Robust stability–guaranteed suboptimal decentralized control of interconnected nonlinear systems with structured parametric uncertainties

This paper presents a decentralized finite-horizon suboptimal control approach for uncertain interconnected nonlinear systems based on the decentralized finite-horizon state-dependent Riccati equation (DF-SDRE). The proposed method extends the classical state-dependent Riccati equation framework to large-scale nonlinear systems composed of multiple interconnected subsystems and affected by structured parametric uncertainties. A Lyapunov-based stability analysis using a quadratic function is developed to derive a new sufficient condition ensuring the global asymptotic stability of the overall interconnected system. The proposed control strategy preserves the decentralized structure while explicitly accounting for uncertainty effects. The effectiveness of the (DF-SDRE) controller is evaluated through numerical simulations on a system of three interconnected inverted pendulums. The obtained results show that the proposed approach ensures robust stabilization and improved transient performance compared with a decentralized LQR (D-LQR) controller.