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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 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 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...
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...
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...
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...
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...
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...
Design, Modeling and Control of a Delta Robot in Fine Machining Application
, M.Sc. Thesis Sharif University of Technology ; Salarieh, Hassan (Supervisor) ; Selk Ghafari, Ali (Supervisor)
Abstract
In recent years, industrial robots have been greatly used as orienting devices in industry, especially in the automotive, shipbuilding and aerospace manufacturing industries. Industrial robots are gradually finding their niche in manufacturing, replacing less universal and more expensive CNC-machines. Application area of robots is constantly growing; they begin to be used for the assembly, pick-and-place operations, machining operations and etc. The use of robots for machining operations is growing because of their flexibility to perform a broad spectrum of tasks at a lower cost when compared with machine tools. Recently, parallel robots have attracted more and more researchers’ attention in...
Design and Construction of Smart Insole to Measure the Force of the Human Foot Dynamics during Daily Activities
, Ph.D. Dissertation Sharif University of Technology ; Selk Ghafari, Ali (Supervisor) ; Zabihollah, Abolghasem (Supervisor)
Abstract
In recent years, leg pain is a consequence of inappropriate foot movement, which is an important health problem for us today. The health problems of the foot and the waist are due to wearing inappropriate footwear that is not designed for different activities. For example, Walking, long-standing on the feet, cycling and so on. A shoe insufflator is not suitable for walking, cycling, and standing. For designing an appropriate shoe insole for different activities, it is important to have a force determination profile for each person. This means that the insoles design shoes should be personal. A low-cost device has been designed, which can be used to measure the pressure on the sole of the...
Multi-Sensory Balance Board for Children with SPD & ADHD Disability
, M.Sc. Thesis Sharif University of Technology ; Selk Ghafari, Ali (Supervisor) ; Zabihollah, Abolghasem (Co-Supervisor)
Abstract
Nowadays, as technology grows, human life formation changes every single second. These changes sometimes create harmful habits and effects on our lifestyle, which unfortunately brings various types of disabilities and disorders. SPD (Sensory Processing Disorder) and ADHD (Attention Deficit Hyperactivity Disorder) are common disorders in children and usually show themselves in younger ages. The cause of these disorders is not unique and multiple factors can lead it. Fortunately, they can be easily treated by considering the appropriate treatments. Research that has been performed on any treatment device available for children with SPD and ADHD disorder shows that the sense of balance has not...
Investigation of the micro-step control positioning system performance affected by random input signals
, Article Mechatronics ; Volume 15, Issue 10 , 2005 , Pages 1175-1189 ; 09574158 (ISSN) ; Behzad, M ; Sharif University of Technology
2005
Abstract
This paper gives the results of simulation and experimental investigation on the effects of random signals on the accuracy of micro-stepping control positioning. For studying and simulation of the effect of random noise signals on performance of the accurate position control systems, such as Hybrid Stepper Motors (HSMs), a micro-step driver and controlling unit using PID controller has been designed and constructed. Several parametric studies have been carried out including different white noise power and micro-step per revolution. Tracking problem for a HSM model has been simulated, and the experimental study for similar cases has been carried out by implementing the designed controller in...
Design and real-time experimental implementation of gain scheduling PID fuzzy controller for hybrid stepper motor in micro-step operation
, Article Proceedings of the IEEE International Conference on Mechatronics 2004, ICM'04, Istanbul, 3 June 2004 through 5 June 2004 ; 2004 , Pages 421-426 ; 0780385993 (ISBN) ; Alasty, A ; Sharif University of Technology
2004
Abstract
In this paper, design and real time experimental implementation of Fuzzy Gain Scheduling of PID controller for Hybrid Stepper Motor in Micro-stepping operation is described that was developed to track the desired positioning problem. The control problems characterized by mathematical models exhibit significant nonlinearity and uncertainty. Good performance of proposed Fuzzy PID controller are shown
An Automated Investigative System of a Plough Movement by Using a Developed Displacement Sensor
, M.Sc. Thesis Sharif University of Technology ; Selk Ghafari, Ali (Supervisor)
Abstract
It is so essential to study a safe dynamics of agricultural mechanical equipment during duty stroke, plus getting a rich information about the nature of the soil under processing and in many cases there are associated simultaneous problems, so the main aim of this study is to create a safe working conditions for such specific equipment to extend their life time span as possible as it could. This study will predict an un-usual working circumstances for agricultural tools including plough of course depending on some automated technologies with fast response supported by smooth working conditions. Simply, the proposed Investigative system consists of a linear potentiometric element with...