Design of nonlinear H_∞ controller for hypersonic vehicle system

For the BTT attitude tracking control problem of hypersonic vehicle, a state-error-space implementation expression of nonlinear H_∞ attitude tracking control for above nonlinear coupling system is given firstly. Then basing on γ-energy-dissipation and L² gain performance criterion in nonlinear system theory, the smooth differentiable stored-energy function is designed, which subject to the Hamilton-Jacobi-Isaacs inequality. Following some assumptions, a local state-space solution of nonlinear H_∞ attitude-tracking control problem for nonlinear coupling hypersonic vehicle system is obtained, by using Riccati differential equation of linear following system in local state-space. The local state-space is the neighborhood around the command state error space. Above approach avoids complicated solving process of Hamilton-Jacobi-Isaacs inequality, thus it's a good reference for engineering.