Controller Design in the Presence of Actuator Failure

, M.Sc. Thesis Sharif University of Technology Morodvandi, Ali (Author) ; Shahrokhi, Mohammad (Supervisor)

Abstract

In control systems, actuators are subjected to faults during operation. In the present work, a controller for nonlinear systems under several restrictions and in the presence of actuator failure has been proposed. The controller is designed for large-scale multi-input multi-output (MIMO) uncertain nonlinear systems subject to unmodeled dynamics, unknown state dependent control gain functions, unknown state time varying delay, unknown subsystems interactions, unknown external disturbances and input nonlinearity. The backlash has been assumed for input nonlinearity. No restriction has been considered regarding the number of actuator failure. The backstepping technique has been applied for...

Behavior of a Four Degree of Freedom Jeffcott Rotor with Clearance and Rubbing in Supports

, M.Sc. Thesis Sharif University of Technology Rayyani, Mohammad Hossein (Author) ; Dehghani Firouzabadi, Roholla (Supervisor)

Abstract

different phenomena occur between rotor and support rub impact causing system parts failure. Still Increasing the accuracy of manufacturing and decreasing the clearance of supports but the probability of rub impact between the rotor and support grows and this phenomenon is going to be more critical. This research would rub impact at two ends of four degrees of freedom Jeffcott rotor considering supports directional degree of freedom. Because the contact points are at two ends of the rotor, the rotational degree of freedom of the rotor is also considered. The system is modeled with 8-DOF and after numerical solving and comparison, the results with other papers, the system's behavior including...

The Effect of the Clearance of the Rolling Bearing Supports on the Stability of the Rotor Using Nonlinear Finite Element Method

, Ph.D. Dissertation Sharif University of Technology Sajjadpour, Mehdi (Author) ; Hosseini Kordkhili, Ali (Supervisor)

Abstract

Rotating shafts are widely used in various industries, especially aerospace industries such as engines, compressors and turbines. Due to the sensitivity of these shafts, considerable efforts have been made by researchers to investigate their dynamic behavior. In this thesis, the finite element numerical method has been used to analyze and investigate rotating shafts using a pipe elbow element. This element has four nodes and six degrees of freedom in each node, that is, three degrees for translation and three degrees for rotation relative to the general coordinate system and has a circular cross section. In the linear part of the dynamic formulation of the finite element for rotating axes...