Sharif Digital Repository

Today, a lot of efforts have been done in order to commercialize space travels. Spacecrafts have a lot of components and producing each of them spends high costs. Components such as propellant tanks and boosters are multi segment and are released simultaneously and therefore it is economically feasible to recover them. Due to Parafoil ability in low-cost, soft (no damage to the cargo) and accurate landing, it is gradually replacing parachute. Parafoil can fly long distances after being released, so its landing point could be determined. The aim of the study is to evaluate this scenario in which some segments of launch vehicle (e.g. booster) that are equipped with Parafoil expand their... 

In this research, a Reusable Flexible Launch Vehicle (RFLV) design problem is presented by Multi-Disciplinary Design Optimization (MDO) approach in primary design phase. Trajectory, structure, aerodynamic, aeroelasticity and thermal protection system are considered as involved disciplines in design problem. The study purpose will be to obtain an optimal trajectory which meets all the control and structure limitation while the estimating body skin and thermal protection thicknesses base on structural evaluating in re-entry trajectory is in process. The flexible launch vehicle body is considered as a free-free Bernoulli-Euler beam and D’alembert’s principle addresses inertia force in static... 

With the development of fractional order calculus and more accurately modeling of physical phenomena, the problem of controlling these systems, by considering the uncertainties in the system, will become necessary and inevitable. In this thesis, the fractional order transfer function model of a satellite with Coupled rigid-flexible structures is used as the reference work of the research. To control this dynamical system, sliding mode control method, which is one of the robust control methods, has been used. It is clear that it is not possible to directly design a sliding mode controller for a transfer function. For this reason, a fractional order pseudo-state space model is first obtained... 

The goal of this thesis is to devise a guidance law that has the required ability and flexibility to construct a variety of return trajectories for a reentry capsule to the atmosphere. One of the commonly used methods for guiding flying vehicles with a fixed initial position and a fixed target is to load the trajectory data into the vehicle's computer memory. But the devised guidance law in this thesis does not require the trajectory data. Based on the relations governing the Bezier curve, it constructs the desired trajectory online. It also has the ability to provide the desired angle of landing and the desired magnitude of final speed. Further studies indicate that this ability is also... 

To make it easier to transition and increase the number of missiles on the launcher, many missiles consider the fins are designed to be foldable. Also, these types of fins can be opened during the flight and therefore reduce the drag force in the initial phase of the flight. One of the disadvantages of this type of design is that the fins may not open during the flight. Moreover, locking the actuator, breaking or destroying some part or all of the control surface of supersonic aircraft due to high speed and temperature and loss of thermal insulation is very probable. This thesis considers the locking, not opening, or even breaking the control surfaces, as well as the destruction of some part... 

Because of advancing fractional calculus and modeling physical phenomena by using fractional calculus more accurately than that by using integer calculus, and also existing uncertainties in models of real world systems, robust stability and performance analysis of fractional order systems are necessary. This thesis deals with the robust -stability analysis of LTI fractional order systems from kind of uncertain typical fractional order systems (UTFOS) and the robust stability analysis of LTI fractional order systems with delays from kind of uncertain retarded type systems (URTS) and uncertain neutral type systems (UNTS) with interval uncertainties. The coefficients of the numerator and the... 

In this research the attitude control of a flexible launch vehicle using fractional order proportional-integral-derivative controller in the presence of actuators failures is described. Other work done in this study is the investigation of on-line fault detection and diagnosis effects in the attitude control of flexible launch vehicle in the presence of actuator failures. Rigid-elastic equations of motion and assumed modes have been used to simulate dynamics of launch vehicle in the Simulink environment of MATLAB software using two elastic bending modes. The performance of fractional order controller has been compared with conventional proportional-integral-derivative and adaptive augmented... 

In this article, guidance and control of reusable launch vehicle at terminal phase has been studied. The goal of this article is increasing the accuracy and safety of the guidance and control system of the launch vehicle in order to successfully land on ground surface. Integrated guidance and control, being a novel method in guidance and control, is used to guide the launch vehicle in the re-entry phase and landing phase on ground surface. The returning object studied is a Falcon 9 rocket for which we find the 6 DOF model. The landing method of this vehicle is vertical. Implementing an integrated guidance and control system is a novel approach in this area. The controller used in this...