Robust DOB design for asymmetric LPV hybrid gantry systems based on mode decomposition and nominal model selection

This paper presents a formalized framework for the design and verification of a disturbance observer (DOB) applied to a hybrid gantry stage with actuator asymmetry and payload-dependent LPV characteristics. The system consists of a rigid actuator and a series elastic actuator (SEA) arranged in parallel along the Y-axis, and an X-axis actuator that modifies payload distribution. Four payload configurations are considered, and frequency responses are analyzed to characterize mechanical coupling via Relative Gain Array (RGA). Canonical Polyadic Decomposition (CPD) is applied to derive transformation matrices for dynamic decoupling. The procedure sequentially integrates nominal model selection and DOB bandwidth determination in the transformed coordinates, followed by robust stability validation under varying operating conditions. The proposed framework provides a structured design procedure for LTI-based DOB implementation in asymmetric LPV MIMO systems.