Sharif Digital Repository

In the navigation surgery, the real time tracking of surgeon tools and patient body are done in order to measure the precise information about the relative position of instruments, tissues and organs during surgery. Optical tracking is the most common system in the real time navigation surgery. The most important problem of the optical tracker is shadowing that obstacle between a marker and camera causes the data loose. It is obvious that in precise and sensitive surgery such as brain and neural surgery, losing the data of surgeon tool may cause irrecoverable injury for patient.The main goal of this study is design and implementation of new model for navigation surgery.We hope to... 

This thesis represents the obstacle avoidance of a fixed-wing small aircraft using optical flow information of cameras mounted on the aircraft. The thesis consists of two main sections. In section one, the ideal optical flow has been simulated based on the camera model, complete six DOF of flight equations, and the geometry of the environment. An analytical formula has been derived to relate the obstacle detection distance to the maneuverability of the aircraft. Having the obstacle detection distance, the control and navigation algorithms have been developed to achieve a collision-free flight for the aircraft in urban canyons and junctions. The effect of some parameters such as approach... 

One of the most important parts of the human’s body is spine. Its anatomy is very complex and has many degrees off freedom. Many kinds of diseases might occur for this part. One of the ways of treatment for this part is surgery that it has different types. In the past decades the surgeries have been done very simple without the help of computers or robots. In other words the surgeon did the surgery with no use of lateral tools. For this reason the error in those surgeries was high. Doing a surgery on the spine level needs a special attention. As the technology improved very much in the last 2 decades the amount of errors has been reduced and various kinds of techniques came in the scene to... 

Attitude estimation means calculating the state variables during the flight, especially in landing and takeoff phases. If we can extract the optical flow using the sensors mounted on the flying object, due to the fact that the optical flow is created by linear and rotational speed of the object relative to the surrounding, we are able to calculate the relative attitude by analyzing the optical flow. Indeed the purpose is developing this idea by using artificial neural networks.
First, we find the optical flow patterns for every attitude condition near the ground, using geometrical calculations. Then we produce an optimal neural network by these patterns. This network has the ability to... 

Control and guidance of a vehicle is vital for it to do its mission correctly. Guidance system and decisional algorithms used in it need exact information of instantaneous position, velocity, and attitude of the guided vehicle to determine and issue proper guiding commands.
Estimation algorithms and navigation sensors are two necessary tools for navigation. In the first section of present study, the satellite equations of motion are derived and a 6-DOF simulation is done for it. In the second section, measurements of star tracker will be simulated using results of the first section. The third section appertains to development of navigation equations, attitude determination using UKF... 

In this article, research has been carried out on the control technique of autonomous mobile robots to navigate in unknown environments, avoiding static and moving obstacles using eight ultrasonic sensors for obstacle recognition.
In this article we used simple three wheeled robots. Each robot has a passive caster wheel and two active fixed wheels which can act independently. In addition robots have holonomic constraints like maximum acceleration, maximum speed and maximum angular velocity, so robot’s speed and orientation change independently and these changes are small in each time step. Each robot has eight ultrasonic sensors, each of them cover 22.5 degree of space from robot‘s... 

Control and guidance of a vehicle is vital for it to do its mission correctly. Guidance system and decisional algorithms used in it need exact information of instantaneous position, velocity, and attitude of the guided vehicle to determine and issue proper guiding commands.
Estimation algorithms and navigation sensors are two necessary tools for navigation. In the first section of present study, the reentry head equations of motion are derived and a 6-DOF simulation is done for it. In the second section, measurements of sensors will be simulated using results of the first section and existing reference models for sun position vector and earth magnetic field. The third section appertains... 

In this thesis first a flrxible launch vehicle is modeled and simulated by taking the moment vibrations into consideration, then navigation system and it’s uncertainties which depicts more realistic performance are added up and the guidance is designed based on pitch-programming. Adaptive robust controller is designed and implemented with the approach of sliding mode such that making the system able to keep it’s despite of navigation uncertainties and flexibilities, also controlling the attitude in the framework of adaptivity and robustness  

Pose and motion estimation using a set of images is a common application in photogrammetry and one of the most popular methods in doing so is Bundle adjustment. This method later got adapted to the field of computer vision and is mainly used to reconstruct a 3d scene while also estimating pose and motion of the camera. There are a variety of other methods used to estimate pose and motion. Most non-visual methods like using inertial navigation system and GPS suffer from shortcomings like accumulative error, availability problems or low accuracy. While most vision based one are computationally expensive. In this thesis two methods are proposed to increase accuracy and efficiency of one variant... 

In this thesis, in order to improve the performance of the mobile robot navigation, a Fuzzy approach is used for making a safe path in the cluttered environment with hurdles in the work space of the robot. To this end, based on data collected from instantaneous location of the robot and location of the robot, heuristic rules are extracted. Also, in order to obtain optimal data fusion of the sensors, Kalman filter is used to localize the robot. In this regards, by using the kinematics of the robot and supposing the white noise in the process and measurements, the position and orientation of the mobile robot are estimated in a real-time and adaptive manner  

Navigation is the science of determining the velocity and attitude of a moving object in every given moment. There have been many methods for navigation. Nowadays with the advancement of technology, advanced navigation systems have been developed. Although each of these navigation systems have their pros and cons, in order to improve the overall performance of the system and to solve their problems, these systems are integrated.The goal of this project is to present an integrated cascade method to decrease error and also decrease dependence on GPS. In this project, INS, DVL & GPS are integrated with the cascade method.To achieve this, INS-GPS and INS-DVL integration are first performed. The... 

Autonomous underwater vehicle are among the subsurface vehicles used today in applications such as ocean floor mapping, environmental studies, finding the wreckage of drowned vehicles, and military applications such as finding mines. The need for control over the navigation components and the importance of the precise position of the mission have made AUV navigation an important issue in these vehicles. Due to the attenuation of the GPS signal underwater, it is not possible to use this method for subsurface navigation. Therefore, inertial navigation (dead reckoning navigation) is usually used for this purpose. Due to the unlimited growth of inertial sensor error over time, this error must be... 

Inspection of confined corridors is one of the important and necessary topics in various industries, including mines, oil and gas industries. Human inspection is very time-consuming and expensive due to the difficulty of accessing these environment, and in some corridors, it is not possible to inspect at all. In this thesis, UAV guidance and navigation algorithms have been developed by using informations got from optical flow, inertial and ultrasonic sensors, so that the UAV can fly automatically inside the confined corridor without colliding the boundaries. At first, a model of the space around the corridor, UAV and its subsystems has been proposed so that we can use it to create a...