Minnesota Mining and Manufacturing Company

Steven M Hamer

Earl B Hoekman

David L Wortman

Ronald A Hagen

Edmund J Ring

Theodore B Keyes

Kim K Christopher

Thomas J Lunn

Jeffrey D Haagenstad

Mark A Schwartz

Timothy J Hall

An embedded system controller-based vehicle tracking system using vehicle positioning. An embedded system controller controls a traffic intersection using an optical system. The embedded system controller receives a vehicle location and a vehicle schedule. The embedded system controller calculates whether the vehicle is on time and reports the on-time status to the driver interface. The driver may -request that the system report a panic or emergency situation to the dispatch center through an external data communications network. The external data communications network may also send vehicle status, such as vehicle position and vehicle condition. A transit company using the system may provide vehicles equipped with the vehicle tracking system with schedules on a daily basis, using a portable data transfer device. The embedded system controller also communicates to the vehicle data network for the communication of vehicle position. A global positioning system receiver may be used to provide the position of the vehicle to the embedded system controller.

Vehicle tracking system incorporating traffic signal preemption

A traffic control preemption system uses data received from a global positioning system (GPS) to determine whether a vehicle issuing a preemption request is within an allowed approach of an intersection. GPS signals are received and processed by the vehicle module to generate vehicle data, including the vehicle's position, heading and velocity. The vehicle data is transmitted via radio transmission or some other medium. Each intersection has an associated intersection module which, if within range of the vehicle's transmitting equipment, compares the received vehicle data with a preprogrammed map of allowed approaches to the intersection. If the vehicle data sufficiently matches the map of allowed approaches, the vehicle's preemption request is forwarded to the intersection controller to appropriately control the phase of the traffic signal at the intersection.

GPS-based traffic control preemption system

A vehicle detector includes an inductive sensor which is driven by an oscillator to produce an oscillator signal having a frequency which is a function of inductance of the inductive sensor. Presence of a vehicle is detected when measured frequency of the oscillator signal changes by more than a threshold value. The effects of magnetic flux produced by adjacent power lines are compensated by measuring the frequency of the oscillator signal during a plurality of sample periods and characterizing the fluctuation of the measured frequency as a function of phase of a power main signal. During a normal measurement period, the frequency of the oscillator signal is measured, and the phase of the power main signal during the measurement period is determined. An output signal is produced based upon the measured frequency, the phase, and the known fluctuation of measured frequency as a function of phase of the power main signal.

Vehicle detector with power main noise compensation

An optical traffic preemption detector detects pulses of light emitted by an approaching emergency vehicle and provides an output signal which is processed by a phase selector. The phase selector can request a traffic signal controller to preempt a normal traffic signal sequence to give priority to the emergency vehicle. A detector assembly is mounted in proximity to an intersection and can have multiple detector channels. A detector channel can have multiple photocells. A detector housing includes a base, at least one detector turret and a cap. A detector channel circuit includes a circuit board, a photocell with a lens placed over the photocell, and circuitry to produce an output signal.

Optical traffic preemption detector

A method of optically transmitting data from an optical emitter to a detector mounted along a traffic route is used in an optical traffic preemption system. The method allows variable data to be transmitted in a stream of light pulses by interleaving data pulses between priority pulses. By allowing data to be transmitted in a stream of light pulses, an optical emitter constructed in accordance with the present invention transmits an optical signal that can include an identification code that uniquely identifies the emitter, an offset code that causes a phase selector to create a traffic signal offset, an operation code that causes traffic signal lights to assume at least one phase and a range setting code that causes a phase selector to set a threshold to which future optical transmissions will be compared. Phase selectors constructed in accordance with the present invention are provided with a discrimination algorithm which is able to track a plurality of optical transmissions with each detector channel. Optical emitters constructed in accordance with the present invention are provided with a coincidence avoidance mechanism which causes overlapping optical transmission from separate optical emitters to drift apart. The present invention provides an optical signal format that allows variable data to be transmitted, while maintaining compatibility with prior optical traffic preemption systems.

System and method for transmitting data in an optical traffic preemption

An inductive sensor is driven by a series resonant oscillator circuit to produce an oscillator signal having a frequency which is a function of inductance of the inductive sensor. An inductive load, which includes the sensor, is connected in series with a capacitive impedance. Power to the series resonant circuit formed by the inductive load and the capacitive impedance is controlled as a function of current in the series circuit as sensed by a current sensor. A detection system provides a detector output based upon the frequency of the oscillator signal.

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Willernie, MN, United States of America

Steven M Hamer