Digital filter design using root moments for sum-of-all-pass structures from complete and partial specifications

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Preliminary design studies of an advanced general aviation aircraft

The preliminary design results are presented of the advanced aircraft design project. The goal was to take a revolutionary look into the design of a general aviation aircraft. Phase 1 of the project included the preliminary design of two configurations, a pusher, and a tractor. Phase 2 included the selection of only one configuration for further study. The pusher configuration was selected on the basis of performance characteristics, cabin noise, natural laminar flow, and system layouts. The design was then iterated to achieve higher levels of performance

Digital Filters

The new technology advances provide that a great number of system signals can be easily measured with a low cost. The main problem is that usually only a fraction of the signal is useful for different purposes, for example maintenance, DVD-recorders, computers, electric/electronic circuits, econometric, optimization, etc. Digital filters are the most versatile, practical and effective methods for extracting the information necessary from the signal. They can be dynamic, so they can be automatically or manually adjusted to the external and internal conditions. Presented in this book are the most advanced digital filters including different case studies and the most relevant literature

Digital Filters and Signal Processing

Digital filters, together with signal processing, are being employed in the new technologies and information systems, and are implemented in different areas and applications. Digital filters and signal processing are used with no costs and they can be adapted to different cases with great flexibility and reliability. This book presents advanced developments in digital filters and signal process methods covering different cases studies. They present the main essence of the subject, with the principal approaches to the most recent mathematical models that are being employed worldwide

Measurements, Models, Systems and Design

531 s.

Design and test of a Displacement Workspace Mapping Station for articular joints

In 2003, 267,000 Americans received total knee replacements prohibiting high impact athletics for the remainder of a patient’s life. A better understanding of the movement and constraint of the knee is necessary to provide more realistic motion of or possibly eliminate the need for joint prosthetics. Fixed Orientation Displacement Workspaces (FODW) can be applied to study the relationship of the passive constraint system and six (6) degree of freedom (DOF) movement of the human knee. A FODW consists of the volume of possible positions the tibia/fibula can occupy relative to a fixed femur without changing the relative orientation of the bones. Theoretical models of the FODW provided a promising snapshot of knee kinematics. A Displacement Workspace Test Station (DWTS) for mapping FODWs was built. An in vitro articular joint completes the loop between a strain gauge-based six (6) axis load cell and a 6 DOF manipulandum mounted to a fixed reference frame. The joint is hand manipulated while a C++ program, Armtalk, operates applications that sample and filter both manipulandum position/orientation and load cell output signals at over 500Hz. Armtalk automatically stores raw data points at 2 Hz or upon a user foot-pedal signal. Forces and moments acting at the joint and its angular orientation are added to each raw data point by algorithms in a spreadsheet. The algorithms select points that represent a particular FODW according to a user specified range of acceptable joint forces and moments and bone orientations. The Cartesian coordinates of individual FODW data points are input into a NURBS-based CAD program for visualization. The DWTS has a 0.2286 mm positional accuracy, a 200 N capacity, and a 0.075 mm/kN compliance. A 2 DOF test checked the Armtalk application and calculated the DWTS angular accuracy to be 0.008°. To calibrate the load cell, moment and force scaling factors of 0.00922 in lb/unit and 0.00554 lb/unit were calculated, respectively. The spreadsheet algorithms successfully reduced data in a 6 DOF test. The CAD program modeled workspaces from 2 and 6 DOF tests with a 1.3 % volumetric accuracy. The apparatus is ready to map FODW of articular joints

Control of large space structures

The control of large space structures was studied to determine what, if any, limitations are imposed on the size of spacecraft which may be controlled using current control system design technology. Using a typical structure in the 35 to 70 meter size category, a control system design that used actuators that are currently available was designed. The amount of control power required to maintain the vehicle in a stabilized gravity gradient pointing orientation that also damped various structural motions was determined. The moment of inertia and mass properties of this structure were varied to verify that stability and performance were maintained. The study concludes that the structure's size is required to change by at least a factor of two before any stability problems arise. The stability margin that is lost is due to the scaling of the gravity gradient torques (the rigid body control) and as such can easily be corrected by changing the control gains associated with the rigid body control. A secondary conclusion from the study is that the control design that accommodates the structural motions (to damp them) is a little more sensitive than the design that works on attitude control of the rigid body only

F-8C digital CCV flight control laws

A set of digital flight control laws were designed for the NASA F-8C digital fly-by-wire aircraft. The control laws emphasize Control Configured Vehicle (CCV) benefits. Specific pitch axis objectives were improved handling qualities, angle-of-attack limiting, gust alleviation, drag reduction in steady and maneuvering flight, and a capability to fly with reduced static stability. The lateral-directional design objectives were improved Dutch roll damping and turn coordination over a wide range in angle-of-attack. An overall program objective was to explore the use of modern control design methodilogy to achieve these specific CCV benefits. Tests for verifying system integrity, an experimental design for handling qualities evaluation, and recommended flight test investigations were specified

A NEW METHOD FOR DESIGN OF SELECTIVE DIGITAL IIR FILTERS WITH ARBITRARY PHASE

In this paper the design of selective digital filters that consists of parallel connection of two all-pass sub-filters is presented. The phase of this filters has given arbitrary shape ϕ(ω) in both pass-band and stop-band. The proposed method allows the calculation of selective filters with elliptic-like magnitude characteristic. Equations given in the paper are general and suitable for design of filters with arbitrary phase. The efficiency of the method is demonstrated on design of filters with piecewise linear and quadratic phase