An optimal approach in negative derivative feedback control gain synthesis

2014 ◽  
Author(s):  
Francesco Ripamonti ◽  
Flavio Cola ◽  
Ferruccio Resta
Keyword(s):  
Feedback Control ◽  
Control Gain ◽  
Optimal Approach

An Efficient Approach to Define the Input Stimuli to Suppress Epileptic Seizures Described by the Epileptor Model

2020 ◽  
Vol 30 (11) ◽  
pp. 2050062
Author(s):  
João Angelo Ferres Brogin ◽  
Jean Faber ◽  
Douglas Domingues Bueno
Keyword(s):  
Nonlinear Dynamics ◽  
Mathematical Model ◽  
Exact Solution ◽  
Feedback Control ◽  
Epileptic Seizures ◽  
Neural Dynamics ◽  
Practical Application ◽  
Control Gain ◽  
The World ◽  
The Mathematical Model

Epilepsy affects about 70 million people in the world. Every year, approximately 2.4 million people are diagnosed with epilepsy, two-thirds of them will not know the etiology of their disease, and 1% of these individuals will decease as a consequence of it. Due to the inherent complexity of predicting and explaining it, the mathematical model Epileptor was recently developed to reproduce seizure-like events, also providing insights to improve the understanding of the neural dynamics in the interictal and ictal periods, although the physics behind each parameter and variable of the model is not fully established in the literature. This paper introduces an approach to design a feedback-based controller for suppressing epileptic seizures described by Epileptor. Our work establishes how the nonlinear dynamics of this disorder can be written in terms of a combination of linear sub-models employing an exact solution. Additionally, we show how a feedback control gain can be computed to suppress seizures, as well as how specific shapes applied as input stimuli for this purpose can be obtained. The practical application of the approach is discussed and the results show that the proposed technique is promising for developing controllers in this field.

scholarly journals Research on the Nonlinear Computer Torque control of the MR Damper Based Above-knee Prosthesis

2019 ◽  
Vol 267 ◽  
pp. 02009
Author(s):  
Qiang Fu ◽  
Chunpeng Pan ◽  
Lei Xu
Keyword(s):  
Feedback Control ◽  
Feedforward Control ◽  
Knee Prosthesis ◽  
Mr Damper ◽  
Torque Control ◽  
Magnetorheological Damper ◽  
Control Law ◽  
Pd Controller ◽  
Control Gain ◽  
And Performance

Aiming at the motion track controlling of the semi-active magnetorheological damper based above-knee prosthesis (MRAKP), according to the LaSalle’s invariant set theorem, a kind of nonlinear compute torque (NCT) control law for the track controlling of the AKMR, is proposed to promote the robustness and performance of the intelligent above-knee prosthesis. The proposed NCT controller includes the feedforward control and the feedback control. The former one is used to compensate the nonlinear terms in the dynamic model of the MRAKP, such as the Coriolis force, the centripetal force, and the gravity. The feedback control, utilizing a nonlinear PD controller, adaptively adjusts the control gain coefficients and reduces the system error. On these bases, numerical simulations on the MRAKPare carried out to analyze the performance of the proposed NCT controller in ADAMS and simulink. For comparing, the track controlling performance of the PD controller and the CT+PD controller are also presented in the paper. Simulation results indicate that the proposed NCT controller for the MRAKP is able to adaptively adjust the control gain coefficients with lower track error and higher robustness than the conventional PD controller and the CT+PD controller.

Characterization of Oil Film Control Forces Under Active Lubrication Regime

2005 ◽  
Author(s):  
Ilmar F. Santos ◽  
Bo F. Christensen
Keyword(s):  
Feedback Control ◽  
Excitation Frequency ◽  
Orifice Diameter ◽  
Load Factor ◽  
Oil Film ◽  
Lubrication Regime ◽  
Control Gain ◽  
Control Forces ◽  
Characterization Procedure

Journal bearings under active lubrication regime are controlled by servo valves and well-tuned feedback control laws. The servo valves dynamically modify the journal pressure distribution generating active oil film forces. Such forces are dependent on the following parameters: Sommerfeld number, bearing pre-load factor, orifice diameter, excitation frequency, feedback control gain and dynamic parameters of the servo valves, i.e. their natural frequencies, damping factors and pressure-flow coefficients. The theoretical and experimental characterization of such active forces is the main focus and the main contribution of this work. The theoretical analyzes are based on the Modified Reynolds’ equation for active lubrication. The experimental analyzes are carried out by using a special test rig, designed to investigate the behavior of tilting-pad bearings (TPJB) under active lubrication. Relative good agreement between theoretical and experimental behavior of the active oil film forces as a function of the excitation frequency and control gain is achieved. Limitations of the characterization procedure is critically discussed in order to explain some discrepancies between theoretical and experimental results.

Anti-Control of Discrete Chaos Based on the Oblique Wave Feedback Control

2013 ◽  
Vol 456 ◽  
pp. 603-606
Author(s):  
Zhi Hong Yang
Keyword(s):  
Feedback Control ◽  
Linear Systems ◽  
Discrete System ◽  
Control Algorithm ◽  
Oblique Wave ◽  
Control Gain ◽  
Discrete Linear Systems ◽  
Wave States ◽  
Discrete Chaos ◽  
The Common

In this paper a method is proposed to anti-control the discrete chaos. When the control gain meets the certain conditions, the common discrete system occurs chaotic behaviors in the sense of Li and Yorke under the oblique wave states feedback control. Using Matlab to simulate one and N-dimensional discrete linear systems, the numerical results demonstrate the validity of the control algorithm.

scholarly journals Analysis and control of the dynamical response of a higher order drifting oscillator

2018 ◽  
Vol 474 (2210) ◽  
pp. 20170500 ◽  
Author(s):  
Yang Liu ◽  
Joseph Páez Chávez ◽  
Ekaterina Pavlovskaia ◽  
Marian Wiercigroch
Keyword(s):  
Feedback Control ◽  
Higher Order ◽  
Numerical Continuation ◽  
Continuation Methods ◽  
Dynamical Response ◽  
Coexisting Attractors ◽  
Control Gain ◽  
Position Feedback ◽  
Feedback Control Strategy ◽  
And Control

This paper studies a position feedback control strategy for controlling a higher order drifting oscillator which could be used in modelling vibro-impact drilling. Special attention is given to two control issues, eliminating bistability and suppressing chaos, which may cause inefficient and unstable drilling. Numerical continuation methods implemented via the continuation platform COCO are adopted to investigate the dynamical response of the system. Our analyses show that the proposed controller is capable of eliminating coexisting attractors and mitigating chaotic behaviour of the system, providing that its feedback control gain is chosen properly. Our investigations also reveal that, when the slider’s property modelling the drilled formation changes, the rate of penetration for the controlled drilling can be significantly improved.

scholarly journals Time-Delayed Feedback Control of Piezoelectric Elastic Beams under Superharmonic and Subharmonic Excitations

2019 ◽  
Vol 9 (8) ◽  
pp. 1557 ◽  
Author(s):  
Jian Peng ◽  
Mingjiao Xiang ◽  
Luxin Li ◽  
Hongxin Sun ◽  
Xiuyong Wang
Keyword(s):  
Feedback Control ◽  
Elastic Beam ◽  
Delayed Feedback ◽  
Subharmonic Resonance ◽  
Delayed Feedback Control ◽  
Feedback Gain ◽  
Control Gain ◽  
Resonance Response ◽  
And Control ◽  
Time Delayed Feedback

The time-delayed displacement feedback control is provided to restrain the superharmonic and subharmonic response of the elastic support beams. The nonlinear equations of the controlled elastic beam are obtained with the help of the Euler–Bernoulli beam principle and time-delayed feedback control strategy. Based on Galerkin method, the discrete nonlinear time-delayed equations are derived. Using the multiscale method, the first-order approximate solutions and stability conditions of three superharmonic and 1/3 subharmonic resonance response on controlled beams are derived. The influence of time-delayed parameters and control gain are obtained. The results show that the time-delayed displacement feedback control can effectively suppress the superharmonic and subharmonic resonance response. Selecting reasonably the time-delayed quantity and control gain can avoid the resonance region and unstable multi-solutions and improve the efficiency of the vibration control. Furthermore, with the purpose of suppressing the amplitude peak and governing the resonance stability, appropriate feedback gain and time delay are derived.

Multistability in a Simplified Underwater Supercavity System

2017 ◽  
Vol 27 (08) ◽  
pp. 1750121 ◽  
Author(s):  
Yipin Lv ◽  
Tianhong Xiong ◽  
Wenjun Yi
Keyword(s):  
Feedback Control ◽  
Deflection Angle ◽  
Initial Conditions ◽  
Major Change ◽  
Basins Of Attraction ◽  
Cavitation Number ◽  
Stable Equilibrium Point ◽  
Periodic Attractor ◽  
Control Gain ◽  
The Stability

Supercavity can increase the velocity of underwater vehicles greatly, however the launching state of vehicle and systematic parameters often lead to unstable motion. To solve the problem, the effect of parameters and initial conditions on the stability of vehicles is studied. With two variable parameters, namely cavitation number and feedback control gain of fin deflection angle, a simple dynamic model of supercavity system is studied. The multistability is verified through simulation. Robustness of the system is also analyzed based on its basins of attraction. There are various coexisting attractors in a relatively large region of parameter space of the supercavity system, namely coexistence of a stable equilibrium point and a periodic attractor, coexistence of various periodic attractors, coexistence of a periodic attractor with a chaotic attractor and so on, which explain the effect of parameters and initial values on stability of vehicles qualitatively. In addition, without major change in cavitation number, there is a negative correlation between the robustness of the vehicle and feedback control gain of fin deflection angle. The robustness can be improved through optimization of parameters.

Hamiltonian Matrix Strategy for Exponential Synchronization of Neural Networks with Diffusion

2014 ◽  
Vol 490-491 ◽  
pp. 947-950
Author(s):  
Qian Ye ◽  
Xu Yang Lou
Keyword(s):  
Neural Networks ◽  
Feedback Control ◽  
Imaginary Axis ◽  
Reaction Diffusion ◽  
Exponential Synchronization ◽  
Hopfield Neural Networks ◽  
Hamiltonian Matrix ◽  
Time Varying ◽  
Chaotic Neural Networks ◽  
Control Gain

In this paper, the problem of exponential synchronization for a class of chaotic neural networks which covers the Hopfield neural networks and cellular neural networks with reaction-diffusion terms and time-varying delays is investigated. A feedback control gain matrix is derived to achieve the state synchronization of two identical neural networks with reaction-diffusion terms, and the synchronization condition can be verified if a certain Hamiltonian matrix with no eigenvalue on the imaginary axis.

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