Sharif Digital Repository

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... 

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... 

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... 

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... 

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... 

In this study, a practical approach for robotic beating heart surgery was proposed. This approach eliminates lateral movements of the heart and compensates for normal heart movement by using 1 DOF heart stabilizer and 1 DOF heart compensator simultaneously. It is a compromise between complete fixation of the heart, which damages the heart tissue, on one hand and complex and impractical compensation of the free heart movement on the other. One of the core components of the proposed system is the slave robot, which includes a 1 DOF compensator and a 4 DOF tool holder robot. Based on the selected laparoscopic tool, a modified agile-eye mechanism for activating the wrist was introduced,... 

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... 

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... 

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... 

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.... 

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... 

Hip replacement surgery is performed with the aim of relieving pain and restoring the normal function of the joint for patients who are in the final stages of arthritis. Standard prostheses offered by implant manufacturers come in a wide variety of models and sizes to meet the needs of patients. However, these commercial prostheses may not be suitable for patients with significant bony abnormalities, leading to implant instability and loosening. In such cases, a suitable solution is to use customized implants that are specifically designed to match the patient's unique anatomy. The purpose of this research was to design a customized cement stem for hip joint replacement surgery in patients... 

The main goal of this project is to design and implementation of the tissue auto-grasping algorithm for a wristed laparoscopic instrument. In this algorithm, the difference between the pinch forces of two jaws was taken into account when the pull force direction corresponding to the rod instrument direction was changed. The term ‘Tissue auto-grasping’ means automatic adjustment of the pinch force corresponding to the pull force exerted on the tissue by the robotic surgical instrument, so that slip and exerting excessive force on the tissue are prevented. In this study, obtaining the pinch force is based on the proximal force-sensing technique. For this reason, the force model of wristed... 

The human brain is the most sensitive and important human organ and surgery must be done with high precision and without risk. During surgery, brain tissue deform continuously due to gravity, out of the cerebrospinal fluid and the changing pressure of the cerebrospinal fluid and the surgical maneuvers. Because the surgeon has no direct view on brain internal, the ways to solve this problem is to pay attention. This method makes it possible to the surgeon see in the brain and the brain tissue deformation. This thesis method is based on biomechanical modeling. After forming finite element model from the pre-operative MRI, brain surface and volume datasets during surgery as a load, apply to the... 

in laparoscopic surgeries, act zone tissues are not directly palpable for the surgeon. Therefore, evaluating the mechanical behavior of the tissue and distinguishing healthiness or illness of that, are not achievable for the surgeon. In this treatise, the matter of discerning the soft and bulky tissues mechanical properties by a robotic arm during the laparoscopic surgery, is regarded. In first step, a tool like a two finger miniature hand was designed in which either of fingers have utilized a parallelogram mechanism for opening and closing. The dimensional design of the mechanism was undertake in away that the tool has the ability of going through a 10mm diameter path and grabbling and... 

During femur fracture reduction surgery, both patients and surgeons are exposed to a great amount of radiation, which is harmful to their health. Computer-assisted orthopaedic surgery (CAOS) is a less invasive approach for its ability to reduce the usage of image intensifiers. Various robots have been developed for femur fracture reduction surgery. Most of these robots are based on serial architectures. Both low load-carrying capacity and poor accuracy are inherent to serial robots, which makes them inappropriate for femur fracture reduction. Some parallel robots using the “Stewart platform” have also been developed for femur fracture reduction, but their restricted workspace limits their... 

Measurement of laparoscopic instrument tip forces plays an important role in the research area of controlling robotic surgeries. The first attempts in this topic were estimating the tip forces using distal force sensors, but these methods were too expensive and required sterilization. On the other hand, proximal sensors do not suffer from the distal sensors problems, however, they were not used to estimate the instrument tip force in previous works. In this regard, the effectiveness of proximal sensors in this project was investigated. To do so, firstly, an appropriate plan for estimating the forces of the laparoscopic instrument’s tip was found using a proximal force sensor, located at the... 

Minimally invasive surgery (MIS) is a new surgical technique in which surgery is performed using smart instruments and viewing apparatus inserted through a very small incision rather than by making a large incision to expose, and afford access to the operation site. Piezo film force sensor can be used in MIS graspers for providing tactile data to overcome problems such as lack of sense of touch or to find hidden arteries.This thesis, investigates fundamental understanding of piezo film sensor especially when we want to connect these sensors to measurement units.Two different approaches for signal conditioning the sensor have been proposed and circuits have been fabricated. Several...