12,707 research outputs found
Control design for discrete-time fuzzy systems with disturbance inputs via delta operator approach
This paper is concerned with the problem of passive control design for discrete-time Takagi-Sugeno (T-S) fuzzy systems with time delay and disturbance input via delta operator approach. The discrete-time passive performance index is established in this paper for the control design problem. By constructing a new type ofLyapunov-Krasovskii function (LKF) in delta domain, and utilizing some fuzzy weighing matrices, a new passive performance condition is proposed for the system under consideration. Based on the condition, a state-feedback passive controller is designed to guarantee that the resulting closed-loop system is very-strictly passive. The existence conditions of the controller can be expressed by linear matrix inequalities (LMIs). Finally, a numerical example is provided to demonstrate the feasibility and effectiveness of the proposed method
Stability Analysis and Stabilization of T-S Fuzzy Delta Operator Systems with Time-Varying Delay via an Input-Output Approach
The stability analysis and stabilization of Takagi-Sugeno (T-S) fuzzy delta operator systems with time-varying delay are investigated via an input-output approach. A model transformation method is employed to approximate the time-varying delay. The original system is transformed into a feedback interconnection form which has a forward subsystem with constant delays and a feedback one with uncertainties. By applying the scaled small gain (SSG) theorem to deal with this new system, and based on a Lyapunov Krasovskii functional (LKF) in delta operator domain, less conservative stability analysis and stabilization conditions are obtained. Numerical examples are provided to illustrate the advantages of the proposed method
Multivariable proportional-integral-plus (PIP) control of the ALSTOM nonlinear gasifier simulation
Multivariable proportional-integral-plus (PIP) control methods are applied to the nonlinear ALSTOM Benchmark Challenge II. The approach utilises a data-based combined model reduction and linearisation step, which plays an essential role in satisfying the design specifications. The discrete-time transfer function models obtained in this manner are represented in a non-minimum state space form suitable for PIP control system design. Here, full state variable feedback control can be implemented directly from the measured input and output signals of the controlled process, without resorting to the design and implementation of a deterministic state reconstructor or a stochastic Kalman filter. Furthermore, the non-minimal formulation provides more design freedom than the equivalent minimal case, a characteristic that proves particularly useful in tuning the algorithm to meet the Benchmark specifications. The latter requirements are comfortably met for all three operating conditions by using a straightforward to implement, fixed gain, linear PIP algorithm
Impulse-Based Hybrid Motion Control
The impulse-based discrete feedback control has been proposed in previous
work for the second-order motion systems with damping uncertainties. The
sate-dependent discrete impulse action takes place at zero crossing of one of
both states, either relative position or velocity. In this paper, the proposed
control method is extended to a general hybrid motion control form. We are
using the paradigm of hybrid system modeling while explicitly specifying the
state trajectories each time the continuous system state hits the guards that
triggers impulsive control actions. The conditions for a stable convergence to
zero equilibrium are derived in relation to the control parameters, while
requiring only the upper bound of damping uncertainties to be known. Numerical
examples are shown for an underdamped closed-loop dynamics with oscillating
transients, an upper bounded time-varying positive system damping, and system
with an additional Coulomb friction damping.Comment: 6 pages, 4 figures, IEEE conferenc
A fast immersed boundary method for external incompressible viscous flows using lattice Green's functions
A new parallel, computationally efficient immersed boundary method for
solving three-dimensional, viscous, incompressible flows on unbounded domains
is presented. Immersed surfaces with prescribed motions are generated using the
interpolation and regularization operators obtained from the discrete delta
function approach of the original (Peskin's) immersed boundary method. Unlike
Peskin's method, boundary forces are regarded as Lagrange multipliers that are
used to satisfy the no-slip condition. The incompressible Navier-Stokes
equations are discretized on an unbounded staggered Cartesian grid and are
solved in a finite number of operations using lattice Green's function
techniques. These techniques are used to automatically enforce the natural
free-space boundary conditions and to implement a novel block-wise adaptive
grid that significantly reduces the run-time cost of solutions by limiting
operations to grid cells in the immediate vicinity and near-wake region of the
immersed surface. These techniques also enable the construction of practical
discrete viscous integrating factors that are used in combination with
specialized half-explicit Runge-Kutta schemes to accurately and efficiently
solve the differential algebraic equations describing the discrete momentum
equation, incompressibility constraint, and no-slip constraint. Linear systems
of equations resulting from the time integration scheme are efficiently solved
using an approximation-free nested projection technique. The algebraic
properties of the discrete operators are used to reduce projection steps to
simple discrete elliptic problems, e.g. discrete Poisson problems, that are
compatible with recent parallel fast multipole methods for difference
equations. Numerical experiments on low-aspect-ratio flat plates and spheres at
Reynolds numbers up to 3,700 are used to verify the accuracy and physical
fidelity of the formulation.Comment: 32 pages, 9 figures; preprint submitted to Journal of Computational
Physic
An automatic controller tuning algorithm.
A project report submitted to the Faculty of Engineering, University of the
Witwatersrand, Johannesburg, in partial fulfillment of the requirements
for 'the degree of Master of Science in Engineering. Johannesburg 1991.The report describes the design of an algorithm which can be used for automatic
controller tuning purposes. It uses an on-line parameter estimator and a pole assignrnent
design method. The resulting control law is formulated to approximate a
proportional-integral (PI) industrial controller. The development ofthe algorithm
is based on the delta-operator, Some implementation aspects such as covariance resetting, dead zone, and signal conditioning are also discussed. Robust stability and
performance are two issues that govern the design approach. Additionally transient
and steady state system response criteria are utilized from the time and frequency
domains. The design work is substantiated with the use of simulation and real plant
tests.AC201
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