Control
Mohamed Shamseldin; Mohamed Sallam; Abd Halim Bassiuny; Abdel Ghany Mohamed
Abstract
This paper presents a practical implementation for a new formula of nonlinear PID (NPID) control. The purpose of the controller is to accurately trace a preselected position reference of one stage servomechanism system. The possibility of developing a transfer function model for experimental setup is ...
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This paper presents a practical implementation for a new formula of nonlinear PID (NPID) control. The purpose of the controller is to accurately trace a preselected position reference of one stage servomechanism system. The possibility of developing a transfer function model for experimental setup is elusive because of the lack of system data. So, the identified model has been developed via gathering experimental input/output data. The performance of the enhanced nonlinear PID (NPID) controller had been investigated by comparing it with linear PID controller. The harmony search (HS) tuning system had built to determine the optimum parameters for each control technique based on an effective objective function. The experimental outcomes and the simulation results show that the proposed NPID controller has minimum rise time and settling time through constant position reference test. Also, the NPID control is faster than the linear PID control by 40% in case of variable position reference test.
Control
Mohammad Hossein Bayati Chaleshtari; Elahe Norouzi; Habib Ahmadi
Abstract
Functional electrical stimulation (FES) is the most commonly used system for restoring function after spinal cord injury (SCI). In this study, we used a model consists of a joint, two links with one degree of freedom, and two muscles as flexor and extensor of the joint, which simulated in MATLAB using ...
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Functional electrical stimulation (FES) is the most commonly used system for restoring function after spinal cord injury (SCI). In this study, we used a model consists of a joint, two links with one degree of freedom, and two muscles as flexor and extensor of the joint, which simulated in MATLAB using SimMechanics and Simulink Toolboxes. The muscle model is based on Zajac musculotendon actuator and composed of a nonlinear recruitment curve, a nonlinear activation-frequency relationship, calcium dynamics, fatigue/recovery model, an additional constant time delay, force-length and force-velocity factors. In this study, we used a classic controller for regulating the elbow joint angle; a Proportional- Integral- Derivative controller. First, we tuned the PID coefficients with trial and error, and then a particle swarm optimization algorithm was used to optimize them. The important features of this algorithm include flexibility, simplicity, short solution time, and the ability to avoid local optimums. This PSO -PID controller uses particle swarm optimization algorithm to get the required pulse width for stimulating the biceps to reach the elbow joint to the desired angle. The fitness function was defined as sum square of error. The results for PSO -PID controller show faster response for reaching the range of the set point than the PID controller tuned by trial and error. However the PSO -PID is much better in terms of the rise time and the settling time, the PID tuned by trial and error has no overshoot. The time to reach the zero steady state error is half in PSO -PID in comparison to PID tuned by trial and error.
Control
Seyed Vahab Shojaedini; Armin Parsiannejad
Abstract
This paper describes a new method for harvesting maximum electrical energy in wind farms. In proposing technique, the stochastic process principles are applied for detecting fault measurements of sensors. On the other hand, the wind farm is modeled by using fuzzy concept. Thereby the turbines are controlled ...
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This paper describes a new method for harvesting maximum electrical energy in wind farms. In proposing technique, the stochastic process principles are applied for detecting fault measurements of sensors. On the other hand, the wind farm is modeled by using fuzzy concept. Thereby the turbines are controlled against continuous changes in speed, direction and eddy currents of the blowing wind. To evaluate the performance of the proposed method three practical conditions of wind blowing are simulated. In the first scenario, the normal wind is simulated with low turbulence and slow changes. The second scenario belongs to high turbulence winds with sudden shifts in their parameters, and finally in the most complex scenario, several eddy currents are considered in blowing winds too. The obtained results show that the proposed method provides greater and more uniform harvested power compared to alternative methods. Furthermore, its superiority against other techniques has increased in parallel with the scenario become more complicated.
Control
M. Zamanian; S. A. A. Hosseini
Abstract
This article studied static deflection, natural frequency and nonlinear vibration of a clamped-clamped microbeam under discontinues electrostatic actuation. The electrostatic actuation was induced by applying AC-DC voltage between the microbeam and electrode plate. In contrast to previous works, it was ...
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This article studied static deflection, natural frequency and nonlinear vibration of a clamped-clamped microbeam under discontinues electrostatic actuation. The electrostatic actuation was induced by applying AC-DC voltage between the microbeam and electrode plate. In contrast to previous works, it was assumed that length of the electrode plate was smaller than that of the microbeam. In addition, it was assumed that a layer whose length was equal to that of the electrode plate was deposited on the lower side of the microbeam. Equation of motion was derived using Newton's second law. The static deflection due to the DC electrostatic actuation and the natural frequency about this position were obtained using the Galerkin method. Nonlinear vibration of the system due to the AC electrostatic actuation was obtained using the multiple scale perturbation method. Variations of static deflection, pull-in voltage, natural frequency and frequency response of vibration about the static deflection of microbeam with respect to variations of second layer length, second layer thickness, electrode plate length and value of electrostatic actuation were also studied. It was shown that, depending on the value of these parameters, static deflection and natural frequency of vibration about static deflection increased or decreased. Moreover, it was demonstrated that, depending on the value of these system parameters, nonlinear vibration of the system due to the AC electrostatic actuation might be realized as a softening or hardening behavior.
Control
R. Mestiri*; F. Aloui; S. Ben Nasrallah
Abstract
The technique used to control the airflow is based on the electro-hydrodynamic actuator which is also called plasma actuator. This actuator ensures the airflow control thanks to the electric wind created by the electrical corona discharge. This ionic wind is developed at the profile surface tangential ...
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The technique used to control the airflow is based on the electro-hydrodynamic actuator which is also called plasma actuator. This actuator ensures the airflow control thanks to the electric wind created by the electrical corona discharge. This ionic wind is developed at the profile surface tangential to the initial free airflow so that it has a significant effect on the boundary layer flow. The studied profile was a NACA4412 airfoil. The electro-hydrodynamic actuator was placed at the surface of the NACA profile. The PIV visualizations made at angle of attack of 18° show an earlier flow reattachment to the profile surface when the plasma actuator is active. PIV measurements confirm that downstream of the actuator, when the discharge is ON, the wall velocity gradient is increased as illustrated by the velocity profiles taken at several positions on the NACA4412 wall. Then the plasma actuator can decrease the boundary layer thickness.
Control
Zuliang Lu*
Abstract
The aim of this work is to investigate the variational discretization and mixed finite element methods for optimal control problem governed by semi linear parabolic equations with integral constraint. The state and co-state are approximated by the lowest order Raviart-Thomas mixed finite element spaces ...
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The aim of this work is to investigate the variational discretization and mixed finite element methods for optimal control problem governed by semi linear parabolic equations with integral constraint. The state and co-state are approximated by the lowest order Raviart-Thomas mixed finite element spaces and the control is not discreted. Optimal error estimates in L2 are established for the state and the control variable. As a result, it can be proved that the discrete solutions possess the convergence property of order. Finally, a numerical example is presented which confirms the theoretical results.
