a wire having sufficient length and flexibility to twist about itself within the hollow interior of the drum.
91 citations
Patent•
30 May 2001
TL;DR: In this article, an induction coil mounted below the surface of the parking area is used to provide positive signals to the electronically operated parking meter and a cpu upon both the entrance of a vehicle into the parking space and the movement of the vehicle from the space.
Abstract: The field of the present invention is parking meters and more particularly to the use of electronically operated parking meters coupled with a sensor for positively sensing unobtrusively the presence or absence of a vehicle in a specified parking space controlled by the sensor and electronically operated parking meter. An induction coil mounted below the surface of the parking area is used to provide positive signals to the electronically operated parking meter and a cpu upon both the entrance of a vehicle into the parking space and the movement of the vehicle from the parking space. Moreover, the detecting system is battery operated and the battery life is extended by duty cycle operation of the detector system, whereby only a small portion of a detecting cycle is actually employed for detecting the status of the parking space.
81 citations
Patent•
25 Apr 2002
TL;DR: A parking area entrance or exit barrier includes a control system which receives inputs from various accessories associated with the operation of the barrier, and which provides control signals to the various accessories.
Abstract: A parking area entrance or exit barrier includes a control system which receives inputs from various accessories associated with the operation of the barrier, and which provides control signals to the various accessories of the barrier. One of the accessories includes a sensor attached to the barrier. The sensor senses an accident event, such as contact between the barrier and a vehicle. Whenever an accident event is sensed, the control system creates an accident event log of information concerning the accident event. The accident event log may include video images of the barrier, a position of the barrier, a movement direction and speed of the barrier, and an approximated speed of the vehicle. The control system may also monitor a performance of the various accessories of the barrier and create a performance log relating to any malfunction of the accessories. The performance of the accessories may also indicate tampering or fraudulent activities concerning the parking barrier, such as an attendant stealing parking fees. The accident event log and/or performance log may be transmitted to a central service facility. Further, the central service facility can remotely change operating parameters of the control system.
77 citations
References
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Patent•
09 Jul 1973
TL;DR: In this article, a digital detecting system for creating an output signal when an electrically conductive object, such as a vehicle, comes within the field of effect of a loop is presented.
Abstract: A digital detecting system for creating an output signal when an electrically conductive object, such as a vehicle, comes within the field of effect of a loop. The system includes means for creating a pulse train having a frequency controlled primarily by the inductance of the loop, means for counting the pulses of the pulse train for a selected time interval to produce a count generally representative of the inductance of the loop during the time interval, means for creating a reference count, means for comparing the representative count with the reference count, and means for creating an output signal when the representative count differs from the reference count by at least a given amount in a given numerical direction, either above or below the reference count.
30 citations
Patent•
07 Dec 1971
TL;DR: In this paper, an elapsed time indicator or delay switch including a cylindrical housing of non-magnetic material closed at one end by a base of magnetic material is presented. But it is not shown how to operate it.
Abstract: An elapsed time indicator or delay switch including a cylindrical housing of non-magnetic material closed at one end by a base of magnetic material. A pair of spaced apart electrically conducting terminals insulated from and extending into and through the base. A permanent magnetic piston slidably positioned within the housing, spaced from said base and having a viscous fluid therebetween. A pressure releasable piston retainer disposed above the piston for limiting the movement thereof and a flexible deformable diaphragm, proximate the retainer, closing the opposite end of the housing. The device is initiated upon pressure being applied to the diaphragm which thereupon deflects the retainer and releases the piston that in turn is attracted toward the base and moves theretoward at a rate dependent, among other factors, on the fluid viscosity, the magnetic force, initial spacing and the clearances between the housing and the piston. Piston travel terminates upon contact with the inner terminals and electrical shorting thereof which may be used to indicate the end of the elapsed period.
18 citations
Patent•
20 Aug 1970
TL;DR: In this article, an electronic device for measuring the elapsed time required for a vehicle to travel a predetermined distance such as a quarter mile is described, which comprises pulse generating means for producing a pulse for each increment of distance traveled in combination with an integrating means for accumulating such pulses and producing a stop count signal when the output of the integrating means reaches a predetermined level.
Abstract: An electronic apparatus for measuring the time required for a vehicle to travel a predetermined distance such as a quarter mile. The exemplary embodiment described comprises pulse generating means for producing a pulse for each increment of distance traveled in combination with an integrating means for accumulating such pulses and producing a stop count signal when the output of the integrating means reaches a predetermined level. By adjusting a duty cycle of the individual pulses input to the integrating means, the predetermined point at which the stop count output is produced may be made to correspond to a desired predetermined value of traveled distance. Clock pulses are counted by a digital counter from a time determined by either manual or automatic start means until said stop count signal is produced at which time the counter is adapted to hold its contents until being reset. An indicator is also associated with the counter for visually displaying the contents of the counter indicating the elapsed time required for the vehicle to travel the predetermined distance as determined by the pulse width adjustment.
17 citations
Patent•
29 May 1973
TL;DR: In this article, an improved magnetic inductance vehicle detection system is provided which responds to changes in the inductance of a wire loop embedded in the roadway to sense the presence of a vehicle.
Abstract: An improved magnetic inductance vehicle detection system is provided which responds to changes in the inductance of a wire loop embedded in the roadway to sense the presence of a vehicle. The system includes a first oscillator connected to the loop whose frequency changes as the loop inductance changes, and it also includes a second oscillator whose frequency is independent of the loop inductance, and which is used as a reference. Appropriate logic circuitry establishes an output signal whenever the frequency of the loop oscillator increases with respect to the frequency of the reference osillator beyond a predetermined frequency differential, so as to indicate the fact that a vehicle has crossed in the area circumscribed by the loop. This output signal is formed into a direct current signal which actuates a relay in a vehicle indicating circuit. The system of the invention also includes a control circuit for compensating for drifts in the system. This control circuit includes a network which responds to an error signal to develop a fast-acting antidrift control whenever the frequency of the loop oscillator falls below the frequency of the reference oscillator; and which also develops a slow-acting anti-drift control to compensate for frequency drifts in the system by which the frequency of the loop oscillator rises above the frequency of the reference oscillator.
15 citations
Patent•
20 Sep 1973
TL;DR: In this paper, an automatic digital tuning arrangement is provided for the reference oscillator to maintain the IF signal at a normal frequency within a predetermined range within which the intermediate frequency is permitted to vary in response to changing environmental conditions.
Abstract: Apparatus for determining whether a movable body, such as a railway car traveling along a track, is present in a preselected zone of interest along its path of travel. In railway applications for detecting the presence of a car over a switch, for example, an inductive loop is laid along the track and forms a part of the tank circuit of an oscillator. The resulting signal is mixed with the output signal from a variable frequency reference oscillator to provide an intermediate frequency signal that is subject to frequency variations as the loop inductance changes. To correct for such variations, an automatic digital tuning arrangement is provided for the reference oscillator to maintain the IF signal at a normal frequency within a predetermined range within which the intermediate frequency is permitted to vary in response to changing environmental conditions. The response of the digital tuner is sufficiently rapid to correct gradual variations in frequency characteristic of changing environmental conditions, but is purposely limited in order to be incapable of making the correction in the event of a sudden frequency variation caused by the presence of a car. When this occurs, the intermediate frequency shifts outside of the normal range and the apparatus assumes an output condition indicative of the presence of the car. Once the car is detected, the automatic tuner is disabled to positively preclude frequency correction until the car is no longer sensed by the loop.
11 citations