Comparison of different lateral acceleration autopilots for a surface-to-surface missile

Abstract

This paper presents a comparison of three lateral acceleration autopilots for a surface-to-surface missile: three-loop conventional acceleration autopilot, and gamma-dot and three-loop acceleration autopilot based upon the inverse-dynamic control. The surface-to-surface missile motion is described by nonlinear differential equations whose parameters change rapidly over a very wide range due to variable velocity and altitude. The requirement for the accurate controlling of the missile in such an environment represents a challenge for the autopilot designer. The brief review of the calculation of the autopilot gains is given using the concept of the 'point' stability for the linear time-varying system with 'frozen' dynamic coefficients. The method of the inverse-dynamic control is presented in the next section for two types of the autopilots: gamma-dot and acceleration autopilot. Both of them require the design of the estimators for the variables used as inputs to the control law. Finally, six-degree-of-freedom simulation results of the missile response to the demanded command on the typical ballistic trajectory are presented. The comparison of three autopilots considers the steady state errors and the sensitivity of the response to the highly variable environment. It was shown that the inverse-dynamic control can be very effective in the controlling of the surface-to-surface missile.

Keywords

• autopilot
• lateral acceleration autopilot
• gamma-dot autopilot
• inverse-dynamic control
• guided surface-to-surface missile
• 'six-degree-of-freedom' model