Slow–fast loop gain-scheduled switching attitude tracking control for a near-space hypersonic vehicle

This article develops a slow–fast loop polytopic linear parameter-varying model and proposes a systematic gain-scheduled switching attitude tracking control scheme for a near-space hypersonic vehicle. First, the dynamics of near-space hypersonic vehicle is modeled as a slow–fast loop polytopic linear parameter-varying model using the Jacobian linearization and tensor-product model transformation approach. Open-loop simulation verification illustrates that the developed polytopic linear parameter-varying model captures the local nonlinearities of the original nonlinear system; therefore, it is suitable for model-based control. Second, for less conservative controller design purpose, the flight envelope is divided into smaller subregions, a family of slow loop and fast loop gain-scheduled controllers are designed, and each of them is suitable for a specific parameter subspace; the slow loop and fast loop gain-scheduled controllers are then switched in order to guarantee the closed-loop near-space hypersonic vehicle system to be asymptotically stable and satisfy a specified performance criteria. The resulting slow loop and fast loop gain-scheduled switching controllers are found by solving a convex constraint problem that can be efficiently solved using available linear matrix inequality techniques. Finally, numerical simulations have demonstrated the effectiveness of the proposed method.