問題描述
設連續系統狀態方程和性能指標
X ˙ = f ( t , X , U ) X ( t 0 ) = X 0 J = ? [ X ( t f ) , t f ] + ∫ t 0 t f F ( X , U , t ) d t \begin{aligned} \dot{X} & =f(t, X, U) \quad X\left(t_{0}\right)=X_{0} \\ J & =\phi\left[X\left(t_{f}\right), t_{f}\right]+\int_{t_{0}}^{t_{f}} F(X, U, t) d t \end{aligned} X˙J?=f(t,X,U)X(t0?)=X0?=?[X(tf?),tf?]+∫t0?tf??F(X,U,t)dt?
HJI與HJB方程
HJB方程
設定如下哈密頓函數定義:
H ( X , U , λ , t ) = F ( X , U , t ) + λ T f ( X , U , t ) λ = ? V ? X \begin{aligned} H(X, U, \lambda, t)=&F(X, U, t)+\lambda^{T} f(X, U, t) \\ \lambda=&\frac{\partial V}{\partial X} \end{aligned} H(X,U,λ,t)=λ=?F(X,U,t)+λTf(X,U,t)?X?V??
HJB方程
? ? V ? t = min ? u ∈ Ω H ( X , U , ? V ? X , t ) = H ? ( X , U , ? V ? X , t ) -\frac{\partial V}{\partial t}=\min _{u \in \Omega} H\left(X, U, \frac{\partial V}{\partial X}, t\right)=H^{*}\left(X, U, \frac{\partial V}{\partial X}, t\right) ??t?V?=u∈Ωmin?H(X,U,?X?V?,t)=H?(X,U,?X?V?,t)
此外,參數 λ \lambda λ滿足協態方程
λ ˙ = ? ? H ? X \dot{\lambda}=-\frac{\partial H}{\partial X} λ˙=??X?H?
橫截條件
λ ( t f ) = ? ? ? X ( t f ) \lambda(t_f)=\frac{\partial \phi}{\partial X(t_f)} λ(tf?)=?X(tf?)???
HJI方程
考慮一個博弈問題其價值函數為
V ( x ) = min ? u p max ? u e J V(\boldsymbol{x})=\min _{\boldsymbol{u}_{p}} \max _{\boldsymbol{u}_{e}} J V(x)=up?min?ue?max?J
HJI方程
? ? V ? t = ? V ? x f ( x ) + F ( x ) -\frac{\partial V}{\partial t}=\frac{\partial V}{\partial \boldsymbol{x}}f(x)+F(x) ??t?V?=?x?V?f(x)+F(x)