Westinghouse Electric Corporation

United States of America As Represented by the Secretary of the Air Force

Northrop Grumman Systems Corporation

Clinton W Moulds

George S Axelby

Carl D Wise

Norman F Powell

David R Iny

Eric W Butler

Vedat Geldiay

A local area positioning system which includes a plurality of platforms or nodes consisting of airborne and/or ground based vehicles that are coupled in a platform-to-platform local area network. The platforms themselves establish a spatial reference system for location and communication between platforms is accomplished using directive millimeter wave beams, and where measurements and communicated estimates of node locations, in a local inertial reference frame, are processed via Kalman tracking filters to generate updated estimates of position and velocity vectors associated with each node.

Local area positioning system

A system for minimizing periodically induced vibration in a mechanical structure, particularly rotary shaft apparatus that is not limited to the use of any particular number or type of forcers or sensors and requires no knowledge of the mechanical structure's transfer function. In accordance with a preferred embodiment the system senses periodically induced vibration utilizing a plurality of sensors and produces a complex output representative of the algebraic sum of the vibrations sensed for each harmonic and counteracting the vibration with a plurality of actuators operatively coupled to the structure by producing a counteracting vibration therein in response to a complex input signal for each actuator in the form of a matrix of system responses to vibrational inputs at selected harmonics of interest. More specifically, the complex inputs for the actuators are produced on the basis of an adaptation cycle wherein the effect of an adjustment of the complex inputs on the complex outputs is utilized to determine the nature of a successive adjustment of the complex inputs utilizing a control algorithm.

Multivariable adaptive vibration canceller

The total periodically induced vibratory disturbance in a structure having unique structural characteristics is minimized. Actuators are operated in response to complex input signals to produce counteractive forces in the structure. Sensors responsive to the vibrational disturbance and the counteractive forces produce outputs indicative thereof. A processor having an electrical characteristic related to the structural characteristic produces complex outputs for each actuator in response to the sensor inputs. The complex outputs are adjusted by the processor to result in a convergence of the structural response to the minimum vibration in response to the disturbance and the actuator inputs.

A method and apparatus for cancelling vibrations caused by periodic pulsating forces acting on a rotating shaft which are synchronous with the shaft rotation. An adaptive algorithm is implemented which utilizes the sensed velocity or acceleration of the difference between the pulsting forces acting on the shaft and an applied control force to generate an estimate of the phase shift existing therebetween to adjust a pair of adaptive weighting coefficients for sine and cosine force components which are adjusted by a least mean square (LMS) algorithm. Actuating signals for the reaction mass actuator are generated from the weighted force components which applies a controlled force to the shaft to oppose the shaft pulsation force and thus cancel the vibration.

Adaptive vibration canceller

A separate adaptive noise canceller receiving a reference input of a rotor speed synchronization pulse is connected in the X and Y axis positional control loops of a magnetic bearing utilized to position a rotor suspended thereby. The output of the noise canceller is self-adjusting by the inclusion of an adaptive filter implementing a least mean square algorithm to force the gain of the control loop to zero at not only the fundamental of the rotational speed, but all harmonic frequencies thereof, thereby reducing the vibration and control system power dissipation of the magnetic bearing at the rotational fundamental as well as at the rotational harmonics.

Adaptive noise cancelling for magnetic bearing auto-balancing

Apparatus and method for controlling the output of a dynamic system which is susceptible to changing dynamic characteristics. The desired present and future outputs of the system are applied to a predictor which determines the inputs to a model reference adaptive control subsystem from which the actual outputs are produced. The predictor uses an impulse model of the subsystem to simulate and predict future outputs. The adaptive control subsystem includes adjustable gain feedback or controlloops which are adjusted to make the dynamic system appear to have constant characteristics even when its dynamic characteristics are changing. A reference model of the dynamic system is used as the basis for the gain adjustments. The equation weights for the mathematical impulse model used by the input predictor are derived from the reference model of the adaptive control subsystem, and remain constant throughout the operation of the controller.

Predictive model reference adaptive controller

Predictive control of a controlled dynamic system having conventional feedback. The input predictor processes the assumed inputs to the controlled system to determine an error output or value corresponding to the outputs only at the prediction horizon interval. The error output is processed by scalar mathematical operations to adjust the assumed inputs and form actual inputs to the controlled system. This method of predicting the inputs can be accomplished in less time than required by previous systems, and the stability of the controlled system, particularly non-minimum phase systems, is improved.

Apparatus and method for predictive control of a dynamic system

An improved pseudo random number generator apparatus utilizing a programmable read only memory to reduce autocorrelation magnitudes by mapping the maximal length shift register states into the final output states.

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Millersville, MD, United States of America

Clinton W Moulds