Burroughs, Inc.

Lockheed Martin Tactical Systems, Inc.

3461513 Canada Inc.

Lockheed Martin Corporation

Lockheed Martin Federal Systems, Inc.

Primetech Electronics, Inc.

Systems Development Corporation

Clifford J Bader

Eugene T Mullin

Charles De Renzi

Edward A Wojtowicz

Charles S DeRenzi

Ronald E Brodeur, Sr

Eugene Mullin

Apparatus for measuring the static coefficient of friction (SCOF) of the surface of an operating conveyor belt comprises a friction roller rotatable about an axis perpendicular to the direction of movement of the conveyor belt, a friction roller actuator for moving the friction roller between a retracted disengaged position and an advanced engaged position, and a friction roller drive motor selectively operable, in one instance, for permitting free wheeling rotation of said friction roller when rotatably engaged with the conveyor belt and, in another instance, for rotating said friction roller about the friction roller axis in a direction opposite the direction of movement of the conveyor belt. A sensor continuously senses the current drawn by the friction roller drive motor and a computer is responsive to the output of the sensor when it reaches a maximum value for calculating the SCOF of the surface of the conveyor belt, the SCOF being a function of the maximum current drawn by the friction roller drive motor. Then, for cleaning the conveyor belt the apparatus comprises a brush roller rotatable about an axis perpendicular to the direction of movement of the conveyor belt, a brush roller actuator for moving the brush roller between a retracted position disengaged from the conveyor belt and an advanced position rotatably engaged with the conveyor belt, and a brush roller drive motor for rotating the brush roller about the brush roller axis when the brush roller is engaged with the conveyor belt.

Conveyor friction measurement and cleaning system

A passive magnetic detector is provided at ground level or buried below ground level in between rails of a railroad track at a distance from the level crossing for detecting magnetic field disturbances caused by ferromagnetic objects passing overhead on the track. Magnetic field reversals are detected in the passive detector signal. The reversal signal is analyzed and a train presence output signal is generated for controlling a level crossing gate system or other such crossing warning system. For parallel tracks, pairs of passive magnetic field detectors detect objects over each track and the reversals are analyzed to check that an inbound train does not sneak by undetected as an outbound train is leaving and passing over the same detector pair. At the level crossing, static magnetic field detectors are used to ensure that no equipment remains on the island after detecting that the moving train has left the crossing, so that the crossing gates can be safely lifted as soon as possible.

Vehicle presence detection system

A system and method which can detect the presence of a vehicle within the protected area of a four gate railroad crossing, determine its location and direction it is moving in, and open an appropriate exit gate to allow the vehicle to escape prior to the arrival of a train at the crossing. The system has a series of magnetometer sensors suitably placed in the crossing to detect the presence of a vehicle. The sensors are connected to a controller which analyzes readings from the sensors. Upon the approach of a train, the controller, based on analysis of readings from the sensor, determines if a vehicle has become entrapped and determines which exit gate must be opened or should remain open to allow the entrapped vehicle to escape. The system also has self test capabilities as well as the ability to continuously update, when no vehicles are present, a baseline reading of the ambient magnetic condition of the crossing area, which baseline the controller uses in analyzing data from the sensors.

A passive magnetic detector is provided at ground level or buried below ground level in between rails of a railroad trace at a distance from the level crossing for detecting magnetic field disturbances caused by ferromagnetic objects passing overhead on the track. Magnetic field reversals are detected in the passive detector signal. The reversal signal is analyzed and a train presence output signal is generated for controlling a level crossing gate system or other such crossing warning system. For parallel tracks, pairs of passive magnetic field detectors detect objects over each track and the reversals are analyzed to check that an inbound train does not sneak by undetected as an outbound train is leaving and passing over the same detector pair. At the level crossing, static magnetic field detectors are used to ensure that no equipment remains on the island after detecting that the moving train has left the crossing, so that the crossing gates can be safely lifted as soon as possible.

A system and method is disclosed for feedback velocity control of a D.C. motor. The system includes a motor (30) which is represented by its circuit equivalent--a series combination of an inductance (32), a resistor (34) and a back EMF source (36). The drive to the motor (30), supplied by a controller, is periodically inhibited by timing logic (22) and AND gate (20). Once the inductive transient decays via clamping diode (38) such that the motor current is zero, switch (40) is closed and the internally generated motor voltage is sampled by a capacitor (42). A/D converter (44) transforms the sampled value to a digital value and sends it to the controller. The controller compares it to a predetermined desired value then makes the necessary adjustments to the drive signal.

System and method for velocity control of a D.C. Motor

Apparatus and method are provided for determining and indicating if certain types of circuit failures have occurred in a D.C. motor circuit such as a locked rotor condition, a short-circuit or an open circuit. The method includes the steps of, and the apparatus involves applying a voltage to two leads of the D.C. motor sufficient to cause motor rotation, determining if flyback exists, determining if back EMF exists, and, finally, if a back EMF does not exist and flyback does exist then indicating a locked rotor condition. However, if a back EMF does not exist and flyback does not exist then an indication is provided that either an open-circuit or short-circuit condition exists. The same apparatus and method can be used with a voltage not sufficient to cause motor rotation, although given this limitation only flyback can be detected, so that only an open-circuit or short-circuit condition can be indicated.

System and method for detecting D.C. motor circuit failures

Apparatus and method are provided for determining indicating if certain types of circuit failures have occurred in a D.C. motor circuit such as a locked rotor condition, a short-circuit or an open circuit. The method includes the steps of, and the apparatus involves, applying a voltage to two leads of the D.C. motor sufficient to cause motor rotation, determining if flyback exists, determining if back EMF exists, and, finally, if a back EMF does not exist and flyback does exist then indicating a locked rotor condition. However, if a back EMF does not exist and flyback does not exist then an indication is provided that either an open-circuit or short-circuit condition exists. The same apparatus and method can be used with a voltage not sufficient to cause motor rotation, although given this limitation only flyback can be detected, so that only an open-circuit or short-circuit condition can be indicated.

System and method for detecting fault conditions in a direct current

The present disclosure describes circuit variants for reducing electromagnetic interference from saturable core keyboards to acceptable levels. The invention finds particular application in conjunction with capacitive-discharge scan techniques used in such keyboards. In order to attenuate the external field resulting from such techniques, a circuit is taught which effectively disconnects the scan line array from the capacitor charging circuit during the time between scans. A second variant, when added to the first, further reduces interference by disconnecting the entire scan circuit from the supply potential during the scan time thereby eliminating steady-state currents and turnoff oscillatory transients.

Circuit for reducing electromagnetic interference from magnetic core

The present disclosure describes an electronic system for use with low cost audio tape recorders whereby a substantially noise-free wide dynamic range is provided for the recording of analog signals in the DC to 30HZ frequency band. In achieving this result, the system utilizes two FM carrier oscillators having center frequencies displaced from each other and modulated respectively in opposite senses by the signal being recorded. The system also provides an additional utility channel of limited dynamic range for the concurrent recording of time markers, digital signals and the like.

Noise cancelling system for low frequency analog recording

An electronic circuit is described for accurately and rapidly initializing long-time constant amplifiers and the like. More specifically, the circuit is designed to establish quiescent conditions in minimal time and with minimal settling in amplifiers or integrators with internal or external voltage offsets. In performing its initializing function, the circuit utilizes a relatively low resistance network which mirrors the resistive network of the amplifier device and provides a charging path for the integrating capacitor. At the same time, the output of the device is permitted to immediately attain its steady-state voltage amplitude. The present auxiliary network automatically compensates for input offset error, so that quiescent conditions may be established extremely rapidly. Finally, the initialization configuration taught by the invention is characterized by simplicity and a small increase in the component count.

Initializing circuit for long-time constant electronic devices

An electronic circuit is described for providing a low current DC supply at increased voltage with high efficiency and minimal hardware complexity. In performing its function, the circuit preferably utilizes a plurality of CMOS voltage-controlled solid state switches in conjunction with a sequenced clock pulse train to implement a compact capacitive-type multiplier. Thus, capacitors are charged in a predetermined order and the charges stacked upon one another to ultimately charge an output storage capacitor to a voltage level which is substantially a desired multiple of the supply voltage applied to the circuit. For descriptive purposes, the present inventive techniques are applied herein to the design for an octupler.

DC Voltage multiplier using phase-sequenced CMOS switches

An electronic circuit is described for providing an analog-to-digital conversion system having an output 'delta' format in which a pulse is produced for each defined change in the amplitude of the input signal. The circuit is characterized by minimal hardware complexity and low current drain. In performing its conversion function, the circuit advantageously employs a single capacitor for coupling the input signal into the system as well as for storing precisely controlled voltage increments for effecting the equality of the input signal and a reference potential. The AC coupling afforded by this configuration eliminates the problems attendant with the digitization of a small AC signal superimposed on a large DC component. Additionally, the circuit of the present invention lends itself to the multiplexing of input signals.

Tracking analog-to-digital converter for AC signals

The present disclosure describes apparatus for the production of small permanent bar magnets accurately adjusted to a stable, predetermined value of magnetic moment. In accordance with the invention, the readout of the moment of the magnet under adjustment is provided simultaneously with the degaussing process, so that the operation becomes a coordinated one rather than the present day process involving trial-and-error. The system provides easily obtainable time-saving consistent results and is especially useful where large numbers of magnets of predetermined moment must be produced. The real-time sensing capability of the system renders it particularly suitable for automation.

Growing community of inventors

West Chester, PA, United States of America

Clifford J Bader