Sharif Digital Repository

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... 

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 recent years with advancement of Robotics, the applications of wide scale use of robots in our homes is not as far-fetched as it was before. One of the important problems for an indoor robot is moving inside a new and unknown environment. To achieve this, the robot should, with the help of its sensors, not only calculate its location; but should also build a map of the environment for later use. Additionally, the robot must be able to explore this unknown environment. The most important drawbacks of the classical solutions to these problems are long computation times, heavy memory usage and absence of precision. In recent years, large amount of research effort has put on solving these... 

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... 

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... 

This thesis examines cooperating robots with minimal sensing to find the particular target described in unknown surroundings. Due to the very high cost sensor robots, Recently researchers are going to use of simple sensors for robot in special purpose and reduce costs. Of course it is clear that doing so will decrease the accuracy and efficiency of the robot and we are going to provide an efficient algorithm for performing the desired action with a good competitive factor. In this thesis the robots movement is online and robots have no knowledge of their environment (such as maps), they only using the data is gathered from the sensors to decide how to move. The accuracy of this information... 

The set of human arm, forearm, and wrist has the ability of performing very miscellaneous movements which has led to human inspiration for designing sorts of robots for various tasks. The aim of the present study is the design and simulation of a robot, similar to the human hand and arm. In the beginning, a shape-adaptive 2 DOF under-actuated mechanism which is actuated by one motor, is selected as the second and third phalanges of the human finger. Also the first phalanx of the finger moves independently by another motor. By adding a ratchet to the second joint of the finger, with the help of only two actuators, the feasibility of exerting isotropic force to the object in three phalanges... 

In this research, path planning in unknown environment is considered. It is assumed that the robot’s sensors are the only tools to collect information from the scene. Volume of the information gathered from the environment depends on the capability of the sensor. So, a detour from the optimal path is unavoidable. In this research, the basic robot is equipped with a minimal sensing system that only detects the iscontinuities in depth information (gaps). We present some online search strategies that guide such a robot to navigate unknown streets from a start point s to reach a target point t. Then, we empower the robot by adding a compass to patrol more general classes of polygons. We present... 

Delivering high quality and clean air into occupied spaces is the main goal of Heating, Ventilation and Air Conditioning (HVAC) systems. HVAC systems draw supply air which usually contains fungi and moisture. Fungi and moisture plus organic materials create a good bed for mold growth. Studies prove that duct cleaning process can definitely reduce the amount of pollutants present in the ducts. Hence, it has positive impact on human lives both regarding psychological and physical points of view. Duct cleaning method’s application difficulties and ducts’ unreachable environments motivated duct cleaning firms to employ robots for duct cleaning tasks. Although there are considerable numbers of... 

Nowadays, regarding the rapid growth of technology, needs for manufacturing different productions has been increased. In this situation, it is very important to train and supervise technicians in machine shops. This supervision can play a key role in semi-automated factories and assembling lines. As we know, most of the machine shops and factories have been designed to be appropriate for human; therefore, using a humanoid robot with similar dimensions to an adult and with the ability to supervise, teach and interact with people, seems to be very useful. Such robot can interact and teach different things to people while moving around factories. Also it can supervise and warn any problem in an... 

Given a set of obstacles as an arrangement of geometric shapes in the plane, we would like to find a path from the initial point s to the target point t that crosses the minimum number of obstacles. In other words, the goal is to determine the minimum number of obstacles that need to be removed to exist a collision-free path between s and t.On one hand, this problem can be used for measuring the strength of barrier coverage which is a fundamental concept in wireless sensor networks (WSNs), and on the other hand, it has been considered as a robot motion-planning problem. The objective of barrier coverage is to guarantee that any path from the start point to the target point, will intersect at... 

In this thesis, the problem of trajectory planning for a high speed planing boat under nonlinear equality and inequality constraints is addressed. First, a nonlinear mathematical model of the craft’s dynamics is derived. To solve a trajectory optimization problem, we can utilize the indirect or direct methods. In the indirect methods, maximum principle of Pontryagin is used to transform the optimal control problem into Euler Lagrange equations, on the other hand, in the direct methods it is necessary to transcribe the optimal control problem into a nonlinear programming problem (NLP) by discretization of states and controls. The resulted NLP can be solved by well-developed algorithms such as... 

The main interest of this study is designing a correction algorithm for intersecting trajectories of two flying robots. For this purpose, path planning algorithms were studied and Rapidly-exploring random tree (RRT) was chosen as a proper algorithm for flying robots in urban environments which is modified for the problem. It should be considered that this project focuses on path correction therefore initial path could be produced by any suitable algorithm. In addition, new paths were designed with flying robots’ performance equations. The correction was done so the paths differ as little as possible in comparison to the original path. Since there are no flight regulations available for... 

Around 20 to 50 percent of the operation costs occurs in manufacturing is related to facility layout. Efficient design would reduce these costs by 10 to 30 percent. Facility layout consists of design of material handling system and plant layout. Design of material handling system includes determining, the flow network and locations of Pick-up and Delivery stations which are defined regarding to the kind of material handling equipment. Today, Automated Guided Vehicles are considered as the basic material handling equipment due to their potentials in production planning and controls, high safety and flexibility and low expenses.
In this thesis, we first discuss the design of the shortest... 

In this work, we try to develop a method for searching for an object which is known to us and also returning it back where the search was begun, through shortest possible path. The surrounding environment was assumed unknown and only a stereo camera and an IMU exist to work with. The proposed method was developed in Linux using GPU and with C++ language and also achieved 58 fps. Parallel programming was utilized in different parts of the algorithm and obstacle avoidance is guarranteed. The surrounding environment and obstacles are assumed changing over the time  

The problem of point to point repetitive time reduction for the rigid manipulators is a major case in industry especially for applications such as point to point welding and part manipulation. These motions are usually repeated for a large numbers of cycles, so that even a minor economization in time can be hugely significant. Nowadays, the time optimal control problem of manipulator with completed theory, is an appropriate solution of the problem. In recent years, with the expansion of design space to structure design, more satisfactory results can be obtained using this method.
Optimal balancing is a new approach based on the optimal control theory in which the balancing unknowns plus... 

Snake-arms are hyper redundant manipulators that have high degree of freedom. Due to their high flexibility they have a great potential to work in the fully restrained, complex and hazardous environments such as Nuclear reactors and space stations. They can also be used for surgery, exploration and rescue. In this thesis the path planning and kinematic control of a special type of snake arm are investigated. In this manipulator, the extra cables are replaced by a locking system to reduce weight of the structure and the number of actuators. Therefore, by releasing and locking the joints in arbitrary sequence and by stretching the cables, the configuration of manipulator will change. This... 

Hyper-redundant manipulators have large number Degrees of Freedom. Because of their redundancy, such manipulators have the advantage of obstacle avoidance, overcoming singularities and intrusion into highly constrained environments. The most challenging task in designing hyper-redundant manipulators is the synthesis of actuating mechanisms with appropriate kinematics and effective power supply. Most of previous techniques in implementing hyper-redundant robots have the disadvantages of: -Using large number of actuators, -Heavy weight due to large number of actuators, -Complexity of the control system due to need of synchronizing subsets of motors. In this thesis a novel hyper redundant... 

Haptic Interfaces have been used as cooperative systems to reproduce and simulate human actions. The Haptic Interface (HI) can be used as a tool capable of interacting dynamically with the operator using haptic technology. By controlling the haptic interface and constraining it to move through the desired trajectory which is required for most of the training systems such as Hand Writing Learning System, Minimally Invasive Surgical Simulation, virtual welding training and gaming applications the users can easily interact with virtual environment through the sense of touch. Haptic device application in virtual handwriting training was investigated in this thesis. Two different modes of... 

In this study, the attitude control of an under-actuated satellite has been investigated. The investigated satellite uses reaction wheels for attitude control. For having full controllability of a satellite attitude, at least three reaction wheels are required. However, due to the high failure rate of reaction wheels, in this study assumed the satellite has two perpendicular reaction wheels, which causes the satellite to be under-actuated. The path planning method is used for controlling the satellite, which is an offline method. In the beginning, tries to define the control input of the satellite in term of limited parameters with different methods. In this regard, the control input is...