Search results for "Nonlinear system"
showing 10 items of 1446 documents
Robust H∞ sliding mode control with pole placement for a fluid power electrohydraulic actuator (EHA) system
2014
Published version of an article in the journal: International Journal of Advanced Manufacturing Technology. Also available from the publisher at: http://dx.doi.org/10.1007/s00170-014-5910-8 In this paper, we exploit the sliding mode control problem for a fluid power electrohydraulic actuator (EHA) system. To characterize the nonlinearity of the friction, the EHA system is modeled as a linear system with a system uncertainty. Practically, it is assumed that the system is also subject to the load disturbance and the external noise. An integral sliding mode controller is proposed to design. The advanced techniques such as the H ∞ control and the regional pole placement are employed to derive t…
Fuzzy dynamic sliding mode control design for high order disturbed systems
2013
In this paper, the problem of fuzzy dynamic sliding mode control design is investigated for a class of disturbed systems. Specifically, the fuzzy controller is constructed based on one feedback signal to estimate the unknown nonlinear terms and to develop the sliding mode control according to the fuzzy rules. Furthermore, it possesses the characteristic of simplicity in design and effectiveness in attenuating chattering. Finally, a numerical example is included to demonstrate the effectiveness and advantage of the proposed method.
Holder continuity of solutions for a class of nonlinear elliptic variational inequalities of high order
2001
Control Strategy for Induction Motor Drives Based on Decoupling Techniques
1989
Abstract In this work a new closed loop, synchronous microprocessor-based controller is proposed for field oriented controlled induction motor drives, using a PWM voltage source inverter. This controller is based on a non linear state feedback compensator which gives decoupling of both rotor current and rotor flux, and direct and inquadrature components of the stator current vector. The compensator has a linearizing effect on the synchronous model of the electromagnetic circuit of the motor. It follows that the control laws can be obtained using optimal control techniques for linear systems. The controller in question gives directly the conduction sequences of the inverter supplying the ind…
Non-fragile sliding mode control for flexible air-breathing hypersonic vehicles
2012
The non-fragile sliding mode tracking control design problem for a flexible air-breathing hypersonic vehicles (FAHVs) is investigated in this paper. A linearized model is constructed with respect to a trim point for the nonlinear, dynamically coupled simulation model of the FAHVs with external disturbance, then a reference model is designed and a tracking error model is proposed. An integral sliding surface is designed, and then the non-fragile H ∞ controller design problem for the sliding mode dynamics is discussed. sufficient condition is derived for the existence of such a controller in the presence of unmatched disturbance. A SMC law is derived to guarantee the reachability of the speci…
Nonlinear vibrations of elastic beams with external general visco-elastic devices
2011
Vibration damping for slender beams is achieved by applying devices at external points. The latter consist of general single visco-elastic springpot elements. An approximate nonlinear boundary value problem is found in frequency domain that holds for moderately large vibrations or for linear beams with external nonlinear devices, both in the vicinity of primary resonances. The interaction force of a so-called springpot element is expressed as a sum of two separate forces: the first develops due to the external loading function at the device location, and the second contribution arises due to an imposed time-harmonic support excitation with no other external forces acting on the structure. F…
Creep Modeling with Time-Dependent Damping Parameters in Piezoelectric Actuators
2019
This paper develops a creep model based on the Kelvin-Voigt model with time varying damping parameters. In the piezoelectric actuators, the creep phenomenon is an important issue in precise positioning applications as well as the hysteresis property. It is well-known that the creep effect can be represented by a series connection of a number of Kelvin-Voigt elements as a viscoelastic model. In the motion for the continuous stepwise positioning, however, the creep shape is different for each response. Since the phenomenon can be captured as temporal creep relaxation, time-dependent damping parameters are introduced to improve the reproducibility of the creep for the various motion. On the ot…
Asymptotic observer of the link states of flexible joint robots with motor-side sensing
2015
This paper proposes an approach for observing the link states, i.e. angular position and velocity, of the robotic joints with elasticities, when only the motor-side sensing is available. By separating the state-dependent nonlinearities of the rigid manipulator dynamics a linear sub-model of the elastic joint robot is obtained in an observable state-space form. The standard asymptotic Luenberger state observer is then designed for the given motor position signal which is measured by encoder and rectified from the nonlinear contribution. The configurable poles of observer allow shaping the estimated states dynamics to be fast enough in relation to the actual resonant joint behavior. Therefore…
Observational constraints on inhomogeneous cosmological models without dark energy
2011
It has been proposed that the observed dark energy can be explained away by the effect of large-scale nonlinear inhomogeneities. In the present paper we discuss how observations constrain cosmological models featuring large voids. We start by considering Copernican models, in which the observer is not occupying a special position and homogeneity is preserved on a very large scale. We show how these models, at least in their current realizations, are constrained to give small, but perhaps not negligible in certain contexts, corrections to the cosmological observables. We then examine non-Copernican models, in which the observer is close to the center of a very large void. These models can gi…
Numerical study of blow-up in solutions to generalized Kadomtsev-Petviashvili equations
2013
We present a numerical study of solutions to the generalized Kadomtsev-Petviashvili equations with critical and supercritical nonlinearity for localized initial data with a single minimum and single maximum. In the cases with blow-up, we use a dynamic rescaling to identify the type of the singularity. We present a discussion of the observed blow-up scenarios.