Search for: lower-limb
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    Design and Prototyping and Experimental Analysis of a Foot with Toe Joint for Exoskeletons

    , M.Sc. Thesis Sharif University of Technology Rostami Barooji, Hosein (Author) ; Vossoughi, Golam Reza (Supervisor)
    One of the recent studies in the field of humanoid robots is to achieve a robot gait close to the human-like gait. Therefore, using the foot equipped with passive or active toe joint is developed in case of robots. The results of several studies show that the segmented foot with a toe joint has several advantages compared to the rigid foot in: walking speed, range of joint angle and ability to kneel and climb higher steps. Both passive and active toe joints of humanoid robots are developed. Advantages of the passive toe joint is obvious; in terms of design, it is more simple and light. Moreover, in normal gait, when the robot is equipped with passive toe joint, body inertial causes an... 

    Modeling and Analysis of Angular Mis-alignments of Lower Extremity and Prediction of the Results of Osteotomy Surgery

    , M.Sc. Thesis Sharif University of Technology Iravani Mohammad Abadi, Mina (Author) ; Farahmand, Farzam (Supervisor) ; Hoviattalab, Maryam (Supervisor)
    Varus-valgus deformity is the improper alignment of lower extremities, which results in the increment of the local stress within the cartilage and the consequent alteration of the performance mechanism of the soft tissues around the knee joint. This accounts for changes within the movement pattern and thus further deformities, which, when continued, can lead to more serious damage in the form of osteoarthritis. The aforementioned cycle can be prevented through the conduction ofosteotomy; a surgical procedure in which the addition or removal of a bone wedge can correct the improper alignment. The correct design and conduction of osteotomy in terms of the location, angle, and size of the... 

    Design and Implementations of an Intelligent Control System for a Lower Limb Extremity Robot Based on Human-Robot Interaction and Muscular Activity to Reduce Human Energy Consumption

    , M.Sc. Thesis Sharif University of Technology Talatian, Hamid Reza (Author) ; Vosoughi, Gholamreza (Supervisor) ; Jahed, Mehran (Co-Supervisor)
    With advancements in control and robotics technology, wearable robots have gained multiple applications in rehabilitation and power augmentation. In robots developed for power augmentation purposes, human decisions are combined with robot power to enhance the human ability to perform various activities, such as carrying heavy loads and walking for a long time. In cases where robots are designed to help humans to carry heavy loads, the robot control strategy should minimize the human-robot interaction forces. In this case, heavy loads influence the robot and the user no longer need to use more energy than normal walking, and the robot works following human intentions. Where the robot works to... 

    Design and Implementation of an Intelligent RL-based Controller for the Lower-limb Exoskeleton to Reduce Interaction Torque

    , M.Sc. Thesis Sharif University of Technology Abbasi, Mohammad Reza (Author) ; Vosoughi, Gholamreza (Supervisor) ; Moradi, Hamed (Supervisor)
    Exoskeletons, or wearable robots, are electromechanical devices that have become the focus of academic and industrial research in recent years, and their applications in power augmentation have increased. One of the most important challenges of these applications is controlling the robot and synchronizing it with the user. The close interaction of the robot with the user and the change of movement pattern between different users and different gait cycles show the importance of estimating the user's movement intention, but the need for online method of estimating the movement intention and the complexity of accurate dynamic modeling has caused researchers to use reinforcement learning (RL) in... 

    Design and control of an assistive exoskeleton with passive toe joint

    , Article International Journal of Mechatronics and Automation ; Volume 6, Issue 2-3 , 2018 , Pages 83-93 ; 20451059 (ISSN) Taherifar, A ; Shariat, A ; Khezrian, R ; Zibafar, A ; Rashidi, A. R ; Rostami, H ; Vossoughi, G. R ; Selk Ghafari, A ; Sharif University of Technology
    Inderscience Enterprises Ltd  2018
    Several exoskeletons with various configurations and degrees-of-freedoms (DOFs) have been introduced in the literature, but not many have addressed the optimal selection of the mechanism's DOFs. In the proposed system a semi-passive toe joint is introduced to achieve several advantages. The performance of the proposed novel passive toe joint is evaluated experimentally. In addition, the semi-passive abduction/adduction DOFs in the hip joint and eversion/inversion DOFs in ankle joint is proposed to facilitate turning while providing more comfort during normal walking. The effect of passive DoFs existence on the user comfortability is studied with the aid of three kinematic indices. In the... 

    Design and fabrication of a new expandable transtibial liner with manual volume control: A prototype

    , Article Journal of Biomedical Physics and Engineering ; Volume 10, Issue 4 , 2020 , Pages 543-548 Nouri, M. J ; Aminian, G ; Farahmand, F ; Rahgozar, M ; Sharif University of Technology
    Shiraz University of Medical Sciences  2020
    Diurnal volume changes is one of the main factors influencing socket fit in trans-tibial prosthesis and causing pressure problem issues. Embedded bladder liners have been recently a potential approach to deal with this problem. The aim of this technical note was to introduce a new transtibial silicone liner designed based on hybrid socket theory. To make expandability in the liner, an integrated wax structure was constructed over the selected areas of the positive model and then removed after lamination process. In addition, a mechanical system with manual control was designed to fit the liner with the residual limb volume by pumping the water in or out of the liner through connec-tive... 

    The effect of temperature on eccentric contraction-induced isometric force loss in isolated perfused rat medial gastrocnemius muscle

    , Article Tehran University Medical Journal ; Volume 66, Issue 6 , 2008 , Pages 388-395 ; 16831764 (ISSN) Vasaghi Gharamaleki, B ; Keshavarz, M ; Gharibzadeh, S ; Marvi, H ; Mosayebnejad, J ; Ebrahimi Takamjani, E ; Sharif University of Technology
    Tehran University of Medical Sciences  2008
    Background: The typical features of eccentric exercise-induced muscle damage are delayed-onset muscle soreness (DOMS) and prolonged loss of muscle strength. It has been shown that passive warmth is effective in reducing muscle injury. Due to the interaction of different systems in vivo, we used isolated perfused medial gastrocnemius skeletal muscle to study the direct effect of temperature on the eccentric contraction-induced force loss. Methods: After femoral artery cannulation of a rat, the left medial gastrocnemius muscle was separated and then the entire lower limb was transferred into a prewarmed (35oC) chamber. With the chamber temperature at 31, 35 and 39oC before and during eccentric... 

    A fuzzy sequential locomotion mode recognition system for lower limb prosthesis control

    , Article 2017 25th Iranian Conference on Electrical Engineering, ICEE 2017, 2 May 2017 through 4 May 2017 ; 2017 , Pages 2153-2158 ; 9781509059638 (ISBN) Shahmoradi, S ; Bagheri Shouraki, S ; Sharif University of Technology
    Control of powered lower limb prostheses has a locomotion mode-dependent structure which demands a pattern recognizer that can classify the current locomotion mode and also detect transitions between them in an appropriate time. In order to achieve this goal, this paper presents a Fuzzy sequential locomotion mode recognition system to classify daily locomotion modes including level- walking, stair climbing, slope walking, standing and sitting using low-cost mechanical sensors. Since these signals have a quasi-periodic nature, using sequential pattern recognition tools, such as Hidden Markov Model(HMM) improves the recognition performance considering they use sequences of information to make... 

    Development and Implementation of a Control System for Minimum Interaction Force between Human and Lower Limb Exoskeleton

    , M.Sc. Thesis Sharif University of Technology Zibafar, Ahmad (Author) ; Vossoughi, Gholamreza (Supervisor)
    Nowadays exoskeltons are developed because of improvements carried out in mechatronic technologies, to use in applications such as human rehabilitation and power augmentation. By reason of interaction between exoskeleton robot and human, an appropriate control strategy should be considered to implement regulated interaction force between them. As an example there are situations that a person wants to carry heavy load with this robot without suffering from weight of the load, so control of robot movements is of great importance. The aim of this thesis is dedicated to develop and implement a control strategy achieving minimum ineraction force in a 2 degree of freedom lower limb exoskeleton.... 

    Design and Implementatioan of a Locomotion mode Recognition Algorithm for Powered Lower-Limb Prosthesis

    , M.Sc. Thesis Sharif University of Technology Shahmoradi, Sina (Author) ; Bagheri Shouraki, Saeed (Supervisor)
    Control of powered lower limb prostheses has a locomotion mode- ependent structure which demands a pattern recognizer that can classify the current locomotion mode and also detect transitions between them in an appropriate time. In the way to achieve this goal, this project presents a locomotion mode recognition system to classify daily locomotion modes consist of level- walking, stair climbing, slope walking, standing and sitting using low-cost mechanical sensors. Since these signals have a quasi-periodic nature, using sequential pattern recognition tools, such as Hidden Markov Model(HMM) improves the recognition performance,because they use sequences of information to make a decision. On... 

    Development and Implementation of a Wearable Robot Interaction Force Control Method Based on Switch Between the Swing and Stance Phases using Hybrid Systems Theory

    , M.Sc. Thesis Sharif University of Technology Safaeifar, Ali (Author) ; Vosoughi, Gholamreza (Supervisor)
    Exoskeleton robot is so useful because of the interaction with them and human and are used in rehabilitation and augmentation applications. These robots can be either passively or actively actuated. Human and robot interaction is an important issue involved with these robots. In this thesis, the interaction force reduction is considered leading to the transparency of a lower limb exoskeleton during switch between swing and stance phasees of walking. Achieving this goal, a robust Lyapunov based motion control method has been developed. The desired reference signals for motion control are generated using a direct force control approach. Robot accelerations are estimated by an observer to be... 

    Design and Implementation of an Intention-based Control System for a Lower Limb Exoskeleton by Combining Biological, Kinematic and Interaction Force Signals

    , M.Sc. Thesis Sharif University of Technology Salarkia, Morteza (Author) ; Vosoughi, Gholamreza (Supervisor)
    The goal of this project is to propose an algorithm to detect human motion intent during level walking. The primary aim of this algorithm should be to reduce human-robot interaction forces by combining EMG and force signals. Human gait is composed of 6 different stages. During each stage, each muscle is activated differently so it is possible to detect human intent by a pattern recognition technique. However, due to the fact that EMG signals are unrepeatable and noisy, we propose that combining EMG, motion and interaction force signals may lead to more concise and repeatable estimates of human motion intent. As a result, this control approach is expected to reduce human robot interaction... 

    Variable Impedance Control of the Lower Limb Exoskeleton

    , Ph.D. Dissertation Sharif University of Technology Taherifar, Ali (Author) ; Vossoughi, Gholamreza (Supervisor) ; Selk Ghafari, Ali (Co-Advisor)
    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... 

    Design and Implementation of Variable Impedance Control for Lower-Limb Exoskeletons with Desired Gate Refinement

    , M.Sc. Thesis Sharif University of Technology Asgari, Taha (Author) ; Vossoughi, Gholamreza (Supervisor)
    The main goal of this thesis is to develop and implement a variable Impedance control method with the ability to refine the desired gait in an online manner. For this purpose, a dataset consisting of 89 healthy gaits was utilized. Then, “Basic shapes” were driven using principal component analysis and their meaningfulness was investigated. Regarding the meaningfulness of coefficients of basic shapes, a normality metric was defined to evaluate the human gaits. Furthermore, as a reference gait refinement in Impedance control, an outer loop was added to change the desired gait, according to traversed gait. Kalman filter was used to estimate the coefficients of basic shapes in this loop. In... 

    Design and Implementation of a FES-Assisted Control for a Lower Limb Hybrid Exoskeleton Robot in order to Reduce the Robot Energy Consumption

    , M.Sc. Thesis Sharif University of Technology Karami, Mohammad (Author) ; Vosoughi, Gholamreza (Supervisor) ; Moradi, Hamed (Supervisor)
    Wearable robots, or exoskeletons, are electromechanical devices that aim to assist user by supplying additional mechanical power as needed. The interaction of these robots with humans and the possibility of robots using their various abilities such as intelligence, control power, sensors, etc., make one of the crucial components of these control algorithms, its interaction and integration with the user. In this regard, functional electrical stimulation is one way to use human abilities to control the robot and achieve broader goals. Adding functional electrical stimulation to a wearable robot creates an emerging group of robots called hybrid exoskeletons. Hybrid exoskeletons provide the... 

    Robust ground reaction force estimation and control of lower-limb prostheses: theory and simulation

    , Article IEEE Transactions on Systems, Man, and Cybernetics: Systems ; 2018 ; 21682216 (ISSN) Azimi, V ; Nguyen, T. T ; Sharifi, M ; Fakoorian, A ; Simon, D ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2018
    Ground reaction force (GRF) characteristics of amputee walking are important for the analysis of clinical gait data, and also to update model reference adaptive impedance (MRAI) controllers. GRF estimation is a better alternative than direct GRF measurement because of the disadvantages of load cells, such as high cost, integration difficulties due to weight and physical dimensions, the possibility of overload, and measurement noise. This paper presents four robust MRAI observer/controller combinations for GRF estimation-based control of a prosthesis and a legged robot model in the presence of parametric uncertainties and unmodeled dynamics, in which the robot model is employed to mimic... 

    vThe effect of saddle-assistive device on improving the gait parameters of patients with the lower limbs weakness: a pilot study

    , Article Journal of Bionic Engineering ; Volume 17, Issue 6 , 2020 , Pages 1175-1185 Hojjati Najafabadi, A ; Amini, S ; Farahmand, F ; Sharif University of Technology
    Springer  2020
    To help walking, using assistive devices can be considered to reduce the loads caused by weight and to effectively decrease the propulsive forces. In this study, a mobility Saddle-Assistive Device (S-AD) supporting body weight while walking was evaluated on two healthy volunteers. This device is based on the support of body weight against gravity with the help of a saddle, which is not used in other passive mobility assistive devices. To prove the efficiency of this device, the experimental results obtained while walking with this device were compared with those related to walking without the assistive device. The results showed that this device could significantly reduce the forces and... 

    Improving sit-to-stand transition by the saddle-assistive device in the spinal cord injury: A case study

    , Article Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine ; Volume 235, Issue 7 , 2021 , Pages 735-742 ; 09544119 (ISSN) Hojjati Najafabadi, A ; Amini, S ; Farahmand, F ; Sharif University of Technology
    SAGE Publications Ltd  2021
    Physical problems caused by fractures, aging, stroke, and accidents can reduce foot power; these, in the long term, can dwindle the muscles of the waist, thighs, and legs. These conditions provide the basis for the invalidism of the harmed people. In this study, a saddle-walker was designed and evaluated to help people suffering from spinal cord injury and patients with lower limb weakness. This S-AD works based on body weight support against the previously report designs. This saddle-walker consisted of a non-powered four-wheel walker helping to walk and a powered mechanism for the sit-to-stand (STS) transfer. A set of experiments were done on the STS in the use of the standard walker and... 

    Design and Implementation of a Control Strategy to Sustain Postural Stability for a Lower Limb Exoskeleton

    , M.Sc. Thesis Sharif University of Technology Khezrian, Reza (Author) ; Vosoughi, Gholamreza (Supervisor) ; Moradi, Hamed (Supervisor)
    Nowadays, the developments in control and robotics provide rehabilitation and power augmentation applications for the exoskeleton robots. In the rehabilitation applications, the goal is to help elderly and persons with paraplegia to do their daily activities and movements. One of this applications is to help these individuals for postural stability and recovering balance after receiving perturbations. In this research, we propose a control strategy for a lower limb exoskeleton to help the wearer to recover balance after a perturbation without using crutches. Here, we concentrate on the stance phase when a push is exerted to the robot and try to make the system quite upright. Therefore, a... 

    Design and Implementation of an Intelligent Control System Based-on Deep Reinforcement Learning for a Lower-limb Hybrid Exoskeleton Robot

    , M.Sc. Thesis Sharif University of Technology Koushki, Amir Reza (Author) ; Vossoughi, Gholamreza (Supervisor) ; Boroushaki, Mehrdad (Supervisor)
    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...