EULER ANGLE ERROR COMPUTATION AND THRUST VECTOR CONTROL SCHEME FOR INITIAL TURNING PHASE OF A VERTICAL LAUNCH SURFACE TO AIR MISSILE

Abstract

A vertical launch missile requires to be turned towards the Predicted Interception Point (PIP) with the target within few seconds from the launch. The autopilot used for the same requires the error in Euler Angles between the missile and the target to be supplied, which is generally computed using Error Quaternions approach [1]. For some kinds of engagement scenarios, say a Near Boundary Low Altitude target, the turn angle required in the pitch plane during the initial phase can become more than 90 degrees. In such cases, the conventional 3-2-1 frame transformation method fails to compute the Euler Angle errors correctly. As an alternative approach the Euler Angle error computation using 2-3-1 frame transformation is proposed in this paper. After computing the Euler Angle Errors, the desired turning is achieved by Thrust Vector Control [2] using jet vanes or thrusters. The initial turning using Aerodynamic control is not desirable because of low dynamic pressure, where as the usage of jet vanes brings more hardware complications for small tactical missiles. The possibility of using thrusters for initial turning phase in a short range tactical missile is studied in this paper with the help of simulation results.