BALLISTIC MISSILE DEFENSE SYSTEMS

Abstract

A successful Guidance, Navigation, and Control (GNC) system for ballistics defence system is critical to a target tracking scenario's success. This thesis applies a GNC system and compares it to state-of-the-art systems that are extensively used today. The work contains an autopilot, guiding law, target tracking law, and a dependable inertial navigation system capable of precisely operating an agile vehicle such as a UAV, missile, or other vehicle utilizing available sensor data. The GNC system is simulated using a non-linear generic missile model in a MATLAB/Simulink environment. The control system is the first component of the GNC system to be examined. Two types of autopilots are contemplated: The commonly used three-loop autopilot is the initial design. The autopilot determines the ideal missile fin deflections to travel towards a target based on the guidance system's intended acceleration directives. The second configuration utilizes two decoupled autopilots for lateral and longitudinal control, with course and flight-path-angle serving as reference commands. Fin deflections are generated to achieve the required missile orientation using a Linear-Quadratic Regulator (LQR) based on the linearized generic missile model. By incorporating extra input from sideslip and angle-of-attack derivatives, performance and resilience features are increased. The navigation system is the second component of the GNC system to be explored. Without trustworthy sensors and filters, other control loop subsystems will lose track of the vehicle's Position, Velocity, and Attitude (PVA). To achieve vehicle state convergence, a Multiplicative Extended Kalman Filter (MEKF) supported by Global Navigation Satellite Systems (GNSS) and gyro and acceleration biases is generated. The MEKF is distinguished from the regular Extended Kalman Filter (EKF) by the fact that it updates the Inertial Navigation System (INS) attitude calculations through quaternion multiplication, resulting in the inclusion of the vi multiplicative property. When calculating guiding instructions in a target-tracking situation, it is critical to have information about the target's location, velocity, and, in certain circumstances, acceleration. Along with the INS-provided estimated missile states, a target-tracking Kalman Filter (KF) is used to monitor the relative states of the target and missile. Finally, two guideline laws are compared to finalize the GNC design. The well known Proportional Navigation (PN) rule is compared to a Line-Of-Sight (LOS) system with a course and flightpath-angle controlled autopilot. By assuming independent control of the horizontal and vertical planes, LOS guidance aims to steer the missile toward a vector connecting the launch platform and the predicted point of interception between the missile and target. Simulink simulations of the GNC system provide encouraging results in both reference tracking for the autopilot and state estimation utilizing both KF designs. Figure 1 Organization of thesis, including the primary content Guidance, Navigation and Control (GNC