Energy Efficiency Enhanced Landing Strategy for Manned eVTOLs Using L1 Adaptive Control

A new landing strategy is presented for manned electric vertical takeoff and landing (eVTOL) vehicles, using a roll maneuver to obtain a trajectory in the horizontal plane. This strategy rejects the altitude surging in the landing process, which is the fatal drawback of the conventional jumping strategy. The strategy leads to a smoother transition from the wing-borne mode to the thrust-borne mode, and has a higher energy efficiency, meaning a better flight experience and higher economic performance. To employ the strategy, a five-stage maneuver is designed, using the lateral maneuver instead of longitudinal climbing. Additionally, a control system based on L1 adaptive control theory is designed to assist manned driving or execute flight missions independently, consisting of the guidance logic, stability augmentation system and flight management unit. The strategy is verified with the ET120 platform, by Monte Carlo simulation for robustness and safety performance, and an experiment was performed to compare the benefits with conventional landing strategies. The results show that the performance of the control system is robust enough to reduce perturbation by at least 20% in all modeling parameters, and ensures consistent dynamic characteristics between different flight modes. Additionally, the strategy successfully avoids climbing during the landing process with a smooth trajectory, and reduces the energy consumed for landing by 64%.

A Robust Longitudinal Stability Augmentation System for Small Aircraft Under Parametric Uncertainty

Small unmanned aerial vehicles (UAVs) face flying quality problems different from those encountered by larger aircraft. The lower airspeeds and small dimensions make these vehicles more susceptible to gusts and stability and control issues, which may render the aircraft difficult to fly. Moreover, due to many factors, UAVs are often built with a considerable degree of uncertainty regarding their aerodynamic properties and flying quality. The resulting aircraft may present poor stability and handling characteristics. This work presents the conceptual design of a robust stability augmentation system (SAS), aimed at increasing stability characteristics and protecting aircraft prone to flying quality problems. In order to deal with parametric uncertainties, the controller was designed with the robust H-infinity technique. The design process is presented, and a parametric aircraft model is provided, together with longitudinal stability and control derivatives. Simulations are presented to show the effects of the controller on the aircraft behavior.

Transient Stability Augmentation of the Algerian South-Eastern Power System including PV Systems and STATCOM

The transient stability of the 12-bus Algerian southeast power system is studied in this paper. This electrical system has abundant reactive power due to the long transmission lines and generators’ voltage. This capacitive power increases bus voltage which leads to network instability. The use of conventional compensators does not provide adequate and fast solutions. FACTS technology improves the efficiency of these compensators in solving the problem of power system instability efficiently. Among its elements, a synchronous compensator STATCOM control is proposed to decrease bus overvoltage and damping oscillations. Disturbance at bus B-1 is taken into consideration. This disturbance represents the photovoltaic (PV) array which exploits the abundantly available solar irradiation in the desert of Algeria. Various simulation tests have been carried out using NEPLAN software and the proposed design algorithms are proved in the relevant discussion.