Sharif Digital Repository

In the past few decades, with the advancement of technology, using autonomous robots has been receiving growing interest. Autonomous semi-submersible vehicles are a subset of autonomous underwater vehicles (AUV). This type of vehicle operates near the surface of the water and is semi-submerged. Nonlinear coupled dynamics, structural uncertainties, model parameters dependency to robot velocity, external disturbances, and model constraints are AUV’s workspace challenges. For this reason, depth control of these vehicles in the presence of environmental disturbances is crucial. However, MPC as one of the advanced control methods in the field of robotics is increasingly developing. This control... 

This dissertation investigates the Multiple-Horizon Multiple-Model Predictive Control method and its application in soft landing problem on an irregular-shaped asteroid. In this way, a predictive framework including a heuristic guidance law named Predictive Path Planning and Multiple-Horizon Multiple-Model Predictive Control (MHMM-PC) as the control scheme is introduced for soft landing on an asteroid. Obviously, reducing the fuel consumption is a priority in space missions. Thus, the employed control framework should minimize the required control effort. Furthermore, the control method should be robust enough to deal with the effects of model uncertainties and disturbances. The unique... 

In comparison to attitude control of a satellite which is widely used in practical missions, orbit control (espescialy autonomous orbit control) has been only recently paid attention. Autonomous, on-board orbit control, also called autonomous stationkeeping, means the automatic maintenance of all of orbital elements by the satellite itself. In this thesis, an autonomous absolute orbit control strategy for a single Low Earth Orbit (LEO) satellite is presented. When the satellite violates the control trigger error limits, then the controller is activated and calculates a sequence of orbital maneuvers that move the satellite towards its desired states. The absolute orbit control of the... 

Optimizing the energy consumption of air conditioning systems has gained great importance in recent years. In addition, maintaining thermal comfort and air quality in buildings is important. The multi-evaporator air conditioning system, which is a direct expansion system, shows the complex and distributed structure of air conditioning systems due to the thermal connection between zones and its large scale. The modeling of these systems is associated with uncertainties. Therefore, designing a suitable control structure for multi-zone systems is very important to achieve optimal energy consumption and maintain comfort conditions in the presence of uncertainty. Model predictive control has been... 

One of the model based control strategies that has been proposed in recent years for the control of process systems is the one based on the economic models, in which objective functions with an economic basis are used along with the equations and constraints to perform control calculations. In this work, the control of a multiproduct continuous stirred reactors is discussed, in which, it is possible to produce different products based on changes in the market demand, the price of the products or the primary raw materials according to a specific schedule. One of the recently used methods is the economic predictive control method based on the Lyapunov function. In this method a quadratic... 

The purpose of this project is designing a controller for a floating offshore wind turbine to exctract maximum power from wind energy in the first operating region of wind turbine. The NREL 5 MW OC3-Hywind floating wind turbine with BARGE platform will be used for this project. By using Turbsim software, proper wind profile for the first operating region of wind turbine will be produced. This profile will be excecuted for the FAST software that is simulates the mechanical part of wind turbine. By implementing the doubly fed induction generator in Simulink enviroment and designing the controller for doubly fed induction generator, the desired torque for maximizing the exctraction power of... 

In industries there are many nonlinear processes which cannot be easily controlled with classical methods. Model predictive control is a useful method for nonlinear processes which not only has high efficiency, but also extension of this control to interferential multi variable case, with constraint on the controlled and manipulated variables and other problematic dynamic specifications such as slow dynamics and inverse response is very simple. Industrial polymerization processes are regarded as significant nonlinear processes. Optimization and control of polymerization reactors have considerable importance in process applicability and in economics. The molecular structure of polymer such as... 

In this thesis, at first upstream transient error propagation and amplification phenomenon is introduced. Then, the previous methods to attenuate this phenomenon are presented. To overcome this drawback, a new method that is based on feed-forward and off-take disturbance estimation and lost data reconstruction in wireless communication is presented. In this thesis, an estimation of unknown off-take disturbance at the present time is approximated or in fact predicted using the last data. Also, in the presented method, the lost data is reconstructed using two different methods. At the end, the satisfactory performance of the proposed control method is illustrated by many computer simulations  

A distributed model predictive control with two-layer structure for communication is presented in the present thesis for elimination of the propagation and amplificationphenomenon of the upstream transient errors in automated irrigation networks. This phenomenon results in the saturation of actuators in long automated irrigation channels and therefore it results in significant reduction in the quality of service of the irrigation network. Hence, the elimination of this phenomenon in long irrigation channels is necessary, in which a distributed model predictive control with two-layer structure for communication is presented in the presentthesis for elimination of this phenomenon. Feasibility,... 

In this thesis, the problem of failure-tolerant control of the satellite in coupled orbital and rotational motion is investigated. All of the actuators of the satellite are thrusters and only the failure of the actuators is considered. At first, the equations of coupled relative translational-rotational motion of the satellite are derived. Then, the required specifications of the approapriate control method for the problem is explored with the conclution that the controller must be able to predict the behavior or planning the future trajectory of the satellite. In the next step, model predictive control, which has the required specifications, is used to control the coupled... 

Many industrial systems have on/off actuators. Traditionally, these systems are controlled using traditional control methods, like PID controller. The performance of this controller is not ideal for these systems, especially in term of transient response and power consumption. Due to the large number of constraints for these systems, to improve the performance of them, it is necessary to use the model predictive control technic. The decision variables of these systems are integer, hence it is necessary to develop the model predictive control method based on integer programming, which is the subject of this thesis. The main challenge in the development of this model predictive control method,... 

This is the first attempt at process modeling in terms of predictive control using a hierachical method based on regression analysis and artificial neural networks(ANNs).This hierachical use leads to the reliability improvement of neural model of process in prediction (extrapolation and interpolation) of process output. such an outlook makes it possible to predict the proper input settings which achieved a desired process output by designing various senarios for process set up. This approach was applied in Tile industry for spray dring process and in order to indicate the achieved improvement,three models:(i) regression model of process using multiple linear regression,(ii)Neural model of... 

The application of fuel cell systems as sources of clean energy production is common. Control, performance optimization, design, manufacturing and the operation management are considered as significant research interest of the fuel cell in academic circles. A major problem, at least in the advanced model-based control, is the slowness of solving the nonlinear multi-scale model (time). One option would be using the black-box neuro-fuzzy models. Then if the predictive controller is used for this distributed system, calling the output of neuro-fuzzy model allocated a negligibility proportion in time of calculations during the optimization. In this project, the data generated by a dynamic... 

In today's world we are dealing with many devices and processes with the goal of efficiency and performance improvement. In many processes particularly chemical ones, the goal is to control the output according to its constraints in the way that the performance is economically efficient, such as reducing energy consumption and energy loss and increasing efficiency. In order to control a process with economical goals, an economical cost function is used and after determination of optimal values a controller is used to guide the process so can achieve them. Model predictive control (MPC) is very common in this economic control Due to advantages such as considering the problem constraints. In... 

Electrochemical treatment of tumors introduces cancer therapy method that uses direct current which passes through cancer tissue. The manipulated variable (direct current density) is applied to the surface of the electrode. As a result of applying direct current on the anode's surface, two competition reactions start to happen on the electrode's surface, Chlorine and Oxygen evolutions. The productions of these two reactions for instance Cl_2 , Cl^- and H^+ caused different reactions in the domain of the electrolyte which is the body tissue. According to the buffer characteristic of blood and organic features of tissue, various types of acids like HClO form in the electrolyte. If the pH in... 

Travel time is the most significant element in choosing among different modes of transportation. In order to increase the public transportation’s utility we need to utilize some methods to reduce public transportation travel time and passenger delay. Bus system, as one of the major types of public transportation, is mainly influenced by the traffic flow more than other types of public transportation. In order to increase the bus system’s reliability we need to utilize a controlling system so that we could increase its movement discipline and reduce line’s disruption. In this research we proposed an optimization model based on bus holding strategy and the real-time data from the route. This... 

The purpose of this thesis is to control altitude and attitude of a Tilt Tri-Rotor UAV in rotorcraft mode and control of altitude, attitude and forward velocity in transition mode (from rotorcraft mode to cruise) by using model predictive control. First, the detailed mathematical model is obtained by the Newton-Euler equations of motion, in both rotorcraft and transition modes. In the next step, a MIMO model predictive controller has been designed, considering input constraints. Then, since, robustness of the model-based control approach is an important challenge, the performance of the controller is presented in the presence of model uncertainties and wind disturbances. The results indicate... 

Recently, there has been a surge of research activities in the area of networks in the systems and control community. One foundational class of questions on networked systems pertains to their controllability. While there are classical tests to check the controllability of linear time-invariant (LTI) systems, their applications to large-scale networks is numerically infeasible. Indeed, finding a minimum cardinality set of input nodes that ensure the controllability of a network is NP-hard. Moreover, when the interaction strengths along the edges of a network are unknown, the classical controllability test cannot be applied. To overcome these issues, an alternative set of approaches involves... 

This research investigates the use of baffles in sector jets for film cooling of turbine blades. The goal of this study is to compare the cooling performance in three conditions: sector jet without baffles (one 90-degree arc), with one baffle (two 45-degree arcs), and with two baffles (three 30-degree arcs). The effect of using this type of cooling is also compared to the crossflow jet, which is the simplest type of cooling jet. In all conditions, the mass flow ratio is constant and equal to 1. The problem is solved for a turbine blade with the “AGTB-B1” airfoil. The problem is first solved with the Transition SST turbulence model, and the results are used as the initial conditions for the... 

Regarding increasing rate of electrical energy demand, paucity of fossil fuels and the pollution stemmed from burning them, using renewable energy is inevitable. For transmitting the generated electrical energy to grid, power electronics converters are used. Inverters and back-to-back converters are some of these converters. Inverters and back-to-back converters are used in connecting photovoltaic power plants and wind systems to grid respectively. Because of technological limitation, converters are paralleled with others at high power transmitting. Paralleling converters has other merits such as increasing system reliability through redundancy and repairing defective converter without...