Sharif Digital Repository

The primary objective of this dissertation is to obtain a mechanism from the family of 5-dof parallel mechanisms of type 3T2R which gains the advantages of higher kinematic performance, low coupling of motion, and simple kinematics and control commands. Based on this aim, at first a method for structural synthesis of this type of mechanisms is introduced. The method is based on the theory of linear transformation and a geometrical analysis. By using this method, a set of novel 5-dof 3T2R parallel mechanism are introduced for the first time in the literature. In order to compare the designed mechanisms and to identify the promising ones, some important criteria which are a) low coupling... 

The goal of fracture reduction in orthopedic surgery is to reposition the bone fragments in their anatomical orientation (alignment), and the fracture ends closed to each other (apposition). Reduction of long bone fractures is became an interesting subject in the field of robotic aided surgery in pervious decade. Nowadays reduction of femur is carried out by surgeons and medical staff in surgery. Due to the large holding forces necessary, exact positioning is difficult and time consuming. What is needed is an automated system whereby the fractured ends of the bone may be precisely positioned without the need for multiple docking attempts. The fragments need to be held in place as long as... 

Microrobots design and manufacturing has been one of interesting fields in robotics in recent decades. They have been designed in various types so far. In this paper a two-leg microrobot is simulated and controlled by using LuGre friction model.
The proposed microrobot is driven by a piezoelectric actuator mounted between centers of two legs. The piezoelectric is actuated by a frequency near the natural frequency of the robot. The nonlinear dynamical equations of the system are obtained considering LuGre friction model. To control the system, the equations of motion are linearized using feedback linearization method. Then a stabilizing control law is designed and the robot model is... 

Impedance measurement is one of the most efficient electrochemical methods to investigate the mechanism and kinetics of electrode reactions. This method can detect the steps of successive or parallel electron and mass transfer chemical reactions based on measuring the response time constant. The method of showing results, commonly known as Nyquist diagram,which is based on drawing real and imaginary components of the impedance, with respect to each other in different measurement frequencies, is very useful for determining the mechanism of electrode reactions and the kinetic measurements. The main objective of this thesis is totheoretically determine the impedance response of six... 

Direct in vivo measurements of spinal loads and muscle forces are invasive. Investigators have thus used musculoskeletal biomechanical models that require kinematic data including trunk and pelvis angular movements as their inputs. . Novel devices measure anglular movements using both inertial sensors (such as gyroscopes and accelerometers) and miniature magnetometers. Relative low cost, portability, and accuracy are among specific characteristics of inertial tracking devices. The main objective of the present study was set to measure spinal kinematics including the lumbopelvic rhythm as the ratio of total lumbar rotation over pelvic rotation during trunk sagittal movement which is essential... 

Manual material handling (MMH) activities are identified as risk factors for occupational low back pain (LBP). Task-related variables including load and posture characteristics are required as input into these models and tools for estimation of trunk external moment. Biomechanical modeling studies that aim to mathematically estimate low back loads currently need an inevitable parallel time-consuming in vivo study in an equipped laboratory to measure trunk posture under physical activities. Inertial sensors as a portable, accurate, almost inexpensive, and small device could be very helpful in order to capture the kinematic data of movement in human activities. My master thesis aims to... 

During the past decade, micromachining technology has become available to fabricate micron-sized mechanical parts. The miniaturization of almost all types of devices and systems is arguably a greater opportunity for commercial profit and beneficial technological advances (e.g., micromechanical, microfluidic, microthermal, micromagnetic, microoptical and microchemical). However, instead of the traditional evolutionary engineering effort to reduce size and power while simultaneously increasing the performance of such a diverse set of systems, the field of microelectromechanical systems (MEMS) represents an effort to radically transform the scale, performance and cost of these systems by... 

Today, obesity, as a major global health challenge, affects more than 30 percent of the world's population. To investigate the effect of obesity on spinal function, a common method is motion analysis (kinematic method). This method is based on the claim that the abnormal mechanical function of the spine is directly related to its abnormal motions.The aim of this study is to measure and compare the range of motions (RoMs) of different segments of the spine in all anatomical plates between obese and normal individuals, as well as to calculate and compare some motion rhythms between the lumbar spine and the pelvis in these two groups. Comparing the posture of the spine between obese and normal... 

Every year, a significant number of people around the world suffer from anterior cruciate ligament injury. Rapid and low-cost diagnosis of anterior cruciate ligament injury is important to prevent further complications as well as timely treatment. Due to the disadvantages of each diagnostic methods, the development of alternative methods for diagnosing anterior cruciate ligament injury is still of interest to researchers. Meanwhile, several studies have shown that the kinematics of the knee joint are different for injured and healthy anterior cruciate ligament. Due to the capability of inertial sensors for kinematic measurement of joints, their use to diagnose damaged anterior cruciate... 

Objective: To assess adequacy of the National Institute for Occupational Safety and Health (NIOSH) Lifting Equation (NLE) in controlling lumbar spine loads below their recommended action limits during load-handling activities in the stoop and squat using a detailed musculoskeletal model,that is, the AnyBody Modeling System.Background: The NIOSH committee employed simplistic biomechanical models for the calculation of the spine compressive loads with no estimates of the shear loads. In addition, NLE does not include the posture of the knee during manual material handling. It is therefore unknown whether the NLE would adequately control lumbar compression and shear loads below their... 

Background: Degeneration of intervertebral joints due to kinetical alterations after fusion surgery is a prevalent back disorder. While in-vivo studies are limited to medical imaging techniques, in-vitro and in-silico (passive FE modeling) investigations lack the crucial role of muscle forces. Available musculoskeletal modeling studies, not only suffer oversimplification of intervertebral joints, but have some shortcomings in incorporation of the contributing factors (that may alter postoperative kinetics). On the other hand, one of the main shortcomings in the available musculoskeletal models is their inability to account for dynamic effects and modeling transient events. Purpose: 1-...