Sharif Digital Repository

The present research has dealt with the modeling and control of a robotic prosthetic foot for transfemoral amputees. In the beginning of this research, we have modeled the normal gait. In order to accomplish this modeling, we have chosen a 7-body segment skeletal model of the human body and derived the motion equations using Lagrangian equations. Then, we have developed a smooth contact model for the ground. After controlling normal gait, we have attempted to model and control the ankle and knee prosthesis. We assumed a rigid model for the ankle prosthesis and derived its dynamic equations. Then, we developed a robust model reference adaptive impedance control (RMRAIC) scheme based on the... 

Nowadays, nano-positioners play an important role in advanced technologies, such as atomic force microscopy, genetic manipulation, nano-metrology, nano-fabrication, semi-conductors and etc.In this paper, a dynamical model has been derived for a nano-positioner. This nanopositioner was designed and fabricated in Sharif university of technology. In this paper the mentioned mechanism has been considered as a planar mechanism. First, a finite element model has been developed in Comsol multi-physics software. This model was used as the reference model in the next steps. Afterward, a 10 degrees of freedom model was proposed to estimate the Comsol model. The mass, stiffness, as well as damping... 

In this dissertation, a data-driven model predictive control (MPC) algorithm has been developed to control unknown linear time invariant systems. This algorithm only needs past measured input-output data of the system and an upper bound on the order of the system to derive the system output to a desired value. To improve the transient response of the system, we define two filters on the performance and the effort terms of cost function of the optimization problem. Moreover, the Hankel matrices used in the optimization problem are updated online based on a multi-step event-triggered MPC scheme to deal with uncertainties and disturbances. With this method, the computational load of this... 

In the present thesis, first of all we consider a particular class of fractional order plants which have uncertainty in their time constant.In order to make the closed loop system robust against variations of the aforementioned parameter, a robust fractional order controller will be designed and the corresponding tuning rule will be expressed. By using the proposed controller, phase margin of the system will be preserved on a desired value for any value of the uncertain parameter and also gain crossover frequency of the system, in the nominal case, will be adjustable.Also another class of fractional order system will be considered. For these systems, the problem is the same as the former... 

Automatic control of depth of anesthesia is an important problem in biomedical engineering. The main challenging problem in anesthesia automation is inter-patients differences which is referred to as uncertainty and is crucial in robust controller design. One of the most appropriate tools in designing robust controllers is H_∞ concept. Furthermore, H_2 concept is used to reject the measurement noise which is unavoidable in practical cases. In this project we use mixed H_2/H_∞ concept to design robust controller for depth of anesthesia. Multi-model controller is another approach to design robust controller for depth of anesthesia, which reject measurement noise and also cover the... 

In this thesis, the theory of robust control is applied to design a controller for hover flight of a tail-sitter unmanned aerial vehicle with 2 ducted-fan propulsion. The control surface deflection (in propeller slipstream) is considered as the input controller of the system. The aircraft dynamical model is developed based on the assumption of no aerodynamic loads on other parts of uav in low speed flight associated with the hovering condition. The controller is primarily designed using both classical and modern control techniques. Then H ∞ and µ synthesis approaches are applied to design the robust controller. The results obtained from different approaches are compared. It is shown that... 

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... 

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... 

Through the last decades, due to environmental issues and to confine CO2 emission and also dependency to the fossil fuels, renewable energy resources has been developed. It’s been expected up to 2035, the renewable energy resources will be scaled three times and among those resources, the wind energy will stand prominently. Out of this king of renewable resource, the horizontal wind turbine has been subjected in this research. The focus of is to design the controller in third of a 2 MW turbine operation by which stable rotor speed and nominal output power to be attained. Besides, to enhance the accuracy of the wind turbine profiles, the TURBSIM software (At the National Renewable Energy... 

Through the last decades, due to environmental issues and to confine CO2 emission and also dependency to the fossil fuels, renewable energy resources has been developed. It’s been expected up to 2035, the renewable energy resources will be scaled three times and among those resources, the wind energy will stand prominently. Out of this king of renewable resource, the horizontal wind turbine has been subjected in this research.The focus of is to design the controller in third of a 2 MW turbine operation by which stable rotor speed and nominal output power to be attained. Besides, to enhance the accuracy of the windturbine profiles, the TURBSIM software (At the National Renewable Energy... 

The main goal of controlling overhead crane systems is to safely transfer the load to its desired position with maximum speed and accuracy, as well as to minimize or eliminate load oscillations. The overhead crane system is considered as an underactuated mechanical system in which the number of control inputs (actuators) is less than the number of degrees of freedom. In addition, overhead crane systems are generally associated with parametric or unmodeled uncertainties. Also, in these systems, external disturbances such as wind have a destructive effect on the system's performance. In addition, if the overhead crane has the hoisting mechanism and the length of the rope changes as the trolley... 

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 purpose of this thesis is to design and implement a controller for a Ducted-Fan in the landing and take-off phase using a linear quadratic tuning method based on differential game theory. This is a control method with a robust control approach and tries to see all the disturbances and unmodulated dynamics in the form of the second actor and produce a control command according to the worst behavior of the second actor. For this purpose, 6 DOF Ducted-Fan have been modeled. then The proposed controller is designed for a linearized model around the hover point. In the next step, the performance of the proposed controller is compared with the SlidingMode Controller. Also, the parameters of... 

Unmanned Aerial Vehicles (UAVs) have attracted huge attention in recent years due to the technology improvements. Among them, Unmanned Helicopters (UHs) have great importance because of their special abilities. In this research, the problem of design and implementation of an actual flight control system for an unmanned helicopter is investigated. For this purpose, first a multi-level flight simulation environment is developed in Simulink software environment to model the helicopter flight dynamics. The system identification, control system design and implementation are successfully performed in this flight simulator. Next, the actual helicopter flight control system is designed and produced... 

No one bears thinking about undergoing a surgery by an unexpirienced surgeon, the consideration of which implies the prominence of effective surgical trainings. The advent of utilizing haptic interfaces as a novelty in this field has led to a more promising surgery education. These haptic interfaces consist of three communicating parts namely: operator’s hand, haptic robot, and tissue virtual environment. Design and implementation of a proper controller in order to stabilize the haptic interface during surgery simulation, with acceptable transparency, is still novel an otherwise challenging research field. In this thesis we consider an appropriate nonlinear model for both virtual tissue as... 

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... 

High speed and high accuracy are two of the major trends for many systems in the 21st century, such as machine tools and semiconductor equipment. For the purpose of high speed, it is well known that active magnetic bearing (AMB) is an inevitable substitute for conventional bearings. The noncontact nature of AMB brings up many advantages over the conventional bearing, including energy efficiency, low wearing, long life span, and absence of lubrication. Hence, AMBs are especially essential for high-speed rotating devices nowadays.
While the 3-pole AMB has been proposed for many years, it received little attention due to the magnetic coupling between poles that makes the 3-pole AMB system... 

In this thesis, two essential issues are investigated. The first issue is, when a general incommensurate fractional-order controller would be a stabilizing controller for an incommensurate fractional-order system in the standard feedback structure, and how one can possibly construct such closed-loop stabilizing controller. The second issue is to synthesize internal model principle based fractional-order controllers. These controllers consist of two main parts: the internal model corresponding to exogenous signals and an arbitrary fractional order controller. The main objective in the internal model principle based controllers, is to synthesize the second part of the controller such that the... 

The wide-area damping controller (WADC) has been proposed to enhance the damping of inter-area oscillations. The most challenging deficiencies to make this controller practical are the power system operating condition changes and the inherent time delay of remote signals. They can deteriorate the controller performance and the whole system stability if not properly accounted for in the design procedure. This thesis presents an adaptive delay compensator (ADC) on the basis of the latest development in the wide-area measurement system (WAMS) to cater to varying latencies. The proposed compensator can effectively reciprocate the phase deviation resulting from varying delays to improve the... 

Nowadays, autonomous underwater vehicles (AUVs) are implemented to carry out various activities under water. Amongst applications of these vehicles we can mention monitoring of marine creatures, mine installation and neutralization, and many military applications. The objective of this research is designing a control algorithm for underwater vehicles such that an under actuated vehicle can reckon a moving target as a reference and whilst chasing it, vehicle can keep a fixed distance from this target. First the dynamics of underwater vehicles are modeled and in this modeling different effects due to under water motion such as drag force, buoyancy force, and also added mass are included...