Sharif Digital Repository

Human walking is widely recognized as one of the most adaptable and robust forms of locomotion in nature, with intricate neural and biomechanical systems interacting to support this complex behavior. It is proposed that these systems are organized in a hierarchical structure, with the lower level comprising a complex distributed system consisting of muscles and the spinal cord, and the higher level being the brain cortex. The higher level is responsible for training and monitoring the output of the lower level, and intervening when the lower system fails to stabilize the system. To control the lower level, one popular model that has emerged is the central pattern generator (CPG). It is... 

Disorders of the lumbar spine are prevalent within the realm of musculoskeletal issues, emphasizing the importance of investigating contributing factors. This research focuses on assessing how flexible footwear influences the kinematics and dynamics of the vertebral column during drop vertical jump. The study involves mechanical tests on various footwear types, including simple, flexible and re entrant shoes with differing levels of rigidity. Bending tests were performed on simple and flexible shoes with hardness of 50 Asker C and flexible shoes with hardness of 40 Asker C. Additionally, compression tests were carried out on all soles at two different angles. The Bending tests revealed that,... 

With technological advances in fabrication and control of prosthesis and assistive devices the importance of such systems has increased drastically. On the other hand the appropriate coupling of these devices, especially the exoskeletal systems with the upper or lower extremities is of immense importance as it is an integral part of the control system. In particular, the control strategy and its ability to adapt the exoskeletal system with the existing and physiological functionality of the user, is an integral part of the system requirement. In the controller implementation, a number of methods are proposed including using the excitation signal, similar to the existing neuromuscular system.... 

The main scope of this research is to develop an anthropometric lower extremity exoskeleal system in a virtual environment for augmentation purposes. The main challenge in the process of doing this research is to employ the biomechanical analysis of the human locomotion to provide the necessary background information for the design of devices that closely mimic the dynamics of the operator's motion. In this case, the appropriate degrees-of-freedom and associated range of motions for each joint should be determined. In addition, the kind of necessary actuators and measurement systems should be selected based on the muscle torque consumption analysis provided by a musculoskeletal model,... 

Some of the most usual problems in rehabilitation are ankle joint disabilities which are caused by stroke or damages like ankle twist and disrupt the movement activities. So rehabilitation of this joint which has important role in daily activities like walking is of high importance.
The aim of this research is design of an unwearable robot for rehabilitation of ankle. After the study of several different mechanisms, this robot was designed based on a 2 DOF mechanism named “Agile Eye”. Based on the mechanism and parametrical analysis, final design of this robot was drafted using optimization method. Next, the musculoskeletal model of lower limb was created in MATLAB and by using this... 

Disconnections in neural paths from the central nervous system to the muscles or vice versa cause different neuropathies, thus paralysis in different limbs may occur. As a result of the lack of muscular activity and the decrease in blood perfusion in paralyzed limbs, problems like osteoporosis, increase in the risk of breaking, decline in muscle size, cardiovascular diseases, renal dysfunction, bedsores, etc may happen. In order to induce movement in paralyzed limbs, thus preventingmentioned problems, rowing exercise through Functional Electrical Stimulation (FES) may be utilized. In FES, electrical Stimulation using current stimulating pulses is applied to contracting and relaxing muscles,... 

Spasticity is a common phenomenon following stroke, which causes increase in muscle resistance to imposed movements. Most of the clinical measurements used by physiotherapists to evaluate spasticity are qualitative. Consequently, the reported results are subjective. The objective of this study was to develop a musculoskeletal model of the upper limb to simulate spasticity of muscles activating in wrist flexion-extension. Subjects in two groups of normal and stroke survivors participated in this study. Six normal subjects and three hemiplegia patients were exercised by the robotic instrument. Simultaneously, the resistive moment, the wrist joint position and the EMG of muscles were recorded.... 

Fixation devices and implants are the most applied devices in orthopedic operation and dentistry. Interference screw is one of these devices that is made by biodegradable nanocomposite polymeric materials in this project. The purpose of this project is designing interference screw, applicable to body, and doing related tests since in vivo tests. For this purpose, hand injection molding, was designed to prepare screws in laboratory scale, first. For making samples, poly(D,L) lacticacid, nano hydroxyapatite as reinforce and polyethylene glycol as plasticizer were used. These samples were made by combination of solvent casting and melt processing methods. Adding nano hydroxyapatite and... 

The behavior movement of human is fundamentally concerned with the relationship between the central nervous system of motor control، and musculoskeletal system of a human. Optimal control was employed to relate these structures together. Movement is one of the important part of human life، CNS is important because it has the fundamental role in the movement. Investigators believe that CNS is learned by iteration movements from childhood and finally it chooses the movement that makes a cost function minimum value of itself. Researching for CNS modeling grows in recent years on the different part of human body. Because upper body have less difficulty in movements، it is more useful for CNS...