Control adaptativo por modelo de referencia con predictor Smith a partir de la regla MIT para una mesa vibratoria de dos grados de libertad

Shake tables have generally been used for civil structure analysis, as they allow the user to estimate and analyze a scale model’s dynamic response to a real earthquake. Many of these systems are built using linear actuators which allow the application of classic control techniques. This article details the implementation of a model reference adaptive control (MRAC) system using the MITC rule with Smith predictor on a two degree-of-freedom shake table powered by a three-phase motor coupled to a cam and connecting rod mechanism. The non-linear characteristics of this equipment, and the high degree of uncertainty and dead time, require the use of advanced control techniques. The MIT rule is the original focus for the MRAC, and a Smith predictor scheme is simultaneously used to compensate for system response delays. The control system is implemented on a 32-bit Microchip® platform connected to a host.Las mesas vibratorias se han generalizado para el análisis de estructuras civiles, debido a que permiten estimar y analizar la respuesta dinámica de un modelo a escala ante un sismo real. Muchos de estos sistemas se construyen a partir de actuadores lineales que permiten aplicar técnicas de control clásico. En este artículo se muestra la implementación de un sistema de control de posición adaptativo por modelo de referencia (MRAC), a partir de la regla MIT con predictor Smith sobre una mesa vibradora de dos grados de libertad impulsados por un motor trifásico acoplado a un mecanismo biela-manivela, cuyas características no lineales con alto grado de incertidumbre y tiempo muerto hacen necesaria la implementación de técnicas de control avanzado. La regla MIT es el enfoque original para el control adaptable basado en el modelo de referencia, al mismo tiempo se implementa un esquema predictor Smith para compensar los efectos del retardo en la respuesta del sistema. El sistema de control es implementado sobre una plataforma de 32 bit de Microchip® conectado a un host

Process modelling and adaptive control of a metal milling process

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Real-time QFT Control for Temperature in Greenhouses

Sudden changes in a greenhouse environment negatively impact the development and production of crops, especially in greenhouses with natural ventilation when temperatures are low at night and change rapidly due to wet winds. To mitigate these variations, a design of a robust controller based on Quantitative Feedback Theory (QFT) as from a Smith predictor structure for the dead-time system is proposed. This structure offers high stability based on the gain margin, the phase margin, and the rejection of disturbances in the system output. This design was contrasted with a PID controller based on performance indices, according to the transient response and error in the presence of changes in the point of operation and charge disturbances. Final results showed that the dynamic response of the QFT controller improved compared to PID controller results

Control of a magnetically levitated ventricular assist device

This work presents theoretical and experimental means for achieving impeller stability in a magnetically levitated left ventricular assist device (LVAD). These types of medical devices are designed to boost the native heart`s ability to pump blood by means of mechanical energy transfer using a rotating impeller. Magnetic suspension of the impeller eliminates bearing friction and reduces blood damage, but it requires active controls that monitor the impeller`s position and speed in order to generate the forces and torques required to regulate its dynamic behavior. To accomplish this goal, this work includes: 1) a dynamic system model derived using energy and momentum conservation 2) dynamic analysis including stability, controllability and observability, and 3) development of two control algorithms: proportional integral derivative and sliding mode control. Experimental validation included component behavior, model accuracy, and the characterization of controller performance using a physiological simulator. The system model proved to be an adequate representation of the system while levitating in air, but additional research is needed to model hydrodynamic and gyroscopic effects. After the prototype`s subcomponents were tested, calibrated and/or modified to fit the control requirements, both control strategies were successful in controlling the rotor as it spun at 6000 rpm pumping 6L/min of water at 80mmHg. A maximum speed of 6500 rpm was achieved with speed control within 5% over most of the operating range. The control platform and many of the methods presented here are continually being used and improved towards the implantation of the device in a human subject in the future

Coordinated multi-robot formation control

Tese de doutoramento. Engenharia Electrotécnica e de Computadores. Faculdade de Engenharia. Universidade do Porto. 201

Eleventh Annual Conference on Manual Control

Human operator performance and servomechanism analyses for manual vehicle control tasks are studied

Multi-axial real-time hybrid simulation framework for testing nonlinear structure systems with multiple boundary interfaces

Hybrid simulation is a widely accepted laboratory testing approach that partitions a proposed structure into numerical and physical substructures, for a space- and cost-effective testing method. Structural elements that are expected to remain in the linear elastic range are usually modeled numerically, while computationally intractable nonlinear elements are tested physically. The loads and conditions at the boundaries between the numerical and physical substructures are imposed by servo-hydraulic actuators, with the responses measured by load cells and displacement transducers. Traditionally, these actuators impose boundary condition displacements at slow speeds, while damping and inertial components for the physical specimen are numerically calculated. This slow application of the boundary conditions neglects the rate-dependent behavior of the physical specimen. Real-time hybrid simulation (RTHS) is an alternative to slow speed hybrid simulation approach, where the responses of the numerical substructure are calculated and imposed on the physical substructure at real-world natural hazard excitation speeds. Damping, inertia, and rate-dependent material effects are incorporated in the physical substructure as a result of real-time testing. For a general substructure, the boundary interface has six degrees-of-freedom (DOF); therefore, an actuation system that can apply multi-axial loads is required. In these experiments, the boundary conditions at the interface between the physical and numerical substructures are imposed by two or more actuators. Significant dynamic coupling can be present between the actuators in such setups. Kinematic transformations are required for the operation of each actuator to achieve desired boundary conditions. Furthermore, each actuator possesses inherent dynamics that need appropriate compensation to ensure an accurate and stable operation. Most existing RTHS applications to date have involved the substructuring of the reference structures into numerical and physical components at a single interface with a one-DOF boundary condition and force imposed and measured. Multi-DOF boundary conditions have been explored in a few applications; however a general six-DOF stable implementation has never been achieved. A major research gap in the RTHS domain is the development of a multi-axial RTHS framework capable of handling six DOF boundary conditions and forces, as well as the presence of multiple physical specimens and numerical-to-physical interfaces. In this dissertation, a multi-axial real-time hybrid simulation (maRTHS) framework is developed for realistic nonlinear dynamic assessment of structures under natural hazard excitation. The framework is comprised of numerical and physical substructures, actuator-dynamics compensation, and kinematic transformations between Cartesian and actuator/transducer coordinates. The numerical substructure is compiled on a real-time embedded system, comprised of a microcontroller setup, with onboard memory and processing, that computes the response of finite element models of the structural system, which are then communicated with the hardware setup via the input-output peripherals. The physical substructure is composed of a multi-actuator boundary condition box, loadcells, displacement transducers, and one or more physical specimens. The proposed compensation is a model-based strategy based on the linearized identified models of individual actuators. The concepts of the model-based compensation approach are first validated in a shake table study, and then applied to single and multi-axis RTHS developments. The capabilities of the proposed maRTHS framework are demonstrated via the multi-axial load and boundary condition boxes (LBCBs) at the University of Illinois Urbana-Champaign, via two illustrative examples. First, the maRTHS algorithm including the decoupled controller, and kinematic transformation processes are validated. In this study, a moment frame structure is partitioned into numerical beam-column finite element model, and a physical column with an LBCB boundary condition. This experiment is comprised of six DOFs and excitation is only applied in the plane of the moment frame. Next, the maRTHS framework is subjected to a more sophisticated testing environment involving a multi-span curved bridge structure. In this second example, two LBCBs are utilized for testing of two physical piers, and excitation is applied bi-directionally. Results from the illustrative examples are verified against numerical simulations. The results demonstrate the accuracy and promising nature of the proposed state-of-the-art framework for maRTHS for nonlinear dynamic testing of structural systems using multiple boundary points

Multi-axial Real-time Hybrid Simulation Framework for Testing Nonlinear Structural Systems with Multiple Boundary Interfaces

Hybrid simulation is a widely accepted laboratory testing approach that partitions a proposed structure into numerical and physical substructures, for a space- and cost-effective testing method. Structural elements that are expected to remain in the linear elastic range are usually modeled numerically, while computationally intractable nonlinear elements are tested physically. The loads and conditions at the boundaries between the numerical and physical substructures are imposed by servo-hydraulic actuators, with the responses measured by loadcells and displacement transducers. Traditionally, these actuators impose boundary condition displacements at slow speeds, while damping and inertial components for the physical specimen are numerically calculated. This slow application of the boundary conditions neglects rate-dependent behavior of the physical specimen. Real-time hybrid simulation (RTHS) is an alternative to slow speed hybrid simulation approach, where the responses of numerical substructure are calculated and imposed on the physical substructure at real world natural hazard excitation speeds. Damping, inertia, and rate-dependent material effects are incorporated in the physical substructure as a result of real-time testing. For a general substructure, the boundary interface has six degrees-of-freedom (DOF); therefore, an actuation system that can apply multi-axial loads is required. In these experiments, the boundary conditions at the interface between the physical and numerical substructures are imposed by two or more actuators. Significant dynamic coupling can be present between the actuators in such setups. Kinematic transformations are required for operation of each actuator to achieve desired boundary conditions. Furthermore, each actuator possesses inherent dynamics that needs appropriate compensation to ensure an accurate and stable operation. Most existing RTHS applications to date have involved the substructuring of the reference structures into numerical and physical components at a single interface with a one-DOF boundary condition and force imposed and measured. Multi-DOF boundary conditions have been explored in a few applications, however a general six-DOF stable implementation has never been achieved. A major research gap in the RTHS domain is the development of a multi-axial RTHS framework capable of handling six DOF boundary conditions and forces, as well as presence of multiple physical specimens and numerical-to-physical interfaces. In this dissertation, a multi-axial real-time hybrid simulation (maRTHS) framework is developed for realistic nonlinear dynamic assessment of structures under natural hazard excitation. The framework is comprised of numerical and physical substructures, actuator-dynamics compensation, and kinematic transformations between Cartesian and actuator/transducer coordinates. The numerical substructure is compiled on a real-time embedded system, comprised of a microcontroller setup, with onboard memory and processing, that computes the response of finite element models of the structural system, which are then communicated with the hardware setup via the input-output peripherals. The physical substructure is composed of a multi-actuator boundary condition box, loadcells, displacement transducers, and one or more physical specimens. The proposed compensation is a model-based strategy based on the linearized identified models of individual actuators. The concepts of the model-based compensation approach are first validated in a shake table study, and then applied to single and multi-axis RTHS developments. The capabilities of the proposed maRTHS framework are demonstrated via the multi-axial load and boundary condition boxes (LBCBs) at the University of Illinois Urbana-Champaign, via two illustrative examples. First, the maRTHS algorithm including the decoupled controller, and kinematic transformation processes are validated. In this study, a moment frame structure is partitioned into numerical beam-column finite element model, and a physical column with an LBCB boundary condition. This experiment is comprised of six DOFs and excitation is only applied in the plane of the moment frame. Next, the maRTHS framework is subjected to a more sophisticated testing environment involving a multi-span curved bridge structure. In this second example, two LBCBs are utilized for testing of two physical piers, and excitation is applied bi-directionally. Results from the illustrative examples are verified against numerical simulations. The results demonstrate the accuracy and promising nature of the proposed state-of-the-art framework for maRTHS for nonlinear dynamic testing of structural systems using multiple boundary points.Ope