Finite-time Attitude Tracking Control Research Articles

Predefined-Time Attitude Tracking Robust Control of Flexible Spacecraft Under Multiple Disturbances

To overcome external environmental disturbances, inertial parameter uncertainties, actuator failures and input saturation, and the structural vibration of flexible appendages, predefined-time attitude tracking based on sliding-mode control for flexible spacecraft is proposed. First, a rotation matrix is adopted for spacecraft attitude description to avoid an unwinding phenomenon. Next, to enhance the robustness of attitude control, a radial basis function neural network is applied to estimate and compensate the lumped disturbances in attitude tracking. Then, based on the predefined-time stability, an adaptive sliding-mode controller is designed to ensure that the maximum convergence time of the system can be arbitrarily configured by setting simple parameters and independent of initial states. The system stability is further proved by the Lyapunov theory. Finally, numerical simulations indicate that the proposed controller can achieve high-precision convergence more rapidly compared to the existing finite-time attitude tracking controller. This work provides new references for high-precision attitude tracking of flexible spacecraft by predefined control with multidisturbance suppression.

Distributed Finite-Time Attitude Tracking Control for Multiple Rigid Spacecrafts with Full-State Constraints

Distributed Finite-Time Attitude Tracking Control for Multiple Rigid Spacecrafts with Full-State Constraints

Adaptive Finite-time Attitude Tracking Control for Solar Sail with State-dependent Torque Saturation

Adaptive Finite-time Attitude Tracking Control for Solar Sail with State-dependent Torque Saturation

Finite-time attitude tracking control of stratospheric airship in the presence of multiple disturbances

AbstractThis paper proposes a composite non-singular fast terminal sliding mode attitude control scheme based on a reduced-order extended state observer for the stratospheric airship’s attitude system affected by multiple disturbances. First, the feedback linearisation method is applied to address the nonlinearity of the attitude motion model and achieve decoupling of the model in three channels. Second, the overall disturbances, encompassing airship parameter perturbations and external disturbances, are treated as an aggregate. A reduced-order extended state observer is designed for each channel to formulate a composite non-singular fast terminal sliding mode surface. In the control design phase, the hyperbolic sine function is adopted as replacement for the sign function to ensure the continuity of the control signal. The estimated disturbances are incorporated in the control law design to directly offset the effects of multiple disturbances on the attitude motion of the airship. Third, based on Lyapunov theory, it has been proven that the control law can drive the attitude tracking error to converge to zero within a finite time. Simulation results demonstrate that the proposed control scheme exhibits favorable disturbance rejection capability, as well as higher tracking accuracy and faster response speed.

Adaptive fractional order non-singular terminal sliding mode anti-disturbance control for advanced layout carrier-based UAV

Advanced layout carrier-based UAV has grabbed increasing attention in aerospace field for its unique characteristics such as fewer casualties, lower labor costs and more capable of carrying out various tasks in shipping environment. However, the complex body structure of advanced layout UAV can bring about insufficiency in terms of stability, making it especially susceptible to changeable working circumstances. To overcome the object complexity and external disturbances mainly consisting of air turbulence that the UAV may come across, a composite adaptive fractional-order non-singular terminal sliding mode control strategy is proposed to achieve finite-time attitude tracking control and disturbance rejection. The distinctive features of the proposed strategy are embodied in active disturbance compensation, finite-time convergence, higher control accuracy and chattering suppression. The mathematical model of flying wing UAV is established first, then a fixed-time disturbance observer applying higher-order sliding mode is designed to obtain the estimation of unknown disturbance so that the carrier-based environment factors can be considered in the later control process. Next, an adaptive fractional-order non-singular terminal sliding mode controller is developed based on fractional order calculus and adaptive double power exponential reaching law to realize finite-time tracking control of advanced layout carrier UAV with great robustness against external disturbances due to the estimation from the proposed observer, and the stability analysis of closed-loop system is implemented by utilizing Lyapunov theory. Finally, a comparison study of the proposed strategy with other sliding mode control methods is presented by numerical simulation, to illustrate its feasibility and superiority.

Finite-Time Attitude Tracking Control for Hypersonic Flight Vehicles with Actuator Saturation

This paper investigates finite-time attitude tracking control strategies for hypersonic flight vehicles (HFVs) with parameter uncertainties, external disturbances, and actuator saturations by applying sliding model control, adaptive mechanism, and nonlinear disturbance observer techniques. A nonlinear dynamic model of HFV attitude system in reentry flight phase is established. Then, a basic attitude control method of the HFV system is designed based on a terminal sliding mode control (TSMC) scheme to accommodate the system-lumped disturbance torques and guarantee the finite-time stability. To relax the prior knowledge of bounded lumped disturbance of the TSMC-based HFV attitude system, an adaptive TSMC (ATSMC) scheme is proposed. In order to relax the limit of compound uncertainties and attenuate chattering phenomenon of the TSMC-based HFV attitude system, a nonlinear disturbance observer-based TSMC (DO-TSMC) scheme is presented, which enhances the disturbance attenuation and robust tracking performance. Finally, simulation results of a generic X-33 nonlinear model exhibit the effectiveness of the proposed TSMC, ATSMC, and DO-TSMC schemes.

Adaptive smooth disturbance observer-based fast finite-time attitude tracking control of a small unmanned helicopter

In this paper, a novel adaptive smooth disturbance observer-based fast finite-time adaptive backstepping control scheme is presented for the attitude tracking of the 3-DOF helicopter system subject to compound disturbances. First, an adaptive smooth disturbance observer (ASDO) is proposed to estimate the composite disturbance, which owns the characteristics of smooth output, fast finite-time convergence, and adaptability to the disturbance of unknown derivative boundary. Then, a finite-time backstepping control protocol is construct to drive the elevation and pitch angles to track reference trajectories. To tackle the "explosion of complexity" and "singularity" problems in the conventional backstepping design framework, a fast finite-time command filter (FFTCF) is utilized to estimate the virtual control signal and its derivative. Moreover, a fractional power-based auxiliary dynamic system is introduced to compensate the error caused by the FFTCF estimation. Furthermore, an improved fractional power-based adaptive law with the $\sigma $-modification term is designed to attenuate the observer approximation error, such that the tracking performance is further enhanced. In terms of the fast finite-time stability theory, the signals of the closed-loop system are all fast finite-time bounded while the attitude tracking errors can fast converge to a sufficiently small region of the origin in finite time. Finally, a contrastive numerical simulation is carried out to validate the effectiveness and superiority of the designed control scheme.

Fast Finite-time Attitude Tracking Control of Rigid Spacecraft with Quantized Input Signals

Fast Finite-time Attitude Tracking Control of Rigid Spacecraft with Quantized Input Signals

Signum-Function-Based Multi-Input Multi-Output Adaptive Homogeneous Finite-Time Control for a Rigid-Body Attitude Tracking

This study is devoted to investigating the robust adaptive finite-time attitude tracking control problem for a rigid body subject to unknown uncertainties. Considering about the nonlinear attitude dynamics for a rigid body, a homogeneous sliding variable is designed by employing the signum-function technique. For the presented homogeneous sliding variable, a real sliding manifold, on which the singularity problem is avoided, could be achieved. Subsequently, a novel signum-function-based MIMO adaptive homogeneous finite-time control (SMAHFTC) algorithm is proposed. Finite-time convergence of the tracking errors to a region around the origin is rigorously proved through the Lyapunov approach. The control gains will not be overestimated, which implies that minimal control gains will be obtained by the adaptation law. Moreover, the controls’ signals are continuous for the SMAHFTC law. Then, by means of the proposed design method, an attitude tracking controller is designed for a rigid body described by the modified Rodrigues parameters’ (MRPs) representation. A comparison simulation is carried out to show the effectiveness and superiority of the proposed method.

Neural Network Based Finite-Time Attitude Tracking Control of Spacecraft With Angular Velocity Sensor Failures and Actuator Saturation

This article investigates the finite-time attitude tracking control problem of spacecraft with angular velocity sensor failures and actuator saturation. A model-free angular velocity observer is proposed first to reconstruct the unmeasurable angular velocity in finite time. Invoking the reconstructed information, a saturated finite-time attitude tracking controller is then designed via the fast terminal sliding mode control technique, while the Legendre polynomial-based neural network is incorporated to approximate the unknown nonlinear dynamics. The finite-time stability of the closed-loop attitude tracking system from the proposed observer and the controller is proved despite the external disturbances. The main feature of the proposed controller is that it can accomplish the attitude tracking maneuver without model and angular velocity information. Numerical and experimental results are presented to verify the effectiveness of the proposed scheme.

Event-triggered-based adaptive dynamic programming for distributed formation control of multi-UAV

This paper is concerned with the distributed formation control problem of multi-quadrotor unmanned aerial vehicle (UAV) in the framework of event triggering. First, for the position loop, an adaptive dynamic programming based on event triggering is developed to design the formation controller. The critic-only network structure is adopted to approximate the optimal cost function. The merit of the proposed algorithm lies in that the event triggering mechanism is incorporated the neural network (NN) to reduce calculations and actions of the multi-UAV system, which is significant for the practical application. What’s more, a new weight update law based on the gradient descent technology is proposed for the critic NN, which can ensure that the solution converges to the optimal value online. Then, a finite-time attitude tracking controller is adopted for the attitude loop to achieve rapid attitude tracking. Finally, the efficiency of the proposed method is illustrated by numerical simulations and experimental verification.

Neuro-adaptive singularity-free finite-time attitude tracking control of quadrotor UAVs

In this paper, a neuro-adaptive finite-time control law is proposed for the quadrotor unmanned aerial vehicles . Instead of employing any piecewise continuous functions, a singularity-free terminal sliding mode surface and an auxiliary function are presented to overcome the singularity issues resulted from the differentiation of the sliding variable and the error-related inverse matrix in the controller design , respectively. A simple neural network is employed to estimate the unknown dynamics, such that no prior knowledge on system model uncertainties is required for designing attitude controllers. With the presented control law, the finite-time convergence of the attitude and angular velocity errors can be guaranteed by rigorously theoretical analysis, and numerical simulations are performed to demonstrate the satisfactory performance of the proposed method. • A new singularity-free sliding mode surface without piecewise continuous functions. • An auxiliary function is designed to solve the hidden singularity. • A controller is proposed to achieve the finite-time convergence of tracking errors. • No prior knowledge about the unknown nonlinear uncertainties is required.

Adaptive finite time attitude tracking control of a rigid spacecraft considering input magnitude and rate saturations

This article investigates the attitude tracking control problem of a rigid spacecraft under the modeling inaccuracy, environmental disturbance, and input magnitude and rate saturations. A robust controller is proposed based on several nonlinear control methods, including the integral terminal sliding mode control, adaptive control, backstepping control, auxiliary system, and nonlinear observer methods. Within the control framework, a new integral terminal sliding mode surface (ITSMS) is first designed which integrates the fast nonsingular terminal sliding mode surface (FNTSMS) with a first-order filter to achieve the finite time stability without the input singularity problem. And adaptive laws are employed to compensate for the modeling inaccuracy and environmental disturbance with no prior knowledge. To satisfy the input magnitude and rate saturation constraints, a dynamic model in the form of a first-order filter is built up to restrict the dynamics of the actuators, which is then associated with the auxiliary system. Meanwhile, a nonlinear observer is used to avoid calculating the derivative of the expected virtual control signal. Semi-globally uniformly ultimate bounded stability is proved for the closed-loop system, and the tracking errors can converge to small regions around the expected equilibrium in finite time. Finally, numerical simulation results are presented to demonstrate the effectiveness of the proposed controller.

Adaptive Finite-Time Attitude Tracking Control for State Constrained Rigid Spacecraft Systems

This brief studies the adaptive finite-time attitude tracking control of rigid spacecraft systems with full-state constraints and external disturbance. Based on the barrier Lyapunov function, a novel finite-time command filtered backstepping control algorithm is proposed, which can not only avoid computing the differential of virtual control signal, but also guarantee the predefined state constraints are not violated. The adaptive control technique is applied to estimate the upper bound of disturbance, and the designed controller with adaptive updating laws can make the tracking error converge to an adjustable neighborhood of the origin in finite time. Simulation results show the effectiveness of the present control method.

Minimum-learning-parameter-based anti-unwinding attitude tracking control for spacecraft with unknown inertia parameters

This paper investigates the finite-time attitude tracking control problem for rigid spacecraft exposed to the external disturbance and unknown inertial parameters. Initially, the basic controller is developed under the assumption that the inertial parameters and the upper bound of external disturbances are available to the designer. However, this assumption is inapplicable in practical applications. Considering this limitation, adaptive laws and Minimum-learning- parameter (MLP) algorithm are employed in the second controller to estimate the unknown system dynamics. Finite-time stability for tracking errors is achievable under the proposed methods. Though theoretical analysis and numerical simulations, effectiveness of the proposed controllers has been validated.

Gliding-Guided Projectile Attitude Tracking Controller Design Based on Improved Adaptive Twisting Sliding Mode Algorithm

The finite-time attitude tracking control for gliding-guided projectile with unmatched and matched disturbance is investigated. An adaptive variable observer is used to provide estimation for the unmeasured state which contains unmatched disturbance. Then, an improved adaptive twisting sliding mode algorithm is proposed to compensate for the matched disturbance dynamically with better transient quality. Finally, a proof of the finite-time convergence of the closed-loop system under the disturbance observer and the adaptive twisting sliding mode-based controller is derived using the Lyapunov technique. This attitude tracking control scheme does not require any information on the bounds of uncertainties. Simulation results demonstrate that the proposed method which is able to acquire the minimum possible values of the control gains guaranteeing the finite-time convergence performs well in chattering attenuation and tracking precision.

Robust adaptive finite-time attitude tracking control of a 3D pendulum with external disturbance: numerical simulations and hardware experiments

The three-degree-of-freedom (3D) pendulum has been used as a benchmark in the field of nonlinear dynamics and control. Nonetheless, the attitude control of 3D pendulum is still an open problem presently since some issues remain not well addressed. In this paper, a robust adaptive finite-time attitude control method is proposed for the attitude tracking control of a 3D pendulum with external disturbance. First, a baseline finite-time attitude controller is designed based on the adding a power integrator technique. Then, a finite-time disturbance observer is designed to exactly estimate the unknown external disturbance. Finally, a robust adaptive finite-time attitude controller is constructed by integrating the baseline finite-time attitude controller with the finite-time disturbance observer. The proposed robust adaptive finite-time attitude controller can guarantee the global finite-time stability of the whole closed-loop system even in the presence of external disturbance owing to the feedforward dynamic compensation. Numerical simulations and hardware experiments are both performed to illustrate the effectiveness and superiority of the proposed control method.

Finite Time Output Feedback Attitude Tracking Control for Rigid Body Based on Extended State Observer

In this paper, the attitude tracking control problem of output feedback is investigated. A finite time extended state observer (FTESO) is designed through the homogeneous Lyapunov method to estimate the virtual angular velocity and total disturbances. Based on these estimated states, a finite time attitude tracking controller is developed. The numerical simulations are given to illustrate the effectiveness of the proposed control scheme.

Attitude trajectory planning and attitude control for quad-rotor aircraft based on finite-time control technique

Abstract The attitude control problem for quad-rotor spacecraft is investigated in this paper. Considering the yaw dynamical rate is slower than that of roll and pitch channel, firstly, we establish the attitude trajectory and then propose an attitude decoupled control strategy. For the specific attitude controller design, we design a finite-time attitude tracking controller based on the finite-time control technology. The rigorous stability analysis method based on homogeneous system theory is given, which proves that spacecraft attitude can reach the expected attitude in a finite time. Experimental results on a real quad-rotor platform show that the proposed control strategy has the advantages of convergence and strong disturbance rejection ability.

Optimal Attitude Control of a Tethered System for Noncoplanar Orbital Transfer Under a Constant Thrust

The problem of an optimal attitude control is studied for a tethered system under a constant thrust in noncoplanar orbital transfer. The contributions of this article mainly include two aspects: first, a noncoplanar orbital transfer scheme and second, a closed-loop optimal control method. Based on a constant thrust, a noncoplanar orbital transfer scheme between two sun-synchronous orbits is proposed, enabling convenient engineering implementation. Compared with existing closed-loop control methods, the hierarchical finite-time attitude tracking control method is presented in the last cycle of the closed-loop optimal control to reduce the error at the final moment. A numerical case of a tethered system in noncoplanar orbital transfer is studied to demonstrate the effectiveness of the proposed control scheme.