Lord Corporation

Digisonix, Inc.

Steve C Southward

Mark R Jolly

Russell E Altieri

Askari Badre-Alam

Mark A Norris

Michael C Heath

Dino J Rossetti

James F Kuhn

Leslie P Fowler

Douglas Edward Ivers

Douglas A Swanson

Matthew K Ferguson

Lane R Miller

Kenneth Alan St Clair

Douglas A Hodgson

Shawn K Steenhagen

Kent F Delfosse

Dino J Rosetti

Methods and systems for monitoring rotating shaft shafts and couplings in an aircraft propulsion system is described. The measurement system/method provides for accurate and precise monitoring of a rotating shaft flexible coupling in a fixed wing aircraft vehicle propulsion system. The measuring system/method provides for a high reliability short take off vertical landing fixed wing aircraft in which the vertical propulsion dynamically rotating drive shaft system and couplings are monitored in real time. The vehicular shaft coupling misalignment measuring system utilizes multiple positional sensors to provide highly reliable and precise determination of the dynamic characteristics of the rotating sensor target components of the propulsion system drive shaft. The relative position of the sensors is rigidly fixed externally from the rotating targets with a structural frame. The collar misalignment measuring system of the invention provide a misalignment measurement of the propulsion system drive shaft flexible coupling which relates to a critical performance of rotating shaft coupling in the operation of an aircraft vehicle. The method/system provides for monitoring a rotating drive shaft system and dynamically measuring a rotating drive shaft coupling in a fixed wing aircraft propulsion system.

Aircraft vehicular propulsion system monitoring device and method

The invention provides a method/system for measuring torque. The method/system includes providing a first rotating disk having a target pattern and providing a second rotating disk having a target pattern. The method/system includes providing a first set of at least three sensors, comprised of a first disk first sensor, a first disk second sensor, and a first disk third sensor, the first set of at least three sensors for sensing the first rotating disk target pattern with the first set of at least three sensors fixed around and encompassing the first rotating disk. The method/system includes providing a second set of at least three sensors, comprised of a second disk first sensor, a second disk second sensor, and a second disk third sensor, the second set of at least three sensors for sensing the second rotating disk target pattern, with the second set of at least three sensors fixed around and encompassing the second rotating disk. The method/system includes measuring an apparent twist of the first rotating disk relative to the second rotating disk with the first set of at least three sensors and the second set of at least three sensors, and determining an actual twist angle from the measured apparent twist.

Method and system for measuring torque

A method for controlling end stop collisions in electro-mechanical systems including dampers or actuators. In a first aspect, a velocity-squared control method determines an end stop control signal (V.sub.end stop) based, at least in part, upon a square of the relative velocity (V.sub.inst). Preferably, the displacement (.delta..sub.end) to the end stop is also used to derive the end stop control signal (V.sub.end stop). In another aspect, a snubber control method is employed which produces a snubber control signal (V.sub.snub) based, at least in part, upon a continuous function of a snubber incursion distance (.delta..sub.z) within a snubber zone (Z). Preferably, the velocity-squared end stop and the snubber control methods operate together. When used in conjunction with an end stop control method, the snubber control method prevents end stop collisions for cases where the end stop control algorithm alone would not. Either of the end stop methods (the velocity-squared end stop control method or the snubber control method) may be used alone, in combination with each other, or in combination with a primary control method.

End stop control method

An Active Structural Control (ASC) system (10) and method which includes a plurality of Active Vibration Absorbers (AVAs) (40) attached to a yoke (32) included within a pylon structure (28) preferably comprising a spar (38) and a yoke (32) which is located intermediate between an aircraft fuselage (20) and an aircraft engine (18) for controlling acoustic noise and/or vibration generated within the aircraft's cabin (44) due to unbalances in the aircraft engine (18). The ASC system (10) includes a plurality of error sensors (42) for providing error signals, and at least one reference sensor (49 or 50) for providing reference signals indicative of the N1 and/or N2 engine rotations and/or vibrations, and a preferably digital electronic controller (46) for processing the error and reference signal information to provide output signals to drive the plurality of AVAs (40) attached to the yoke (32). The AVAs (40) preferably act in a radial, tangential, or fore and aft directions and may be preferably located at the terminal end and/or at the base portion of the yoke (32). Further, the AVAs (40) may be Single Degree Of Freedom (SDOF) or Multiple Degree Of Freedom (MDOF) and may be tuned to have a passive resonance which substantially coincides with the N1 and/or N2 engine rotation and/or vibrations. In another aspect, reference signal processing is described which includes a modulo counter, a lookup table, and a digital IO.

Active structural control system and method including active vibration

Actuators for active vibrational energy control systems which are frequency focused. The high-frequency cancellation function is decoupled from the low-frequency cancellation function to enable the size, force, number and placement of the actuators to be optimized. A hybrid system employing structural actuators to cancel low-frequency vibrations and speakers to cancel higher-frequency vibrations is also taught.

Frequency-focused actuators for active vibrational energy control systems

An active control method and apparatus for controlling vibration or sound wherein the computational burden to adaptively update the control filter within the update model is reduced. The apparatus includes means for producing an input signal for input to the update model and the reduction block, means for generating an error sensor, and an output device for canceling sound and/or vibration at a selected location. The method uses a gradient descent algorithm such as the filtered-x LMS algorithm and replaces the long filter model with a shortened length filter model. Error signal information together with the output information from the shortened length filter model are used to update the coefficients of the control filter according to an update calculation method. The shortened filter model only contains frequency response information at the L frequencies of interest. Because of the reduced amount of information contained in the shortened filter model, more updates per unit of time can be performed on the control filter(s) or a smaller or fewer processors or CPU's may be utilized. The method has applicability to feed-forward and feed-back type systems and also to systems using a waveform generator for supplying the input signal. The reduction method may be implemented on-line or off-line.

Reduction of computational burden of adaptively updating control

An active adaptive control system and method has frequency dependent filtering with a transfer characteristic which is a function of a frequency dependent shaped power limitation characteristic maximizing usage of available output transducer authority. Band separation is provided for different tones. Power limit partitioning is provided for effectively distributing power between correction tones to maximize model performance.

Frequency selective active adaptive control system

An active system for controlling vibration or sound. The system includes a method for limiting the output gain G from a gradient descent algorithm, such as an LMS algorithm, according to the relationship ##EQU1## and reducing one of first and second filter weights W.sub.1 and W.sub.0 such that G.ltoreq.G.sub.max ensuring the output canceling signal is never saturated. This eliminates the square wave shape which may impart unwanted harmonics or resonances to the dynamic system. In another aspect, the system eliminates drift of the output devices toward saturation when situations are encountered such as singularities in the quadratic performance surface. This is accomplished by applying leakage factor r(k) to a function f(k) at or near a predetermined limit to avoid saturation of the output device. The function f(k) can be the gain G or the weights W(k). Another aspect is to provide a constant, optimum, and stable adaptation rate in an LMS system by providing an optimum adaptation coefficient .mu..sub.opt that provides a constant, uniform, and optimum adaptation rate on a per period basis for all frequencies. Various combinations of the above are described and are useful in active control systems.

Active control of noise and vibration

An active noise and vibration control system (20) for cancellation of noise or vibration. The system (20) provides a system whereby the adaptation path and feedforward path are implemented in separate hardware. As a result, the computational burden on the digital signal processor (DSP) (28) is reduced allowing the DSP (28) to handle multiple inputs (22), error sensors (34), and transducers (32). In one embodiment, the processing of the input signal from sensor (22) takes place in a waveform generator (24) comprising a phase-locked loop, a frequency divider, a shift register, and at least one switched capacitor filter. In another embodiment the input signal processing takes place in separate feedforward circuitry including a field programmable gate array (64).

Active noise and vibration cancellation system

An active mount for fixed wing applications. One aspect of the invention provides decoupling of two tones which are close in frequency by positioning the mount actuators and error sensors in the primary transmission path of the disturbance vibration and by providing adequate spatial separation between the two sets of error sensors to reduce or eliminate cross-coupling of the signals. Another aspect of the invention utilizes orthogonally positioned actuators with corresponding actuators of paired mounts being focalized for each engine.

Active mounts for aircraft engines

An active noise and vibration cancellation system with broadband control capability. A broadband disturbance signal detector positioned within a closed compartment such as an aircraft cabin or vehicle passenger compartment provides a signal representative of the frequency spectrum and corresponding relative magnitude of a broadband signal emanating from a vibrational energy source to a controller. The controller receives the broadband disturbance signal as well as error signals from error sensors which, by virtue of adaptive filters within the controller, enhance the cancellation capability of the control signals produced by one or more actuators positioned within the compartment.

Broadband noise and vibration reduction

A waveform generator (20) for generating an analog wave which is synchronized with a signal from an input source (22). The waveform generator (20) includes a phase-locked loop (24) for receiving an input source signal and multiplying said signal by a multiplier. The multiplied square wave signal is then provided to a frequency divider (28) and to a first clock input (39) of a first switched-capacitor filter (29). The frequency divider (28) outputs a divided output signal that is received as an input to the phase-locked loop (25) and by the first switched-capacitor filter (35). As a result, the first switched-capacitor filter (29) outputs a first analog wave of a constant amplitude which is phase synchronized with the input source signal. This waveform generator (20) allows the 3 dB point of the filter to move as the input frequency changes. Further embodiments allow the addition of second switched-capacitor filter (50) and a shift register (45) for providing a second analog wave which is phase shifted from said input source signal yet is synchronized therewith.

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Cary, NC, United States of America

Steve C Southward