Sharif Digital Repository

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... 

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... 

In the beginning of the 90’s a new type of robot was introduced by Fukuda. The brachiation is a type of mobile robot that moves from branch to branch like a long-armed ape. Here, as a new innovation, optimal control is used to obtain the optimal trajectories for two different problems. The first problem is “Brachiation between fixed branches with different distance and height” and the second is “Brachiating and catching the 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 in prior articles for this robot. The obtained optimal trajectory also minimizes the... 

A new generation of physical and industrial systems is evolving towards communication and information technology as communication and information technologies progress. Cyber-Physical Systems, or CPSs, are physical systems situated in a cyber environment and use communication and information technology to improve efficiency. A CPS is an integrated synthesis of the principles of "control," "communication," and "computation" from an engineering point of view, attempting to provide a comprehensive framework in which all aspects of these three fields are covered. One of the capabilities of CPSs is the ability to deal with and implement a large scale system. A group of control missions in large... 

In many modern medical procedures, needle insertion is an inevitable part of the diagnosis or treatment protocols. The accuracy of the needle insertion is adversely affected by a number of factors. A needle, frequently assumed to be flexible, is inserted into a soft tissue and induces complex mechanical interactions that may result in considerable uncertainties. Tissue intrinsic characteristics as well as its deformation and rotation may cause dramatic complexities. This work considers the needle movement inside the tissue from the dynamics and control point of view. The proposed approach can be regarded as an initial step towards automation of needle insertion procedures; it can also be... 

Today, the need to access very small environments is felt in various medical, industrial, biological and military fields. Due to their small size, microrobots have the ability to perform tasks that would be very difficult to do on a larger scale, but this ability of microrobots makes feeding and controlling them challenging. There are several methods for providing power and control of microrobots, which include their internal or external stimulation, among which the magnetic stimulation method is used in this research, which does not cause damage to body tissues.In this thesis, an electromagnetic system with nine cylindrical coils is used to control the three-dimensional movement of magnetic... 

Transparency is a measure of performance in haptic devices. In order to improve transparency and reduce the difference between the impedance transmitted to the user and the target impedance it is necessary to compensate for the dynamics of the haptic device. Due to stability reasons improvement of transparency is limited. Passivity as a stability criterion has been used widely in design and analysis of haptic devices. Since passivity is a conservative criterion, it acts as an obstacle in improving transparency of the haptic interfaces. In this project instead of passivity, robust stability of the interaction is studied in the presence of parametric uncertainties due to variations in user... 

In this thesis, kinematic, dynamic modeling and simulation, and control of SQ15-06N industrial robot have been presented. This robot is mostly used in the painting industry. Studying the robot requires familiarity with the robot programming and the hardware used in the robot. In this research, robot characteristics such as repeatability, load carrying capacity and accessibility have been investigated. The principles of industrial robot programming and robot programming language have been studied. The use of simulation software is common due to cost savings, reduced time, no need for robots and controllers, and the ability to test programs in a virtual environment. For this purpose, the... 

In the recent decade many researches have been done on optimizing urban traffic. The invention of single-axel two-wheeled vehicle -which is also known as Segway- is toward this goal. This vehicle was invented in 2002 by Dean Kaman. The Segway doesn’t need fossil fuels, occupies very little space, is very convenient to use and its parallel wheel configuration makes it compact enough to be maneuvered through most spaces. After the invention of the Segway, two wheel balancing robots has attracted more attention and in recent researches Passenger-carrying capacity has been considered. In this project, by taking into account passenger-carrying capacity and possibility of wheel slippage, an exact... 

With the increasing expansion of modern DC loads and utilizing energy storage systems along with distributed renewable energy resources, grid-following bidirectional voltage-sourced converters (GFBVSCs) with fast dynamic performance are required. Due to the presence of single-phase loads and asymmetrical short circuit faults, unbalanced grid voltage conditions are available in the distribution system. Under unbalanced conditions, an oscillating component with a frequency of twice the grid angular frequency appears on the DC side. Removing double-frequency ripple in the DC link voltage without third harmonic current injection and reactive power injection to the grid based on the grid codes to... 

Low-frequency oscillation damping in power system is main determinants of the stability of the system. According to increasing of wind farms with high penetration levels in the power system, participation and control of wind farms for increase damping inter area oscillations seems important. In this study a damping controller suggested for Doubly Fed Induction Generator (DFIG). Using this controller and only available local signal as input controller and combination of both active and reactive power modulation, can greatly increase damping inter area oscillations and stability of uncertainty and different working points. Using linear analysis system, identified modes oscillating system and... 

This thesis addresses the problem of configuration selection for an urban air mobility EVTOL aircraft utilizing a robust controller approach.First of all, to arrive at a final configuration, different feasible concepts for an urban transportation EVTOL aircraft have been proposed and studied during several brainstorming sessions. As a result, five potentially viable configurations have been selected for further investigation and analysis. These preliminary designs have been nominated utilizing the method of decision matrices and considering the design team and control system designer’s selection criteria. Finally, a tilt-rotor tandem-wing configuration has been selected to go through the...