A missile longitudinal autopilot is designed using a new nonlinear control synthesis technique called the θ-D approximation. The particular θ-D methodology used is referred to as the θ-D H2 design. The technique can achieve suboptimal closed-form solutions to a class of nonlinear optimal control problems in the sense that it solves the Hamilton-Jacobi-Bellman equation approximately by adding perturbations to the cost function. 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 θ-D H2 design has the same structure as that of the linear H2 formulation, except that the two Riccati equations are state dependent. Numerical simulations are presented that demonstrate the potential of this technique for use in an autopilot design. These results are compared with the recently popular SDRE H2 method.


Mechanical and Aerospace Engineering

Keywords and Phrases

Hamilton-Jacobi-Bellman Equation; Riccati Equations; Approximation; Control System Synthesis; Cost Function; Longitudinal Autopilot; Missile; Missile Control; Nonlinear Control Synthesis; Nonlinear Control Systems; Nonlinear Optimal Control; Perturbations; State-Dependent Riccati Equations; Suboptimal Control

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Document Type

Article - Conference proceedings

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Final Version

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© 2003 Institute of Electrical and Electronics Engineers (IEEE), All rights reserved.

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