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Unmanned autonomous helicopter (UAH) path planning problem is an important component of the UAH mission planning system. The performance of the automatic path planner determines the quality of the UAH flight path. Aiming to produce a high-quality flight path, a path planning system is designed based on human-computer hybrid augmented intelligence framework for the UAH in this paper. Firstly, an improved artificial bee colony (I-ABC) algorithm is proposed based on the dynamic evaluation selection strategy and the complex optimization method. In the I-ABC algorithm, the following way of on-looker bees and the update strategy of nectar source are optimized to accelerate the convergence rate and retain the exploration ability of the population. In addition, a space clipping operation is proposed based on the attention mechanism for constructing a new spatial search area. The search time can be further reduced by the space clipping operation under the path planning result within acceptable changes. Moreover, the entire optimization process and results can be feeded back to the knowledge database by the human-computer hybrid augmented intelligence framework to guide subsequent path planning issues. Finally, the simulation results confirm that a feasible and effective flight path can be quickly generated by the UAH path planning system based on human-computer hybrid augmented intelligence., Competing Interests: All authors declare no conflict of interest., (Copyright © 2021 Zengliang Han et al.)

This article deals with the problem of attitude tracking control for flexible satellite under flexible vibration disturbance, actuator fault and time delay. Based on disturbance observer and fault tolerant control techniques, the flexible vibration disturbance and actuator fault are effectively estimated by disturbance observer and fault estimation observer, respectively. Meanwhile, a delay-dependent attitude tracking feedback controller is designed to ensure that the reference attitude is stably tracked. To reduce the conservatism of the designed algorithm, a time delay correlative decomposition factor is introduced to make the flexible satellite have a better performance for attitude tracking control. Finally, the effectiveness of the proposed method is illustrated by numerical simulations. [ABSTRACT FROM AUTHOR]

Summary: This paper proposes a robust active fault‐tolerant control (AFTC) approach for medium‐scale unmanned autonomous helicopter (UAH) with rotor flapping dynamics in the presence of unknown external disturbances and actuator faults. The robust items are adopted to improve the disturbance rejection capability of the UAH system. The adaptive fault observers are developed to estimate the fault parameters and the fault detection (FD) algorithms are presented to detect the actuator faults in different loops. In order to obtain satisfactory trajectory tracking performance, a backstepping‐based robust AFTC scheme is designed for the simplified 6‐degree‐of‐freedom (DOF) UAH nonlinear dynamics model and the global stability of the closed‐loop system is proved by using the Lyapunov method. Several groups of numerical simulation results are carried out to verify the effectiveness of the developed method. [ABSTRACT FROM AUTHOR]

The reference governor strategy is presented for the flight envelope protection control of the aircraft during high angle of attack maneuvers. Limits of key flight parameters and amplitude saturation of control surfaces are explicitly considered by imposing the output and input constraints on the flight system. Firstly, a nominal flight control scheme is designed using eigenstructure assignment approach. The static and dynamic reference governors are discussed for flight envelope protection control of the aircraft during stability-axis roll maneuver. Then, a new reference governor is presented based on step response model. The performance of these reference governors for flight envelope protection is demonstrated and compared by numerical simulations. Results show that the dynamic reference governor and the proposed step response model based reference governor are valid for the flight envelope protection control and the latter is easier to be realized. [ABSTRACT FROM AUTHOR]

This paper investigates the tracking control problem of multi-input and multi-output nonlinear systems simultaneously considering the user-specified tracking performance, the asymmetric input saturation, and external disturbances. By introducing the modification signals into the user-specified performance functions, we propose a flexible performance-based control scheme, featuring the capability of avoiding the violation of the resulted modified performance functions (MPFs) due to the input saturation. These modification signals are associated with input saturation errors (the errors between the actual and desired control inputs) and generated by a novel auxiliary system in which all the states are guaranteed to be nonnegative. Consequently, the MPF can degrade the user-specified tracking performance when saturation happens and can recover it when no saturation occurs. Furthermore, the disturbance observer is utilized to estimate external disturbances and relieve the burden on the selection of control gains. With the developed control scheme, it is theoretically shown that the output can always track the reference signal and satisfy the constraints of the MPFs. Finally, the numerical simulation results are presented to show the effectiveness of the proposed control scheme. [ABSTRACT FROM AUTHOR]