Fault-tolerant Attitude Tracking Control Research Articles

Prescribed Performance Fault-Tolerant Attitude Tracking Control for UAV with Actuator Faults

This paper proposes a prescribed performance fault-tolerant control based on a fixed-time extended state observer (FXTESO) for a carrier-based unmanned aerial vehicle (UAV). First, the attitude motion model of the UAV is introduced. Secondly, the proposed FXTESO is designed to estimate the total disturbances including coupling, actuator faults and external disturbances. By using the barrier Lyapunov function (BLF), it is proved that under prescribed performance control (PPC), the attitude tracking error is stable within the prescribed range. The simulation results for tracking the desired attitude angle show that the average overshoot and stabilization time of PPC-FXTESO is 0.00455rad and 6.2s. Comparatively, the average overshoots of BSC-ESO and BSC-FTESO are 0.035rad and 0.027rad, with stabilization times of 14.97s and 12.56s, respectively. Therefore, the control scheme proposed in this paper outperforms other control schemes.

Event-triggered fault-tolerant attitude tracking control for spacecraft with fixed-time controller and disturbance observer under input constraints

This paper studies the attitude tracking problem for rigid spacecraft under restricted communication resources. This work proposes a novel composite control scheme for spacecraft subjected to system uncertainty, exogenous disturbance, periodic vibrations and uncertain modeled disturbance of actuator, actuator faults, and input saturation, which consists of a fixed-time controller (FiTC) based on an integral non-singular fast terminal sliding mode technique and a fixed-time disturbance observer (FiTDO). The FiTDO estimates the total disturbance (combination of the abovementioned effects) within a fixed time. Further, it improves the attenuation disturbance property of the composite controller by feedforward compensation. The proposed controller relaxes the prior upper-bound knowledge of the total disturbance and has anti-unwinding characteristics. Moreover, the designed event-triggered mechanism reduces control workload reduction and guarantees the Zeno-free behavior in the proposed composite scheme. The stability analysis of the closed-loop system under the proposed scheme using Lyapunov theory ensures the system states converge to a small invariant set within a fixed time. Simulation analysis and comparative studies demonstrate that the proposed scheme is effective in terms of convergence time, steady-state performance, and anti-interference ability, rate of controller update.

Adaptive predefined-time fault-tolerant attitude tracking control for rigid spacecraft with guaranteed performance

In this article, the attitude tracking problem for rigid spacecraft systems with the consideration of actuator fault, input saturation, inertia uncertainties. and external disturbances is investigated. By introducing a shifting function, the requirement for accurate values of the initial tracking errors has been removed. A novel adaptive prescribed performance function is developed to enable the relaxation and recovery of the performance bounds under the different conditions of the shifted tracking error. Then, an error transformation is employed to convert the problem of prescribed performance tracking into the stabilization problem of a new system. Subsequently, an adaptive controller is designed based on a nonsingular predefined-time sliding mode manifold and an auxiliary system. The proposed controller ensures a predefined-time convergence with prescribed static and transient performance for the tracking error. The stability analysis of the proposed attitude controller is rigorously established using Lyapunov methods. Finally, numerical simulations are conducted to exhibit the efficacy and superiority of the propounded scheme.

Fault-tolerant attitude tracking control for carrier-based aircraft using RBFNN-based adaptive second-order sliding mode control

This paper proposes a fault-tolerant attitude tracking control for carrier-based aircraft with external disturbances and actuator faults, which is based on backstepping control, second-order sliding mode control (SOSMC) and the radial basis function neural network (RBFNN) adaptation algorithm. First, the generic attitude dynamic model of carrier-based aircraft is presented. Based on backstepping method, the attitude control system is divided into two simple and low-order subsystems. Then, the basic SOSMC using the type of proportional integral (PI) sliding mode variable are designed respectively for two subsystems, which can guarantee the system stable with no chattering in the finite time. To compensate for disturbances and faults more accurately, we design RBFNN-based adaptive second-order sliding mode control (RASOSMC) where RBFNN algorithm is utilized to approximate the lumped perturbation, which attenuates the impact of disturbances and faults more effectively and improves attitude tracking performance. Furthermore, the adaptive online algorithms for the RBFNN weights are proposed based on Lyapunov theory. Finally, numerical simulation results are given to indicate the effectiveness and robustness of the SOSMC scheme and RASOSMC scheme.

Fault-Tolerant Attitude Tracking Control Driven by Spiking NNs for Unmanned Aerial Vehicles.

In this article, we proposed a novel fault-tolerant control scheme for quadrotor unmanned aerial vehicles (UAVs) based on spiking neural networks (SNNs), which leverages the inherent features of neural network computing to significantly enhance the reliability and robustness of UAV flight control. Traditional control methods are known to be inadequate in dealing with complex and real-time sensor data, which results in poor performance and reduced robustness in fault-tolerant control. In contrast, the temporal processing, parallelism, and nonlinear capacity of SNNs enable the fault-tolerant control scheme to process vast amounts of sensory data with the ability to accurately identify and respond to faults. Furthermore, SNNs can learn and adjust to new environments and fault conditions, providing effective and adaptive flight control. The proposed SNN-based fault-tolerant control scheme demonstrates significant improvements in control accuracy and robustness compared with conventional methods, indicating its potential applicability and suitability for a range of UAV flight control scenarios.

Fuzzy adaptive fixed-time fault-tolerant attitude tracking control for tailless flying wing aircrafts

This work investigates the fault-tolerant attitude tracking control problem for the tailless flying wing aircraft in the presence of an external disturbance, uncertain parameters, and time-varying actuator failures. First, the external disturbance, uncertainty, and time-varying actuator failures are skillfully transformed into a lumped uncertainty, followed by an approximator constructed by employing an interval type-2 fuzzy logic system (IT2-FLS). On this basis, a fixed-time IT2 fuzzy fault-tolerant control scheme is proposed, which can guarantee that all the signals of the closed-loop system have fixed-time convergence. The desired control torque is allocated to each control surface through a recurrent neural network (RNN) based control allocation algorithm by considering the magnitude and rate constraints of the actuators. Finally, the two representative simulations have been conducted to validate the effectiveness and superiority of the proposed control scheme and control allocation algorithm.

A novel learning observer-based fault-tolerant attitude control for rigid spacecraft

This paper investigates a learning observer-based fault-tolerant control strategy for a rigid spacecraft attitude system with external disturbance, parameter uncertainty and actuator faults. An adaptive learning observer design approach, which does not require the upper bound information of generalized perturbation, is proposed to estimate the attitude angular velocities and reconstruct actuator faults accurately and quickly. On this basis, a fault tolerant attitude tracking control scheme is developed for spacecraft attitude stabilization by combining the estimation value and backstepping control technique. The stability of the faulty attitude system under the designed fault-tolerant control method is analyzed using Lyapunov framework. Finally, simulations are given to show the effectiveness of the proposed method.

Adaptive Fault-Tolerant Attitude Tracking Control for Flexible Spacecraft With Guaranteed Performance Bounds

Fault-tolerant attitude tracking control for rigid-flexible coupled spacecraft is studied in this article. Taking actuator faults, measurement errors of attitude and angular velocity, unmeasured modal displacements, model uncertainties, and external disturbances into consideration, an adaptive fault-tolerant attitude tracking control is designed. Then, based on the sequential Lyapunov method, the stability of the closed-loop system is analyzed showing that if the attitude and angular velocity measurement errors are bounded, then successively less conservative bounds on the attitude tracking error and the angular velocity error can be obtained.

NN-Based Fixed-Time Attitude Tracking Control for Multiple Unmanned Aerial Vehicles with Nonlinear Faults

This paper focuses on the fixed-time fault-tolerant attitude tracking control problem for multiple unmanned aerial vehicles (MUAVs) with nonaffine nonlinear faults. First, the command filter and neural networks (NNs) are employed to characterize unknown nonlinearities in MUAVs, and the update law of NN is developed via convex optimization technique. Second, the algebraic loop problem caused by nonaffine nonlinear faults is adequately solved by introducing the Butterworth low-pass filter. Then, the curve-fitting method is utilized to construct a piecewise virtual control signal to avoid the singularity problem in fixed-time control. Furthermore, based on the Lyapunov stability theory, a general fixed-time stability criterion is adopted to prove that the designed fault-tolerant attitude controller can guarantee the stability of MUAVs in fixed time. Finally, the effectiveness of the proposed control design method is verified via illustrative examples.

Observer-based fault-tolerant attitude tracking control for rigid spacecraft with actuator saturation and faults

This work mainly addresses the attitude tracking problem for rigid spacecraft subject to external disturbances, actuator saturation and faults. Firstly, a finite-time prescribed performance function (FTPPF) is defined to limit the tracking errors of original system into the boundary constraints and converge into a small residual set around zero within the preassigned time. An error transformation is employed to transform the constrained control system into an unconstraint one to simplify the relevant controller design. With the aid of the hyperbolic tangent function, the actuator saturation is approximated, and the approximation error is included into the external disturbances to be restrained. Then, a linear extended state observer (LESO) is developed to address the synthetic disturbances mentioned above with fewer tuning parameters. Wherein, the nominal matrix replaces the actual input gains is employed in the LESO design to avoid the singularity in disturbance rejection resulted from saturation approximation. Furthermore, an observer-based fault-tolerant tracking controller is derived to stabilize the attitude tracking error system and realize the disturbance compensation. Compared with the existing methods based on neutral networks (NNs) or fuzzy approximations, the developed scheme can achieve simultaneous estimations of multiple disturbances with simpler design. Meanwhile, the disadvantage that the NNs and fuzzy approximations are only effective on some compact sets is avoided. Finally, numerical simulations and analyses are employed to verify the superiority and robustness of the proposed method.

Integrated fault tolerant tracking control for rigid spacecraft using fractional order sliding mode technique

In this study, the integrated fault estimation (FE) and fault tolerant control (FTC) design problem is investigated for the attitude system of a rigid spacecraft with inertia uncertainty, Lipschitz nonlinearity, external disturbance and multiple type actuator faults. An adaptive sliding mode observer design approach, which does not require the known upper bound of generalized perturbation, is proposed to obtain the estimation of unknown actuator faults. On this basis, a fault tolerant attitude tracking control scheme is developed for the faulty rigid spacecraft attitude system by combining the fractional order sliding mode control and backstepping control with adaptive fuzzy approximation technique. The stability of faulty closed loop attitude system under the designed FTC strategy is analyzed using Lyapunov approach. Finally, simulation results are given to show the superiority of the proposed integrated FE and FTC compared with some existing results.

Finite-time fault tolerant attitude tracking control of spacecraft using robust nonlinear disturbance observer with anti-unwinding approach

This paper investigates the composite control scheme of robust nonlinear disturbance observer (RNDO) with adaptive non-singular fast terminal sliding mode control (NSFTSMC) technique for the attitude tracking of rigid spacecraft. The spacecraft is subjected to the parametric uncertainties, external disturbances, and actuator faults. The proposed RNDO estimates the overall lumped disturbance (combination of faults and disturbances) in finite-time. Moreover, it improves the disturbance rejection property of the composite control by feedforward compensation. An adaptive law is also employed in the composite control to enhance the robustness against the cases where RNDO takes some time for estimation, e.g., when there is a sudden change in the lumped disturbance. Further, the proposed controller is also enriched with anti-unwinding property to tackle the problem of unwinding in the quaternion based attitude representation. The stability analysis of the closed-loop system under the composite control scheme guarantees the finite-time convergence of relative state variables using the Lyapunov stability theory. The simulation analysis with the comparative study illustrates the effectiveness of the proposed strategy in terms of better disturbance rejection ability, higher accuracy, faster convergence, and better steady-state performance.

Active fault-tolerant attitude tracking control with adaptive gain for spacecrafts

In this paper, an active fault-tolerant control (AFTC) method with adaptive gain is proposed for spacecrafts which subject to model uncertainty, external disturbance and actuator fault. A novel adaptive-gain finite-time observer is designed to solely estimate fault in the presence of disturbance for fault diagnosis. By incorporating the dual-layer gain adaption scheme into the nonlinear integral sliding mode control (ISMC), a reconfigurable controller is designed to accommodate fault. Due to the reaching phase elimination of ISMC, the gain tracking to the unknown bounded disturbance can be accelerated while it is maintained that the control gain will not be overestimated and the bound knowledge of fault/disturbance is not required. Simulation results verify the effectiveness and improvement of the proposed FTC method.

A fault-tolerant attitude tracking control of spacecraft using an anti-unwinding robust nonlinear disturbance observer

This paper investigates the application of an integral sliding mode control with a robust nonlinear disturbance observer to obtain an anti-unwinding spacecraft attitude tracking response with robustness against external disturbances, inertia matrix uncertainties, and actuator faults. In the controller design, external disturbances, uncertainties, and actuator faults are lumped together and estimated by the robust nonlinear disturbance observer. The proposed robust nonlinear disturbance observer guarantees the convergence of estimated lumped disturbance error to origin in finite time. The estimated disturbance is then used in the controller as a feed-forward compensator. Further, an adaptive law is also incorporated in the proposed controller to ensure additional robustness. The stability of the overall system and anti-unwinding characteristic are proved using the Lyapunov stability theory. Finally, numerical simulation analysis is performed in the presence of all the sources of lumped disturbances. It is observed that the proposed control strategy is ensuring higher accuracy, good steady-state precision, and eliminates the unwinding phenomenon.

Robust fault-tolerant attitude tracking with guaranteed prescribed performance

The robust fault-tolerant (FT) attitude tracking control problem with guaranteed prescribed performance is addressed in this paper. We consider the actuator fault, misalignment, sensor fault and external disturbance simultaneously and incorporate the L2 control allocation (CA) method to minimize the use of faulty actuators. To guarantee the prescribed performance such as the steady-state tracking error, convergence rate, as well as overshoot and undershoot, the constrained quaternion error is transformed to an unconstrained state, whose stabilization is proven to be sufficient and necessary to guarantee the performance requirement. With the utilization of the transformed state and the compromised angular velocity error suffering from gyro faults, a novel adaptive sliding mode FT control law with CA is developed. Ultimate uniform boundedness of the compromised angular velocity error and transformed state is ensured to satisfy the specified tracking performance. Numerical simulations are conducted on a rigid spacecraft to illustrate the efficiency of the proposed robust FT control law.

Fault-tolerant attitude tracking control of combined spacecraft with reaction wheels under prescribed performance

Capture and control of a failed spacecraft can be achieved by a space manipulator installed in a service spacecraft. After this target has been captured, the combined spacecraft must be controlled in a prescribed way. The attitude attacking control of the combined spacecraft system is one major challenge since the mass properties of the whole spacecraft system and configuration matrix of the reaction wheels change, especially when actuator fault occurs. In this paper, a nonlinear disturbance-observer-based fault-tolerant attitude control scheme is developed for the combined spacecraft with prescribed performance. Firstly, an approach is given to reconstruct the attitude tracking dynamics of the combined spacecraft with reaction wheels. Then, a fault-tolerant controller, based on dynamic surface method and nonlinear extended state observer, is developed whereby performance in the light of convergence time, stability and accuracy with inertia uncertainty, actuator saturation and external disturbance can be prescribed. Finally, comparative simulations in both actuator faults and actuator fault-free cases are conducted to show the superiority of the developed attitude tracking control method.

Appointed-time fault-tolerant attitude tracking control of spacecraft with double-level guaranteed performance bounds

This paper investigates the issue of appointed-time fault-tolerant control for spacecraft attitude tracking in the presence of external disturbances and actuator faults. By “appointed-time”, it is meant that the maneuver completion time can be preassigned offline according to mission-oriented demands. Firstly, appointed-time performance functions are tactfully developed, which seek to impose a priori desired performance metrics on both the attitude and angular velocity errors (double-level). After that, an adaptive fault-tolerant controller is derived using structurally simple error transformations in combination of asymmetric barrier Lyapunov functions. Based on Lyapunov synthesis, it is then shown that the derived controller is capable of guaranteeing the boundedness of all the signals in the closed-loop system, and of achieving double-level guaranteed performance bounds for output tracking errors, despite the presence of external disturbances and actuator faults. In particular, the attitude tracking can be accomplished in a user-appointed time without resorting to judicious control parameters selection. Finally, simulation results are presented to illustrate the efficacy of the proposed control scheme.

Adaptive fault-tolerant attitude tracking control for spacecraft with time-varying inertia uncertainties

This paper is devoted to adaptive attitude tracking control for rigid spacecraft in the presence of parametric uncertainties, actuator faults and external disturbance. Specifically, a dynamic model is established based on one-tank spacecraft, which explicitly takes into account changing Center of Mass (CM). Then, a control scheme is proposed to achieve attitude tracking. Benefiting from explicitly considering the changing CM during the controller design process, the proposed scheme possesses good robustness to parametric uncertainties with less fuel consumption. Moreover, a fault-tolerant control algorithm is proposed to accommodate actuator faults with no need of knowing the actuators’ fault information. Lyapunov-based analysis is provided and the closed-loop system stability is rigorously proved. Finally, numerical simulations are presented to illustrate the effectiveness of the proposed controllers.

Constrained adaptive fault-tolerant attitude tracking control of rigid spacecraft

A saturated fault-tolerant attitude tracking controller for disturbed rigid spacecraft is derived using nonlinear state feedback control method. The proposed controller achieves the constraints of control inputs by directly using the bounded function instead of the traditional saturation compensator technique, and the active tolerance to the partial loss of actuator effectiveness is also achieved by directly using the known bounds of the actuator faults in the controller. Specifically, compared with the traditional saturated control methods, a continuously bounded nonlinear function in the proposed controller is used to guarantee that the actuator outputs are smoothly bounded under the prescribed constraints. Based on some properties of the attitude tracking dynamics, the proposed controller can ensure the attitude tracking errors converge to small neighborhoods of zero via stability analysis in the Lyapunov framework. Simulation results are presented to illustrate the effectiveness of the control scheme.

Fault tolerant tracking of Mars entry vehicles via fuzzy control approach

In this paper, a fault tolerant attitude tracking control scheme is proposed for Mars entry vehicles (MEVs) with disturbances and actuator failures. The original attitude dynamics of MEVs is divided into two subsystems, named as slow subsystem and fast subsystem, respectively. For slow subsystem, the control-like angular velocity command is generated. For fast subsystem, the Takagi–Sugeno (T-S) fuzzy models are used to describe it at first. Based on these, the partial loss of actuator effectiveness with the generated angular velocity problem is transformed into solving the tracking problem with uncertain parameters. Then, a fault tolerant tracking control scheme is proposed by combining fuzzy line-integral Lyapunov function method with robust H∞ control approach. The proposed controller design is simple and can guarantee the faulty closed-loop system to be stable with acceptable attenuation level. Finally, the effectiveness of the proposed design method is demonstrated in a MEVs attitude control system subject to loss of actuator effectiveness.