Sharif Digital Repository

This thesis deals with the attitude estimation based on low cost sensor for a micro satellite in a circular, low earth orbit (LEO) and sensor calibration. With two body problem theory and Quaternion formulation, rotational motion is modeled. In addition gravity gradient effect is considered on satellite orbital elements. Using a 3-axis MEMS-based magnetometer and a sun sensor as two measurement systems, low cost attitude estimation is proposed. Bias and Scale factor are presented to model deterministic sensor error and white Gaussian noise to model stochastic sensor error. It is shown that by sensor calibration the estimation accuracy will improve. Non-linear estimation methods EKF, SRUKF... 

In this thesis, the orbit determination of Low Earth Orbits (LEO) using the integrated magnetometer and horizon sensor data has been investigated. Orbit determination is an essential part of a space mission. Not only the modeling, guidance, navigation and control errors may results in error in injecting the satellite into its nominal orbit, the environmental disturbances deviate the satellite from its predicted orbit and from an operational perspective most satellites need continuous orbit determination. Traditionally, ground based orbit determination is used which are non-autonomous and expensive and just can be used for specific times which the satellite can be observed from the ground... 

Ultra-sensitive magnetometers based on Radio Frequency Superconducting Quantum Interference Device (rf SQUID), have wide applications in Non-destructive Evaluation (NDE), geophysical measurements and biomagnetic measurements, especially in magnetocardiography (MCG) systems. A superconducting module coupled to rf SQUID is designed to provide a resonance frequency in GHz range (according to the electronic system frequency), as well as concentrating the magnetic flux in the effective area of SQUID. The signal can be measured through a port pumping AC power to the module. The resonator has been also implemented by lumped element tank circuits, but the quality factor of these circuits are usually... 

The attitude determination (AD) and control system (ADCS) tasks in an operational satellite includes attitude determination, stabilization and pointing against internal and external disturbance moments. Where these tasks are carried out using several sensors, actuators as well as some pertinent attitude determination algorithms. In this sense, the magnetometer (MAG) sensor is among the most common sensors used to attitude estimation that can be utilized in association of reaction wheels (RWs) as a reliable and efficient actuation mechanism for a three-axis attitude control satellite. Unfortunately, RWs generate magnetic field disturbances during operation as commanded by ADCS that adversely... 

This thesis deals with the construction of software tools necessary to calculate the position and orientation of the robot. The aim of this project is to use accelerometer, gyroscope, magnetometer and GPS sensors; Determine the position and orientation of the robot where the mobile phone is located. The proposed sensors are used to measure acceleration, angular velocity and magnetic field in 3 axes, respectively. GPS is also a system for calculating the position using signals received from satellites. To do this, an Android application has been designed and written in Java. The sensor information is collected by the software designed in the mobile phone and after proper coding is sent to a...