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Lateral-directional handling qualities and roll control power requirements for the executive jet class of airplanes in the landing approach flight phase were investigated in the USAF/CAL variable stability T-33 airplane. Particular emphasis was placed on the effects of crosswinds and turbulence. Simulated IFR ILS approaches and VFR offset and crosswind approaches were made. Specifically, two Dutch roll frequencies, three Dutch roll damping ratios, three roll-to-sideslip ratios and three roll mode time constants were investigated. It was found tht for the range of parameters investigated, lateral-directional dynamics do not establish a limiting crosswind value; however, they do determine the ease or difficulty with which a crosswind approach can be accomplished. Roll control power requirements were determined from actual control usage data obtained throughout the evaluation program and were found to be a function of the lateral-directional dynamics. Minimum acceptable levels of roll control power were determined by re-evaluating a number of configurations with limited roll control power. It was found that available roll control power can establish a limiting crosswind component.

Lateral-directional handling qualities and roll control power requirements for the executive jet class of airplanes in the landing approach flight phase were investigated in the USAF/CAL variable stability T-33 airplane. Particular emphasis was placed on the effects of crosswinds and turbulence. Simulated IFR ILS approaches and VFR offset and crosswind approaches were made. Specifically, two Dutch roll frequencies, three Dutch roll damping ratios, three roll-to-sideslip ratios and three roll mode time constants were investigated. It was found tht for the range of parameters investigated, lateral-directional dynamics do not establish a limiting crosswind value; however, they do determine the ease or difficulty with which a crosswind approach can be accomplished. Roll control power requirements were determined from actual control usage data obtained throughout the evaluation program and were found to be a function of the lateral-directional dynamics. Minimum acceptable levels of roll control power were determined by re-evaluating a number of configurations with limited roll control power. It was found that available roll control power can establish a limiting crosswind component.

Lateral-directional handling qualities and roll control power requirements for the executive jet class of airplanes in the landing approach flight phase were investigated in the USAF/CAL variable stability T-33 airplane. Particular emphasis was placed on the effects of crosswinds and turbulence. Simulated IFR ILS approaches and VFR offset and crosswind approaches were made. Specifically, two Dutch roll frequencies, three Dutch roll damping ratios, three roll-to-sideslip ratios and three roll mode time constants were investigated. It was found tht for the range of parameters investigated, lateral-directional dynamics do not establish a limiting crosswind value; however, they do determine the ease or difficulty with which a crosswind approach can be accomplished. Roll control power requirements were determined from actual control usage data obtained throughout the evaluation program and were found to be a function of the lateral-directional dynamics. Minimum acceptable levels of roll control power were determined by re-evaluating a number of configurations with limited roll control power. It was found that available roll control power can establish a limiting crosswind component.

The Solar Dynamics Observatory is an Explorer-class mission that will launch in early 2009. The spacecraft will operate in a geosynchronous orbit, sending data 24 hours a day to a devoted ground station in White Sands, New Mexico. It will carry a suite of instruments designed to observe the Sun in multiple wavelengths at unprecedented resolution. The Atmospheric Imaging Assembly includes four telescopes with focal plane CCDs that can image the full solar disk in four different visible wavelengths. The Extreme-ultraviolet Variability Experiment will collect time-correlated data on the activity of the Sun's corona. The Helioseismic and Magnetic Imager will enable study of pressure waves moving through the body of the Sun. The attitude control system on Solar Dynamics Observatory is responsible for four main phases of activity. The physical safety of the spacecraft after separation must be guaranteed. Fine attitude determination and control must be sufficient for instrument calibration maneuvers. The mission science mode requires 2-arcsecond control according to error signals provided by guide telescopes on the Atmospheric Imaging Assembly, one of the three instruments to be carried. Lastly, accurate execution of linear and angular momentum changes to the spacecraft must be provided for momentum management and orbit maintenance. In th~sp aper, single-fault tolerant fault detection and correction of the Solar Dynamics Observatory attitude control system is described. The attitude control hardware suite for the mission is catalogued, with special attention to redundancy at the hardware level. Four reaction wheels are used where any three are satisfactory. Four pairs of redundant thrusters are employed for orbit change maneuvers and momentum management. Three two-axis gyroscopes provide full redundancy for rate sensing. A digital Sun sensor and two autonomous star trackers provide two-out-of-three redundancy for fine attitude determination. The use of software to maximize chances of recovery from any hardware or software fault is detailed. A generic fault detection and correction software structure is used, allowing additions, deletions, and adjustments to fault detection and correction rules. This software structure is fed by in-line fault tests that are also able to take appropriate actions to avoid corruption of the data stream.

A geometric form of Euler-Lagrange equations is developed for a chain pendulum, a serial connection of $n$ rigid links connected by spherical joints, that is attached to a rigid cart. The cart can translate in a horizontal plane acted on by a horizontal control force while the chain pendulum can undergo complex motion in 3D due to gravity. The configuration of the system is in $(\Sph^2)^n \times \Re^2$. We examine the rich structure of the uncontrolled system dynamics: the equilibria of the system correspond to any one of $2^n$ different chain pendulum configurations and any cart location. A linearization about each equilibrium, and the corresponding controllability criterion is provided. We also show that any equilibrium can be asymptotically stabilized by using a proportional-derivative type controller, and we provide a few numerical examples.

A geometric form of Euler-Lagrange equations is developed for a chain pendulum, a serial connection of $n$ rigid links connected by spherical joints, that is attached to a rigid cart. The cart can translate in a horizontal plane acted on by a horizontal control force while the chain pendulum can undergo complex motion in 3D due to gravity. The configuration of the system is in $(\Sph^2)^n \times \Re^2$. We examine the rich structure of the uncontrolled system dynamics: the equilibria of the system correspond to any one of $2^n$ different chain pendulum configurations and any cart location. A linearization about each equilibrium, and the corresponding controllability criterion is provided. We also show that any equilibrium can be asymptotically stabilized by using a proportional-derivative type controller, and we provide a few numerical examples.

A geometric form of Euler-Lagrange equations is developed for a chain pendulum, a serial connection of $n$ rigid links connected by spherical joints, that is attached to a rigid cart. The cart can translate in a horizontal plane acted on by a horizontal control force while the chain pendulum can undergo complex motion in 3D due to gravity. The configuration of the system is in $(\Sph^2)^n \times \Re^2$. We examine the rich structure of the uncontrolled system dynamics: the equilibria of the system correspond to any one of $2^n$ different chain pendulum configurations and any cart location. A linearization about each equilibrium, and the corresponding controllability criterion is provided. We also show that any equilibrium can be asymptotically stabilized by using a proportional-derivative type controller, and we provide a few numerical examples.

A geometric form of Euler-Lagrange equations is developed for a chain pendulum, a serial connection of $n$ rigid links connected by spherical joints, that is attached to a rigid cart. The cart can translate in a horizontal plane acted on by a horizontal control force while the chain pendulum can undergo complex motion in 3D due to gravity. The configuration of the system is in $(\Sph^2)^n \times \Re^2$. We examine the rich structure of the uncontrolled system dynamics: the equilibria of the system correspond to any one of $2^n$ different chain pendulum configurations and any cart location. A linearization about each equilibrium, and the corresponding controllability criterion is provided. We also show that any equilibrium can be asymptotically stabilized by using a proportional-derivative type controller, and we provide a few numerical examples.

A geometric form of Euler-Lagrange equations is developed for a chain pendulum, a serial connection of $n$ rigid links connected by spherical joints, that is attached to a rigid cart. The cart can translate in a horizontal plane acted on by a horizontal control force while the chain pendulum can undergo complex motion in 3D due to gravity. The configuration of the system is in $(\Sph^2)^n \times \Re^2$. We examine the rich structure of the uncontrolled system dynamics: the equilibria of the system correspond to any one of $2^n$ different chain pendulum configurations and any cart location. A linearization about each equilibrium, and the corresponding controllability criterion is provided. We also show that any equilibrium can be asymptotically stabilized by using a proportional-derivative type controller, and we provide a few numerical examples.

A geometric form of Euler-Lagrange equations is developed for a chain pendulum, a serial connection of $n$ rigid links connected by spherical joints, that is attached to a rigid cart. The cart can translate in a horizontal plane acted on by a horizontal control force while the chain pendulum can undergo complex motion in 3D due to gravity. The configuration of the system is in $(\Sph^2)^n \times \Re^2$. We examine the rich structure of the uncontrolled system dynamics: the equilibria of the system correspond to any one of $2^n$ different chain pendulum configurations and any cart location. A linearization about each equilibrium, and the corresponding controllability criterion is provided. We also show that any equilibrium can be asymptotically stabilized by using a proportional-derivative type controller, and we provide a few numerical examples.

A geometric form of Euler-Lagrange equations is developed for a chain pendulum, a serial connection of $n$ rigid links connected by spherical joints, that is attached to a rigid cart. The cart can translate in a horizontal plane acted on by a horizontal control force while the chain pendulum can undergo complex motion in 3D due to gravity. The configuration of the system is in $(\Sph^2)^n \times \Re^2$. We examine the rich structure of the uncontrolled system dynamics: the equilibria of the system correspond to any one of $2^n$ different chain pendulum configurations and any cart location. A linearization about each equilibrium, and the corresponding controllability criterion is provided. We also show that any equilibrium can be asymptotically stabilized by using a proportional-derivative type controller, and we provide a few numerical examples.

Process Dynamics And Control Seborg 2nd Edition 3

Software-in-the-loop and Hardware-in-the-loop testing of failure prognostics and decision making tools for aircraft systems will facilitate more comprehensive and cost-effective testing than what is practical to conduct with flight tests. A framework is described for the offline recreation of dynamic loads on simulated or physical aircraft powertrain components based on a real-time simulation of airframe dynamics running on a flight simulator, an inner-loop flight control policy executed by either an autopilot routine or a human pilot, and a supervisory fault management control policy. The creation of an offline framework for verifying and validating supervisory failure prognostics and decision making routines is described for the example of battery charge depletion failure scenarios onboard a prototype electric unmanned aerial vehicle.

Software-in-the-loop and Hardware-in-the-loop testing of failure prognostics and decision making tools for aircraft systems will facilitate more comprehensive and cost-effective testing than what is practical to conduct with flight tests. A framework is described for the offline recreation of dynamic loads on simulated or physical aircraft powertrain components based on a real-time simulation of airframe dynamics running on a flight simulator, an inner-loop flight control policy executed by either an autopilot routine or a human pilot, and a supervisory fault management control policy. The creation of an offline framework for verifying and validating supervisory failure prognostics and decision making routines is described for the example of battery charge depletion failure scenarios onboard a prototype electric unmanned aerial vehicle.

The dynamics and control of slewing maneuvers of a large flexible spacecraft, namely, NASA Spacecraft Control Laboratory Experiment (SCOLE) test article are studied. The dynamical equations obtained for slewing maneuvers are highly nonlinear and coupled. The maneuver is expressed in terms of four Euler parameters and is specified as the angular displacement about an arbitrary axis. The slew maneuver control problem is developed in terms of rigid-body slewing and suppression of two elastic modes is analyzed using the method of nonlinear decoupling.

The Hubble Space Telescope features the most exacting line of sight jitter requirement thus far imposed on a spacecraft pointing system. Consideration of the fine pointing requirements prompted an attempt to isolate the telescope from the low level vibration disturbances generated by the attitude control system reaction wheels. The primary goal was to provide isolation from axial component of wheel disturbance without compromising the control system bandwidth. A passive isolation system employing metal springs in parallel with viscous fluid dampers was designed, fabricated, and space qualified. Stiffness and damping characteristics are deterministic, controlled independently, and were demonstrated to remain constant over at least five orders of input disturbance magnitude. The damping remained purely viscous even at the data collection threshold of .16 x .000001 in input displacement, a level much lower than the anticipated Hubble Space Telescope disturbance amplitude. Vibration attenuation goals were obtained and ground test of the vehicle has demonstrated the isolators are transparent to the attitude control system.

A study was made to define the long-range technical objectives and goals for the Space Structure (Dynamics and Control) theme area. The approach was to evaluate ongoing and proposed technology activities such that the technology gaps and voids could be identified. After the technology needs were identified, a set of recommended experimental activities was defined including the technical objectives of each and their relationship.

Simulation of structural response of multi-flexible-body systems by linearized flexible motion combined with nonlinear rigid motion is discussed. Advantages and applicability of such an approach for accurate simulation with greatly reduced computational costs and turnaround times are described, restricting attention to the control design environment. Requirements for updating the linearized flexibility model to track large angular motions are discussed. Validation of such an approach by comparison with other existing codes is included. Application to a flexible robot manipulator system is described.

The topics are presented in viewgraph form and include the following: dynamics and control problems of joining structures in orbit; spring-and-mass models; and a simple example.

A number of future DOD and NASA spacecraft such as the space based radar will be not only an order of magnitude larger in dimension than the current spacecraft, but will exhibit extreme structural flexibility with very low structural vibration frequencies. Another class of spacecraft (such as the space defense platforms) will combine large physical size with extremely precise pointing requirement. Such problems require a total departure from the traditional methods of modeling and control system design of spacecraft where structural flexibility is treated as a secondary effect. With these problems in mind, the Air Force Rocket Propulsion Laboratory (AFRPL) initiated research to develop dynamics and control technology so as to enable the future large space structures (LSS). AFRPL's effort in this area can be subdivided into the following three overlapping areas: (1) ground experiments, (2) spacecraft modeling and control, and (3) sensors and actuators. Both the in-house and contractual efforts of the AFRPL in LSS are summarized.

A workshop on structural dynamics and control interaction of flexible structures was held to promote technical exchange between the structural dynamics and control disciplines, foster joint technology, and provide a forum for discussing and focusing critical issues in the separate and combined areas. Issues and areas of emphasis were identified in structure-control interaction for the next generation of flexible systems.

This work uses a fundamental approach to the problem of simulating the flight of flexible aircraft. To this end, it integrates into a single formulation the pertinent disciplines, namely, analytical dynamics, structural dynamics, aerodynamics, and controls. It considers both the rigid body motions of the aircraft, three translations (forward motion, sideslip and plunge) and three rotations (roll, pitch and yaw), and the elastic deformations of every point of the aircraft, as well as the aerodynamic, propulsion, gravity and control forces. The equations of motion are expressed in a form ideally suited for computer processing. A perturbation approach yields a flight dynamics problem for the motions of a quasi-rigid aircraft and an 'extended aeroelasticity' problem for the elastic deformations and perturbations in the rigid body motions, with the solution of the first problem entering as an input into the second problem. The control forces for the flight dynamics problem are obtained by an 'inverse' process and the feedback controls for the extended aeroservoelasticity problem are determined by the LQG theory. A numerical example presents time simulations of rigid body perturbations and elastic deformations about 1) a steady level flight and 2) a level steady turn maneuver.

The structural dynamics and control of the Solar Power Satellite (SPS), a concept which holds promise for meeting a portion of the energy needs of the United States beyond the year 2000 are examined. The assumptions, methodologies and conclusions of existing SPS studies in the areas of structural dynamics and control (with structural design and materials also being considered) are assessed.

The results of a fixed-base simulator study of the effects of variable longitudinal control-system dynamics on pilot opinion are presented and compared with flight-test data. The control-system variables considered in this investigation included stick force per g, time constant, and dead-band, or stabilizer breakout force. In general, the fairly good correlation between flight and simulator results for two pilots demonstrates the validity of fixed-base simulator studies which are designed to complement and supplement flight studies and serve as a guide in control-system preliminary design. However, in the investigation of certain problem areas (e.g., sensitive control-system configurations associated with pilot- induced oscillations in flight), fixed-base simulator results did not predict the occurrence of an instability, although the pilots noted the system was extremely sensitive and unsatisfactory. If it is desired to predict pilot-induced-oscillation tendencies, tests in moving-base simulators may be required. It was found possible to represent the human pilot by a linear pilot analog for the tracking task assumed in the present study. The criterion used to adjust the pilot analog was the root-mean-square tracking error of one of the human pilots on the fixed-base simulator. Matching the tracking error of the pilot analog to that of the human pilot gave an approximation to the variation of human-pilot behavior over a range of control-system dynamics. Results of the pilot-analog study indicated that both for optimized control-system dynamics (for poor airplane dynamics) and for a region of good airplane dynamics, the pilot response characteristics are approximately the same.

The attitude stabilization of a charged rigid spacecraft in Low Earth Orbit (LEO) using torques due to Lorentz force in pitch and roll directions is considered. A spacecraft that generates an electrostatic charge on its surface in the Earth magnetic field will be subject to perturbations from Lorentz force. The Lorentz force acting on an electrostatically charged spacecraft may provide a useful thrust for controlling a spacecraft's orientation. We assume that the spacecraft is moving in the Earth's magnetic field in an elliptical orbit under the effects of the gravitational, geomagnetic and Lorentz torques. The magnetic field of the Earth is modeled as a non-tilted dipole. A model incorporating all Lorentz torques as a function of orbital elements has been developed on the basis of electric and magnetic fields. The stability of the spacecraft orientation is investigated both analytically and numerically. The existence and stability of equilibrium positions is investigated for different values of the charge to mass ratio ($\alpha^*$). Stable orbits are identified for various values of $\alpha^*$. The main parameters for stabilization of the spacecraft are $\alpha^*$ and the difference between the components of the moment of inertia of spacecraft.

Formation flying is an enabling technology for many future space missions. This paper presents extensions to the equations of relative motion expressed in Keplerian orbital elements, including new initialization techniques for general formation configurations. A new linear time-varying form of the equations of relative motion is developed from Gauss Variational Equations and used in a model predictive controller. The linearizing assumptions for these equations are shown to be consistent with typical formation flying scenarios. Several linear, convex initialization techniques are presented, as well as a general, decentralized method for coordinating a tetrahedral formation using differential orbital elements. Control methods are validated using a commercial numerical propagator.

Laser dynamics, control, and stabilization of optical frequency radiation

The problem of optimal control with a minimum time criterion as applied to a single boom system for achieving two axis control is discussed. The special case where the initial conditions are such that the system can be driven to the equilibrium state with only a single switching maneuver in the bang-bang optimal sequence is analyzed. The system responses are presented. Application of the linear regulator problem for the optimal control of the telescoping system is extended to consider the effects of measurement and plant noises. The noise uncertainties are included with an application of the estimator - Kalman filter problem. Different schemes for measuring the components of the angular velocity are considered. Analytical results are obtained for special cases, and numerical results are presented for the general case.

The purpose of the book is to present an integrated, analytical treatment of the dynamics of the aircraft and of its flight control systems. The book has been written by and for engineers concerned with the analysis of aircraft dynamics and with the synthesis of aircraft flight controls.

The most significant research progress and accomplishment in our project is on the modelling, analysis and designs of stabilizing joints for coupled structures. In a series of papers, we have studied second order dynamic structures modelling vibrating strings and cables, and fourth order dynamic structures modelling vibrating beams. We are able to classify all linear dissipative joints into types. Dr. H.H. West of the Civil Engineering Department of the Pennsylvania State University has collaborated with us and completed mechanical designs for all of them. Numerical and experimental verification have also been carried out. Dr. Chen's Ph.D. student M.P. Coleman is now using the Cyber 205 supercomputer to compute eigenfrequencies of a damped plate. Experiments were conducted at the MIPAC Facility of the University of Wisconsin in collaboration with Dr. D.L. Russell.

This report is the final report of a three-year program with a 9-month NCE comprising both theoretical and experimental work on problems arising with unsteady combustion of gases intended for use in propulsion systems. The experimental work comprises two main efforts: (I) measurements providing the basis for inferring the local response function of a reacting mixture: and, (2) accurate determination of the behavior of a Rijke tube. Part (1) is based on greatly extended equipment purchased before this program began, with a DURIP grant from AFOSR. The basic part of the facility is apparatus for PLIF (planar laser induced fluorescence) measurements of a combustion system exposed to a sinusoidally varying pressure field, p' with q , the local fluctuation of heat release, appropriate measurements allow inference of q'/p', proportional to the response function and q'p', the integral over volume is proportional to the Rayleigh factor. In principal, knowledge of these two quantities permits deduction of all important dynamical properties of a dynamical system in the second part of this program, a particularly simple combustion system, the Rijke tube, has been investigated. We believe that we have produced the most accurate data ever obtained to confirm quantitatively much of basic behavior of the device. This result does much to solidify the basis for theoretically and practically treating the dynamics of time-dependent combustion systems.

Longitudinal pressure oscillations in a combustion chamber are studied theoretically by means of a low order model obtained by systematic reduction from a complete representation. The formulation is based on the derivation of a generalized wave equation that accommodates the effects of mean flow, combustion, noise and control action. By using spatial averaging, the equations describing the dynamics of the chamber are reduced to a set of coupled ordinary differential equations. The form of the resulting equations is particularly convenient for model reduction and for introducing feedback control terms, while retaining all physical processes. Active feedback control of longitudiual instabilities is then introduced by using the same formulation, rewritten in statespace form. The broad objective of control simulations covered here is to investigate in a unified fashion various aspects of the problem. These include the influences of noise, parameter uncertainties, unmodeled modes and time-delay. A criterion is derived that guarantees the stability of the controlled closed-loop system in the presence of those quantities. The particular controller used here is based on a standard LQR design, but any design technique can be used as long as the stability criterion is fulfilled.

vA control strategy is proposed for a minimally-actuated flapping-wing micro air-vehicle (FWMAV). The proposed vehicle is similar to the Harvard RoboFly that accomplished the first takeoff of an insect scale flapping wing aircraft, except that it is equipped with independently actuated wings and the vehicle center-of-gravity can be manipulated for control purposes. Using the results from the derivation of the aerodynamic forces and moments from Part I, a control allocation strategy and a feedback control law are designed that enables the vehicle to achieve untethered, stabilized flight about a hover condition. The control laws are designed to make use of three actuators, two of which control the angular position of the wing in the stroke plane, and one that moves a bob-weight that manipulates the vehicle center-of-gravity. The Split-Cycle Constant-Period Frequency Modulation technique, introduced in Part I, is used to allow each wing to generate nonzero cycle-averaged rolling and yawing moments. The technique achieves this objective by varying the frequency of the oscillators, that drive each wing throughout the wing-beat cycles, such that the dynamic pressure acting on each wing during the upstroke is different from that which acts on the wing during the downstroke. Pitching moment and high speed translation are controlled by varying the vehicle center-of-gravity using a bob-weight actuator.

We present a detailed description of the application of a noncanonical Hamiltonian formulation to the modeling, analysis, and simulation of the dynamics of gyrostat spacecraft with internal mass motion. The methods have been applied to the practical implementation of control of a three-dimensional air bearing spacecraft simulator. We also present the analysis of electrodynamic tether systems, including optimal control of a simplified model.

A high order rotorcraft mathematical model is developed and validated against the XV-15 and a Large Civil Tiltrotor (LCTR) concept. Separate modeling of each rotorcraft component in a multi-body like formulation allows for structural flexibility to be included, which is important when modeling large aircraft where structural modes affect the flight dynamics frequency ranges of interest. Details of the formulation of the mathematical model are given, including derivations of structural, aerodynamic, and inertial loads. Flexibility effects are evaluated by looking at the nature of the couplings between rigid-body modes and wing structural modes and vice versa. A proportional-integral feedback on the structural acceleration is used to improve damping and reduce the overall excitation of a structural mode. A model following control architecture is then implemented on full order flexible LCTR models. The impact of structural feedback investigated. A rigid aircraft model has optimistic performance characteristics, and a control system designed for a rigid aircraft could potentially destabilize a flexible one. The various control systems are flown in a fixed-base simulator. Pilot inputs and aircraft performance are recorded and analyzed.

Improved understanding of unsteady flow physics has led to a wealth of flow control applications in which fluid perturbations are deliberately introduced into a large-scale flow with the goal of affecting its global characteristics. Research into these methods has included separation control, enhanced mixing, and reduction of turbulent skin friction. Interest in turbulence control has grown due to numerical computations at low Reynolds number flow [3, 4, 5] which indicate that the turbulence and drag can be reduced by a variety of fluidic actuations. The difficulty with these methods is that even though computationally they provide promising results, implementing them in a physical experiment proves very difficult. Other actuation methods that have been studied experimentally include localized heating [6], piezo-electric flaps [7], oscillatory blowing [8], synthetic jets [9], surface motion [10] and plasma discharge [11].

This Trident Project focuses on the development of a controller for the coordination of a swarm of Autonomous Surface Vessels (ASVs) under mission and environmental constraints. For this research project, we first improved an existing Four Degree of Freedom (4DOF) vessel model. The model of a 360 metric ton patrol contains nonlinear hydrodynamics for the vessel's surge, sway, roll, and yaw motions. This model was modified to take into account environmental conditions including wind, waves and currents. Additionally, the control inputs of the model (propeller thrust, and desired ruder angle) were adapted for easier integration with a swarm level controller and additional nonholonomic motion constraints were applied to increase model fidelity. We then integrated this model into a simulated swarm of ASVs. It is the intention that this model will more accurately depict nonlinear vessel dynamics than did models used in previous ASV swarm studies. Using a redundant robot manipulator formulation, the swarm controller enables ASVs to travel in a formation with the intent of protecting and escorting a hypothetical asset. To provide flexibility, the controller is capable of modifying its overall formation shape and mission parameters in response to varying environmental conditions. The Atlantic Center for the Innovative Design and Control of Small Ships, a research initiative sponsored by the Office of Naval Research, plans to apply techniques and methods developed in this study towards the construction and testing of a physical swarm of ASVs.

The STIR project focused on a set of highly challenging problems to set the stage for future work at a deeper level. These problems are (1) to design a circuit system that simulates the transformation of an incident impulse into a solitary wave, (2) to study how the width of a solitary wave depends on the geometry of the grain-grain contacts, (3) how to make solitary waves in noisy environments, (4) to find what kind of physical situations precipitate large energy fluctuations in nonlinear systems and (5) how to model the presence of fluids in the inter-stitial space between grains in a 3D granular bed. All of these tasks have either been accomplished or have seen substantial progress during the period of this exploratory study. The report details the findings.

This study investigates how control discrepancy relates to anxiety symptoms in a multi‐wave longitudinal design. We will assess the stability of control discrepancy scores across waves, within‐wave concurrent associations between control discrepancy and anxiety symptoms, and within‐person change in control discrepancy and anxiety symptoms.

The goal of the research was to understand key issues of vorticity dynamics prior to, during, and after the initiation of dynamic stall. The first portion of this work examined the of indicial theory to the predIction of dynamic applicability stall. The research focused on extending the semi-analytical formalism of indicial theory to predict the vorticity fluxes and the vorticity accumulation at the leading edge during unsteady maneuver. In the second portion of this work, highly accurate two-dimensional solutions of the Navier-Stokes equations were used on a model problem to investigate the Reynolds number scaling of incipient flow separation between Re =50,000 and Re = 800,000. This portion of the work was motivated by the suggestion that the appearance of eruptive plumes of vorticity at high Reynolds number might be critical to the formation of the dynamic stall vortex. The results of the research appear to contradict the hypothesis that a form of Reynolds number bifurcation must take place at some intermediate laminar Reynolds number. Instead, sell- similar behavior was observed, at least up to the time of formation of the primary stall vortex.

A momentum exchange controller where the time rate of change of the flexible momentum relative to the rigid body motion is used as a part of a feedback control law for maneuvers and flexible vibration suppression is introduced. This control concept is applied to: (1) a model of a rigid hug (based) with a cantilevered flexible appendage undergoing a single axis maneuver; and (2) as a component of an adaptive feedback control strategy for the retrieval of an orbiting tethered antenna/reflector system. The optimal linear quadratic Gaussian (LQG) digital control of the orbiting tethered antenna/reflector system is analyzed. The flexibility of both the antenna and the tether are included in this high order system model. With eight point actuators optimally positioned together with tether tension modulation it is seen that the degree of controllability is very high. A method of measuring tether transverse motions is proposed and is required to guarantee system observability. An analytical formulation for the modelling of the solar radiation disturbance on the tethered antenna/reflector system is introduced. A control law based on tension modulation where the gains are based on the linear quadratic regulator theory is able to maintain satisfactory pointing accuracy for low and moderate altitude orbits under the influence of solar pressure. For the higher altitudes a combination of tether tension modulation together with active (actuator) control will be required. Dynamics and control; Orbiting/reflector.

The analysis and design of robust controllers for multivariable discrete-time feedback systems in the frequency domain are studied. The robustness stability conditions for discrete-time systems with additive alteration, and with multiplicative alteration are developed. The robust LQG/LTR method has been extended from the continuous-time system to the discrete-time system. It has been proven that the LQG/LTR method is also valid for the LQG control of the discrete-time system with the filtering observer. As an application of the LQG/LTR technique for discrete-time systems, the design of reduced order optimal digital LQG controllers for the orbiting flexible shallow spherical shell system is considered. The comparison between the digital optimal LQG controller with the filtering observer and with the predicting observer for the orbiting flexible shallow spherical shell has been made.... Digital control, Large space structures, LQG/LTR method for discrete-time system, Robust controller design, Design of reduced order LQG controller.

A combined analytical and test program has been performed to develop a method of designing high-speed power turbine rotors to (1) minimize rotor- induced dynamic loads under normal operating conditions, (2) minimize rotor tip- to-shroud clearance to maintain high flow-path efficiency, and (3) minimize rotor deflections due to sudden abusive imbalance loads associated with blade loss. A design/prediction system was established for both synchronous and nonsynchronous rotor whirl and the best compromise design for a rotor subjected to these excitations. Two mathematical models were developed in the course of the program. First, a squeeze film damper model and subsequent computer program were developed to quantify the effects of end-seal leakage and inlet feedback on damper performance. Secondly, a spline coupling friction mathematical model and computer program were developed to predict the destabilizing forces which excite rotor nonsynchronous whirl. To verify the accuracy of the analytical models developed in the program and other existing rotor dynamic models, a comprehensive test program was run. This program included: (1) a high speed film damper test rig, (2) bearing flexible support testing, (3) a synchronous response rotor rig, and (4) a nonsynchronous response rotor rig. Using the results of the analytical models and experimental tests, a method of design optimization was developed to obtain the best trade-off between all the rotor design variables considered in this program. (Author)

A low-cost maneuver control system was successfully developed to provide enhanced maneuverability of gun-launched munitions. The unique environment and aspects of the system are described. Electromechanical design of the maneuver system was undertaken. Laboratory experiments were conducted to ensure survivability at gun launch and characterize the response. Aerodynamics and flight mechanics of the projectile roll behavior and actuator dynamics were formulated. These nonlinear dynamics were expressed in a linear state-space model for controllability, control design, and stability analysis. Roll response was investigated through nonlinear simulation and wind tunnel experiments. Monte Carlo simulations illustrate suitable performance of the maneuver control system. Experiments further validate the unique projectile maneuver technology and approach, reveal nonideal characteristics of the system, and verify modeling and simulation.

LONG-TERM GOALS. My long-term goal is to help improve versatility of underwater gliders as platforms for ocean sampling and other applications b y contributing to the development of a methodology for designing and analyzing high-performance, cost-effective underwater glider controllers. OBJECTIVES. I am in interested in establishing a framework for studying dynamics and control of underwater gliders. I am focussing on dedicated gliding vehicles that have the ability to change mass (or volume) for buoyancy control and to redistribute mass for attitude control. Later on it is of in interest to consider vehicles that use glide maneuvers to complement more traditional methods of control actuation. The framework will consist of a dynamical systems model of underwater gliding vehicles together with techniques for generating and controlling glide maneuvers in the presence of uncertainty. The first objective is to develop a model that is representative of a general class of underwater gliders. Then, dynamics and stability should be studied followed by the development of control laws for stabilizing individual glide motions, e.g., straight-line or spiral glide paths. Next, it is intended to develop techniques for concatenating stabilized glide motions to perform maneuvers, follow wwaypoints and track trajectories. A further objective is to develop methodology for assigning performance measures and then to optimize vehicle control design with respect to these measures. Additionally, it is of interest to address problems in coordinating control for a network of underwater gliders.

The paper describes progress in the development of a lightweight, deployable passive Synthetic Thinned Aperture Radiometer (STAR). The spacecraft concept presented will enable the realization of 10 km resolution global soil moisture and ocean salinity measurements at 1.41 GHz. The focus of this work was on definition of an approximately 1/3-scaled, 5-meter Phase 0 test article for concept demonstration and dynamics and control testing. Design requirements, parameters and a multi-parameter, hybrid scaling approach for the dynamically scaled test model were established. The El Scaling Approach that was established allows designers freedom to define the cross section of scaled, lightweight structural components that is most convenient for manufacturing when the mass of the component is small compared to the overall system mass. Static and dynamic response analysis was conducted on analytical models to evaluate system level performance and to optimize panel geometry for optimal tension load distribution.

Launched on April 4, 1983 onboard STS 6 (Space Shuttle Challenger), the First Tracking and Data Relay Satellite (TDRS 1) was retired above the Geosynchronous Orbit (GEO) on June 27, 2010 after having provided real-time communications with a variety of low-orbiting spacecraft over a 26-year period. To meet NASA requirements limiting orbital debris 1, a team of experts was assembled to conduct an End-Of-Mission (EOM) procedure to raise the satellite 350 km above the GEO orbit. Following the orbit raising via conventional station change maneuvers, the team was confronted with having to deplete the remaining propellant and passivate all energy storage or generation sources. To accomplish these tasks within the time window, communications (telemetry and control links), electrical power, propulsion, and thermal constraints, a spacecraft originally designed as a three-axis stabilized satellite was turned into a spinner. This paper (a companion paper to Innovative Approach Enabled the Retirement of TDRS 1, paper # 1699, IEEE 2011 Aerospace Conference, March 5-12, 2011 sup 2) focuses on the challenges of maintaining an acceptable spinning dynamics, while repetitively firing thrusters. Also addressed are the effects of thruster firings on the orbit characteristics and how they were mitigated by a careful scheduling of the fuel depletion operations. Periodic thruster firings for spin rate adjustment, nutation damping, and precession of the momentum vector were also required in order to maintain effective communications with the satellite. All operations were thoroughly rehearsed and supported by simulations thus lending a high level of confidence in meeting the NASA EOM goals.

This class is an introduction to the dynamics and vibrations of lumped-parameter models of mechanical systems. Topics include kinematics; force-momentum formulation for systems of particles and rigid bodies in planar motion; work-energy concepts; virtual displacements and virtual work; Lagrange's equations for systems of particles and rigid bodies in planar motion; linearization of equations of motion; linear stability analysis of mechanical systems; free and forced vibration of linear multi-degree of freedom models of mechanical systems; and matrix eigenvalue problems. The class includes an introduction to numerical methods and using MATLAB® to solve dynamics and vibrations problems. This version of the class stresses kinematics and builds around a strict but powerful approach to kinematic formulation which is different from the approach presented in Spring 2007. Our notation was adapted from that of Professor Kane of Stanford University.

Achieving full control of the time-evolution of a many-body quantum system is currently a major goal in physics. In this work we investigate the different ways in which the controllability of a quantum system can be influenced by its complexity, or even its chaotic properties. By using optimal control theory, we are able to derive the control fields necessary to drive various physical processes in a spin chain. Then, we study the spectral properties of such fields and how they relate to different aspects of the system complexity. We find that the spectral bandwidth of the fields is, quite generally, independent of the system dimension. Conversely, the spectral complexity of such fields does increase with the number of particles. Nevertheless, we find that the regular o chaotic nature of the system does not affect signficantly its controllability.

Book Source: Digital Library of India Item 2015.166797 dc.contributor.author: Gordon S. Brown dc.contributor.author: Donald P. Campbell dc.date.accessioned: 2015-07-07T00:36:28Z dc.date.available: 2015-07-07T00:36:28Z dc.date.digitalpublicationdate: 2004-07-29 dc.date.citation: 1948 dc.identifier: RMSC, IIIT-H dc.identifier.barcode: 2999990038921 dc.identifier.origpath: /data/upload/0038/926 dc.identifier.copyno: 1 dc.identifier.uri: http://www.new.dli.ernet.in/handle/2015/166797 dc.description.numberedpages: 400 dc.description.numberedpages: 24 dc.description.scanningcentre: RMSC, IIIT-H dc.description.main: 1 dc.description.tagged: 0 dc.description.totalpages: 424 dc.format.mimetype: application/pdf dc.language.iso: English dc.publisher.digitalrepublisher: Universal Digital Library dc.publisher: John Wiley Amp Sons, Inc. dc.rights: Copyright Protected dc.title: Principles Of Servomechanisms Dynamics And Synthesis Of Closed Loop Control Systems dc.rights.holder: John Wiley Amp Sons, Inc.