Sharif Digital Repository

Swarm robots have been interested by researchers in recent years. The most important reason of this attention is the abilities of these systems for doing some works that a single robot can’t do them alone. The goal of this article is formation control of a group of flying robots with nonholonomic dynamics. The agents are considered helicopters with dimension, mass and moment of inertia. Firstly, the dynamics equation of helicopter will be derived as for Newton-Euler method. Next, input-output equations will be derived and controller will be designed by using sliding mode method. Main rotor and tail rotor thrusts, roll and pitch torques of main rotor are the system inputs. The control method... 

Today, a new approach in the use of robots and the division of task between them to accomplish a specific mission or doing group exercises, has emerged. In fact, the main idea is that the multi agent robotic systems, soon is the most economically advantageous and will take variety of tasks that require distribution understanding of the environment (eg, search and rescue, surveillance, environmental monitoring and military operations). In recent years, the autonomous wheeled mobile robots, OMR, have special significance. This type of robots for independent control of translational and rotational motion, have the holonomic behavior dynamic that this means unlike other nonholonomic robots, be... 

Coordinate motion is a considerable phenomenon in biology and very powerful tool for leading and controlling a group of robots. In recent years, robotic becomes a helpful technology for acompilishing in works which is impossiple for human, such as working in toxic environments. In this project, we introduce coordinate motion problems which are applicable in multi-agent systems, and we also present suitable control algorithms for solving this problem. In other word, we use potential field method to model coordinate motion. We propose a three-cycle robot as an agent, such that it has two nonholonomic constraints. Designing an algorithm for solving coordinate motion problems, we propose these... 

According to the importance of obstacle and collision avoidance for multiple Autonomous underwater vehicle (AUV) that are synchronized for starting the path following, in this study the coordination path following controller for a group of underactuated underwater vehicle with considering of obstacle and collision avoidance presented. The proposed control method is based on graph theory and back stepping with modeling of obstacle using limit cycle. At first, for controller design the back stepping method for path following of one AUV is used. Then the designed controller using of principles of graph theory, has been extended for multiple AUV and as the result multiple AUV is synchronized and... 

The field of microrobotics has seen tremendous advances in recent years. Potential high impact applications of untethered microrobots such as minimally invasive diagnosis and treatment inside the human body, biological studies or bioengineering, microfluidics, desktop micromanufacturing, and mobile sensor networks for environmental and health monitoring are reported. However, There are significant challenges in microrobotic technology, including energy resources, control systems, reliability and safety, design and manufacturing of micromotors and localization. In this work, overall size scale being micron scale is emphasized where mobile robots able to fit in spaces smaller than a millimeter... 

Magnetic shape memory alloys (MSMAs) are a new class of smart materials which exhibit properties such as large reversible strains and high performance frequencies. These unique properties, offer magnetic shape memory alloys as an option in applications such as actuators, sensors and energy harvesters. In this thesis, the equations of magnetic shape memory alloys by considering nonlinear terms of Von karaman in strain-displacement relations, is expanded by using the theory of thin plates in two dimensions which can be used for plate equations with any boundary conditions by applying elastic boundary. In order to verify the obtained model, the equations of motions of magnetic shape memory... 

In a world where energy conservation is a critical topic, cooperative flexible manipulators will play an important role. Conventional robotic manipulators have been designed to have maximum stiffness to achieve both minimum vibration and good positioning accuracy of the end-effector, which causes more power consumption and reduced efficiency. Due to the high inertia of such arms, interaction with humans or sensitive environments is hazardous. On the other hand, Flexible Link Manipulators are designed to be lightweight, using lower energy and producing higher efficiency. Unfortunately, the link's flexibility increases vibrations and decreases the accuracy of the end-effector. Since, the... 

Due to the destructive effects of sudden and adverse changes in acceleration on the human body, drivability control has a particular importance in the automotive industry. Driveability control makes car occupants feel a smooth and comfortable driving, and it will play a vital role in the competition between companies to provide a good product with optimal driving quality.In this project, the aim is to achieve a smooth acceleration curve in a vehicle equipped with a manual transmissions. The meaning of smooth acceleration curve is to reduce jerk and shock caused by inappropriate driver behaviors and to control the car's torque and acceleration to a desirable level. In this project, first, the... 

In this study, we create an evolution function that assesses prosthetic hands in terms of their ability to grasp various objects like a human hand. It is required to evaluate the reachable workspace of prosthetic hands and grasp ability to assess it completely. The first one can be done by using forward kinematics. The Volume of the Grasp Wrench space, one of the grasp qualities indexes, is used to measure the second one. Randomization and grasp taxonomy are used to generalize the grasp quality to indicate the prosthetic hand functionality. Afterward, the created evaluation function is used to specify the importance of each finger and DOF. The results show that the most significant finger is... 

Motion strategies result from the management of priorities by the central nervous system in response to complex interactions with the peripheral nervous system, the musculoskeletal system, and the surrounding environment. The use of physics-based predictive neuro-mechanical simulations can play an important role in discovering and studying these complexities. With the development of detailed musculoskeletal models and neural models that include the control principles of the higher layers of the nervous system, it is possible to synthesize natural human movements, such as rising from a squat, without the need for experimental data and in novel conditions and environments. This can contribute... 

The increasing demand for the mechanized harvesting of delicate agricultural products, aimed at reducing dependence on human labor and enhancing productivity, necessitates the development of advanced robotic systems. One of the main challenges in this field is designing robots capable of harvesting fragile products with precision and without causing damage. This study focuses on the design and modeling of a serial robot equipped with an image processing system and a soft gripper inspired by the fish fin effect, intended for harvesting sensitive agricultural products such as tomatoes, strawberries, and plums. Initially, image processing is used to identify and analyze the condition of the... 

Behavioral investigation and control of multi-agent systems was one of the most attractive problems in robotics which has been studied since the middle of 20th century. Tracking a target is shown by many organic mechanisms during hunting and etc. and is one of the important topics of researches. In this thesis tracking a target by a multi-agent system has been considered which the agents are wheeled mobile robots and have non-holonomic motion constraints. A sample dimensionless and continuous time synchronous dynamic is proposed for the motion of these agents and the goal is to track a moving target while the agents create and keep a desired formation during their tracking process.... 

This paper was directed to recognize maneuver equations perfectly, and with regard to CFD method maneuver simulation is going to be done in form of two and three dimensional. Today, since CFD methods have been exerted in different works, further and more actual development of floating body's maneuver is going to be our special need. As numerical methods for floating body's maneuver simulation by RANS method are developing, more researches are being done about this field as well. This thesis is going to simulate primitively maneuver of one floating body by Smoothed Particle Hydrodynamic(SPH) method in order to be as the beginning of maneuver simulation by this method in which with regard to... 

Due to the advantages of multi-agent systems, research in this area and the use of these systems in industry are increasingly growing. Applying these robots, various complex tasks can be done faster, safer and with better results. In our country, many different algorithms have been proposed and simulated, but due to the lack of a real environment for implementation, their actual performance has not been assessed. This project aims to create a platform for research and development of this field. This goal is achieved by performing the first phase of implementation, namely the design and construction of the robot platform. In the first step, qualitative and quantitative characteristics of the... 

The main purpose of the present thesis is to establish a decentralized controller for some car–like multi robots to follow and hunt moving targets. Robots are very similar to actual cars considering geometric dimensions, mass and moment of inertia and so on; and outputs of the controller are steering-wheel and driving-wheel torques appropriately. Dynamics of the moving target is so that it escapes from the robots. Robots are equipped with antenna for getting wireless sensory signals, including range and bearing sensors. Kalman filter is used for estimation the target relative position and speed and robots state variables. The controller is designed for doing the above mentioned group... 

In this project, we use an off-line motion capture technique for walking pattern recognition and reconstruction, and apply a sensory data acquisition system for extracting knee and ankle joints angular movements. Our approach is a marker-based object tracking technique using only one camera and four markers as data acquisition system, and a neural network method is developed for marker detection. Different walking condition considered including: straight position, inclined position with 〖+5〗^° slope, and 〖-10〗^° slope. Using pattern obtained from above process, the BVH format of the motion is built for 3D reconstruction of the performer’s motion. Since the obtain data describe the motion of... 

The aim of this article is ancestral control of a set of 3-wheel robots with non-holonomics dynamics for hunting and covering around moving target. Robots have mass and inertia and the wheels' mass have been considered in the dynamics of robots. The output of controller is wheel's torque and front wheel's steering torque. Moving target dynamics has been considered in a way that it is escaping from invader and the target has holonomics dynamic. To derive the equation of motion, Kane's dynamics procedure has been used. Robots are equipped to sensors for distance assessment, vision angle assessment and also signal receiver antenna. To estimate relative position and variables of other robots'... 

Permanent magnets play an essential role in the structure of the electric motor, but due to limited resources, many efforts have been made to meet the need for them. One of the most important types of non-permanent electric motors is reluctance motors. Despite their antiquity in design, torque ripples have led to the limited use of reluctance motors, but advances in science have made it possible to control these ripples.As a result of the major advantages such as low manufacturing costs, high efficiency, and uncomplicated structure, these motors have been the subject of many researches. One way to eliminate the problem of torque ripples is to increase the number of teeth, but in the common... 

Today, robots have been widely used in various tasks. Swarm robots are the focus of many researchers because of their low cost and their flexibility. However, due to the nature of dynamics in water and locomotion systems in it, very few of them have been developed. Applications of Swarm Robotics at sea include: the formation of temporary sea bridges, the collection of marine litter, assistance to large ships for maneuvering in ports, and carrying of oceanographic sensors. Therefore, the purpose of this study is to design a system for self-control and autonomy of unmanned surface robots with the ability to connect and carry objects. First, the robot was modeled according to its hydrodynamic... 

The basic type of suspension systems, which is known as passive suspension systems, creates a balance and compromise between the two goals of ride comfort and road holding. In order to improve the performance of the suspension system, the use of active actuators has been considered. However these actuators require energy and control strategies. To supply the required energy, recovering the energy of vehicle vibrations can be a solution. Therefore, ride comfort, keeping the wheels in contact with the road and the amount of recoverable energy are three important control objectives for modern active and semi-active suspension systems. The control of these systems is considered a challenging...