Sliding Mode Attitude Tracking Control Research Articles

Robust distributed fixed-time cooperative hunting control for multi-quadrotor with obstacles avoidance

This paper addressed the robust distributed fixed-time cooperative hunting problem of multiple quadrotors subject to disturbances in obstacles environment. To handle the underactuated issue inherent in quadrotor dynamics, an inner–outer (attitude-position) loop cascade control configuration is proposed to achieve the cooperative flight control of quadrotors. For position subsystem, as the information of target cannot be accessible to all quadrotors, a distributed fixed-time observer is devised to estimate the target’s information. To improve the system’s robustness, a fixed-time extended state observer is designed to reject disturbances actively. Based on two observers, the sliding mode position encirclement control protocol with repulsive force is presented to avoid obstacles and encircle the target within a fixed time. For attitude subsystem, a sliding mode attitude tracking control protocol is proposed such that tracking errors can converge to zero even under disturbances. The stability analysis is performed to show the stabilization of the whole closed-loop system with fixed-time convergence. Finally, two sets of comparison simulation are provided to show the superiority of the developed control strategy.

Adaptive Sliding Mode Attitude Tracking Control for Rigid Spacecraft Considering the Unwinding Problem

Based on the unwinding problem caused by the dual valued property of the quaternion description method, this paper designs an anti-unwinding sliding mode adaptive attitude tracking control with external disturbances and inertia matrix uncertainty. The sliding mode surface used in this paper contains two equilibrium points and adopts an indirect method, which greatly reduces the computational complexity. The stability and anti-unwinding performance have been proven. The simulation results have verified the effectiveness of the control method and we have compared it with the general linear sliding mode. The results show that the control method proposed in this paper is more stable, has higher convergence accuracy and has anti-unwinding performance.

Terminal sliding mode attitude tracking control for unmanned vehicle with predefined-time stability

In this paper, we proposed a predefined-time terminal sliding mode approach for attitude tracking control of unmanned aerial vehicle (UAV). In order to obtain the high convergence speed and steady-state performance controller, the modified non-singular terminal sliding mode control (TSMC) we adopted can switch sliding mode surfaces under different conditions. The system stability is achieved within a predefined time, which can be set by modifying the explicit parameters in advance. Due to the existence of model uncertainties and unknown external disturbances, an adaptive neural network-based approach is applied to compensate the error between the actual and nominal model without requiring any prior knowledge of the disturbances. Several comparative studies are carried out between the proposed approach and other predefined-time techniques in previous work, and simulation results and experimental results are presented to validate the correctness of analysis and superiority of the proposed control scheme.

Anti-unwinding terminal sliding mode attitude tracking control for rigid spacecraft

In this paper, terminal sliding mode attitude tracking control without unwinding for rigid spacecraft is investigated. In order to guarantee the finite-time convergence of the system states and unwinding-free performance of the system on the sliding surface, a novel switching function is constructed by a hyperbolic sine function such that the obtained terminal sliding surface contains two equilibria. Then, a terminal attitude tracking control law is developed to ensure that the system states are driven to the sliding surface in a finite time. Moreover, a boundary layer is introduced to solve the chattering problem of the designed controller. The convergence of the system states within the boundary layer is guaranteed by imposing a constraint for the parameter of the developed switching function. Furthermore, the subsets of attraction domains of the two equilibria are given by designing a dynamic parameter for the proposed control law. The simulation results illustrate that the attitude tracking of rigid spacecraft without unwinding is realized by adopting the proposed attitude control law.

Adaptive quantized sliding mode attitude tracking control for flexible spacecraft with input dead-zone via Takagi-Sugeno fuzzy approach

This paper addresses the sliding mode control design problem for the flexible spacecraft attitude tracking control system with Takagi-Sugeno fuzzy model based method. In this design, the external disturbance and actuator input dead-zone are considered simultaneously, and the signals between sensors and controller are quantized before transmission over digital communication channels. A quantized adaptive integral sliding mode control law is proposed to ensure that the sliding motion is globally asymptotically stable, and the effects of unknown external disturbances, actuator nonlinearity and quantization errors are compensated via the online adaptive mechanism simultaneously. Moreover, under the proposed digital control law the finite-time reachability of the designed sliding surface can be guaranteed strictly. Finally, simulation results are presented to illustrate the feasibility and effectiveness of the developed quantized spacecraft attitude control method.

Fixed-time disturbance observer-based chattering-free sliding mode attitude tracking control of aircraft with sensor noises

The challenging attitude tracking control problem of aircraft with external disturbance and sensor noises is investigated. A disturbance observer-based control approach is presented. In this approach, a fixed-time disturbance observer is preliminarily developed. The external disturbance is estimated with the estimation error governed to zero after a fixed-time regardless of any initial state. Moreover, with measurement noises explicitly considered, a discrete tracking differentiator extracting the real signals from the polluted measurement is introduced into that fixed-time observer to improve its application potential. Invoking the estimation information, a sliding mode attitude controller is then synthesized. The main feature of the proposed approach is that the closed-loop attitude tracking system is guaranteed to be exponentially stable. External disturbance rejection is achieved, while its upper bound is not required to implement that approach. In contrast to the conventional sliding mode control schemes, the proposed controller is chattering-free. Numerical simulation and experimental tests are finally carried out to verify the effectiveness of the proposed approach.

Adaptive Fixed-Time Nonsingular Terminal Sliding Mode Attitude Tracking Control for Spacecraft with Actuator Saturations and Faults

This paper focuses on the potential actuator failures of spacecraft in practical engineering applications. Aiming at the shortcomings and deficiencies in the existing attitude fault-tolerant control system design, combined with the current research status of attitude fault-tolerant control technology, we carry out high-precision, fast-convergent attitude tracking algorithms. Based on the adaptive nonsingular terminal sliding mode control theory, we design a kind of fixed-time convergence control method. This method solves the problems of actuator faults, actuator saturation, external disturbances, and inertia uncertainties. The control method includes control law design and controller design. The designed fixed-time adaptive nonsingular terminal sliding mode control law is applicable to the development of fixed-time fault-tolerant attitude tracking controller with multiple constraints. The designed controller considers the saturation of the actuator output torque so that the spacecraft can operate within the saturation magnitude without on-line fault estimation. Lyapunov stability analysis shows that under multiple constraints such as actuator saturation, external disturbances, and inertia uncertainties, the controller has fast convergence and has good fault tolerance to actuator fault. The numerical simulation shows that the controller has good performance and low-energy consumption in attitude tracking control.

Adaptive sliding mode attitude tracking control for flexible spacecraft systems based on the Takagi-Sugeno fuzzy modelling method

This paper addresses the problem of adaptive sliding mode attitude tracking control for a class of nonlinear flexible spacecraft systems with a redundant four reaction wheels’ setting and unknown actuator dead-zone, where configuration misalignment and external disturbance are considered simultaneously. By using the Takagi-Sugeno (T-S) fuzzy modelling method, the overall nonlinear spacecraft attitude dynamics system is first reconstructed into several local linear systems. Then, an adaptive integral-type sliding mode control scheme is introduced based on a T-S fuzzy model to stabilize the considered attitude tracking control system of flexible spacecraft. In this design, the external disturbance with unknown bound is counteracted in real-time by the adaptive estimate technique. Additionally, the integral sliding surface we introduced is insured to be asymptotically stable under the condition of given matrix inequality. The proposed adaptive sliding mode controller guarantees the finite-time reachability of the specific sliding surface. A practical example with simulation results is given to verify the validity of the attitude tracking control strategy we put forward.

Fixed-time sliding mode attitude tracking control for a submarine-launched missile with multiple disturbances

This paper studies a novel adaptive fixed-time sliding mode attitude tracking control for a submarine-launched missile, which is affected by sea winds, sea waves, ocean currents and other disturbances during the water-exit process. Firstly, the nonlinear water-exit dynamic model of the submarine-launched missile is established, and then it is transformed into a simple second-order attitude tracking system. Subsequently, a novel non-singular fixed-time fast terminal sliding mode surface (NFFTSMS) with fixed-time convergence is presented, and the pre-established settling time is also developed. Moreover, a novel adaptive non-singular fixed-time fast terminal sliding mode control (ANFFTSMC) is presented by employing a fixed-time disturbance observer, a fixed-time differentiator and the proposed NFFTSMS. Closed-loop stability of the proposed controller is proved by utilizing the Lyapunov methodology. Finally, numerical simulations including two typical launch trajectories of the missile are carried out to demonstrate the strong robustness of the proposed control scheme.

Disturbance observer-based second order sliding mode attitude tracking control for flexible spacecraft

Disturbance observer-based second order sliding mode attitude tracking control for flexible spacecraft

Adaptive output feedback integral sliding mode attitude tracking control of spacecraft without unwinding

This article studies an output feedback attitude tracking control problem for rigid spacecraft in the presence of parameter uncertainties and external disturbances. First, an anti-unwinding attitude control law is designed using the integral sliding mode control technique to achieve accurate tracking responses and robustness against inertia uncertainties and external disturbances. Next, the derived control law is combined with a suitable tuning law to relax the knowledge about the bounds of uncertainties and disturbances. The stability results are rigorously proved using the Lyapunov stability theory. In addition, a new finite-time sliding mode observer is developed to estimate the first time derivative of attitude. A new adaptive output feedback attitude controller is designed based on the estimated results, and angular velocity measurements are not required in the design process. A Lyapunov-based analysis is provided to demonstrate the uniformly ultimately bounded stability of the observer errors. Numerical simulations are given to illustrate the effectiveness of the proposed control method.

Fault-tolerant sliding mode attitude tracking control for flexible spacecraft with disturbance and modeling uncertainty

This article investigates the attitude tracking control problem for a class of flexible spacecraft with a redundant four reaction wheels’ setting. In this study, inertia uncertainties, external disturbance, wheel torque saturation, and configuration misalignment are taken into account simultaneously. Two types of sliding mode controllers are presented to solve this design problem. First, supposing the norm upper bound of external disturbances, bounds of inertia, and input uncertainties are available, a terminal sliding mode attitude tracking control strategy is developed, where the controller and steering laws are synthesized together. Second, supposing these norm upper bounds are unavailable, an adaptive control law is designed to cope with attitude tracking problem. Under both control schemes, the system trajectory can be ensured to arrive on the specified sliding surface in finite time. Finally, an illustrative example is given to verify the effectiveness of the proposed attitude tracking control methodologies.

On the Parametrization of the Three-Dimensional Rotation Group

Parameterization of group of rotations of Euclidean three-dimensional space applied to integration of rigid body motion equations