The codes for a robust state-dependent Riccati equation controller with parameter uncertainty and matched disturbance are presented for a set of coupled k-th order ordinary differential equations (ODEs), for general nonlinear systems.
The codes are for the simulation section of the mentioned article bellow:
Saeed Rafee Nekoo and Anibal Ollero, "A Robust State-Dependent Riccati Equation Controller with Parameter Uncertainty and Matched Disturbance," Journal of the Franklin Institute, 2023. https://doi.org/10.1016/j.jfranklin.2023.11.023
The state-dependent Riccati equation (SDRE) unveils a nonlinear optimal control approach; the method is sensitive to uncertainty and disturbance that provokes the necessity of precise modeling and omitting disturbance from the model and environment which is occasionally impossible. These codes provide, a robust state-dependent Riccati equation using only the pure SDRE itself.
A fourth-order differential equation is simulated to show the effectiveness of the suggested method and the results were compared with conventional SDRE. The robust version could handle the matched disturbance with a steady-state shift from the equilibrium point where the conventional SDRE failed.
Additionally, a comparison and detailed analysis have been performed between the proposed design and sliding mode control.