Sharif Digital Repository

All humanare subject to a physiligical phenomenon known as tremor, which introduces unintended, relatively high frequency movments into various limbs. This involuntary movment is main reason of human disability in doing of precision tasks. Precision surgery like eye surgery is among them that surgeons must have very ittle tremor to enable them to oprate on the small anatomy of the eye. In this reaearch by emphasizing on reduction of muscle fatigue in precision surgery, weight balancing mechanism designed and analyzed. Fatigue is most important cause of tremor, thus we expected tremor amplitude reduce by reduction of muscle fatigue. Purpose mechanism is passive mechanism that balances the... 

Human joints wear gradually by diseases like arthrosis and will fail. The Pain from joint erode, preventing tracking daily activities, wont disappear by medicines and joint replacement is a common treatment. Hip joint as one of the most important, largest and heaviest joints of the body,is no exception.
Over 600,000 worldwide annual hip replacement surgery is done. The joints are designed in such a way that it can move 15 years without significant wear. Different materials such as ceramics, polymers and metals are used in making it which before in vivo use, itmust succeed many tests like wear test.
Since making artificial joints become increasingly important in recent years and... 

Functionally graded porous structures are very close to the bone tissue. Parameters that are related to the pore size and other parameters that determine mechanical properties, can closely represent properties of bone tissue. These parameters contain the percentage of the porosity and the pore size on the porosity side, and modulus of elasticity and yield stress from mechanical view. Calibrated structures with complex geometries, containing porous material, also can be produced by 3D printing technology. One application of porous structures is in production of dental implant with a cylindrical shape, containing a dense core, surrounded by a porous region. The aim of the present study is to... 

Dental implants should be biocompatible. This ability cause bone growth beside implant and increases stability of implant. Manufactoring method and materials used in implants are main parameters affectig biocompatibility of implants. Fabrication of functionally graded structures is a novel method to increase biocompatibility. Stress shielding is one of the main causes of failures in current dental implants. This phenomenon takes place due to different young modulus of dental implants and host bone. Pouros structures remedial this problem and implant’s young modulus comes closer to host bone. The aim of this project is to study feasibily of fabrication of functionally graded titanium dental... 

Flexible cones are one of the latest bone loss treatment methods in the ever-increasing revision total knee arthroplasty. This study is conducted to assess the biomechanical performance of the tibial flexible cellular cones in enhancing the initial stability of the implant system through the analysis of implant micromotion, as well as minimizing stress shielding through the analysis of strain distribution in the bone. The research evaluates the impact of various geometrical variables, including the thickness of the porous wall, the presence, type, width, number, and location of the inner solid wall notches on the spring stiffness and stress distribution of these cones. The research... 

Suture anchors are implants used for reattaching torn soft tissues to bone. Tilting anchors, a subtype of suture anchors, not only maintain the features of conventional suture anchors but can also be manufactured via 3D printing with a porous surface, enabling bone ingrowth and thus ensuring secure, long-term fixation. Additionally, these anchors can achieve fixation beneath the cortical bone layer, making them effective for secure attachment in areas of low bone density. Despite these advantages, limited research exists on this type of anchor, particularly regarding its performance and strength. One of the most influential factors in suture anchor strength is the method of fixation within... 

Bones adapt their form and structure to make an efficient use of their mass against the applied mechanical loads. So, it is not surprising to assume that the geometry and density distribution of a bone contains information about its loading history. The objective of this work was to develop a framework to simulate the bone remodeling procedure as a topology optimization process and then use this framework to develop a simple technique for estimating the dominant joint loads based on the bone’s density distribution.
At first, the remodeling equation was derived from the structural optimization task of minimizing the strain energy in each time step, using the level set method. Employment... 

In order to perform laparoscopic surgery of large intra-abdominal organs with minimum trauma on patient’s body, an endoscopic tool is designed, analyzed and fabricated in this project. This instrument is capable of passing through a 10mm incision point on patient’s abdomen and then be opened to grasp and hold large organs up to 80mm in diameter. It acts as a miniature hand with three fingers which are opened and closed parallel with each other. Using this tool, there will be no need for a 7-9 cm incision for entering surgeon hand which is required in hand assisted laparoscopic surgery method. In order to evaluate the capability of the tool in grasping and manipulating large organs, the... 

Walking on legs using orthosis for spinal cord injury patients has many advantages and decreases the physiological and psychological problems comparing with wheelchair application, however high energy consumption and early exhaustion of patients are disadvantages of orthosis usage. The most important group of orthosis for spinal cord injury patients is RGO (Reciprocating Gait Orhtosis) which a reciprocating cable mechanism links two hip joints motion. So swinging of mobile leg gets easier and stability of patient in standing and walking step increases. Regarding to existent reports about high energy consumption in walking by orthosis, this project has been fulfilled to design an improved... 

Common fracture treatments include open reduction and intramedullary nailing technology. However, these methods have disadvantages such as intraoperative X-ray radiation, delayed union or nonunion and postoperative rotation. Robots provide a novel solution to the aforementioned problems while having new challenges. The robotic system used in the study by providing more precise motion and exerting higher amount of forces makes the operation procedure more straightforward. In a normal operation 300-400 N of extension force would be needed which is fully provided by the surgen which leads to physical his/her (khastegi), by using the robotic system however, this force is simply provided without... 

In recent years, computer haptics research area have gradually grown all around the world. It deals with displaying the rendered contact properties in a virtual environment to a human user while interaction to a haptic interface. In general, a haptic interface provides essential haptic feedback information of a remote environment to a human user. The human operator, as a part of computer haptic system, will usually make an interaction by the haptic interface in a real environment which is usually limited to the end-effector of the physical device. On the other hand, the virtual tool in the virtual environment will interact by the virtual based remote environment which is generated from the... 

Sina surgical system is a telesurgery robotic system which is capable of using the conventional laparoscopic tools. In order to provide the wrist degree of freedom and increase the surgical maneuverability, a mechanism is introduced here which enables Sina to use and activate the wristed laparoscopic instrument Laparo-Angle. At first, the kinematics and dynamics characteristics of Laparo-Angle were identified experimentally. This tool contains 4 degrees of freedom, pitch, yaw, grasp and distal Roll. Activation of pitch and Yaw degrees of freedom requires a mechanism which at least has two rotational degrees of freedom to move the tool handle in a cone shape workspace with an apex angle of 36... 

A popular way for performing minimally invasive heart surgery is to use cardiac stabilizers that fix the heart during surgery. In the recent years several research works have been conducted to develop effective cardiac stabilizers. While these developments have attempted to improve fixation of the heart, there are reports indicating that a rigid cardiac stabilization may induce injury to heart muscle tissues due to restricting the heart motion in all directions. A more efficient approach than rigid cardiac stabilization might be to use a flexible cardiac stabilizer in combination with a surgical robot having motion compensation capability. The scope of this research is designing a device to... 

2D-3D image registration has been adopted in many clinical applications such as kinematic analysis of bones in knee and ankle joints. Because it is not possible to take dynamic images in 3D and 2D dynamic images such as fluoroscopic images lack spatial information. For comparing two images it’s necessary to make their dimensions the same. So in this research we prepared a code in MATLAB to generate digitally Reconstructed Radiograph (DRR) from the CT image in different positions and then be compared with 2D fluoroscopic image. Registering two images could be done either with comparing their intensities or their mutual features. We combined these two methods and developed a cost function with... 

In this study, pyrolysis features and corresponding kinetic behavior of non-metallic fractions of the paper-laminated phenol resin printed circuit boards (P-PCB) and fiberglass-reinforced epoxy resin printed circuit boards (E-PCB) were investigated by the use of simultaneous thermogravimetric analysis (TGA/DTG). The kinetic parameters of the P-PCB abs E-PCB during pyrolysis process were estimated from the experimental data by means of three iso-conversional kinetic models, including Friedman, Flynn-Wall-Ozawa (FWO), and Kissinger-Akahira-Sunose (KAS) methods. The activation energy range obtained for P-PCB and E-PCB utilizing the Friedman method was within 117–594.1 and 88.42-295.3 kJ.mol-1,... 

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... 

Human body movements are achieved by activating a number of muscles. It has been shown that the central nervous system (CNS) plays the main role in controlling rhythmic activities (including walking, chewing, etc.). However, the way the central nervous system works in controlling different parts of the body has always been discussed due to the excess degrees of freedom to perform certain tasks. Controlling a group of muscles (under the name of muscle synergy analysis) instead of each one of them has been one of the most attractive and efficient recent ideas to better understand the CNS function. Also, a similar concept can be expressed for kinematic synergies (by the degrees of freedom of... 

The mechanical interaction of a tilting anchor and cancellous bones of various densities was simulated using finite element modeling. The model enjoyed a sophisticated representation of the bone, as an elasto-plastic material with large deformation capability. The anchor’s tilting action during implantation phase, as well as its fixation stiffness during pull-out test, were predicted by the model, and a parametric study was performed to investigate the effects of the anchor’s distal width, corner fillet radius and bone engagement edge’s coefficient of friction (COF) on these measures. The model predictions were validated against the results of an experimental test on ovine humerus specimens.... 

Cerebral Palsy is the most common motor disability in childhood. It’s caused by an injury or impaired development of brain. As result, CP children have disability in motor system. All people with cerebral palsy have problem with movement. The symptoms of CP vary from person to person. Therefore, gait analysis was used to investigate those child’s problems and help therapist to find better therapy. Given that, we analyze stance phase of gait cycle of CP children. Also, we calculate and compare variability between traditional development (TD) children and CPs to find a better understanding of how central nerves system (CNS) work. Kinematic Data during walking were collected from 100 CP and TD... 

One of the most important problems in the field of robotic surgery is the measurement of the laparoscopic instrument Tip force. Many efforts have been made with the use of distal sensors to issues such as high cost and need to be disinfected, but the use of proximal sensors for estimating the Tip force of the tool is very rare, which can improve distal sensor problems.In this project, first, using data obtained from simulating a set-up for the Sina robot, two static MLP, and dynamic NARX neural networks are trained to evaluate the use of machine learning algorithms to determine whether the Tip force neural network can be used. Did the robot estimate Sina's surgeon? Then, by comparing this...