Sharif Digital Repository

Fuzzy Control of rowing exercise using Functional Electrical Stimulation (FES) concerns ankle, knee and hip joints. Muscular Modeling for each joint may contain two groups of muscles, namely extension and flexion. In the proposed method, joint controllers provide electrical stimulation pulses to the appropriate muscle group based on the trajectory error and according to a prescribed pattern designed for rowing exercise. Results indicate that the simulated Fuzzy control of desired angles closely match the experimental values for prescribed joints. Moreover, the robustness of the controller in presence of external disturbance is examined and the results show that the tracking of each joint... 

The reverse shoulder implant is an implant for total replacement of the glenohumeral joint of patients suffering from osteoarthritis and with a damaged rotator cuff. The problem that arises with these conjoined ailments is that the displacement of the humeral head causes limited movement of the upper limb, with vertical mobility restricted to only allow for the arm to ascend to roughly the height of the shoulder. Attaching the ball to the scapula and the socket to the top of the humerus fixes the centre of rotation of the joint to increase the moment arm over the healthy shoulder's original position enabling patients' movement and dexterity to return. In this study the numerical evaluation... 

With increasing importance of exoskeletons as rehabilitation apparatuses, suitable and delicate control strategies has received much attention. In order to control the exoskeleton, there should be a complete understanding of torques produced by the limb itself which makes the musculoskeletal modeling of the limb essential but also complex. In addition, the musculoskeletal model can be used to discover the user's desired movement to control the exoskeleton. In this paper a complete musculoskeletal model for the elbow with two degrees of freedom is developed and simulated. Next the model is used to determine user's desired movement. Finally based on this evaluation, an exoskeleton model is... 

A two-dimensional, seven link, nine degrees of freedom biped model was developed to investigate the dynamic characteristics of normal and transfemoral amputee locomotion during the entire gait cycle. The equations of motion were derived using the Lagrange method and the stance foot-ground contact was simulated using a five-point penetration model. The joint driving torques were obtained using forward dynamic optimization of the normal human gait and applied to the intact joints of the amputee. Three types of motion controllers; frictional, elastic and hydraulic were considered for the prosthetic joints of the amputee and their design parameters were optimized to achieve the closest... 

A two-dimensional seven link biped dynamic model was developed to investigate the mechanical characteristics of the normal and amputee locomotion during the complete gait cycle. The foot-ground contact was simulated using a five-point penetration contact model. The equations of motion were derived using Lagrange method. Optimization of the normal human walking model provided constant coefficients for the driving torque equations that could reasonably reproduce the normal kinematical pattern. The resulting torques were then applied to the intact joints of the amputee model with a prosthetic leg equipped with a kinematical driver controller for the ankle and either a hydraulic, elastic or... 

Loss of lower extremities has been one of the main problems in human life. Although most of the available knee devices are aesthetically acceptable, there is a necessity for lighter and more compact mechanisms, especially for younger amputees. This problem can be solved by the combining compliant mechanism design with traditional mechanism design methods. In this study, one group of the prosthetics that is known as the compliant knee mechanisms" is evaluated. At first, the different knee mechanisms, such as fourand six-bar knee linkages are investigated to calculate the values of the control moments (actuator torque). Then, the suitable location (where the actuator torque is to be exerted)... 

To date various commercial systems have been used in the GAIT analysis. These systems have some difficulties for clinical use, such as interfering with normal movement and high prices. The possibility of utilization of Kinect as a sensor for GAIT analysis has been studied in this research. The accuracy of Kinect in calculation of GAIT parameters such as lower limb joint angles, stride time, and stride length were computed during normal walking. The effects of the sensor's position and direction relative to the walkway were also investigated. The Kinect sensor was installed at different positions toward the motion path. In each position the data was recorded by both Kinect and a commercial... 

In this paper, two online path planning methods are presented for SURENA III humanoid robot by using model predictive control scheme. The methods are general control schemes which can generate the online motions for walking of a humanoid robot. For lowering computational costs a three dimensional linear inverted pendulum model is used instead of the full dynamical model of the robot. The generated trajectories are then used for computing the zero-moment point (ZMP) of the robot and the joint torques. The resulted joint torques of the two methods are compared to torques obtained from Genetic Algorithm (GA) path planning method presented for SURENA III humanoid robot in previous studies. The... 

Animal walking is one of the most robust and adaptive locomotion mechanisms in the nature, involves sophisticated interactions between neural and biomechanical levels. It has been suggested that the coordination of this process is done in a hierarchy of levels. The lower layer contains autonomous interactions between muscles and spinal cord and the higher layer (e.g. the brain cortex) interferes when needed. Inspiringly, in this study we present a hierarchical control architecture with a state of the art intrinsic online learning mechanism for a dynamically walking 5-link biped robot with compliant knee joints. As the biological counterpart, the system is controlled by independent control... 

Motion capture systems are used to gauge the kinematic features of the motion in numerous fields of research. Despite superb accuracy performance, the commercial systems are costly and difficult to use. To solve these issues, Kinect has been proposed as a low-priced markerless motion capture sensor, and its accuracy has been assessed using previous motion capture systems. However, in many of these studies, the anatomical joint angles captured using the Kinect are compared to the 3D rotation angles reported by the gold standard motion capture systems. These incompatibilities in the determination of the human joint angles can lead to higher error estimation. To accomplish a valid accuracy... 

This study addresses optimal walking pattern generation for SURENA III humanoid robot in a stair-climbing scenario. To this end, the kinematic configuration of the 31-DOF humanoid robot is studied. Integrating the detailed dynamic properties of the robot, a comprehensive and precise dynamic model is developed for its lower-limb. In order to generate the optimal walking pattern for the considered humanoid robot, trajectories for feet and pelvis are first designed, and then joint angles are derived by means of inverse kinematics. Such a complete model provides the designer with the necessary tools to optimize the trajectory generation. Using two different types of objective functions, namely... 

This paper focuses on the biomechanical aspects of human load carrying in order to provide a physiological framework for designing the more anthropometric assistive systems. An 8degrees-of-freedom musculoskeletal model with twenty functional muscle groups in the lower extremity was developed to simulate the movement in sagittal plane. Inverse dynamics based optimization approach was employed to estimate the excitation level of the muscles. Activation patterns of the muscles illustrate the importance role of the soleus in supporting of the body during load carrying. Also power distribution analysis of the muscles reveals that the plantar flexors of the ankle, extensors of the knee and hip... 

An approximate method is presented that can be used to determine the nonlinear behavior of a new structural bracing system called the 'Chevron Knee Bracing' (CKB). In this framing system, an especial form of diagonal brace connected to a knee element instead of a beam-column joint is investigated. The diagonal element provides lateral stiffness during a moderate earthquake. However, the knee element is designed to have three plastic joints or two yielded specimens in flexural and shear yielding mode, respectively, for dissipation of the energy caused by a strong earthquake. This article demonstrates the transformation of a complex problem into a new, practical set of design charts and... 

In this paper, a new structural lateral bracing system called 'Chevron Knee Bracing' (CKB) is investigated. This new form of framing system is constructed through the knee and the diagonal brace elements. The knee part is a fuse-like component that dissipates energy by the formation of plastic flexural and/or shear hinges at its ends and mid-span, when the building is subjected to severe lateral loads. However, the diagonal brace component, on the other hand, provides the required level of lateral stiffness and remains in the elastic range without buckling at any time. In this investigation, first, by studying of the system in the elastic region, three new and practical parameters are... 

In this study, a 3-DOF dynamic model is developed for the lower limb in the cycling activity using Lagrangian mechanics. An exponential reaching law sliding mode controller is then applied to the system in order to imitate the joints' real motion. The kinematic data of the joints are obtained through conducting experiments with an ergometer bike. Results show acceptable tracking performance for the control system. The study's outcome can be used by rehabilitation experts in their work. It is also useful for the engineers in designing rehabilitation devices or developing muscular models. © 2022 IEEE  

The optimal design of complex systems in engineering requires pursuing rigorous mathematical modeling of the system's behavior as a function of a set of design variables to achieve goal-oriented design. Despite the success of current knee implants, the limited life span remains the main concern of this complex system. The mismatch between the properties of engineered biomaterials and those of biological materials leads to insufficient bonding with bone, stress shielding effects and wear problems (i.e. aseptic loosening). The use of a functionally graded material (FGM) for the femoral component of knee implants is attractive because the properties can be designed to vary in a certain pattern... 

In this study, a new structural bracing system named 'Hat Knee Bracing' (HKB) is presented. In this structural system, a special form of diagonal braces, which is connected to the knee elements instead of beam-column joints, is investigated. The diagonal elements provide lateral stiffness during moderate earthquakes. However the knee elements, which is a fuse-like component, is designed to have one plastic joint in the knee elements for dissipation of the energy caused by strong earthquake. First, a suitable shape for brace and knee elements is proposed through elastic studying of the system and several practical parameters are established. Afterward, by developing applicable and highly... 

There is ambiguity on the quantitative validity of the predictions revealed by musculoskeletal models for muscle forces. This study investigated the consistency between the predictions of a musculoskeletal model of the upper limb and the experimental data for a number of different subjects and functional tasks. Six normal subjects performed isokinetic eccentric or isotonic concentric contraction tests of the wrist muscles in well controlled conditions, using a robotic apparatus, and the net joint torque and angular velocities, as well as the surface electromyograms (EMG) signals of the muscles, were recorded. The experiments were then simulated using a parametric musculoskeletal model of... 

This paper proposes a new method to improve accuracy and real-time performance of inertial joint angle estimation for upper limb rehabilitation applications by modeling body acceleration and adding low-cost markerless optical position sensors. A method based on a combination of the 3D rigid body kinematic equations and Denavit-Hartenberg (DH) convention is used to model body acceleration. Using this model, body acceleration measurements of the accelerometer are utilized to increase linearization order and compensate for body acceleration perturbations. To correct for the sensor-to-segment misalignment of the inertial sensors, position measurements of a low-cost markerless position sensor are... 

This paper focuses on the biomechanical aspects of the human lower extremity loading condition during backpack load carrying. A biomechanical framework was generated with the aim of employing a block-oriented structure of Simulink integrated with the Virtual Reality Toolbox of MATLAB software to provide a simulation study of the musculoskeletal system in a virtual environment. In this case, a ten-degrees-of-freedom musculoskeletal model actuated with sixteen muscles in each leg was utilized to simulate movement in the sagittal plane. An inverse dynamics based optimization approach was employed to estimate the excitation level of the muscles. In addition, distributions of the mechanical power...