Coupled dynamics analysis and adaptive control of rigid-flexible vehicles with model uncertainties

This paper presents the design and application of an adaptive sliding mode control (ASMC) strategy for a rigid-body vehicle with flexible structures and uncertain dynamics, modeled through a linearized dynamic framework. The dynamics of the planar rigid–flexible system are derived using the finite element method, resulting in a linear matrix–vector form that captures the rigid–flexible coupling within the vehicle’s structure. The control approach combines nominal and uncertainty compensation control laws. The nominal control law employs a linear quadratic regulator with a reference input to achieve desired state tracking in the absence of uncertainties. To address system uncertainties, an ASMC law originally developed for single-input, single-output systems is extended to large-dimensional, multi-input, multi-output systems with potentially differing numbers of inputs and outputs. The ASMC framework accounts for system uncertainties without requiring a priori knowledge of the uncertainty bounds. The controller incorporates both full-order (when all state measurements are available) and reduced-order (when some state measurements are unavailable) observers to estimate both nominal and actual states. The proposed algorithm relies on a limited set of physically meaningful parameters, facilitating straightforward adjustment and implementation. Simulation results validate the effectiveness of the ASMC strategy, demonstrating robust stabilization, accurate tracking, and chattering mitigation despite model uncertainties. A parametric analysis further examines the influence of the ASMC parameters on system response and control performance. Compared to an adaptive nonsingular fast terminal sliding mode controller in the literature, the proposed ASMC achieves comparable state convergence while exhibiting superior vibration suppression and reduced control effort.