www.tjprc.org editor@tjprc.org International Journal of Electrical and Electronics Engineering Research (IJEEER) ISSN(P): 2250-155X; ISSN(E): 2278-943X Vol. 4, Issue 2, Apr 2014, 65-70 © TJPRC Pvt. Ltd. ROBUST CONTROLLER FOR AIRCRAFT YAW K. VIJAYAKRIS HNA 1 & P. R. SAGAR 2 1 Department of Electrical, PVP Siddhartha Institute of Technology, Kanuru, Vijayawada, Andhra Pradesh, India 2 Department of Aeronautical, PVP Siddhartha Institute of Technology, Kanuru, Vijayawada, Andhra Pradesh, India ABSTRACT In general, yaw control of aircraft plays a major role. It is controlled by rudder deflection by creating side force with help of rudder pedals. The aircraft yaw is controlled by several methods such as Fuzzy logic, linear quadratic controller (LQR), optimal pole placement method. These methodologies achieved only the transient response, but failed to obtain the steady state response. There are some cases, where the steady state response is necessary. In this res earch paper, we propose a new methodology called Linear Algebraic approach, where both the transient and steady state responses are achieved and the disturbance conditions are totally suppressed. KEYWORDS: Aircraft, Flight Control, Two Parameter, Yaw, Rudder, Disturbance Suppression INTRODUCTION After the first flights, articulated control surfaces were introduced for basic control which is operated by the pilot through a system of cables and pulleys. This technique survived for decades and at present used for small airplanes. The solution to this problem was made by the introduction of aero dynamic balances and tabs. But further growth of the aircraft and flight envelopes enhanced the need of powered systems to control the articulated aerodynamic surfaces. Modern aircraft include a variety of automatic control system that aids the flight crew in navigation, flight management and augmenting the stability characteristic of the airplane. Designing an autopilot requires control system theory background and knowledge of stability derivatives at different altitudes and Mach numbers for a given airplane . Aircraft have a number of different control surfaces: the primary flight controls are pitch, roll and yaw controls which are controlled by deflection of elevators, ailerons and rudder. Yaw is controlled by the rudder. The pilot moves the rudder sideways and the necessary yaw angle to change the direction of the flight as per requirement of mission profile of the aircraft. A modern controller (LQR) and intelligent fuzzy logic controller (FLC) is Developed for control the yaw of an aircraft system, but it failed to suppress the disturbances. In this research paper, the control system design for yaw control is designed. A feed forward and feedback controller design is developed for control of the yaw of an aircraft system. In this the disturbances are totally suppressed based on the wind axis direction and flight path envelope. MODELING OF YAW CONTROL System Two types of dynamical equations are present for an aircraft. The lateral dynamic equations of motion, which represents the dynamics of aircraft with respect to lateral axis and longitudinal dynamic equations of motion which