Sharif Digital Repository

The primary objective of this dissertation is to obtain a mechanism from the family of 5-dof parallel mechanisms of type 3T2R which gains the advantages of higher kinematic performance, low coupling of motion, and simple kinematics and control commands. Based on this aim, at first a method for structural synthesis of this type of mechanisms is introduced. The method is based on the theory of linear transformation and a geometrical analysis. By using this method, a set of novel 5-dof 3T2R parallel mechanism are introduced for the first time in the literature. In order to compare the designed mechanisms and to identify the promising ones, some important criteria which are a) low coupling... 

Nano/Microelectromechanical systems have generated a great impact on industry and technology. There are many applications for these systems in micropumps, airbag accelerometers and inkjet printer heads. In theses systems mechanical and electrical fields are involved with each other, and complexities due to this involvement has prevented the scientific society from an effective tool for analysis of this systems in computational point of view. So the objective of this project is to use the Extended Kantorovich method to solve the equations of microplate deformation due to electrostatic actuation. This method is based on variational principals and it uses an initial guess function which doesn’t... 

Micro electromechanical systems (MEMS) such as sensors and actuators are gaining more popularity in recent years. These systems have different application in automation, medicine and other industries. Mechanical structures are governed by electrical systems in MEMS devices and this is one of the challenges of MEMS studies. Usually these systems made by one deformable beam or plate over a fixed substrate. Due to applied voltage between substrate and deformable plate or beam, the deformable plate deflects toward the fixed substrate. The voltage at which the system becomes unstableis called pull-in voltage. Pull-in voltage is the most important characteristics of MEMS beyond which pull-in takes... 

Slosh phenomenon is described as the motion of the fluid’s free surface in a tank or partially-filled container. This motion can induce undesired forces that can change the path of a vehicle. In some liquid carrying vehicles these undesired changes is sensed by the driver or control system and can lead to instability. Some examples of this phenomenon are aircrafts, rockets, ships and fuel carrier trucks.
In this project, a coupling between the dynamics of the vehicle and the contained fluid is implemented for in depth understanding of the interactions. This is done by Co-Simulation. With the help of Co-Simulation, corrective control actions can be taken and the design of more powerful... 

Cable-driven parallel robots (CDPRs) form a class of robotic manipulator in which the actuation end-effector is transmitted through cables. Due to the unique characteristics and advantages of cable transmission, CDPRs have become increasingly studied in recent years. In this thesis, the study of Geometric Analysis and Dynamic Trajectory of a 5-DOF Cable-Suspended Spatial Parallel Robot is investigated. Geometric analysis is corresponds to the workspace on which the robot is designed. The design of cable mechanisms allows the robot to be used with appropriate configuration in various fields such as industry, medicine, etc. The study of CDPR design has been limited due to several reasons.... 

As the leading kind of multi-rotors, quadrotors have become one of the most popular Unmanned Areal Vehicles (UAVs). These robots are very agile, but their speed is limited when performing decent maneuvers. In this project, a special quadrotor with dihedral-rotating arms is presented in order to increase the decent velocity of the vehicle. The conceptual and detailed designs of the vehicle are presented first, followed by the construction of the quadrotor. The fabricated quadrotor measures 25 cm in size, has a weight of about 1 kg, and can support up to 70 degrees of dihedral angle. Afterwards, the dynamic equations of the dihedral quadrotor are driven and simulated. The effects of dihedral...