Sharif Digital Repository

Phenomena such as collective movements of birds and fish, collective and harmonious activities of ants, termites, bacteria, etc. have inspired engineers to create and develop the idea of swarm robotics. Robotic groups can be used for applications such as searching the environment, patrolling, cooperation in moving heavy objects and so on. One of the issues considered regarding swarm robotics is the formation of geometric shape by the multi robots system. Two main methods are employed for solving the problem of shape formation: the leader-follower method, and the artificial potential functions method.This thesis presents some control algorithms for shape formation in multi-robot systems on... 

The accuracy, speed, and ability to do work in hazardous environments has led to the development of robots in everyday life. Accordingly, research on quadruped robots for use in military environments is expanding. Designing control algorithms for walking and stepping on quadruped robots is one of the most important parts of the design of these robots, which creates complex movements despite the lack of sophisticated equipment in the robots. One of the robot gaiting control methods is dynamic based method that is based on the robot’s dynamics and resistant to perturbations. Trajectory based method is another robot gaiting control method that is inspired from CPG algorithm and has learning... 

Once the satellite is in space, it is very important to make sure that it is in its correct and prescribe orbit, along with the appropriate attitude, at any given point of time. Orbit determination and finding the exact position and velocity of a satellite is one of the most important factors in space missions. The purpose of this work is improvement in orbit determination of LEO satellites. In order to achieve this goal, combination of SGP4 and HPOP algorithms with Kalman filter is used. The HPOP algorithm uses from integration of equations of motion for finding the position and velocity of a satellite. So this algorithm is very accurate for the short time propagation, but since it is... 

Nowadays, there are various applications for swarm robots in different fields such as agriculture, healthcare, and entertainment. Among these, the field of agriculture is of greater importance due to the increasing population and the growing need for food resources. To address this need, industrialization of agriculture and the use of swarm robots have been proposed as a solution in most developed countries. Despite extensive research in this area, there are still challenges in implementing swarm robots. In many of the mentioned applications, determining the position and orientation of the robots relative to each other at long distances and accurately perceiving their surroundings are vital... 

This paper presents a robust adaptive backstepping control design for TREX-600 helicopter with flapping dynamics and dynamic uncertainties in the presence of Dryden wind gust. A nonlinear dynamic model is used to design the controller to let the helicopter track pre-defined time-varying waypoints and heading angles. In order to use the recursive design, the helicopter’s dynamic model is divided into three subsystems, such as altitude subsystem, yaw subsystem and horizontal subsystem. Adaptive backstepping method combines backstepping control and adaptation laws to deal with parameters uncertainties are designed for each sybsytem considering the coupling effects. The global asymptotic... 

Algorithms for online identification of parameters of a satellite’s moment of inertia tensor based on two methods (recursive least squares and Kalman Filter) is presented and compared with each other. It is assumed that the satellite actuators are three orthogonal reaction wheels. The only available sensor is a 3-axis rate gyro, which measures the angular velocity of satellite in body coordinate system. For validation of algorithms on earth, a similar identifier was designed for a satellite simulator. Due to difference in Dynamics of satellite and satellite simulator, capability of identifying center of gravity was added to algorithms. In order to account for friction in air bearing of... 

Nowadays precise nano positioning plays an important role in micro systems. Precise positioning at nano scale plays a basic role in nano science such as micro -robotics, solid state physics and photonics. Manipulating matter in a molecular scale creates a dramatic change and restruturing in macro scale engineering. During this research a novel TEM micro actuator is designed and fabricated based on calibration criteria. This structure was fabricated with SOI wafer (silicon on insulator) in micro scale level for the first time in Iran. This compliant consists of 12 TEM actuators end in 3DOF (In-plane) motion. The new micro actuator operates based on the thermal expansion due to voltage. Each... 

A swarm robotic is made up of a number of similar robots (identical) that these robots alone do not have any potential, but they can with each other have considerable potential. In recent years, engineers have become more interested in swarm robotic. Swarm robotic allows the use of several colleague robots instead of an advanced robot that eliminates excessive complexity and expensive equipment. The purpose of this study is to provide a method for solving the crossing problem and interfering between robot swarms. In previous studies conducted at the Sharif University of Technology, the main goal was to design algorithms for the swarm behavior of a swarm robotic. In this research, the aim is... 

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... 

Nowadays, Specific applications of micro-mirrors in MEMS industry as actuartors have been found. In optical networks, these instruments are used to transfer data between optical fibers as an optical switch. According to the high desired precision for the relevant applications, many different aspects should be considered in controlling of these systems. Some of these criteria include: high speed response, overshoot elimination, minimal energy consumption by regulating the system inputs, minimal vibration, consideration of system uncertainities and some unmeasurable state variable, and system rubostness against environmental disturbances. In this research by addressing all of these... 

Coaxial helicopters are one of the kinds of helicopters that have two main rotors spinning opposite to each other. These helicopters have no tail rotor and their size varies from very small (about 100 grams) to large (manned). The widespread use of helicopters justifies controller design for them.
In this research, at first step coaxial helicopter is controlled with two linear control methods. In many control problems linear control responds to the diverse needs. In addition it has good robustness in situations like uncertainties, disturbances, noise etc. For this purpose, nonlinear dynamic model of helicopter is used in the beginning. This model is linearized around hover condition to... 

Over the past years, several approaches have been used for navigation. Along with the advancement of technology, complicated navigation systems such as inertial navigation system and global positioning system have been employed. These navigation systems have their own strengths and weaknesses. To improve overall system performance they are integrated together as one system.
Presented research aims at developing the integrated navigation system through particle filters. In this study, after a brief overview of the data integration techniques, several techniques which are more common and have better performance than others are examined. This contribution concentrates on filtering methods... 

Air-handling unit (AHU) is one of the installations that is responsible to control the temperature and humidity inside a space using the heating, cooling, humidifier and drying air. At present, energy efficiency in building is an important issue to maintain the comfort conditions. One of the most common ways to optimize the performance of industrial installations is the use of control systems, which leads to the reduction in both of the costs and energy consumption. In this research, a multivariable nonlinear dynamic model of the AHU with one zone in the VAV (variable air volume) system for working in summer is considered. At first, introduction, limitations and driving the equations for the... 

Due to various applications of human motion capture techniques, developing low-cost methods that would be applicable in non-laboratory environments is under consideration. MEMS inertial sensors and Kinect are two low-cost devices that can be utilized in home-based motion capture systems, e.g. home-based rehabilitation. In this work, an unscented Kalman filter approach was developed based on the complementary properties of Kinect and the inertial sensors to fuse the orientation data of these two devices for human arm motion tracking during both stationary shoulder joint position and human body movement. A new measurement model of the fusion algorithm was obtained that can compensate for the...