State-space self-tuner for on-line adaptive control

Dynamic systems, such as flight vehicles, satellites and space stations, operating in real environments, constantly face parameter and/or structural variations owing to nonlinear behavior of actuators, failure of sensors, changes in operating conditions, disturbances acting on the system, etc. In the past three decades, adaptive control has been shown to be effective in dealing with dynamic systems in the presence of parameter uncertainties, structural perturbations, random disturbances and environmental variations. Among the existing adaptive control methodologies, the state-space self-tuning control methods, initially proposed by us, are shown to be effective in designing advanced adaptive controllers for multivariable systems. In our approaches, we have embedded the standard Kalman state-estimation algorithm into an online parameter estimation algorithm. Thus, the advanced state-feedback controllers can be easily established for digital adaptive control of continuous-time stochastic multivariable systems. A state-space self-tuner for a general multivariable stochastic system has been developed and successfully applied to the space station for on-line adaptive control. Also, a technique for multistage design of an optimal momentum management controller for the space station has been developed and reported in. Moreover, we have successfully developed various digital redesign techniques which can convert a continuous-time controller to an equivalent digital controller. As a result, the expensive and unreliable continuous-time controller can be implemented using low-cost and high performance microprocessors. Recently, we have developed a new hybrid state-space self tuner using a new dual-rate sampling scheme for on-line adaptive control of continuous-time uncertain systems

Signal Reconstruction via H-infinity Sampled-Data Control Theory: Beyond the Shannon Paradigm

This paper presents a new method for signal reconstruction by leveraging sampled-data control theory. We formulate the signal reconstruction problem in terms of an analog performance optimization problem using a stable discrete-time filter. The proposed H-infinity performance criterion naturally takes intersample behavior into account, reflecting the energy distributions of the signal. We present methods for computing optimal solutions which are guaranteed to be stable and causal. Detailed comparisons to alternative methods are provided. We discuss some applications in sound and image reconstruction

A design tool for high-resolution high-frequency cascade continuous- time Σ∆ modulators

Event: Microtechnologies for the New Millennium, 2007, Maspalomas, Gran Canaria, SpainThis paper introduces a CAD methodology to assist the de signer in the implementation of continuous-time (CT) cas- cade Σ∆ modulators. The salient features of this methodology ar e: (a) flexible behavioral modeling for optimum accuracy- efficiency trade-offs at different stages of the top-down synthesis process; (b) direct synthesis in the continuous-time domain for minimum circuit complexity and sensitivity; a nd (c) mixed knowledge-based and optimization-based architec- tural exploration and specification transmission for enhanced circuit performance. The applicability of this methodology will be illustrated via the design of a 12 bit 20 MHz CT Σ∆ modulator in a 1.2V 130nm CMOS technology.Ministerio de Ciencia y Educación TEC2004-01752/MICMinisterio de Industria, Turismo y Comercio FIT-330100-2006-134 SPIRIT Projec

A preliminary look at control augmented dynamic response of structures

The augmentation of structural characteristics, mass, damping, and stiffness through the use of control theory in lieu of structural redesign or augmentation was reported. The standard single-degree-of-freedom system was followed by a treatment of the same system using control augmentation. The system was extended to elastic structures using single and multisensor approaches and concludes with a brief discussion of potential application to large orbiting space structures

Project management techniques for highly integrated programs

The management and control of a representative, highly integrated high-technology project, in the X-29A aircraft flight test project is addressed. The X-29A research aircraft required the development and integration of eight distinct technologies in one aircraft. The project management system developed for the X-29A flight test program focuses on the dynamic interactions and the the intercommunication among components of the system. The insights gained from the new conceptual framework permitted subordination of departments to more functional units of decisionmaking, information processing, and communication networks. These processes were used to develop a project management system for the X-29A around the information flows that minimized the effects inherent in sampled-data systems and exploited the closed-loop multivariable nature of highly integrated projects

Development of a sensitivity analysis technique for multiloop flight control systems

This report presents the development and application of a sensitivity analysis technique for multiloop flight control systems. This analysis yields very useful information on the sensitivity of the relative-stability criteria of the control system, with variations or uncertainties in the system and controller elements. The sensitivity analysis technique developed is based on the computation of the singular values and singular-value gradients of a feedback-control system. The method is applicable to single-input/single-output as well as multiloop continuous-control systems. Application to sampled-data systems is also explored. The sensitivity analysis technique was applied to a continuous yaw/roll damper stability augmentation system of a typical business jet, and the results show that the analysis is very useful in determining the system elements which have the largest effect on the relative stability of the closed-loop system. As a secondary product of the research reported here, the relative stability criteria based on the concept of singular values were explored

Explicit and Iterative LQG Controller Design

This dissertation presents two new LQG controller designs, namely, explicit and iterative designs. For the explicit design, the explicit solutions to the corresponding Riccati equations of controller design for large structures with collocated rate sensors and actuators are derived. Numerically solving the Riccati equations for state feedback and state estimation is no longer required. Since the number of design parameters for either state feedback or state estimation equals the number of controlled modes, the performance of each mode can be easily adjusted. NASA\u27s Spacecraft COntrol Laboratory Experiment (SCOLE) configuration is used to demonstrate the effectiveness of the explicit design. For the iterative design, a closed-loop identification method is developed for identifying an open-loop system and Kalman filter gain when the system is under closed-loop operation. The iterative controller design basically consists of the closed-loop identification and state-feedback redesign cycle. In each cycle, the identification is used to identify the open-loop model and Kalman filter. The identified Kalman filter can be directly used for state estimation so that the noise statistics are no longer needed to be detected. The identified model is then used to redesign the state feedback. The state feedback and the identified Kalman filter are used to form an updated LQG controller for next cycle. This iterative process continues until the updated controller converges. Since the updated model is identified under the previous controller, the effect of the controller on noise statistics is automatically taken into account. NASA\u27s Large-Angle Magnetic Suspension Test Facility (LAMSTF) is used to validate the iterative design

Transformada de Laplace y sus aplicaciones en sistemas dinámicos: una revisión

This paper presents a review of Laplace Transform (LT) applications in the analysis of linear dynamic systems. Is presented the importance of the transforms; the definition of the Transform; theorems and properties with applications and finally, the use of LT for the calculation of: steady state error, transfer functions, ordinary differential equations solution, frequency responses, signal analysis and block diagrams. The modeling and operational analysis with LT of a multipurpose reactor is proposed as a didactic situation for academic purposes.Este artículo presenta una revisión sobre las aplicaciones de la transformada de Laplace (TL) en el análisis de sistemas dinámicos lineales. Se presenta la importancia de la transformada; la definición de la transformada; los teoremas y propiedades con aplicaciones y por último, aplicaciones del uso de la TL para el cálculo de: error de estado estacionario, funciones de transferencia, solución de ecuaciones diferenciales ordinarias, respuestas en frecuencia, análisis de señales y diagramas de bloques. Se propone, como situación didáctica para propósitos académicos, el modelamiento y análisis operacional con TL de un reactor multipropósito