Missile Longitudinal Autopilot Design Using A New Suboptimal Nonlinear Control Method

In this paper, a missile longitudinal autopilot is designed using a new nonlinear control synthesis technique (called theθ -D approximation). The particular D θ − methodology used in this paper is referred to as the D θ − 2 H design. The D θ − technique can achieve suboptimal solutions to a class of nonlinear optimal control problems in the sense that it solves the Hamilton-Jacobi-Bellman (HJB) equation approximately by adding perturbations to the cost function. By manipulating the perturbation terms both semi-globally asymptotic stability and suboptimality properties can be obtained. An interesting feature of this method is that the expansion terms in the expression for suboptimal control are nothing but solutions to the state dependent Riccati equations associated with this class of problems. The D θ − 2 H design has the same structure as that of the linear 2 H formulation except that the two Riccati equations are state dependent. In using the D θ − technique, we do not require online solutions of the Riccati equation like the recently popular State Dependent Riccati Equation (SDRE) technique. Development of the D θ − technique is presented and an acceleration tracking autopilot for a missile is designed. Numerical simulations are presented that * Ph.D student ** Professor and contact person