Nonlinear modeling and designing transition flight control scenarios for a dual thrust hybrid UAV

Researchers have recently focused on studying the flight dynamics and control of multicopters and fixed-wing aerial vehicles. However, investigating the transition phase between multicopter hover and fixed-wing cruise modes for a Dual-thrust Aerial Vehicle (DAV) is still challenging. In this paper, we develop two sets of nonlinear equations of motion for a DAV to create a multi-purpose dynamic model for designing control and transition mode scenarios. The first set considers the multicopter torque as the control input, while the second set considers the elevator torque as the control input. By analyzing three transition scenarios between multicopter hover and fixed-wing cruise flights, we observe that the best performance occurs for the third scenario in which the control system switches from multicopter control torque to elevator control torque when the multicopter thrust equals the wings’ lift. In this case, the vehicle will be protected from critical flight conditions like wing stalls while the transition will go smoothly with minimum height drop. The transition mode strategies are implemented using a model predictive controller in flight simulation. The numerical results show the dynamic behavior of the DAV in different transition scenarios from hover to cruise and vice versa, demonstrating successful altitude control and stable transitions in both phases.