Abstract
The flight stability and safety of the quadrotor unmanned aerial vehicle (UAV) with variable mass are the key problems that limit its application. In order to improve the stability and steady-state control precision of the quadrotor system against slow-varying mass and external disturbance, a new robust adaptive flight control algorithm is developed and analyzed in detail in this paper. Firstly, a mass observer based on adaptive control theory is designed to estimate the real-time mass and correct the mass parameter of the UAV. Then, a hyperbolic tangent function and a proportional integral (PI) controller is added into the attitude controller to eliminate the effect of the external disturbances. Finally, a hybrid robust adaptive controller (HRAC) developed with backstepping control method is used here for the trajectory tracking of quadrotor. The boundedness of the nonlinear system is verified by Lyapunov stability theory and uniformly ultimately bounded theorem. The trajectory tracking simulation experiments are presented in MATLAB/SIMULINK simulation environment. According to the simulation results, the real-time mass of quadrotor can be estimated by HRAC satisfactorily under the condition of external disturbances, while the estimate error of mass is only 6.4% of its own. In addition, HRAC can provide a higher trajectory tracking accuracy compared with robust optimal backstepping control (ROBC) and robust generalized dynamic inversion (RGDI). The results suggest a promising route based on the mass observer and hybrid robust controller toward slow-varying mass and the external disturbance as effective robustness control strategy for quadrotor UAV.
Highlights
A linear matrix inequality (LMI) based robust quadrotor control algorithm by Ryan and Kim13; a fuzzy backstepping algorithm has been used to study the problem of trajectory tracking according to Yacef et al.,14; Nikolakopoulos and Alexis’s15 studied an attitude control through switching networked; a disturbance observer based on sliding mode control is proposed by Besnard et al.16 to eliminate the effect of the external disturbances; Shirzadeh et al.17 has studied a tracking problem of moving targets by neural network
Due to the existence of the unpredictable external disturbance, a hybrid robust adaptive controller which is comprised of a proportional integral (PI) controller and the hyperbolic tangent function of the second kind of error is added into attitude control law
A mass observer is designed based on adaptive control theory, and a new controller hybrid robust adaptive controller (HRAC) is developed by combining the backstepping control
Summary
As a new kind of unmanned aerial vehicle (UAV), quadrotor has been developed as a promising contender in small UAV research field for its compact size, light weight and flexible operation, compared with helicopter and fixed-wing airplane. quadrotor has been widely concerned and used in military surveillance, border interdiction, rescue missions, agriculture services, photography, etc., due to its functions of performing vertical taking-off and landing, low-altitude hovering and low-speed cruising. Though quadrotor has many advantages compared with other vehicles, the application of quadrotor has been restricted because the quadrotor system is underactuated (six control outputs and only four control inputs), high nonlinear, strongly coupled and has a time-varying nature. Real-time estimation of quality parameters is the key difficulty to improve the control performance of slow-variable quality UAV control system at present. In this paper, in order to solve the problems caused by the slow-varying mass and the external disturbance, a new hybrid robust adaptive flight control algorithm is designed and developed for the quadrotor UAV. The design process of the control method is as follows: Firstly, a mass observer based on adaptive control theory was designed for the quadrotor UAV with slow-varying mass to estimate the real-time mass and correct the mass parameter of the quadrotor. According to the results of this study, HRAC is proved to be a promising technology to be applied effectively in controlling quadrotor UAV with slow-varying mass under the external disturbance. Using the Newton–Euler approach, the dynamic equations of quadrotor can be written as below:
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
