Robust trajectory tracking control problem is dealt with for quadrotors with multiple uncertainties and multiple delays. The vehicle model is described as a multiple-input multiple-out time-varying ...system subject to parametric perturbations, nonlinear and coupled dynamics, external disturbances, and state and input delays. A robust cascade controller including an attitude controller and a position controller is proposed based on the hierarchical control scheme and the robust compensating technique. It is proven that the position and attitude tracking errors can converge into the given neighbourhood of the origin in a finite time, subject to multiple uncertainties and delays. Experimental results on the quadrotor system are provided to verify the effectiveness of the proposed controller.
In this paper, a robust decentralized and linear time-invariant controller is proposed for quadrotors to achieve trajectory tracking. The designed closed-loop control system includes three loops: (1) ...an attitude loop that controls the attitude angles; (2) a position loop that controls the translational trajectory of the quadrotor; and (3) a robust compensating loop that restrains the influence of uncertainties including parameter uncertainties, nonlinear and coupling dynamics, and external disturbances in the rotational and translational dynamics. It is proven that the tracking errors can converge into a priori set neighborhood of the origin ultimately. Experimental results are given to confirm the advantages of the proposed control method, compared with the linear time-invariant H ∞ control method.
This paper addresses a new trajectory tracking controller for quad-rotor aircrafts in the presence of time-varying aerodynamic effect and bounded external disturbance using the novel L 1 adaptive ...control methodology augmented with nonlinear feed-forward compensations. The proposed augmented L 1 adaptive controller achieves uniformly bounded transient and asymptotic tracking of the output signal for any designated bounded reference trajectory. Finally, simulations of tracking a circular reference trajectory are performed to illustrate the validity of the proposed controller.
The attitude control of quadrotor unmanned aerial vehicle (UAV) is investigated. The aim of this paper is to develop a continuous multivariable attitude control law, which drives the attitude ...tracking errors of quadrotor UAV to zero in finite time. First, a multivariable super-twisting-like algorithm (STLA) is proposed for arbitrary order integrator systems subject to matched disturbances. A discontinuous integral term is incorporated in the control law in order to compensate the disturbances. A rigorous proof of the finite time stability of the close-loop system is derived by utilizing the Lyapunov method and the homogeneous technique. Then, the implementation of the developed method in an indoor quadrotor UAV is performed. The remarkable features of the developed algorithm includes the finite time convergence, the chattering suppression and the nominal performance recovery. Finally, the efficiency of the proposed method is illustrated by numerical simulations and experimental verification.
The finite/fixed-time stabilization and tracking control is currently a hot field in various systems since the faster convergence can be obtained. By contrast to the asymptotic stability, the ...finite-time stability possesses the better control performance and disturbance rejection property. Different from the finite-time stability, the fixed-time stability has a faster convergence speed and the upper bound of the settling time can be estimated. Moreover, the convergent time does not rely on the initial information. This work aims at presenting an overview of the finite/fixed-time stabilization and tracking control and its applications in engineering systems. Firstly, several fundamental definitions on the finite/fixed-time stability are recalled. Then, the research results on the finite/fixed-time stabilization and tracking control are reviewed in detail and categorized via diverse input signal structures and engineering applications. Finally, some challenging problems needed to be solved are presented.
This paper investigates the fixed-time consensus tracking problem for second-order multi-agent systems in networks with directed topology. Global well-defined nonlinear consensus protocols are ...constructed with the aid of a newly-designed sliding surface for each double-integrator agent dynamics. In particular, the proposed framework eliminates the singularity and the settling time is assignable for any initial conditions. This makes it possible for network consensus problems to design and estimate the convergence time off-line. Finally, simulation is included to demonstrate the performance of the new protocols.
This paper deals with the consensus control design for Lipschitz nonlinear multi-agent systems with input delay. The Artstein-Kwon-Pearson reduction method is employed to deal with the input delay ...and the integral term that remains in the transformed system is analyzed by using Krasovskii functional. Upon exploring certain features of the Laplacian matrix, sufficient conditions for global stability of the consensus control are identified using Lyapunov method in the time domain. The proposed control only uses relative state information of the agents. The effectiveness of the proposed control design is demonstrated through a simulation study.
This study addresses a fixed-time terminal sliding-mode control methodology for a class of second-order non-linear systems in the presence of matched uncertainties and perturbations. A newly defined ...non-singular terminal sliding surface is constructed and a guaranteed closed-loop convergence time independent of initial states is derived based on the phase plane analysis and Lyapunov tools. The simulation results of a single inverted pendulum in the end are included to show the effectiveness of the proposed methodology.
This note deals with control design for Lipschitz nonlinear systems with time-varying input delay. Based on a truncated prediction of the system state over the delay period, both a state and an ...output feedback control law are constructed. Within the framework of Lyapunov-Krasovskii functionals, a set of conditions are identified under which the closed-loop system under either the state feedback or the output feedback law is globally asymptotically stable at the origin. A numerical example is included to demonstrate the effectiveness of the proposed designs.
Summary
A continuous multivariable output feedback control scheme is developed for trajectory tracking and attitude stabilization of quadrotor helicopters. The whole closed‐loop system is composed by ...position loop and attitude loop. The homogeneous technique is used to design finite‐time stabilizing controller and observer in each loop. The virtual control is introduced in position loop to ensure that the real control is smooth enough such that it can be tracked by attitude loop. The finite‐time stability of the closed‐loop system is guaranteed through homogeneity and Lyapunov analysis. Finally, the efficiency of the proposed algorithm is illustrated by numerical simulations.
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