Search results

The paper aims to address the combined attitude control and Sun tracking problem in a flexible spacecraft in the presence of external and internal disturbances. The attitude stabilization of a flexible satellite is generally a challenging control problem, because of the facts that satellite kinematic and dynamic equations are inherently nonlinear, the rigid–flexible coupling dynamical effect, as well as the uncertainty that arises from the effect of actuator anomalies.

To deal with these issues in the combined attitude and Sun tracking system, a novel control scheme is proposed based on the adaptive fuzzy Jacobian approach. The augmented spacecraft model is then analyzed and the Lyapunov-based backstepping method is applied to develop a nonlinear three-axis attitude pointing control law and the adaptation law.

Numerical results show the effectiveness of the proposed adaptive control scheme in simultaneously tracking the desired attitude and the Sun.

Reaction wheels are commonly used in many spacecraft systems for the three-axis attitude control by delivering precise torques. If a reaction wheel suffers from an irreversible mechanical breakdown, then it is likely going to interrupt the mission, or even leading to a catastrophic loss. The pitch-axis mounted solar array drive assemblies (SADAs) can be exploited to anticipate such situation to generate a differential torque. As the solar panels are rotated by the SADAs to be orientated relative to the Sun, the pitch-axis wheel control torque demand can be compensated by the differential torque.

The proposed Jacobian control scheme is inspired by the knowledge of Jacobian matrix in the trajectory tracking of robotic manipulators.

The purpose of this paper is to develop a novel nonlinear H_∞ control approach for the nonlinear multivariable attitude tracking of rigid spacecraft.

Based on the transformation of the attitude tracking problem into quaternion error stabilization, the feedback control law is developed by using the normal matrix control theory with the inverse‐additive perturbation description of systems uncertainties, and the Hamilton‐Jacobi‐Isaacs (HJI) partial differential inequality is employed for providing the nonlinear H_∞ control criteria for the proposed control law. The onboard recursive least squares (RLS) estimation algorithm of inertia tensor is used for the further improving of the normal matrix property of the control system. The RLS algorithm is simple enough for the spacecraft borne computer. Computer simulation is performed to demonstrate the effectiveness of the control law proposed.

By the normal matrix control theory, the nonlinear H_∞ control law for attitude tracking is developed without solving the HJI inequality and with the inflight estimation of inertia, the proposed control law is adaptive and robust to the variation of mass properties, and its normality is further improved.

The paper is limited in rigid spacecraft with slowly changing mass property. The flexible influences are not considered.

The paper provides an alternative to the spacecraft researchers/engineers for developing the robust attitude control law with a simple structure and self‐tuning ability.

The paper is the first to provide a robust control based on the normal matrix approach, the HJI inequality, and the estimation of inertia.

This paper aims to present a three-axis attitude tracking control law to solve the attitude maneuver of a flexible satellite in the presence of parameter uncertainties and external disturbance.

Based on the relative dynamic equation where the relative attitude is described by quaternion, a robust control law composed of a proportional derivative (PD) part plus a signum function is designed and only requires the measurement of attitude and angular velocity. Furthermore, the stability analysis of the proposed control law is given through a two-step proof technique.

Numerical simulation results demonstrate that fine convergence of the attitude and angular velocity error and low-level vibration of flexible appendages are obtained by the proposed controllers.

The controller with the structure of a PD term plus a switching function about a sliding variable has low computational complexity and does not need to measure the modal variables of elastic appendages, so it can be used in orbit without modification.

The globally asymptotic stability of the controller in the presence of model uncertainties and external disturbances is proven rigorously through a two-step proof technique.

The purpose of this paper is to present μ-synthesis-based robust attitude trajectory tracking control of three degree-of-freedom four rotor hover vehicle.

Comprehensive modelling of hover vehicle is presented, followed by development of uncertainty model. A μ-synthesis-based controller is designed using the DK iteration method that not only handles structured and unstructured uncertainties effectively but also guarantees robust performance. The performance of the proposed controller is evaluated through simulations, and the controller is also implemented on experimental platform. Simulation and experimental results validate that μ-synthesis-based robust controller is found effective in: solving robust attitude trajectory tracking problem of multirotor vehicle systems, handling parameter variations and dealing with external disturbances.

Performance analysis of the proposed controller guarantees robust stability and also ensures robust trajectory tracking performance for nominal system and for 15-20 per cent variations in the system parameters. In addition, the results also ensure robust handling of wind gusts disturbances.

This research addresses the robust performance of hover vehicle’s attitude control subjected to uncertainties and external disturbances using μ-synthesis-based controller. This is the only method so far that guarantees robust stability and performance simultaneously.

Accurate glide path tracking is vital to the automatic carrier landing task of unmanned aerial vehicle (UAV). The purpose of this paper is to develop a reliable flight controller that can simultaneously deal with external disturbance, structure fault and actuator fault.

The automatic carrier landing task is resolved into the glide path tracking problem and attitude tracking problem. The disturbance observer-based adaptive sliding mode control scheme is proposed for system stabilization, disturbance rejection and fault tolerance.

Both the Lyapunov method and exemplary simulations can prove that the disturbance estimation error and the attitude tracking error converge in finite time in the presence of external disturbances and various faults.

The presented algorithm is testified by a UAV automatic carrier landing simulation, which shows the potential of practical usage.

The barrier function is introduced to adaptively update both the sliding mode observer gain and sliding mode controller gain, so that the sliding mode surface could converge to a predefined region without overestimation. The proposed flight controller ensures a secure carrier landing task.

The purpose of this paper is to design a global robust and continuous control scheme for the attitude tracking control problem of the reentry vehicle with parameter uncertainties and disturbances.

First, feedback linearization is applied to the model of reentry vehicle, resulting in three independent uncertain subsystems. Then a new second-order time-varying sliding function is proposed, based on which a continuous second-order time-varying sliding mode control (SOTVSMC) law is proposed for each subsystem. The global robustness and convergence performance of the closed-loop reentry vehicle control system under the proposed control law are proved.

Simulation is made for a reentry vehicle through the assumption that there is external disturbance to aerodynamic moment and the aerodynamic parameters as well as the atmospheric density are perturbed. The results verify the validity and robustness of the proposed strategy.

The SOTVSMC attitude controller based on feedback linearization is proposed for the reentry vehicle. The advantages of the proposed SOTVSMC are twofold. First, the global second order sliding mode is established, which implies that the closed-loop system is global robust against matched parameter uncertainties and disturbances in reentry. Second, the chattering problem is significantly alleviated.

The purpose of this paper, is to solve the problem of finite-time fault-tolerant attitude synchronization and tracking control of multiple rigid bodies in presence of model uncertainty, external disturbances, actuator faults and saturation. It is assumed that the rigid bodies in the formation may encounter loss of effectiveness and/or bias actuator faults.

For the purpose, adaptive terminal sliding mode control and neural network structure are used, and a new sliding surface is proposed to guarantee known finite-time convergence not only at the reaching phase but also on the sliding surface. The sliding surface is then modified using a proposed auxiliary system to maintain stability under actuator saturation.

Assuming that the communication topology between the rigid bodies is governed by an undirected connected graph and the upper bounds on the actuators’ faults, estimation error of model uncertainty and external disturbance are unknown, not only the attitudes of the rigid bodies in the formation are synchronized but also they track the time-varying attitude of a virtual leader. Using Lyapunov stability approach, finite-time stability of the proposed control algorithms demonstrated on the sliding phase as well as the reaching phase. The effectiveness of the proposed algorithm is also validated by simulation.

The proposed controller has the advantage that the need for any fault detection and diagnosis mechanism and the upper bounds information on estimation error and external disturbance is eliminated.

The purpose of this paper is to design a disturbance observer-based finite-time global sliding mode control scheme for the attitude tracking control problem of the reentry vehicle with parameter uncertainties and disturbances.

Feedback linearization is first introduced to transform vehicle model into three independent second order uncertain subsystems. Then a finite-time controller (FTC) is proposed for the nominal system on the basis of the homogeneity theory. Thereafter the integral sliding mode method is introduced for the vehicle with disturbances. The finite time convergence is achieved and global robustness is also assured by the combination of finite time control method and integral sliding mode strategy. Furthermore, to improve the attitude angle tracking accuracy a novel finite time disturbance observer (DO) is constructed.

Simulation is made for the reentry vehicle with disturbances involved. And the results show the finite-time convergence, tracking accuracy and robustness of the proposed strategy.

The proposed control strategy has three advantages. First of all it can achieve finite time convergence and avoid singularity. Moreover, it can also realize global robustness. Finally, a new kind of DO is introduced to improve the tracking accuracy.

This paper aims to present an intelligent motion attitude control algorithm, which is used to solve the poor precision problems of motion-manipulation control and the problems of motion balance of humanoid robots. Aiming at the problems of a few physical training samples and low efficiency, this paper proposes an offline pre-training of the attitude controller using the identification model as a priori knowledge of online training in the real physical environment.

The deep reinforcement learning (DRL) of continuous motion and continuous state space is applied to motion attitude control of humanoid robots and the robot motion intelligent attitude controller is constructed. Combined with the stability analysis of the training process and control process, the stability constraints of the training process and control process are established and the correctness of the constraints is demonstrated in the experiment.

Comparing with the proportion integration differentiation (PID) controller, PID + MPC controller and MPC + DOB controller in the humanoid robots environment transition walking experiment, the standard deviation of the tracking error of robots’ upper body pitch attitude trajectory under the control of the intelligent attitude controller is reduced by 60.37 per cent, 44.17 per cent and 26.58 per cent.

Using an intelligent motion attitude control algorithm to deal with the strong coupling nonlinear problem in biped robots walking can simplify the control process. The offline pre-training of the attitude controller using the identification model as a priori knowledge of online training in the real physical environment makes up the problems of a few physical training samples and low efficiency. The result of using the theory described in this paper shows the performance of the motion-manipulation control precision and motion balance of humanoid robots and provides some inspiration for the application of using DRL in biped robots walking attitude control.

A novel proportional integral derivative-extended state disturbance observer-based control (PID-ESDOBC) algorithm is proposed to solve the nonlinear hydrodynamics, parameters perturbation and external disturbance in yaw control of remote operated vehicles (ROVs). The effectiveness of PID-ESDOBC is verified through the experiments and the results indicate that the proposed method can effectively track the desired attitude and attenuate the external disturbance.

This study fully investigates the hydrodynamic model of ROVs and proposes a control-oriented hydrodynamic state space model of ROVs in yaw direction. Based on this, this study designs the PID-ESDOBC controller, whose stability is also analyzed through Kharitonov theorem and Mikhailov criterion. The conventional proportional-integral-derivative (PID) and active disturbance rejection control (ADRC) are compared with our method in our experiment.

In this paper, the authors address the nonlinear hydrodynamics, parameters perturbation and external disturbance problems of ROVs with multi-vector propulsion by using PID-ESDOBC control scheme. The advantage is that the nonlinearities and external disturbance can be estimated accurately and attenuate promptly without requiring the precise model of ROVs. Compared to PID and ADRC, both in overshoot and settling time, the improvement is 2X on average compared to conventional PID and ADRC in the pool experiment.

The delays occurred in the control process can be solved in the future work.

The attitude control is a kernel problem for ROVs. A precise kinematic and dynamic model for ROVs and an advanced control system are the key factors to obtain the better maneuverability in attitude control. The PID-ESDOBC method proposed in this paper can effectively attenuate nonlinearities and external disturbance, which leads to a quick response and good tracking performance to baseline controller.

The PID-ESDOBC algorithm proposed in this paper can be ensure the precise and fast maneuverability in attitude control of ROVs or other underwater equipment operating in the complex underwater environment. In this way, the robot can better perform undersea work and tasks.

The dynamics of the ROV and the nominal control model are investigated. A novel control scheme PID-ESDOBC is proposed to achieve rapidly yaw attitude tracking and effectively reject the external disturbance. The robustness of the controller is also analyzed which provides parameters tuning guidelines. The effectiveness of the proposed controller is experimental verified with a comparison by conventional PID, ADRC.