Sharif Digital Repository

Path planning is essential for unmanned aerial vehicles (UAVs) to navigate complex and hazardous environments. Many algorithms have been proposed to solve this problem, but heuristic, meta-heuristic, and hybrid algorithms have recently gained attention due to their ability to find approximate solutions quickly. In this thesis, we propose using the Late Acceptance Hill Climbing (LAHC) algorithm for UAV path planning. We compare LAHC's performance to classical and state-of-the-art optimization algorithms, including simulated annealing (SA), grey wolf optimization (GWO), symbiotic organisms search (SOS), and simplified grey wolf optimizer-modified symbiotic organisms search (SGWO-MSOS).... 

Quadcopters are a bunch of vertical takeoff and landing UAVs and generally consist of four symmetric arms, each possessing a rotor-blade at the end. Quadcopters are able to retain their state and position by performing static maneuverability. Conventional quadcopters have less actuators (four engines) than their DOF (six degrees of freedom in the space). Thus, it is impossible to control all DOF of the system independently. Nevertheless, one can make a solution to this problem by increasing the number of actuators, so that each rotor-blade can also rotate about the corresponding arm. Such a quadcopter is so called a “tilt-rotor quadcopter”. The aim of this work is to model a tilt-rotor... 

Topic that is investigated in this article include identify and localization a number of aerial target penetrating into a protected by area by a swarm of UAVs is fixed wing. UAVs do not have any prior notice of positioning targets. In addition, it is assumed that lacks any radiation exploitable targets and thus use UAVs for Targets Detection from an active radar system. Obviously this article focus on developing a guidance algorithm UAVs to this particular issue and also as the targets participatory is localization algorithm. In addition, extraction type and performance characteristics radar system required and also performance characteristics of the class of UAVs, which is suitable to... 

In this thesis, a method is presented for improving the observability of the heading angle in a UAV when using the Visual-Inertial navigation algorithm MSCKF by adding a magnetometer sensor. The proposed algorithm serves as a complementary extension to the primary algorithm, and efforts have been made to seamlessly integrate the magnetometer sensor into the primary algorithm to allow for easy modifications to the sensor's characteristics and to observe the resulting output in system simulations. Improving the observability of the heading angle will lead to an enhancement in the overall system state estimation. To achieve this, a new update stage is added to the existing algorithm.... 

In this thesis, an identified dynamic model of a fixed wing UAV, known as WAYO, is presented. To do so, frequency domain system identification technique is utilized. Due to physical and environmental constraints, it was impossible to carry out precise flight tests of the aircraft in all flight phases. Instead, a small-sized UAV, called Twin Star-BL was selected to carry out the tests and to validate the simulation model. In both cases (WAYO and Twin Star-BL) transfer functions were obtained using frequency responses and employing extensive identification process. Identified models were then assessed using time domain data for different test records. Finally, handling qualities of both aerial... 

Human blood is a valuable and scarce product which is only produced by human body. There is no replaceable material for our blood and there has always been a constant need to donors and blood products in societies. Like every other product, blood has to be transfused to patients after it is donated and this process requires a complete and effective blood supply chain. Considering all properties, complexities and uncertainties of a blood supply chain, we need to develop stable methodologies in order to simplify decision making in blood supply chain. In this research, we develop a novel blood distribution system from a regional blood center (RBC) to its nearby hospitals. It helps RBCs plan the... 

The purpose of this thesis is to control the attitude of a tail-sitter UAV in transition phase (from hover to cruise and vice versa). This UAV has a pusher shrouded fan propulsive. Due to the fact that in transition phase the dynamic model of the UAV is associated with a significant uncertainties and the stability is more important than the performance, robust controller has been used. The propulsion part of the tail-sitter UAV can be assumed as a separate ducted fan UAV. In the first step both UAVs have been designed. then, in order to have an accurate model of UAV, the dynamics of actuators, including the engine and servo motor, has been identified. Then, modeling and verification for both... 

This thesis focuses on the development of a flight formation control algorithm and obstacle avoidance of a UAV team using fuzzy predictive artificial potential field (FPAPF) method. One of the common methods for path generation and obstacle avoidance is the artificial potential field (APF) method. The basis of the APF method is that the UAV is attracted to the target point and repelled from the obstacles by using the potential fields of attraction and repulsion. The popularity of this method is due to its computational simplicity and efficiency. The APF method has limitations due to constant attraction and repulsion coefficients. The proposed real-time FPAPF method uses fuzzy logic to... 

The aim of this study is to develop a new algorithm to perform high performance and precise maneuvers for variety of fixed-wing UAVs. Iterative learning in conjunction with an adaptive control technique is developed here for this purpose. In this research, the guidance and control laws are initially developed by classic algorithms that exist in most of commercial autopilot systems. Then, the learning algorithm is combined with the classic autopilot system to improve trajectory tracking performance. The algorithms have been tested by simulation in the loop technique, utilizing Simulink and X-Plane software. So, the navigation data was provided by the X-Plane, solving dynamic equations, and... 

The purpose of this thesis is to design and implement a controller for a Ducted-Fan in the landing and take-off phase using a linear quadratic tuning method based on differential game theory. This is a control method with a robust control approach and tries to see all the disturbances and unmodulated dynamics in the form of the second actor and produce a control command according to the worst behavior of the second actor. For this purpose, 6 DOF Ducted-Fan have been modeled. then The proposed controller is designed for a linearized model around the hover point. In the next step, the performance of the proposed controller is compared with the SlidingMode Controller. Also, the parameters of... 

In recent years, autonomous unmanned aerial vehicles (UAVs) have attracted considerable amount of interest because of a wide area of applications and a lot of advantages. UAVs have been extensively used for military operations that include tracking, surveillance, active engagement with weapons and airborne data acquisition. UAVs are also in demand commercially due to their advantages in comparison to manned vehicles. These advantages include lower manufacturing and operating costs, flexibility in configuration depending on customer request and not risking the pilot on demanding missions. Quadrotor, which is a kind of rotary wing UAVs, has many advantages such as the vertical take-off and... 

The rapid growth of e-commerce and home delivery has increased the number of vehicles on the streets. As a result of that, traffic congestion and, in return, air pollution have got worse. To prevent this trend, using electric vehicles is highly suggested, and in recent years, some companies have started using autonomous delivery robots. Since these robots can travel for a limited time, it is better to use them in conjunction with other vehicles, like vans. In this research, we propose a mixed-integer programming model to formulate a two-echelon time-dependent vehicle routing problem with simultaneous pick-up and delivery. In the first echelon, vans travel from a central depot to parking and... 

In this study, an effective collective control strategy is presented for the decentralized behavior control of a heterogeneous multi–cluster swarm robotic system composed of a group of quadrotors as aerial agents, and a group of two–wheeled mobile robots as ground agents. In this regard, first of all, a new element for swarm robotic systems is introduced. This element, which is made up of a portion of swarm members and encircles the whole swarm, is called the shell element. An algorithm for developing the shell element in swarm robotic systems composed of agents moving in the two–dimensional space is established. Subsequently, inspired by the thermodynamic science and based on the introduced... 

In this project, the final goal is to create a team consisting of a UGV and a quadrotor capable of relative tracking and coordinated landing, with focus on quadrotor control. What we mean by cooperative control in this project is control of quadrotor for the purpose of cooperation with a UGV; This should not be mistaken with another sense of cooperative control in which the control algorithms are developed for both of the robots or are based on the interactive dynamics of the robots.In order to accomplish this goal, an experimental testbed consisting of a quadrotor and a UGV capable of communication and data exchange was developed as a first step. The quadrotor was constructed using... 

A cooperative aerial system to defense a Ground Station (GS), against an Incoming aerial Targets (IT) is presented. GS is surrounded by given terrains and a group of homogenous Unmanned Aerial Vehicles (UAVs) are employed using a novel online guidance algorithm in a decentralized manner. The proposed algorithm includes loiter, midcourse and terminal phases. During loiter; UAVs follow an optimal circular path. IT is supposed to approach GS along an optimal low altitude trajectory with respect to the terrains. UAVs are informed the initial position and velocity of IT and they are unaware of IT trajectory. Each UAV decides on whether to engage with IT or not, and shares its decision with other... 

In this study, integrated navigation systems that utilize velocity-matching algorithm and are used in automatic landing of Unmanned Aerial Vehicles (UAV) are investigated. At first, the accuracy of the navigation system in the landing phase is analyzed and the relationship between the accuracy of inertial sensors, flight parameters and the accuracy of the navigation system is derived analytically. Then, by integrating the dynamic model of the UAV and the inertial measurement unit, a new algorithm for navigation of fixed-wing UAVs is presented. The integration mechanism of the proposed algorithm is tightly coupled; hence, it is capable to eliminate the errors of UAV model and inertial system.... 

The purpose of this thesis is to control altitude and attitude of a Tilt Tri-Rotor UAV in rotorcraft mode and control of altitude, attitude and forward velocity in transition mode (from rotorcraft mode to cruise) by using model predictive control. First, the detailed mathematical model is obtained by the Newton-Euler equations of motion, in both rotorcraft and transition modes. In the next step, a MIMO model predictive controller has been designed, considering input constraints. Then, since, robustness of the model-based control approach is an important challenge, the performance of the controller is presented in the presence of model uncertainties and wind disturbances. The results indicate... 

Using unmanned aerial vehicles in aerial payload carrying leads many changes requiring significant study and research. In recent years, there has been considerable maturation in Micro Aerial Vehicles (MAV) developement especially quadcopters. In addition to the endurance restriction, considerations on volume and weight that can be carried, and safety issues are also obstacles to the development of unmanned aerial payload carrying in urban environments. One of the ways to make a quadcopter more agile while carrying a load is to hang the cargo from the quadcopter via a cable. In this way, it is possible that quadcopters carry the cargo in a cooperative way, which if properly arranged,... 

Over the past two decades, the production of ultra-light drones has increased dramatically. These aircraft are used in applications such as filming, surveying, etc. One of the most important goals is to fly them for a long time. From time immemorial, a lot of work has been done to get such birds to fly, but nothing has ever been done on their engines and propellers, and they have always been considered ideal models (in other words, their efficiency is a bit ideal). In this dissertation, the main purpose is to study some of these sets and to obtain the flight time of a particular drone. First, a low-velocity wind tunnel was built to examine these complexes, then we tested these complexes... 

In this project, a method for cooperative search and localization of RF ground moving targets by a group of UAVs is developed. It should be noted that UAVs are just equipped with GPS and directional sensors. Since there is fuel constraint for UAVs, they take fuel from a tanker whenever they require. Moreover, searching method enables the UAVs to see different parts of the desired area with almost uniform distribution. In addition, the proposed approach enables the UAVs to perform a local search with the aim of finding the targets having lost their signal during localization mode. Finally, based upon a fueling decision function the UAVs take turn, approach to the fuel tanker, and start...