Sharif Digital Repository

This project is intended to introduce a semi-active control for suspension systems of passenger cars wherein, in addition to usual dampers, the damper using Magnetorheological (MR) fluid instead of ordinary oil is used. In order to model the suspension system, a mass-spring model with eight degree-of-freedoms without considering the effect of car velocity is developed. A semi-active vibration control is presented to reduce the amplitude of automotive vibration caused by the alteration of road profile. In order to design a suitable control mechanism, first, an optimal control algorithm, Linear Quadratic Regulator (LQR) and Linear Quadratic Gaussian (LQG), are used to control the system;... 

The present study discusses the problem of enabling a PUMA 560 electrical robot manipulator to interact with the environment using impedance control concept. The impedance control strategy maintains a pre-specified desired second order dynamic relation between the end-effector position and force and enables a stable transmission between unconstrained and constrained motion. In this study Position-Based Impedance Control (PBIC) is used which is more suitable for industrial manipulators. PBIC requires a position controller with high accuracy. Therefore, a nonlinear PID controller is used in the position loop which is capable of both tracking and regulating of the input signals and shows better... 

In this paper, controlling the cutting force of an end-milling process using a supervisory fuzzy controller has been investigated. The proposed control consists of an ordinary fuzzy controller and a fuzzy supervisor. In a machining process, there are several parameters which do not contribute to the force control system directly. Therefore an ordinary fuzzy force controller is suitable when these parameter have only small amount of variations. Since in practice this assumption is not valid, then a supervisory fuzzy controller has been added to the system. The designed fuzzy supervisor, inspects the dynamic behavior of the cutting force, estimates a pre-defined ‘sensitivity’ parameter and... 

Magnetic levitation is an appropriate solution for noncontact 3D manipulation. Workspace of the previously proposed maglev systems is confined to a relatively small cube, which severely limits the application of this technology. In addition, most of the previously given mechanisms require the design and application of a subsystem in order to unify their magnetic field. In this paper, a moving magnet is proposed which results in a horizontally extendable workspace; moreover, the field unifying section is not needed since one electromagnet only is used. Further, details of the mechanism and finite element based design procedure of the magnet are presented. Dynamic equations of the system... 

In recent years، one of the most popular and wide areas of research have been focused on Unmanned Aerial Vehicles (UAVs). Among them، Quadrotor which has the capability of Vertical Take-off and Landing (VTOL)، hovering، great agility and maneuverability، simple structure، light weight and reasonable size has particular importance. In the industry، we always deal with plants which there are no precise information about their dynamic model، or their model is too complex to identify. So designing controllers with less dependency to system model and no need to exact knowledge of the system is absolutely vital. The arrangement of motors in a Quadrotor provides six Degree Of Freedoms (DOF) for... 

Subcutaneous needle insertion is one of the key methods of limited invasive surgery in medical diagnosis and treatment. However, errors in needle targeting can reduce the effectiveness of such efforts. One of the main factors of errors is due to the human guidance of the needle, which many researches have approached in recent years, and among the suggested solutions is the use of automatic or semi-automatic assist systems. Considering the treatment of prostate cancer by brachytherapy method, this research has developed a semi-automatic physician assistance system using navigation based on the potential field method and ultrasound images of the needle location, and sliding mode fuzzy... 

This study presents the application of the doubly fed induction generator (DFIG) to reduce the frequency deviation and improve frequency of a power system. This has been done by proposing a wind turbine model and a new fuzzy controller. The fuzzy controller has been suggested to change the speed of the wind turbine rotor and modify the impacts of wind speed fluctuations on the output power. The fuzzy controller parameters are optimized using the genetic algorithm (GA) to achieve the appropriate transient response. A smart controller is combined with fuzzy controller to optimize the usage of wind turbine’s kinetic energy. Furthermore, the DFIG with the proposed controller participates in the... 

There are lots of researches performed to investigate human being learning and try to model it. But, in case of huge complexity of its structure and function, almost none of so-far learning algorithms can model human learning process and, indeed, performance of human brain in real problems is much more than these algorithms. Moreover, in many cases, human is not aware or informed about internal structure or mathematical model of the present system he is working on; a child learning to walk has no information about his neuromuscular system and his brain slowly learns how to convey his little body by choosing the proper timing of muscle contractions. One of the accomplished researches in order... 

One of the most important processes in the manufacture of mechanical parts in the industry is the machining process. High-speed milling is growing in aerospace, automotive, and many other industries due to advantages such as high material removal rates and better surface finish. However, the instability caused by self-excited vibration (chatter) is not only one of the main limitations for the productivity and quality of the workpiece but also reduces the life of machines and tools. In this research, after introducing the matter of milling flexible parts, the basic concepts of machining are first described, and common terms in machining are explained. Then, a review of past research has been... 

In past decades, we have seen the rise of integration density in chips making it possible to design a whole system on a single chip. The previously designed interconnection architectures for multiprocessors systems cannot directly be applied in on-chip systems (especially when the number of processor elements increases) since they require a different type of a cost-performance trade-off. This is why the interconnection networks of systems-on-chip (SoC) are such a problem. Network-on-chip (NoC) was being proposed as a scalable and reusable communication platform for SoCs, which makes use of the network model to develop efficient on-chip communication infrastructures. The NoC has a layered and... 

Fish robot has attracted many attentions in the last decade due to several types of its applications. Many researches have been done recently on this type of robot. Dynamic modeling and control of a fish robot are important and challenging problems. This issue has a great influence on design, manufacturing, efficiency and control of the fish robot. According to the literature review, it seems that no exact analytical model exists for predicting the propulsive forces which are used in controlling and simulating dynamic behavior of the robot. Fortunately, Lighthill has proposed an analytical relation to predict propulsive forces of carangiform fishes in his research. Large amplitude elongated... 

The aerial vehicle capable of vertical takeoff and landing (VTOL), have created an interest in the community of researchers and admirers of Unmanned Aerial Vehicles. Among the existing UAV's, those with the capability of vertical takeoff and landing are prominent due to their higher maneuverability and hover capability. Quadrotors mostly have been considered as a flying robot for save and rescue operations in dangerous and unreachable places in addition to its military application. In cross shape of Quadrotor platform on each edge is appointed an electric motor with light rotors that usually are controled by considering motor rates as their only inputs. This thesis aims, to simulate and... 

Dynamic positioning system is a controller system used to maintain the position and heading of a vessel with no use of anchors, jack ups but only using the propellers installed on the vessel. A vessel has six degrees of freedom, including three rotations and three transfer. In dynamic positioning systems, the vessel is controlled only on the horizontal plane such that its position and heading are controlled according to predetermined values. To achieve this, position and heading of the vessel is determined and the controller system computes the direction and required power of each propeller. Preliminary systems utilized PID controllers. As the control science has advanced, model based... 

Polymer membrane fuel cell is a rich source of renewable energy. Two problems of short life and low reliability in fuel cells are the main problems of this system. The difference in partial pressure of hydrogen and oxygen causes serious damage to the fuel cell and inefficiency of the electricity production capacity. On the other hand, the life and optimal performance of the fuel cell depends on the moisture content of the membrane because the membrane needs sufficient moisture to pass ions. Transparent fuel cells can be used to study the water in the fuel cell. With direct imaging of this type of fuel cells, the phenomenon of water creation in the fuel cell can be studied with the help of... 

In control systems, actuators are subjected to faults during operation. In the present work, a controller for nonlinear systems under several restrictions and in the presence of actuator failure has been proposed. The controller is designed for large-scale multi-input multi-output (MIMO) uncertain nonlinear systems subject to unmodeled dynamics, unknown state dependent control gain functions, unknown state time varying delay, unknown subsystems interactions, unknown external disturbances and input nonlinearity. The backlash has been assumed for input nonlinearity. No restriction has been considered regarding the number of actuator failure. The backstepping technique has been applied for... 

The final target of this research is to design an appropriate intelligent control strategy for energy management purposes in a well designed parallel hybrid electric vehicle. In the first step, the conventional “Samand” vehicle has been simulated using real data for vehicle parameters and power train components, has been simulated. Using experimental results, simulation results are validated. In the second step due to the primarily defined parallel electric assist control strategy (PEACS) for the hybrid electric vehicle and performance requirements, components such as engine, electric machine and battery pack were selected and sized. In the final step a Fuzzy Logic Controller (FLC) has been... 

Recently, many investigations have been devoted to problems of controlling mobile-wheeled inverted pendulum (MWIP) models, which have been widely applied in the field of autonomous robotics and intelligent vehicles. The MWIP models are not only of theoretical interest but are also of practical interest. Many practical systems have been implemented that were based on the MWIP models, such as the JOE, the Segway, etc. Among these applications, the Segway PT has been a popular personal transporter, since it was invented in 2002 Such systems are characterized by the ability to balance on its two wheels and spin on the spot. This additional maneuverability allows them to easily navigate on... 

The flexible magnetic robot is used for minimally invasive surgeries where there is a complex environment. Precise control of the position of the end of the robot and quick adaptation of the robot to uncertainties are among the most important challenges in this field, where the controller is responsible for compensating the error and controlling the position of the end of the robot. Now, is it possible to create a kind of memory in the system that when faced with the same or similar errors in the same situations or close to previous errors, the system uses its past and compensates the error? The importance of this work is that the response speed of the system is increased and the system can... 

The Active Learning Method is in fact an adaptive recursive algorithm which embodies a Multi Input and a Single Output (MISO) system as in a fuzzy combination of several Single Input systems and Single Output systems (SISO), and by utilizing a fuzzy technique of Ink Drop Spread tries to explore and extract input to output transfer function behavior in the system of a single-input to a single-output. Although in simulation state, the speed of this model is set at a much higher speed in comparison to other presented models, still is slower than the processing speed of human brain. In regards to hardware implementation, also there remain the fundamental implementation challenges through more... 

Problems of global warming have motivated energy communities to design and develop green power generators. Energy of the ocean waves is one of the most fascinating clean energies which have not been completely explored yet. The present work intends to design and develop a novel efficient system to generate electricity using the power of ocean waves. The proposed device can operate in most ocean situations. The device floats with the buoyancy of the buoy over the ocean surface. Regarding the ocean inputs the device is sinking or floating at the ocean to control and optimize input force. In the proposed system kinetic energy of the ocean wave is converted into force. This force moves the...