Sharif Digital Repository

Low Back Pain (LBP) is one of the most common diseases in the world that according to the statistics 80% of people experience it at least once in their lifetime and a lot of money is spent for its therapy. Finding some methods for prediction and diagnosis of people with LBP from people without LBP helps to reduce these expenses. One of the most effective methods for diagnosing this problem, is the modeling and simulation of its skelomuscular system. However, because of the complications in modeling, simulation and neural control of human spine, it’s not been studied comprehensively. On the other hand, most of the numerical methods are based on optimization and approximation of muscle... 

The goal of this thesis is modeling and simulation of aircraft landing motion in order to evaluate the performance of an optimal anti-skid brake system (ABS) for the main landing gears with friction effects. In this process, the aircraft 6DOF perturbed equations of motion augmented with pertinent friction and brake forces and moments have been utilized. Subsequently, the problem is formulated within the framework of an optimal LQR that has allowed for generation of control brake commands as well as aircraft landing performance at different landing conditions with and without the proposed ABS. The results demonstrate the proposed ABS has been effective in providing admissible landing... 

New electric Unmanned Aerial Vehicles (UAV) has unconventional methods for design and performance analyzing. Using the electric power sources and reduce power with time, cause to confusion about operating this type of planes, so new optimization methods are generated. This methods, can used for some part of flight and special problems and involve some assumptions. One of these new methods is using Singular Perturbation theory for prediction optimal path trajectory of Aerial Vehicles. In this research, we solve the optimal climb trajectory for an electric UAV in rested (no wind) atmosphere. Solution of this problem, involve some parameters such as velocity, altitude and flight path angle with... 

In this project, modeling and control of grasping phase of flight is investigated inspired by birds’ aerial hunting. For this purpose, grasping mechanism and its challenges in flight is studied. In the following, an explanation about gripper, its design and its performance in flight is given. Both 1-DOF and 2-DOF gripper is modeled. Then, the simulation is evaluated during different test cases. After modeling, optimum trajectory for an air-vehicle in grasping phase is studied and analyzed. When using a 2-DOF gripper instead of a 1-DOF gripper, the vehicle is capable of grasping in different positions and attitudes. Therefore, the results of trajectory generation show more chances of grasping... 

The purpose of this thesis is to obtain a logical decision making for the landing of multiple electric vertical takeoff and landing (eVTOL) aircraft that are simultaneously approaching a skyport. This research was conducted in response to the expansion of cities and the increased demand for transportation. In fact, the increase in population in cities makes the existence of a new mode of air transportation unavoidable, and in this regard the landing and take-off of such aircraft is very important because using a control tower for managing the take-off and landings of these aircraft doesn’t seem possible. To do this, the problem of simultaneous landing of multiple eVTOL aircraft was divided... 

Marine transportation is an essential aspect of global trade, as it is responsible for transporting large quantities of goods and commodities between different countries and continents. The efficient optimization of shipping routes can greatly reduce operational costs, save time, and increase the overall competitiveness of the maritime industry. One of the most critical aspects of route optimization is the selection of the most efficient path, taking into account various constraints such as fuel consumption, voyage duration, vessel speed, and port constraints. The PSO algorithm has been successfully applied to a variety of optimization problems, including the optimization of marine routes.... 

The problem of launching a satellite to low earth orbit has been considered. Preliminary concepts such as satellite orbits, launcher missiles and their equations of motion, and traditional methods for guidance of launchers are reviewed first. Then a new method for optimizing the launch trajectory under non-ideal conditions is introduced in which the solution of a known ideal trajectory optimization problem is used as an initial guess for the actual optimization problem. Several methods for guiding a launcher to place a satellite in Earth orbit are presented next; they have been titled as (1) launch path re-computation outside the atmosphere, (2) prediction error minimization, and (3) output... 

Nowadays, robots are become more common in many important applications, such as academic and industrial issues. One of the most important robots are Multi-Arm manipulators which are used in many application such as moving objects, coloring, automatic welding and etc. Working with this kind of robots needs some vital attentions like planning their moving path. It is Because of the large number of obstacles that they face with in the path. Therefore, not only robots are not allowed to collision with themselves, but also they must not touch the obstacles. In the other words, they need Path planning. Generally, the equations of these robots are nonlinear. Therefore, computers and numerical... 

In this thesis, satellite aided capture of spacecraft around Jupiter is optimized with the final goal of capture into a circular orbit around Europa. The cost functions of the multi-objective optimization process that should be minimized are: 1) summation of the propulsive ΔVs, 2) the total duration of the capture scenario, and 3) the integral flux of the energetic electrons and protons during the maneuvers. In this study, the spacecraft trajectory is modeled by patched conics method and is optimized by metaheuristic methods of genetic algorithm and simulated annealing. In some cases, interior point method is used for improving the final converged solution. Due to the limitations of... 

The formation flight of satellites corresponds to a group of small satellites, performing the mission of a presumed larger and more expensive satellite. Usually mission designers tend to put these satellites in such orbital configurations that their trajectories do not intersect. Although a stable configuration in a certain collision-free orbit is desirable for long term purposes, most of the missions including maneuvers like forming or changing a configuration and inserting new satellites need to be planned using a proper path planning algorithm. In this thesis, a path planning algorithm is suggested that acquires the optimal and impact-free trajectories for a group of satellites for... 

In this work the problem of optimal spacecrafts reconfiguration and formation keeping is investigated for Asteroid attraction. Due to potential impact probability of the Apophis asteroid with Earth in 2036, the study is focused on optimal intercept avoidance via gravity attraction of multiple spacecrafts suitably arranged on halo orbits of Apophis. In this regard, a space mission is defined in which initially several spacecrafts are optimally reconfigured onspecial Halo orbits of the asteroid via several techniques that include pseudospectral, linear quadratic regulator as well as the integral sliding mode control. The utility of three methods is for verification purposes as well as... 

In this Thesis, the necessary steps to implement near-optimal atmospheric flights in order to create micro and partial gravity condition has specified. This documentary has been prepared in a comprehensive way. The goal of this project is to reach the optimal throttle and elevator inputs and consequently optimal paths to perform the maneuver with maximum time. The basis of my work is to integrate two methods of tabu search and continuous ant colony system in order to find the best match for inputs. As a result, the aircraft’s proper inputs as a function of time can be accommodated. The constraints here refers to the safety of the flight, which are maximum operating speed, stall angle of... 

Outer space mission design utilizing restricted four-body model for spacecrafts equipped with impulsive engines is investigated. Applied researches in the field of space mission design are typically based on two-body models and in some more advanced cases involve application of the restricted three-body models. As the general solution of the two-body problem is known (conic sections), the transfer trajectories are generally designed using simple Hohmann transfers. But, when considering three-body problem, there is no closed-form solution and low-energy transfer trajectories are designed through the use of stable/unstable manifolds of the corresponding halo orbits. In this way, some... 

The employment of strategies with low operational and capital investment to reduce ship's voyage costs is gaining considerable attention. With rising fuel prices, shipping companies are concerned with the increase of fuel costs of the ships. In this research, the smart steaming strategy, including the simultaneous optimization of ship's sailing route and speed, is proposed as an efficient alternative for the slow steaming to minimize ships' fuel consumption and voyage costs. By implementing the smart steaming strategy, ships owners can ensure that the ship sails at the optimal and safe sailing route and reaches the destination port on time. In addition, the proposed shipping strategy can... 

In this work, A new hybrid approach is presented to optimize a trajectory of Micromechanical Flying Insect in an obstacle reach environment. Here, a singleobjective Evolutionary Algorithm is utilize for finding solutions corresponding to multiple conflicting goals, which include minimizing the length of the path while maximizing safety margin by avoiding hard and non-moving obstacles. On the other hand, dynamic constraints of Micromechanical Insect such as maximum and minimum attitude angles and speed should be taken into account. In order to reduce the computational cost, a novel hybrid two-layer procedure is suggested for trajectory optimization. In the first layer, the algorithm generates... 

In the present work, trajectory optimization of the Dual-Arm Cam-Lock robot considering kinematic and dynamic redundancy is performed. First, the optimal control problem is solved only considering kinematic redundancy and then is solved considering dynamic redundancy. General form of the dynamic model for the system is developed using Lagrangian relations. Global optimization method is used for redundancy resolution problem. A performance index is defined based on the consumed kinetic energy and is minimized through a desired trajectory using the global optimization method. Formulations of optimal control problem are derived and initial boundary problem is changed to two point boundary value... 

Optimum highway alignment problem is among the most substantial but large and complicated topics in transportation area. Infinite number of feasible solutions, numerous local optima and the constrained feature of the problem, associated with complex and mainly non-linear constrains, has put an extra effort into the problem-solving process. Moreover, the problem has a sensitive objective function to input variables. Due to the nature of the problem, conventional methods fail to find any exact solution, and so, using heuristic methods during the solving procedure is inevitable. Large-scale, complexity and sensitivity of the problem leads to a solution which is time-consuming and... 

One of the most interesting and at the same time the newest methods to launch a satellite into space is Air Launch or Launch throw the mother aircraft. The placement of the satellite into space by a rocket in specific altitude and speed is separated from the mother aircraft, takes place. The most problems in multi stage rocket launching is trajectory optimization to reaching the maximum height. The survey was conducted using classical optimization methods, which is derived the equations for the gradient based on the calculus of variations. that can be used or modified for emissions control wings and changing the direction of thrust exhaust. It should be noted that in the model of rigid body... 

In this thesis, the optimal trajectories of a spacecraft in the binary asteroids system is studied. The objective functions of optimal trajectories in these system are the maximum coverage of the asteroids surface and minimum time and fuel consumption. For this purpose, the dynamic of binary system is modeled. The binary system of 1999 KW4 is selected as a case study. The ellipsoid-sphere model is a good approximation for the case of this study. In this model, the asteroids orbit in a circular orbit around each other in a spin-spin-orbit resonance configuration, in which the asteroids’ rotational velocity is equal to orbital mean motion. Then, the equations of motion of the spacecraft as the... 

In this thesis, the problem of offline trajectory optimization of a flying vehicle has been solved. Terrain following/ terrain avoidance has been considered as a guiadanec strategy of vehicle. The point-mass model in three dimensional space for flight simulation and the transfer functions for modeling of vehicle dynamics has been used. One of the constraints of this problem is related to engine’s dynamic behavior, which is not considered in the privious works. So in this thesis at first, a turbofan engine has been modeled and it’s static and dynamic model has been obtained. Then, the effect of engine’s dynamic model in the trajectory optimization has been investigated. The results show that...