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Feedback control of the neuro-musculoskeletal system in a forward dynamics simulation of stair locomotion [electronic resource]
, Article Proc. of IMechE Part H: Journal of Engineering in Medicine ; 2009, Vol. 223, No. 6, pp. 663-675 Journal of NeuroEngineering and Rehabilitation ; Volume 11, Issue 1, 30 April 2014, Article number 78 ; Meghdari, Ali ; Vossough, Gholam Reza ; Sharif University of Technology
Abstract
The aim of this study is to employ feedback control loops to provide a stable forward dynamics simulation of human movement under repeated position constraint conditions in the environment, particularly during stair climbing. A ten-degrees-of-freedom skeletal model containing 18 Hill-type musculotendon actuators per leg was employed to simulate the model in the sagittal plane. The postural tracking and obstacle avoidance were provided by the proportional—integral—derivative controller according to the modulation of the time rate change of the joint kinematics. The stability of the model was maintained by controlling the velocity of the body's centre of mass according to the desired centre of...
Design and Construction of a Soft Actuated Exoskeleton for Hand Rehabilitation of Stroke Patients
, M.Sc. Thesis Sharif University of Technology ; Ghafari, Ali (Supervisor) ; Meghdari, Ali (Supervisor)
Abstract
The main goal of this thesis is the design and development of a rehabilitation device for helping patients “to improve blood circulation” & retain and recover their abilities if possible that were lost during the stroke or a accident like that (my research in karaj/iran shows that it is possible by just movement of the specific body part). The focus is on hand in this thesis because Injuries to the hand are common and can be very debilitating since our hands are our primary means for interacting with our world. For rehabilitation in case of human hand there are several practices that should be done for patients either in home or in a rehabilitation center, time and money that is supposed to...
Design and Construction of an Upper Extremity Wearable Exoskeleton for Rehabilitation of Stroke Patients
, M.Sc. Thesis Sharif University of Technology ; Selk Ghafari, Ali (Supervisor)
Abstract
Exoskeleton is a wearable active device used to augment human power in upper or lower extremities. The integration of robotic devices and conventional physiotherapy is becoming more and more acceptable worldwide. The main scope of this thesis is to design and develop a prototype of a light, low-cost and wearable robotic exoskeleton to rehabilitate the upper extremity in stroke patients at home. For this purpose mechanism of a wearable exoskeleton will be proposed compatible with upper extremity degrees of freedoms with minimum number of actuators which is constructed inexpensively to eliminate the demand of expensive and professional therapists. The conceptual design of such a system should...
Design and Construction of an Artificial Thumb Controlled by Command from the Index Finger
, M.Sc. Thesis Sharif University of Technology ; Salak Ghafari, Ali (Supervisor)
Abstract
This study provides preliminary work on the development of manual rehabilitation device for wearable and robotic manual applications. This work examines the motion of the fingers using the sensors. The developed mechanism is based on a combination of strain gauge sensors and a stepper motor, which forms the motion of the artificial thumb. In this thesis, the creation of an artificial thumb has been done with one degree of freedom, the movement and grabbing of lightweight objects. For grabbing objects, the command of controlling and keeping objects is performed through the IAR software and labVIEW software which is given to the stepper motor.This study describes the details of the work done...
Design and Fabrication of a Fish Robot
, M.Sc. Thesis Sharif University of Technology ; Meghdari, Ali (Supervisor) ; Selk Ghafari, Ali (Supervisor)
Abstract
In this research a robotic fish was designed and fabricated. For this propose different types of manufactured robotic fish were investigated and this model was developed and made with a one-piece flexible tail with an actuator that creates lateral movement through cable strings attached to the tail. Proposed mechanism has a simple, low cost structure that facilitates the control of the robotic fish movement. To control this robotic fish, a four-channel radio controller with 40 kHz frequency, was used. Swimming mode of this robotic fish is categorized in Subcarangiform swimming mode which is faster and has better maneuverability compared to its counterparts. It should be noted that the...
Sensitivity Analysis and Optimal Control of a Nano-Newton CMOS-MEMS Capacitive Force Sensor for Biomedical Applications
, M.Sc. Thesis Sharif University of Technology ; Meghdari, Ali (Supervisor) ; Selk Ghafari, Ali (Supervisor)
Abstract
In the first part of the thesis, we introduce the structure of a Nano-Newton CMOS-MEMS capacitive force sensor. This force sensor has been utilized out-of-plane sensing mechanism with high accuracy and reliability. Also, we discuss about sensitivity analysis of this force sensor. The largest change of capacitance (increased capacitance + decreased capacitance) occurs in ℓ=2/3. Sensitivity for increased capacitance grows by 8.33% and for decreased capacitance grows by 2.27%. The proposed method provides useful guidelines to increase the sensitivity of the sensor up to 250%. In the second part, a fixed structure controller, PID type, is proposed to control and suppress the in-plane vibration...
Dynamic Analysis & Control of a Biomimetic Robotic Fish Employing the Bond Graph Approach
, M.Sc. Thesis Sharif University of Technology ; Selk Ghafari, Ali (Supervisor) ; Meghdari, Ali (Supervisor)
Abstract
In this thesis, a dynamic model of the biomimetic robotic fish with a flexible tail is developed. In this model, the oscillating frequency of the tail controls the forward velocity, and the body spline offset parameter controls the heading angle. The robotic fish were divided to two parts: a rigid body, and a flexible tail. The rigid body includes the head and the electrical and mechanical equipment. The bond graph model was developed and the numerical values were extracted from constructed robotic fish have also been hydrodynamically analyzed. Simulation results were quantitatively compared and verified with Matlab Simmechanics simulations. These simulations described the lateral movement...
Vibration Analysis of Kish Island Elevated Water Storage Tank
, M.Sc. Thesis Sharif University of Technology ; Selk Ghafari, Ali (Supervisor)
Abstract
Elevated water tanks are one of the most critical elements in civilized society to provide safe servicing resources of drinking water after natural and human-made disasters. Dynamic analysis plays a vital role in investigating structural behavior of the elevated storage system subjected to the earthquake-induced vibration. The main scope of this paper is to address the structural stability analysis of the Kish Island’s elevated reinforced concrete water tank employing finite element method. A complete solid model of the structure with detailed design was constructed, and finite element analysis was carried out utilizing ABAQUS software. To investigate the dynamic behavior of the structure, a...
Muscle-driven forward dynamics simulation for the study of differences in muscle function during stair ascent and descent
, Article Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine ; October 1, 2009 Vol.223: 863-874 ; Meghdari, A ; Vossoughi, G. R ; Sharif University of Technology
Abstract
The main scope of this study is to analyse muscle-driven forward dynamics simulation of stair locomotion to understand the functional differences of individual muscles during the movement. A static optimization was employed to minimize a performance criterion based on the muscle energy consumption to resolve muscle redundancy during forward dynamics simulation. The proposed method was employed to simulate a musculoskeletal system with ten degrees of freedom in the sagittal plane and containing 18 Hill-type musculotendon actuators per leg. Simulation results illustrated that simulated joint kinematics closely tracked experimental quantities with root-mean-squared errors less than 1 degree. In...
Variable Impedance Control of the Lower Limb Exoskeleton
, Ph.D. Dissertation Sharif University of Technology ; Vossoughi, Gholamreza (Supervisor) ; Selk Ghafari, Ali (Co-Advisor)
Abstract
Todays, the exoskeleton is known as a practical device for use in robotic rehabilitation and elderly assistance and has attracted the attention of many researchers. Impedance control is the most widely recognized control strategy in research on exoskeletons. Impedance control can properly handle soft interaction of robots with the environment. Optimal target impedance selection can increase the performance of the overall system and guarantee the stability. The main objective of this research was to introduce a variable impedance control system and verifying the presented control system on an exoskeleton. In this research, an exoskeleton with 4 active DoF and 8 semi-passive DoF is designed...
Simulation of Bushehr Nuclear Power Plant Hot Channel Using ANSYS CFX 18.0 Software
, M.Sc. Thesis Sharif University of Technology ; Ghafari, Mohsen (Supervisor) ; Hosseini, Abolfazl (Co-Supervisor)
Abstract
In nuclear power plants, the fission reaction takes place inside the fuel rods, and the heat generated inside the fuel rods is transferred through the clad wall to the cooling fluid, which is single-phase, subcooled and in the turbulence zone. In the hot channel of the reactor core, where the axial and radial heat flux reaches its maximum state, the fluid leaves the single-phase state and some steam is formed in the area close to the clad wall.Therefore, in some cases, in the hot channel, the steam near the clad wall may reach a point that reduces the heat transfer coefficient, rapidly increases the wall temperature and thus destroys or melts the sheath surface. If this happens, it means...
Fault Diagnosis of Crack Growth in Power Transmission Systems, using Neural Network
, M.Sc. Thesis Sharif University of Technology ; Selk Ghafari, Ali (Supervisor) ; Khayyat, Amir Ali Akbar ($item.subfieldsMap.e)
Abstract
Nowadays, industrial companies deal with a wide range of serious problems in the field of power transmission maintenance and also fault detection. A large amount of money and time is spent on these issues in order to solve them; consequently, there is an essential need for this subject. In this thesis, in order to tackle those major issues which were referred above, an artificial neural network is trained with only one hidden layer. Also, a suitable database for training an efficient neural network is needed. Thus, a one-stage gearbox system with appropriate degrees of freedom is used to set up referred database. In this system, a crack is imposed to a tooth of spur gear with different sizes...
Modeling, Simulation, and Sliding Mode Control Analysis of SQ15-06N Robot
, M.Sc. Thesis Sharif University of Technology ; Khayyat, Amir Ali Akbar (Supervisor) ; Selk Ghafari, Ali (Supervisor)
Abstract
In this thesis, kinematic, dynamic modeling and simulation, and control of SQ15-06N industrial robot have been presented. This robot is mostly used in the painting industry. Studying the robot requires familiarity with the robot programming and the hardware used in the robot. In this research, robot characteristics such as repeatability, load carrying capacity and accessibility have been investigated. The principles of industrial robot programming and robot programming language have been studied. The use of simulation software is common due to cost savings, reduced time, no need for robots and controllers, and the ability to test programs in a virtual environment. For this purpose, the...
Dynamic Analysis of an Exoskeletal System to Assist a Paraplegic Motion
, Ph.D. Dissertation Sharif University of Technology ; Meghdari, Ali (Supervisor) ; Vossoughi, Gholam Reza (Co-Advisor)
Abstract
This research focuses on the dynamic analysis of an exoskeletal system to assist a paraplegic motion. Research in powered human exoskeletons began in the late 1960s, almost in parallel between the numbers of research groups for different applications. The main challenges for the recent work in exoskeletons were focused on the design and demonstration of an initial prototype. To this point, the reported advantages of the autonomous exoskeleton systems are largely anecdotal. Indeed, there is a marked lack of published quantitative performance results for exoskeleton devices that reportedly improve human locomotion. Considering this, there are many design challenges remained that may lead to...
Structural Health Monitoring of Oil Pipeline Using Guided Lamb Waves
, M.Sc. Thesis Sharif University of Technology ; Zabihollah, Abolghasem (Supervisor) ; Selk Ghafari, Ali (Supervisor)
Abstract
Pipeline systems are one of the cheapest ways for distribution and transportation of petroleum and natural gas. The testing of pipes used in the petroleum industry is necessary to avoid unplanned process interruptions, environmental pollution and provide good safety. One of the methods which is used for pipeline inspection is the ultrasonic non-destructive testing (NDT) technique. The use of conventional NDT techniques such as ultrasonic thickness gauging is a slow inspection process, which becomes very expensive when full inspection is needed. Ultrasonic guided waves provide an appropriate fast screening technique. These waves stress the whole pipe wall and propagate along the length of the...
Modeling and Simulation of a 6DOF Quadrotor Helicopter
, M.Sc. Thesis Sharif University of Technology ; Selk Ghafari, Ali (Supervisor) ; Zabihollah, Abolghasem (Supervisor)
Abstract
The aerial vehicle capable of vertical takeoff and landing (VTOL), have created an interest in the community of researchers and admirers of Unmanned Aerial Vehicles. Among the existing UAV's, those with the capability of vertical takeoff and landing are prominent due to their higher maneuverability and hover capability. Quadrotors mostly have been considered as a flying robot for save and rescue operations in dangerous and unreachable places in addition to its military application. In cross shape of Quadrotor platform on each edge is appointed an electric motor with light rotors that usually are controled by considering motor rates as their only inputs. This thesis aims, to simulate and...
Structural Design Optimization and Dynamics Analysis of Non-Uniform Thickness Laminated Beam Reinforced with Nano-Particles
, M.Sc. Thesis Sharif University of Technology ; Zabihollah, Abolghassem (Supervisor) ; Selk Ghafari, Ali (Co-Advisor)
Abstract
Non-uniform laminated beams are being used in many engineering applications as primary elements. Helicopter blades, wind turbine blades and robot arms are examples of applications of these structures, in which the high stiffness-to-weight ratio and the non-uniform geometry are of high importance. Changing the thickness in laminated structures is a big challenge in fabrication view as different tapering configurations may significantly alter the stiffness of the structure. Thus, increasing the stiffness and dynamics characteristics of tapered beams with simple configuration is of high importance. The present work aims to investigate the effect of adding nano particles in resin during the...
Impedance Control of Stewart Platform with Optimal Gains
, M.Sc. Thesis Sharif University of Technology ; Ghafari, Ali (Supervisor) ; Ghaemi Osgouie, Kambeaz (Supervisor)
Abstract
The main scope of this research is developing an impedance control strategy for a six-degree-of-freedom parallel manipulator with the application in the milling process. One of the most common known parallel manipulators is the Stewart platform, which was proposed in 1965. [It evolved into a popular research topic of robotics in the 1980s.] Problems in various aspects of design, kinematics, dynamics, singularity and workspace analysis have been investigated in the literature. Derivation of control strategies taking advantage of the in-parallel structure or catering for the special problems arising out of that is another important field, whichhas been almost untouched till now.
The main...
The main...
The Effect of Stress Due to Repair of a Heat Exchanger on Crack
, M.Sc. Thesis Sharif University of Technology ; Farrahi, Gholamhossein (Supervisor) ; Selk Ghafari, Ali (Co-Advisor)
Abstract
A heat exchanger is a piece of equipment is built for efficient heat transfer from one medium to another. They are widely used in air conditioning, chemical plants and petrochemical plants, so studying the different failures and problems of them is important.
One of the common problems is fracturing of the tubes. This will allow the hot water to enters them and then hit the refractory of the tubesheet. This coating slowly washing away and that will lead to direct contact between the hot fluid and the tubesheet. Tubesheet is not designed for such a hot thermal load so cracks will initiate on it due to this new situation. They will shut the fractured tube by shut it down and welding a...
One of the common problems is fracturing of the tubes. This will allow the hot water to enters them and then hit the refractory of the tubesheet. This coating slowly washing away and that will lead to direct contact between the hot fluid and the tubesheet. Tubesheet is not designed for such a hot thermal load so cracks will initiate on it due to this new situation. They will shut the fractured tube by shut it down and welding a...
Dynamic Analysis and Intelligent Control of an Offshore Marine Crane for Safe Load Carrying
, M.Sc. Thesis Sharif University of Technology ; Selk Ghafari , Ali (Supervisor) ; Zabihollah, Abolghasem (Co-Advisor)
Abstract
Marine cranes are installed on vessels to transfer or transport payloads between ships or between ships and decks. One of the most critical issues in this case is the safety during load transferring. Marine cranes move or sway in unexpected direction, when they are influenced by wave, wind and storm. Theprocess of controlling them became difficult without using automatic control methods. Ingeneral, the movement of cranes has no prescribed path.This master thesis is about dynamic modeling and control of fixed crane placed on an offshore vessel. The main challenging problem in this work will be developing an accurate mathematical model of the crane. Therefore, bond graph method which is known...