Sharif Digital Repository

The precise positioning of magnetic catheters is critical for a range of medical procedures, ensuring efficacy while minimizing potential complications. This research delves into the position control of a magnetic catheter influenced by an external permanent magnet. Due to the intricate and complex equations describing the plant's behavior, a neural network approach was deemed suitable for modeling. Using a 5 degree of freedom manipulator carrying an external permanent magnet, data was gathered from real-world positionings, tracking the coordination of the magnetic catheter's end. These data points served to train the neural network, subsequently allowing for an effective simulation of the... 

Nowadays, micro systems are one of the most important scientific and industrial tools and become very important. Most of these systems are working based on deflection of a micro beam. As a result, studing performance of micro beams and controlling them have significant importance for science and engineering.Amoung micro beams cantilever and clamp-clamp beams, which are actuated by electrostatic or piezoelectric actuators, are very applicable. For example, micro cantilevers are used in Atomic Force Microscopy, Microswitches, acceleromiteres, and micro clamp-clamp beams are employed in micro mirrors and Grating Light Valves.In this research, a micro cantilever actuated with a piezoelectric... 

In this study, adaptive control of attitude and position of a rigid body insect-like flapping wing is investigated. For this purpose, a non-linear dynamic and time varying modeling and simulation is carried out initially with six degrees of freedom, and then the accuracy of the simulation is evaluated during different test cases. In order to design the controller, non-linear and time varying dynamic is transformed into non-linear and time-invariant dynamic using theory of averaging. Then, a non-linear controller is designed based on Lyapunov stability theory. Due to the inefficiency of the aforementioned controller under disturbances and unknown uncertainties in the model, an adaptive... 

In this thesis, multi-body modeling of a monocopter air vehicle is developed based on the Newton-Euler approach along with nonlinear simulation in vertical flight phases consist of climb, hover and descent. Aerodynamic and thrust forces and moments are modeled utilizing blade element momentum theory. The sole control surface is modeled like a conventional flap on a wing. Free flight simulation is implemented in MATLAB Simulink environment to appraise the behavior of the monocopter dynamic and to show the efficiency and productivity of the suggested model. Simulation results present harmonic oscillations in Euler angles, linear and angular velocities that are compatible with the physics and... 

Systems that are electrostatically actuated have found a vast role in MEMS application. This technology is used in optical systems, sensors, micro switches, and deformable mirrors. Raising the use of these systems in fields that needs better performance highlighted the need to accurate study of dynamics and control of electrostatic actuated systems in micro scale. This work is dedicated to design of an estimation and control system for a micro-beam that is actuated by electrostatic. After a comprehensive survey on pervious works that are done on dynamic, applications, fabrication and control of these systems dynamic of the system is fully derived. The environmental factors like fringing... 

Humans can take lots of advantages from influencing on small particles. Since manipulation of micro sizes by humans or macro robots, due to their precession and size, is not possible, a new field of study, called Microrobotics, has been introduced. To better understand the working principles in small dimensions, we first need to know the governing physics laws. This step helps us to identify the dominant forces in the small dimensions, which, in turn, leads to better actuation of miniature robots. Because of the size of the miniature robots, one of the best actuation methods is the interaction of the magnetic field on magnetic dipoles. To use the magnetic field as an actuation force, the... 

This project deals with the design, fabrication and control of a tilting-rotor quadrotor. This type of UAV can have high maneuverability in all 6 degrees of freedom (3D attitude and 3D position). The rotor axes can be tilted independently to produce desired force and torque vectors. This capability resolves limitations of the classic quadrotors and provides independent control of orientation and position. To control this UAV, we have proposed a control scheme relating the desired trajectory to the required forces and torques. Then a PID controller for the simultaneous control of position and attitude is designed. This controller is tested in a simulation and the results show that the control... 

A simple control system contains at least an actuator, a controlled link, and a foundation. These structures are not ideally rigid, this flexibility can appear willingly or unwillingly in any parts of the system or the connections between them. As a consequence of this flexibility, the movement of the controlled part will fluctuate unintentionally. In this thesis, a control system with rigid controller and flexible torsional base is investigated and controllers are designed and compared to reduce these unwanted vibrations. Finally, by implementing the controllers on the constructed system, the experimental results are obtained and compared with the analytical results.To fabricate the... 

In this thesis, a fault-tolerant method for controlling the relative position and attitude between two satellites in a leader and follower formation is proposed. The follower satellite is equipped with twelve thrusters which are installed on the satellite in a particular pattern. These thrusters are assumed to be afflicted by faults. The satellites are subject to external disturbances – such as the ellipsoidal gravity of Earth (J2), drag force, solar radiation pressure, and the third body, and a controller is designed to attain the desired formation under these disturbances.For this purpose, six separated neural networks are trained, one for each of the position or attitude channels. Since... 

The focus of this project was on gaining the knowledge of design characteristics and manufacturing of a hydraulic servo valve. Hence, in the first stage, the model of the valve was considered. After investigating the important parameters which influence the performance of the valve, the effect of each parameter on the valve's efficiency was examined. One of the most important characteristics of the valve is the amount of lapping between the spool and sleeve. Numerical analysis was done and all the characteristic curves were elicited. Equations governing the dynamics of the plant including a servo valve, servo actuator and dynamic model of the turbine and waterway were presented. Then the... 

This research aims to identify dynamic behavior, determine stability properties, and choose an appropriate control method for nonlinear time-periodic (NLTP) systems by using the optimal design approach. The primary objective is to address the challenges associated with these systems, particularly in making them smarter and more autonomous, while acquiring the knowledge needed to overcome these challenges. In this respect, multi-body modeling and nonlinear simulation of a mono-wing, as a modern NLTP micro air vehicle, are initially developed. A trade study is performed in free-flight conditions based on sensitivity analysis of parameters such as initial conditions, geometry, and mass...