Session: 02-03-03: Dynamic Loads, Wave Propagations, Response, Vibration, Control, and Alleviation of Aerospace Structures and Vehicles

Paper Number: 152508

152508 - LPV System Identification of VTOL Aircraft With Hybrid Configuration 

This paper presents the modeling and LPV system identification of a tiltable electric Vertical Take-Off and Landing (eVTOL) aircraft using experimental flight data. The eVTOL aircraft features a hybrid configuration with fixed wings and four rotors: two front rotors are tiltable for transitioning from vertical takeoff to level flight, while the two rear rotors remain fixed. First, a six-degree-of-freedom (6-DoF) nonlinear dynamical model is derived as a state-space model, which is then reduced to longitudinal motion and expressed in in the linear parameter-varying (LPV) formulation. The thrust and aerodynamic forces are expressed using assumed formulas with coefficients that need to be identified.
Using real flight data collected from a test aircraft, the unknown parameters in the LPV dynamic model are identified using a modified Least-Squares Regression (LSR) method. This modified LSR algorithm introduces constraints on system parameters to ensure they have physical significance. Both constant parameters and second-order polynomial coefficients are identified and their accuracies are compared. The results show that at slow tilting rates and takeoff velocities, a constant-coefficient dynamic model is sufficiently accurate for describing the transition flight. However, at faster rates, a polynomial-coefficient dynamic model is required for accuracy.
Additionally, the identified data is used to analyze and numerically study the flow interference between the rotors and fixed wings. The experimental data, covering various tilting rates and vertical takeoff velocities, is used to compare the magnitude of interference in different scenarios.

Presenting Author: Tianyi He Utah State University

Presenting Author Biography: Dr. He is an assistant professor at Utah State University, and his research interest includes controls of ground/air vehicles.