* Presenting Author DESIGN OF A STAND ALONE NAVIGATION SYSTEM USING POSITION ESTIMATION ALGORITHM M.Jayachandran 1 , J.Manikandan 2 and Yousef Hwegy 1* 1 Professor, Computer Engineering Department, Al-Fetah University, Tripoli, Libya. 2 Research Scholar, National Institute of Technology, Trichy, Tamil Nadu, India, ABSTRACT Pilot has to navigate the aircraft even when GPS is non-operational or when there is GPS drop-out. The major contribution in this paper is to provide the navigation information to the pilot on a cockpit display unit by using a standalone attitude and heading reference system and position estimation algorithm. To implement this using low-cost sensor for the navigation of aircraft is an extremely challenging area. This paper presents an approach called as dead reckoning by which aircrafts present position may be calculated from the knowledge of initial position and measurements of speed and acceleration. The navigation loop provides continuous and reliable navigation solutions to the guidance and flight control loop of the flight. The whole navigation algorithm shall be implemented within an embedded display system that receives attitude information. Fig.1 shows the block diagram of the proposed stand alone navigation system. An Attitude and Heading Reference System (AHRS) that gives information about attitude and heading angles, angular rates and angular accelerations is employed. The AHRS provides the roll angle, pitch angle, yaw angle, roll angular rates, pitch angular rates, yaw angular rates, x-accelerations, y-accelerations and z-accelerations parameters to the cockpit display unit in digital RS422 format. A self-customized RS422-to-RS232 level converter is designed [1] due to shortage of RS422 channels and availability of free RS232 channels in the cockpit display unit. The advantage of the converter is that it can be potted like a cable and can be used along with the wire harness. The cockpit display unit receives the information about the height of the aircraft above earth from the radio altimeter (RADALT) connected to it using analog input. The initial latitude and longitude information is also provided to the cockpit display unit from the flight control system of the aircraft. The parameters from various interfaces are used by the navigation algorithm proposed in this paper which when implemented in the cockpit display unit and the navigation page on the cockpit display unit displays latitude vs longitude information with the aircraft current position as dot. It may be noted that the display on the cockpit screen can be changed using switches on the front panel of display system to display various pages such as for target recognition [2], radar page and for navigation parameters based on the press of a switch. The cockpit display unit referred here is a stand-alone display, often called as Get-U-Home, whose interfaces are independent and is used by the pilot to return to the base when other cockpit displays doesn’t work. Fig. 1. Block Diagram of proposed Stand-alone Navigation System Dead reckoning allows a pilot to determine the aircraft’s present position by projecting its past courses steered and speeds over ground from a known past position. It also determines the future position by projecting an ordered course and speed of advance from a known present position. The dead reckoning position is only an approximate position because it does not allow for the effect of errors such as maneuvering or gyro error. In