Sharif Digital Repository

During the turning operation, the interaction of the metal cutting process and machine tool causes a dynamic instability called self-excited vibration or chatter. Limited productivity rate, decrease in tool life, poor surface quality and noisy workplace are some adverse effects of the chatter vibration. Chatter suppression in machining processes results in more material removal rate, high precision and surface quality. In this thesis, two control strategies are developed to suppress chatter vibration in turning process including a worn tool. A single degree of freedom model of the turning process including tool wear is briefly described. In the first stage, a sinusoidal spindle speed... 

Nowadays, applications of industrial robots are significantly increasing due to their flexibility, programmable, accuracy, rapidity and etc. Among these, machining robots play an important role at manufacturing industries. One of the main concerns of the researchers, is the tip vibrations of robot arms. In most times, these vibrations are self-excited, unpredictable and intolerable. Thus, finding a method for reducing vibration should be investigated. The purpose of vibration control is vibration suppression to enhance the reliability of the system. The aim of this project is the modeling of the machining robot arm in turning process and then application of robust control to reduce... 

Eigenvalue analysis is a fundamental tool in control issues, however, in some abnormal matrixes it can lead to an incorrect judgment of the matrix dynamic behavior. Pesudospectra, as an eigenvalue generalization, can provide more extensive information of the system dynamic behavior, whereas, the obtained data from eigenvalue analysis can be incomplete. In applying robust controllers, the concept of uncertainty has been attracted researcher interest in system modelling, nevertheless, the controller implementation may not be fault free or the parameters may vary over time. In this project the aforementioned issue will be studied and additionally, the pseudospectra will be employed to design a... 

Power system operators are facing with imperative challenges to integrate high penetration of renewable power plants. The main challenge is required investment cost for accommodating the grid with uncertainties of renewable resources. In addition, intermittency and fluctuations of renewable resources are another challenges of system operators. Therefore, choosing a proper control procedure to respond the grid disturbances is a crucial task. However, the strategic behaviours of generation companies lead to a competition between them which affects the control performance. In this thesis, an integrated mechanism is proposed that consider both dynamic and strategic behaviours of generation... 

Three-phase voltage source converter (VSC) is vastly utilized in the renewable energy resource and distributed generation (DG) systems interface units due to its high controllability and flexibility. Because of the high nonlinear nature of the system, the gird-connected inverter shows poor performance if the conventional control scheme are used. In this thesis, a new control scheme based on backstepping strategy is presented for control of a grid connected DG systems. The proposed scheme is responsible for regulating the active and reactive power components of the VSC power of the DG system. The VSC of the DG system is connected to a stiff utility grid through an L-type filter. In the first... 

Endoscopic sinus surgery is a minimally invasive surgery. Today, for the education of such surgeries, the surgical simulators are used. They could be used for both training of such a technique and pre operation planning. One of the features that could improve the efficiency of these systems and prepare the effective interaction with them is haptic.
In this thesis, an inexpensive sinus surgery simulator has been designed and implemented such that the operator could see sinus nasal in real time and could detect collisions between tool and virtual environment.
In this research, a 3D surface rendered model that extracted from 2D CT images has been used for construction of virtual... 

In this project roll channel autopilot of an agile flight vehicle has been studied. In skid-to-turn tactical flight vehicles according to the type of control strategy, for achievment of acceleration commands, the roll angular velocity should be kept near zero. In usual autopilot design, effects of channels on each others is ignored. But three channels of agile flight vehicles have some mutual effects, that consists of kinematic, inertial and aerodynamic couplings. In the case of roll channel dynamics, aerodynamic couplings are dominant and apears because of two factors: roll induced moment and roll cross coupling moment.
After study and aerodynamic modeling of mentioned factors, based... 

Best cancer treatment is the one which reduces the tumor density in minimum time and side effects, considering the input limitations. In this paper, tracking controller and robust controllers are designed to achieve the mentioned objectives, simultaneously. An ODE-based mathematical model of the human body under chemovirotherapy is selected, which includes the uninfected and infected tumor cells, free viruses, immune cells, and a chemotherapeutic drug. For tracking purposes, a servo controller based on the entire eigenstructure assignment (EESA) approach is applied to the model, continuously and discretely. For robust purposes H-infinity and D-K iteration approaches are implemented and... 

Nowadays electricity power has a key role in developing various aspects of the world. The great importance of fossil fuel power plants come from their large contribution in electricity power generation. Among the different fossil fuel power generation technologies, supercritical power plants have great advantages. They are an advanced power generation technology with high plant efficiency, high coal utilization and low emission. Their complexity and existing many unavoidable uncertainty sources in their dynamic such as changes of ambient temperature, climate condition and wear of components make their control challenging. To overcome mentioned problems and achieving a good performance, a... 

Capsule endoscopy is a minimally invasive diagnostic technology for gastrointestinal diseases providing images from the human’s digestion system. Developing a robust and real-time localization algorithm to determine the orientation and position of the endoscopic capsule is a crucial step toward medical diagnostics. In this thesis, we propose a novel model-aided real-time localization approach to estimate the position and orientation of a magnetic endoscopic capsule swimming inside the stomach. In the proposed method, the governing equations of the motion of an ellipsoidal capsule inside the fluid, considering different hydrodynamics interactions, are derived. Then, based on the dynamic... 

A control strategy for islanded (autonomous) operation of a microgrid consisting of two Distributed Generation (DG) units is proposed in this thesis. The DG units are connected together in a radial configuration. Each DG unit utilizes a voltage-sourced converter (VSC) to interface to its dedicated load. The DG units and the loads are to operate in the islanded mode of operation. To provide autonomous operation for the microgrid, voltage and frequency of the loads should be regulated. The proposed control strategy utilizes (i) an internal oscillator for frequency control in an open loop manner and (ii) a decentralized servomechanism controller to regulate the load voltage. The microgrid is... 

In this thesis, two-level optimal control of uncertain and non-uncertain large-scale systems is presented. In the proposed two-level approach, using a decomposition/coordination framework, the large-scale system is first decomposed into several interactive subsystems, at the first-level, where a smaller optimization problem is solved at each subsystem. At the second-level, a substitution type prediction method, as a coordination strategy, is used to predict the interaction between subsystems. The coordinator mainly evaluates the next update for the coordination parameters and continues to exchange information with the first-level, so that the overall optimum solution is obtained. It is shown... 

Spacecrafts formation flying is defined as tracking or keeping of desired distance, relative position and attitude of two or more spacecrafts during a maneuver. Division of tasks between various smaller spacecraft’s and so reduction of need to advanced technologies, increase in reliability in system and doing special missions like 3-D imaging of planets and combining parameter measurements are some advantages of this method. For development of this method, in this thesisin addition of reviewing the common methods in spacecraft’s formation flying, we are supposed to provide a simple and new method called distributed control for controlling a formation of spacecrafts. Additionally by providing... 

In this research, we have examined the efficiency of solar tower power plant. The solar tower power plant is one of the most important types of solar power plants that have been noticed due to the possibility of reaching high temperatures and good thermal efficiency. A concentrated solar tower power plant is one of the ways to convert solar radiation into electricity. In this process, the cold water at the top of the tower turns into hot water and then turns into steam, and from there it is given to the generator, which produces electricity. In this type of power plant, there are a large number of mirrors, which are called heliostats, and they are controlled separately and reflect the...