Sharif Digital Repository

The Delta parallel robot is used extensively in many industries, including packaging, because of its superior speed and precision. In this project a Delta robot was designed and then controlled specifically for use in the production line of a plastic container factory. In order to optimally design the robot, a number of desirable fitness functions were defined thus: minimizing the dimensions of the robot for a specific desired workspace, minimzing the effect of the robot’s weight on its actuators and satisfying the demands of the “Design for Control” approach. Design for control means considering the complexity of controlling a system while designinig it. Therefore the remaining fitness... 

The thrust vector control problem is studied for a Satellite with fuel slosh dynamics. The sloshing propellant is modeled as a 3D pendulum. The coupled equations of motion of the satellite and the fuel are expressed in terms of the three dimensional satellite translational velocity vector, the attitude, the angular velocity, and the internal coordinates representing the slosh modes. A nonlinear feedback control law with the idea of backstepping integrator is proposed to control the translational velocity vector and the attitude of the satellite, while attenuating the sloshing modes. A simulation example is included to illustrate the effectiveness of the control law  

In the class of unmanned air vehicles (UAV), there is a class entitled as Quad-rotor that engineers pay much attention due to specific features to them. Main applications of this class are because of vertical take-off and landing capability and high controllability. This class has high controllability in environments with high barriers because of the inherent imbalance. All of the Quad-rotors have already studied, had a fixed structure. So the designer's main focus was on improving the guidance and control systems and almost all forms of linear and nonlinear control methods and fuzzy, adaptive and robust control have been investigated. In this study variable structure is examined instead... 

The main objective of this study is evaluation of several nonlinear observers and comparing their performances.First, the literature review is presented; and then the process model is described. Second, observability and the observer design is disscused. Performances of Lunberger, sliding, and high gain nonlinear observers have been compared. Finally, the performance of a high gain observer in a closed-loop system including the back stepping controller has been evaluated.
 

According to the importance of obstacle and collision avoidance for multiple Autonomous underwater vehicle (AUV) that are synchronized for starting the path following, in this study the coordination path following controller for a group of underactuated underwater vehicle with considering of obstacle and collision avoidance presented. The proposed control method is based on graph theory and back stepping with modeling of obstacle using limit cycle. At first, for controller design the back stepping method for path following of one AUV is used. Then the designed controller using of principles of graph theory, has been extended for multiple AUV and as the result multiple AUV is synchronized and... 

In this study design of controller for a nonlinear system in the presence of state observer was investigated. First, nonlinear observers including non-adaptive and adaptive versions and their design procedures were studied. Then nonlinear adaptive controllers, based on sliding mode, feedback linearization and back-stepping techniques were implemented in the presence of observer dynamics. Two versions of adaptive law were proposed for unknown parameters identification in feedback linearization and sliding mode techniques. A new adaptive law was proposed to relax the restrictive condition that is used in adaptive observer design. The closed loop stability of back stepping technique was studied... 

Integrated guidance and control (IGC) as a new approach to guidance and control methods has been studied in this thesis. A new approach to nonlinear aerodynamic formulation with backstepping controller has been proposed in order to improve interception. Various curve fitting techniques like Gram-schmidt method has been tested. But finally a planar aerodynamic formulation was used which only varies with angle of attack. Results showed that the proposed method requests smaller control input than the linear IGC formulation and conventional G&C methods, because of more precise knowledge of normal force coefficient. Thus the vehicle experiences smaller angle of attack and normal acceleration.... 

Design and development of Unmanned Aerial Vehicles (UAVs) has been a hot topic in the past decades. In particular, Vertical Take Off & Landing Vehicles (VTOLs) have been extensively studied and are under constant development. Quad rotors are one of the major subcategories of VTOLs and a lot of effort have been devoted to their control optimization. In the present study, we have utilized a novel transformer quad rotor structure that can change the angle between its arms. This structural change is a type of design feature modification that can effect the moments of inertia by changing the flight dynamics of quad rotor. Modification of height difference between adjacent rotors, while avoiding... 

In this Thesis, an unmanned multicopter with a new structure is modeled and a nonlinear controller is designed for it to track the trajectories precisely. The multicopter in this thesis, has six propellers with a hybrid propulsion system (a combination of fuel and electric propulsion system) that has the ability to carry more payload and maintain more flight duration compared to electric multicopters. In the beginning, the performance characteristics and technical specifications of the hexacopter are presented. For modeling, first the equations of six degrees of freedom movement of the hexacopter are derived by the Newton-Euler method. In the next step, the forces and torques applied to the... 

Modeling and Controlling of a satellites fuel slosh is considered a vital problem in the field of satellite attitude control. In this paper modeling and control of the attitude of a satellite carrying a partially filled spherical fuel tank, which uses the diaphragm as a propellant management device (PMD), has been studied. The fuel slosh dynamics is modeled using a spherical pendulum with two degrees of freedom and a rigid arm, which represents the first mode of sloshing. The effects of the diaphragm that surround the fuel surface, are considered as torsional springs and dampers attached to the satellite body. The combined dynamics equations of the satellite rigid motion and the fuel slosh...