Sharif Digital Repository

This paper describes an application of intelligence- based predictive scheme to load-frequency control (LFC) in a two-area interconnected power system. In this investigation, at first, a dynamic model of the present system has to be considered and subsequently an efficient control scheme which is organized based on Takagi-Sugeno-Kang (TSK) fuzzy-based scheme and linear generalized predictive control (LGPC) scheme needs to be developed. In the control scheme proposed, frequency deviation versus load electrical power variation could efficiently be dealt with, at each instant of time. In conclusion, in order to validate the effectiveness of the proposed control scheme, the whole of outcomes are... 

In the aspect of further development of investigations in the area of spacecraft modeling and analysis of the control scheme, a new hybrid finite-time robust three-axis cascade attitude control approach is proposed via pulse modulation synthesis. The full quaternion based control approach proposed here is organized in association with both the inner and the outer closed loops. It is shown that the inner closed loop, which consists of the sliding mode finite-time control approach, the pulse width pulse frequency modulator, the control allocation and finally the dynamics of the spacecraft is realized to track the three-axis referenced commands of the angular velocities. The pulse width pulse... 

Design of robotic fish based on hydrodynamics is presented and Lighthill's Large Amplitude Elongated Body Theory (LAEBT) is used for modeling of the robotic fish in linear path. A PID controller for control of speed in linear path is designed and simulations are presented which shows its effectiveness for speed control of the robotic fish. It has been shown that in perspective of used approximate LAEBT model, the used control law maintains kinematic parameters and therefore, the associated efficiency will be maintained  

Fuzzy sliding mode control (FSMC) as a robust and intelligent nonlinear control technique is proposed to control processes with severe nonlinearity and unknown models. The performance of the proposed method has been evaluated for both single input single output (SISO) and MIMO nonlinear systems through its application in three severely nonlinear processes that are frequently used as benchmarks of nonlinear process control strategies. The evaluation shows that, despite its lack of dependence on the process model, the proposed method performs almost the same as conventional sliding mode control alternatives that utilize all the information that exists in the mathematical model of the process.... 

This paper is concerned with estimation and stability of control systems over communication links subject to limited capacity, power constraint, fading, noisy feedback, and different transmission rate rather than system sampling rate. A key issue addressed in this paper is that in the presence of noisy feedback associated with channel, which models transmission of finite number of bits over such links as is the case in most practical scenarios, the well-known eigenvalues rate condition is still a tight bound for stability. Based on an information theoretic analysis, necessary conditions are derived for stability of discrete-time linear control systems via the distant controller in the mean... 

In addition to perfectly steering the output concentration of a process network to an exogenous set-point, a desired synthetically implemented biological controller should be able to robustly maintain this regulated output in the face of the extrinsic disturbances and inherent uncertainties due to an evervarying environment besides the imprecise modeling. Such an ability, which is called robust perfect adaptation (RPA), can be achieved by integral feedback control (IFC). Answering how IFC is (biochemically) constructible in generally unknown synthetic networks has been a research focus in the community. One of these answers, which has been well investigated previously, is to utilize a simple... 

Fractional order PID controllers are suitable for almost all types of dynamic models. In this paper, a new adaptive fractional order PID controller using neural networks is introduced.The overall performance using the proposed adaptive fractional order PID controller is demonstrated through some examples. It is shown that the new controller scheme can give excellent performance and more robustness in comparison with the conventional controllers like GPC  

In this paper, a modified frequency control model is proposed, where the demand response (DR) control loop is added to the traditional load frequency control (LFC) model to improve the frequency regulation of the power system. One of the main obstacles for using DR in the frequency regulation is communication delay which exists in transferring data from control center to appliances. To overcome this issue, an adaptive delay compensator (ADC) is used in order to compensate the communication delay in the control loop. In this regard, a weighted combination of several vertex compensators, whose weights are updated according to the measured delay, is employed. Generating the phase lead is the... 

A practical design method is presented which used the fuzzy logic advantages in adaptation of sliding mode control. The combined Fuzzy Adaptive Sliding Control (FASC) is designed in such a way to enhance satisfactory sliding performance and robustness with good level of chattering alleviation. The design approach is valid for a class of nonlinear uncertain MIMO systems. This control algorithm does not require the system model. A supervisory term is appended to the controller to assure the stability of fuzzy sliding mode control through Lyapunov theory. The design approach has been applied to a 2DOF twin propeler system with large uncertainty. Simulation results verified effectiveness of... 

A fractional order PID controller is designed to stabilize fractional delay systems with commensurate orders and multiple commensurate delays, where the time delays in the system may belong to several distinct intervals. Moreover, the controller parameters should belong to given intervals. In order to stabilize the system, the D-subdivision method is employed to choose the stabilizing set of the controller parameters from their available values. Furthermore, the nearest values of the obtained stabilizing set to their mean values are selected as the controller parameters so that a non-fragile controller is concluded. Two numerical examples evaluate the proposed control design method  

Many actions have been taken by researchers to design an appropriate controller for a quadruped robot. These efforts can be divided into two main categories: analytical and intelligent methods. The analytical method is based on the motion equations of the robot which are mostly complicated. These complication leads to difficulty in implementation. In contrast, there exists intelligent method which is based on the learning algorithms. Despite lots of improvements in the controlling of the quadruped robots, their ability of walking is still far less from the four legged animals' capability. Many researchers believe that four legged animals owe this priority to the learning attribute. Therefore... 

The control of a brachiation robot has been the primary objective of this study. A brachiating robot is a type of a mobile arm that is capable of moving from branch to branch similar to a long-armed ape. In this paper, to minimize the actuator work, Pontryagin's minimum principle was used to obtain the optimal trajectories for two different problems. The first problem considers brachiation between fixed branches with different distance and height, whereas the second problem deals with the brachiating and catching of a moving target branch. Theoretical results show that the control effort in the proposed method is reduced by 25% in comparison with the target dynamics method which was proposed... 

This paper considers a closed-loop system consisting of a fractional/integer order system and a fractional PID controller. Assuming that the uncertain coefficients of the fractional PID controller lie in some known intervals independently (i.e. that controller is a member of an interval family), the paper presents some easy to use theorems to investigate the robust bounded-input bounded-output stability of the resultant closed-loop system. Moreover, a finite frequency bound required in drawing the related graphs has also been provided. Finally, some numerical examples are presented to illustrate the results  

A predictive functional controller based on ARMarkov model structure has been designed to control welding current and arc voltage in a GMAW process. The closed loop system performance is investigated through computer simulations and is compared by those achieved from implementing two commonly used controllers i.e. PI and feedback linearization based PID. The local stability of the closed loop system is analyzed in the presence of uncertainties in the linearized model of the process as well as the control parameters. Finally it is shown that the proposed controller performs like a PI controller along with a pre-filter compensator  

The introduction of demand response concept, in addition to increment of penetration of distributed generation (DG) based on renewable energies, make opportunities for the novel control schemes to be integrated in power system on a smart grid framework. Voltage control methods in power systems needs proper coordination among reactive power resources and conventional volt/var control equipments. In this work, potential reactive power resources are investigated and then, reactive power output of renewable DG units and controllable loads along with operation of conventional voltage controllers are optimized using a centralized control scheme. Considering the variability of demand and... 

This paper presents a new method for tuning linear controllers such as Proportional-Integrating (PI) and Proportional-Resonant (PR) structures which are frequently used in different power electronic and power system applications. Those controllers are placed within a general structure offered by the Internal Model Principle (IMP) of control theory. In this paper, the first perspective uses the well-known concept of Linear Quadratic Regulator (LQR) to address the problem as a regulation problem. Matrix Q of the LQR design is then finely adjusted in order to assure desired transient response for the system. The second perspective is based on redefining the LQR problem in order to make it... 

The performance of hapticdevicesisevaluatedbasedontheconceptoftransparency, whiletheirstabilityhasprevalentlybeenevaluatedbasedonthepassivitycriterion. Duetotheconservativenessofpassivity, itappearsasanobstacletoimprovingtransparency.Inthepresentpaper, passivityissuggestedtobereplacedbythecomplementarystabilitycriterionwhichaccoun tsfortherobuststabilityoftheinteractioninthepresnceofuncertainuserhanddynamics. Inthisrespect, analgorithmisproposedwhichguaranteestransparencyofthehapticdeviceinastablemanne r.Assumingthatthedynamicsofthedeviceisknown, acertaincompensatorystructureisassigned. Thisspecialstructureguaranteestransparencyofthedevicebycompensatingforthedynami... 

In this paper, the fractionalized differentiating method is implemented to reduce commensurate fractional order models complexity. The prominent properties of this method are its simplicity and guarantee of preserving the stability of a specific class of fractional order models in their reduced counterparts. The presented reduction method is employed in simplifying complicated fractional order controllers to a fractional order PID (FOPID) controller and proposing tuning rules for its parameters adjustment. Finally, the efficiency of the FOPID tuning rule obtained based on the proposed reduction method is shown in the temperature control of a cutting process  

The model of emotional masks is a newly developed AI paradigm based on Minsky's model of emotional mind in his recent book "The emotion machine". The model takes a resource management approach toward modeling the mind and views different processes of mind as resources that need to be managed. In the present work an intelligent controller (SCELIC) is developed based on the model of emotional masks. SCELIC is a model free controller which advantages from several learning tasks. Multiple learnings and adaptive structure make it a powerful adaptive and self-learning tool that performs the tasks of system identification and control in parallel. Although the test-bed considered here is a nonlinear... 

Fractional order PI and PID controllers are the most common fractional order controllers used in practice. In this paper, a simple analytical method is proposed for tuning the parameters of these controllers. The proposed method is useful in designing fractional order PI and PID controllers for control of complicated fractional order systems. To achieve the goal, at first a reduction technique is presented for approximating complicated fractional order models. Then, based on the obtained reduced models some analytical rules are suggested to determine the parameters of fractional order PI and PID controllers. Finally, numerical results are given to show the efficiency of the proposed tuning...