Sharif Digital Repository

Hybrid Exoskeletons refer to simultaneous use of wearable robots and functional electrical stimulation technology. Hybrid exoskeletons have many advantages compared to the separate application of each of these technologies, such as reducing the robot’s energy consumption and the need for lighter and cheaper actuators for the robot, using humans muscle power, and reducing muscle fatigue. As a result, these robots have recently attracted a lot of interest in rehabilitation applications for patients suffering from mobility impairment.Control in hybrid exoskeletons is more complicated than control in traditional exoskeletons. Because in addition to robot and functional electrical stimulation... 

Design and modeling of a micromechanism for generating planar, nano-scaled locomotion is the subject of this thesis. First, we introduced the concepts and fundamental definitions used throughout the thesis. Then, based on the classification of the locomotion principles employed in microrobots, the related literature about design and fabrication of different microrobots is investigated. Inertial slip generation and contact force variation, as the preferred group, is utilized for further analysis. Since friction force is the main propelling source in the microrobot’s locomotion principle, different models proposed for this phenomenon are investigated and the Coulomb friction model is selected... 

Underwater robots are broadly used in oceanography to explore ocean environments,inside inspection of pipes, and also to provide security at maritime boundaries. To design an underwater autonomous robot, it is compulsive to take advantage of a high efficient propulsion mechanism to lengthen the tour time span. Since fish-like propulsion mechanisms have presented higher efficiency comparing other mechanisms, they have been paid a lot of attention.In the present research, the hydrodynamic of a thunniform fish robot is analyzed under some reasonable simplifications. Based on the results achieved from this study, closed expressions are developed to predict the steady mean velocity and the... 

The final target of this research is to design an appropriate intelligent control strategy for energy management purposes in a well designed parallel hybrid electric vehicle. In the first step, the conventional “Samand” vehicle has been simulated using real data for vehicle parameters and power train components, has been simulated. Using experimental results, simulation results are validated. In the second step due to the primarily defined parallel electric assist control strategy (PEACS) for the hybrid electric vehicle and performance requirements, components such as engine, electric machine and battery pack were selected and sized. In the final step a Fuzzy Logic Controller (FLC) has been... 

Laser ultrasonic is a novel method for measuring sheet parameters. In this technique an intense pulse is irradiated to the target which instantaneously vaporizes the surface layer into the high temperature and high pressure plasma. Expansion of plasma produces shock wave that propagates through the surface. Mechanical properties of target can be calculated by measuring and analyzing produced shock wave. In this project wave propagation is simulated using finite element and numerical-computation methods. The numerical-computation simulation was performed using lamb wave equations. ANSYS software was employed for finite element simulation. The results corroborate each other. Next, simulation... 

Nowadays, many researches are inspired by nature and living creatures in order to build various scientific and industrial products such as robots, because of the highest level of creativity which is used in creating them along with their high level of efficiency in power consumption and designing parameters. Underactuated Robots are the type of robots which have more degrees of freedom comparing to the number of operators. As a result their optimum control has a lot of complications. Brachiating robots are designed and built based on an inspiration from long armed apes (Gibbons). This type of monkey is highly skilled in twisting in trees and traversing. This type of movement benefits from... 

Providing energy for small but out-of-access devices has led industries to harvest energy from the environment, especially environmental vibrations. The problem of vibrational energy harvesters with linear behavior, is their small bandwidth and consequently, their high sensitivity to frequency content and excitation spectra. Particularly in random excitations with vibrational energy spreading over a frequency range, linear harvesters do not seem appropriate. Under these conditions, harvesters with nonlinear stiffness are possible substitutes for linear systems. However, prediction and estimation of the behavior of systems with nonlinear stiffness under random excitation has been complicated,... 

Magnetic levitation is an appropriate solution for noncontact 3D manipulation. Workspace of the previously proposed maglev systems is confined to a relatively small cube, which severely limits the application of this technology. In addition, most of the previously given mechanisms require the design and application of a subsystem in order to unify their magnetic field. In this paper, a moving magnet is proposed which results in a horizontally extendable workspace; moreover, the field unifying section is not needed since one electromagnet only is used. Further, details of the mechanism and finite element based design procedure of the magnet are presented. Dynamic equations of the system... 

The main objective of this project is to investigate modeling for a robotic swarm with suitable sensors and to analyze effect of sensory noise on the control and unity of the swarm. This project is an extension of analytical study done by S. Etemadi, A. Alasty and G. Vossoughi in Sharif University of technology. The flocking frame assumed to have a leader robot that controls over all behavior of the swarm made of agents’ robots with limited equipments and low intelligence that only obey some basic attraction and repulsion laws that will be explained. As an initial step of the analysis, we investigate proper physical model, sensors and navigation systems suitable to the model. Next, the... 

An essential requirement for performing robotic assisted surgery on a freely beating heart is a prediction algorithm which can estimate the future heart trajectory with a high accuracy in a long horizon. The main objective of this research was measurement and prediction of the heart motion for robotic assisted beating heart surgery. In this study, first the feasibility of a stereo infrared tracking system for measuring the free beating heart motion was investigated by experiments on a heart motion simulator. Simulator experiments revealed a high tracking accuracy when the capturing times were synchronized and the tracker pointed at the target from an appropriate distance.Then, the heart... 

In this paper, a novel control approach for one-dimensional bilateral teleoperated nanomanipulation system is proposed. While manipulating objects with a nanomanipulator, real time visual feedback is not available. So, force feedback is used to compensate for the lack of visual information. Since nanometer scale forces are dominated by surface forces instead of inertial forces as in macro world, scaling of nanoforces is one of the major issues of teleoperation system. The Hertz elastic contact model is used to model the interactions between the slave robot and the environment. The proposed framework uses the simple proportional derivative control, i.e., the master and slave robots are... 

Microrobots are generally suitable for implementation of certain works in miniature dimensions such as micro assembly, microsurgery, adaption with small animals and so on. In this way, there is special position for mobile microrobots capable of moving in the range of more than theirs dimensions. Achivieng to high resolution and high speed locomotion are the challenging issues in the microrobot’s development in which much effort has been done.The goal of this project is dynamic modeling and velocity control of an A-shaped microrobot with with nanometric locomotion. During this project, first the dynamic modeling of microrobot is investigated and simplified based on the previous studies.... 

In this thesis, an extended nonlinear model of peripheral milling process (2D) is presented. For the first time, cutting forces are described through a complete third order polynomial function of the axial depth of cut. Also, cubic nonlinearity is considered for the structural stiffness as a function of tool tip displacement. To complete the model, process damping and tool wear effects are also considered. A set of experiments including modal tests to determine natural frequencies and structural damping ratios; and also cutting force measurements at different feed rates to determine nonlinear cutting force coefficients, are carried out. Also, measurement of critical axial depth of cut at... 

Nowadays, due to the advancement of robotic technologies and development of industrial robots, the robot manipulators are widely used for automation of various manufacturing processes, such as finishing processes. In these applications, the contact has to be made between robot end-effector and environment. Therefore, control of interaction force in the constrained manipulators is an important demand. On the other hand, due to use of gear box and belts for energy transmission in robot joints, robot manipulators have flexible joints. The vibration, generated due to the interaction force and robot joint flexibility, can deteriorate surface roughness in automated finishing processes. In order to... 

In recent years, the seat suspension system in commercial vehicles, industry, agriculture, transportation and … have been focused by researchers. Designing the spring-damper isolators for vehicle’s seat can be an achievable and suitable strategy to increase the comfort and decrease the risk of injuries in vehicles. In this research, the effect of vibrations due to road roughness has been examined by dynamic modeling of a vehicle in combination with the human body model. Thus by using spring-damper isolators and genetic algorithm, we try to optimize the performance of the system. Designing parameters includes the stiffness and viscosity of seat isolator and our target functions include the... 

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... 

The human body has more than 600 muscles that cause movement. Disability and motor disorders are some of the problems that people may face due to some factors such as accident, spinal cord injuries, disorders and brain damage, and the presence of a problem in neurological commands due to stroke. One of the proposed methods for solving the problems of people with motor disorder is the use of exoskeletons to generate stimulus. Exoskeletones are electromechanical devices designed to assist human movement, and patients are used to correct their movements using specific motor patterns. Exoskeletones can also be used as an auxiliary device for carrying heavy loads. Many studies have been conducted... 

There is many sources of uncertainty in the power plants such as continuous changes of the ambient temperature and the climate condition. The controller of the boiler-turbine unite should be robust against uncertainties and overcome the changes in the operating condition. In this regard, a robust adaptive variable structure control scheme (RAVCS) is proposed to control a nonlinear multi-input multi-output (MIMO) model of industrial boiler-turbine unite, in the presence of unknown parameters and bounded uncertainties as well as external disturbances. Moreover, a robust controller based on and in the presence of rational deviation in parameters, is designed. To investigate the zero... 

Over the years, The robots have entered the human community in addition to the factories and industrial centers, and a new branch in the field of robotics called social robots has been created. Such robots can become a personal companion for children and elderly people who accompany that person at home or outside. Social robots can even be used as a platform for health services or as a vendor in stores. The interaction of humans and robots in social robots and communicating with the audience is the main part of this series of robots. Human-robot interaction can be divided into three parts: visual, auditory and facial or body movements. Also, the behavior of a social robot must be as natural... 

Many workers and soldiers suffer from musculoskeletal problems due to carrying heavy loads. Using exoskeleton robots which are designed for power augmentation can be effective in preventing these disorders. Due to the interaction of these robots with human, it is necessary to design an appropriate control system for these robots, therefore, the aim of this research is to design a predictive nonlinear control system for a three degrees of freedom lower-limb Exoskeleton robot, in order to improve the performance of the robot, follow trajectory of human joints and reduce the interaction forces between human and the robot during the squatting activity. Multi-stage model predictive controller...