Multi-source Disturbances Research Articles

Electromechanical coupling modeling and fractional-order control of the seeker stabilization platform

To address the electromechanical coupling and multi-source disturbance problems of the seeker stabilized platform, this paper constructs an electromechanical coupling model of the seeker stabilized platform based on the Lagrange-Maxwell equation. To mitigate the influence of electromechanical coupling on the control performance of the seeker, a super-twisting controller based on a fractional-order terminal sliding mode surface (FOSTSMC) is proposed. Additionally, to handle various disturbances in the system, this paper introduces a method that combines the extended state observer (ESO) with the proposed controller to enhance the system’s stability and anti-disturbance performance. The Lyapunov function is designed to prove that the proposed controller can reach a convergence state within finite time. Finally, the proposed control method is compared with PID control, fuzzy PID control, linear sliding mode control, and super spiral control combined with a disturbance observer (DOB). Multiple simulation experiments demonstrate that, under the influence of electromechanical coupling and multi-source disturbance, the FOSTSMC-ESO significantly improves the stability and anti-disturbance performance of the seeker stabilization platform.

Composite anti-disturbance predictive control of unmanned systems with time-delay using multi-dimensional Taylor network

A composite anti-disturbance predictive control strategy employing a Multi-dimensional Taylor Network (MTN) is presented for unmanned systems subject to time-delay and multi-source disturbances. First, the multi-source disturbances are addressed according to their specific characteristics as follows: (A) an MTN data-driven model, which is used for uncertainty description, is designed accompanied with the mechanism model to represent the unmanned systems; (B) an adaptive MTN filter is used to remove the influence of the internal disturbance; (C) an MTN disturbance observer is constructed to estimate and compensate for the influence of the external disturbance; (D) the Extended Kalman Filter (EKF) algorithm is utilized as the learning mechanism for MTNs. Second, to address the time-delay effect, a recursive τ−step-ahead MTN predictive model is designed utilizing recursive technology, aiming to mitigate the impact of time-delay, and the EKF algorithm is employed as its learning mechanism. Then, the MTN predictive control law is designed based on the quadratic performance index. By implementing the proposed composite controller to unmanned systems, simultaneous feedforward compensation and feedback suppression to the multi-source disturbances are conducted. Finally, the convergence of the MTN and the stability of the closed-loop system are established utilizing the Lyapunov theorem. Two exemplary applications of unmanned systems involving unmanned vehicle and rigid spacecraft are presented to validate the effectiveness of the proposed approach.

Adaptive Disturbance Suppression Output Regulation for Switched Systems With Multi-Source Disturbances

Adaptive Disturbance Suppression Output Regulation for Switched Systems With Multi-Source Disturbances

Composite anti-disturbance dynamic positioning for mass-switched unmanned marine vehicles with multisource disturbances and actuator saturation: A switched model method

This article focuses on the composite anti-disturbance dynamic positioning (CADDP) control problem for the unmanned marine vehicle (UMV) system subject to mass switching, multisource disturbances and actuator saturation. The multisource disturbances include the unmeasurable modeled disturbances and measurable unmodeled disturbances. First, a switched model is introduced to describe the mass-switched UMV (MSUMV) system. Then, a series of switching observers are built to capture the unmeasurable disturbances. Meanwhile, the convex hull technique is exploited to address the actuator saturation. Further, based on the disturbance observer, the CADDP control scheme is developed to alleviate the influences of the multisource disturbances and actuator saturation, and to achieve the dynamic positioning (DP) of the MSUMV model. In the end, the established CADDP control strategy is carried on a supply vessel to illustrate the feasibility of the developed theory.

A Compact Aerial Manipulator: Design and Control for Dexterous Operations

The lack of aerial physical interaction capability is one of the choke points limiting the extension of aerial robot applications, such as rescue missions and aerial maintenance. We present a new aerial robotic manipulator (AEROM) for aerial dexterous operations in this work. It contains a robotic manipulator with 6-degree-of-freedom and a compact flight platform. Firstly, we propose a quantitative capability index to evaluate and guide the mechanical design of the AEROM. Based on the proposed quantitative index, we construct a lightweight bird-inspired manipulator to imitate a raptor hindlimb. An additional telescopic joint and an end-effector consisting of three soft fingers allow the AEROM to execute aerial interaction tasks. In addition, the wrist joints enable independent control of the end-effector attitude regardless of the flight platform. After explicitly analyzing the multi-source disturbances during the aerial operation tasks, we develop a refined anti-disturbance controller to compensate for the disturbances with different characteristics. The proposed controller further improves the position accuracy of end-effector to enable dexterous operations during aerial interaction tasks. Finally, the physical experiments verify the effectiveness of the proposed AEROM system.

Multisource disturbances rejection control for linear systems with unmeasured states under process and measurement disturbances

In this paper, a multisource disturbances attenuation and rejection control method is proposed for linear systems with unmeasured states under process and measurement disturbances. Since some internal states of control systems are hard to be measured via sensors in the realistic engineering process, a novel output feedback control scheme is proposed for designing the anti-disturbance controller by using measurement outputs, although these outputs mix with measurement disturbances. In addition, the dynamics of control system states also suffer from the influence of multiple process disturbances. To enhance the anti-disturbance ability of control systems, two kinds of disturbance observers are adopted to estimate process and measurement disturbances, respectively. And the anti-disturbance output feedback controller is constructed based on the process disturbance observer, state observer and H∞ control theory. In which the state observer is built via the measurement outputs and measurement disturbance observer. Then, the linear matrix inequality technology is used for analyzing the stability of closed-loop systems and decoupling the observers and the controller. Finally, the effectiveness of proposed control scheme is verified by using a numerical example.

Invariant manifold based nonsingular terminal sliding mode control for systems with multi-source disturbances via output-feedback

Invariant manifold based nonsingular terminal sliding mode control for systems with multi-source disturbances via output-feedback

Fixed time containment control of multi-agent system under multi-source mismatched disturbance

Aiming at the cooperative control problem of multi-agent system, the fixed-time containment control of general second-order multi-agent system under mismatched disturbances is studied. Firstly, the problem of multi-agent system fixed-time containment control in ideal state is analyzed, and a distributed control protocol based on variable structure control is proposed. Then, a nonlinear fixed-time disturbance observer is designed, aiming at the mismatched disturbance, and a fixed-time control protocol based on the nonlinear disturbance observer is proposed. Finally, the effectiveness of the proposed control protocol under switching topology and multi-source disturbance is verified by numerical simulation.

Study on the Mechanism and Suppression of Harmonic Vibration of AMB-Rotor System

The AMB-rotor system is complex and has strong coupling characteristics, which allows multi-harmonic disturbances to enter the system through different ways to produce vibrations with rich spectrum components, which has a great influence on the improvement of micro-vibration accuracy of the rotor system. To further achieve active control of the micro-vibration in the AMB-rotor system, firstly, the mechanism of multi-source disturbance is analyzed according to the working principle of the AMB-rotor system, and the mathematical and physical relationship between the mechanism of disturbance generation and the inducement is deeply studied. Then, the structure of a novel adaptive notch filter, the method of adaptive frequency estimation and analysis of harmonic current suppression in the AMB system are presented. Finally, simulation and experimental research using an MSCMG system demonstrate the feasibility of the proposed method regarding the elimination of harmonic control current.

Event-Triggered Adaptive Antidisturbance Switching Control for Switched Systems With Dynamic Neural Network Disturbance Modeling.

In this article, a dynamic event-triggered adaptive antidisturbance (ETAAD) switching control strategy is proposed for switched systems subject to multisource disturbances. The disturbances are divided into two categories: the available unmodeled disturbance and the unavailable dynamic neural network modeled disturbance. First, a dynamic ET criterion is set based on the system state. Then, a novel dynamic ETA disturbance estimator is introduced to observe the modeled disturbance. Furthermore, according to the ET rule and adaptive disturbance observer, a switched controller is designed. Next, under the controller and switching criterion with the average dwell time limitation, sufficient conditions are given to force the switched systems to realize multisource disturbance suppression (DS), trajectory tracking, and communication resource (CR) saving simultaneously. Meanwhile, the Zeno phenomenon may be caused by the ET rule being excluded. In addition, the presented ETAAD approach is also applicable to the nonswitched systems case. Finally, a simulation case is given to validate the effectiveness of the dynamic ETAAD switching control method.

Adaptive Integral Sliding-Mode Control for a class of Nonlinear Spacecraft Proximity Systems under Multi-source Disturbances and Unmodeled Dynamics

Adaptive Integral Sliding-Mode Control for a class of Nonlinear Spacecraft Proximity Systems under Multi-source Disturbances and Unmodeled Dynamics

Disturbance observer–based backstepping sliding mode cascade control of 2–degrees of freedom hydraulic tunneling robot

For the 2–degrees of freedom position tracking problem of the robotized hydraulic-driven roadheader with high nonlinearities and strong uncertainties, a practical disturbance observer–based backstepping sliding cascade control method together with an adaptive compensator is proposed and investigated. The presented methodology mainly includes a continuous nonsingular fast terminal sliding mode with the backstepping technique and the power reaching law with time-varying coefficients used to achieve satisfactory performance against the multi-source disturbances, two disturbance observers used to approximately estimate the unknown dynamics in the mechanical and hydraulic subsystem, respectively. Simultaneously, a continuous robustifying term is also utilized to compensate for the residual disturbances and enhance the robustness. The presented control method doesn’t need the precise model thanks to the auxiliary disturbance observer, and can ensure fast convergence and small tracking error thanks to the backstepping sliding cascade control and the adaptive robust compensator. Based on Lyapunov theory, stability of the overall closed-loop system is proved rigorously, and asymptotically bounded tracking performance of the robotic manipulator is guaranteed. Finally, 2–degrees of freedom trajectory tracking experiments are conducted, and comparative results effectively verify the superiorities of the proposed method.

Dissipativity-based asynchronous control for time-varying delay T–S fuzzy Markov jump systems with multisource disturbances and input saturation

Dissipativity-based asynchronous control for time-varying delay T–S fuzzy Markov jump systems with multisource disturbances and input saturation

High-Precision Suppression of Harmonic Vibration Force by Repetitive Controller With Triple-Loop Structure

The harmonic vibration force generated by multi-source disturbances through the magnetic bearing closed-loop control system seriously affects the improvement of the performance of the magnetically suspended control moment gyroscope (MSCMG). The harmonic noise introduced by the displacement sensor generates harmonic components through a closed-loop control system, and the compensation accuracy of synchronous displacement stiffness force is reduced by the low-pass characteristics of the power amplifier. In this paper, the rotor displacement signal and current signal are used as inputs to the repetitive controller and notch filter, and the power amplifier and repetitive controller are constructed into three closed-loop systems to achieve high-precision suppression of harmonic vibration forces. Finally, the effectiveness of the method is demonstrated by using a 200Nms MSCMG and a micro-vibration test system.

Vision Guided Dynamic Synchronous Path Tracking Control of Dual Manipulator Cooperative System

Abstract Compared with a single manipulator manufacturing cell, a dual manipulator cooperative system has more advantages in reconfigurability and flexibility. However, there are calibration errors and multi-source disturbances in the collaborative process, which lead to the processing trajectory accuracy defects of large-scale associated machining features. To solve the above problems, a practical path tracking synchronous control algorithm based on position-based visual servoing (PBVS) is proposed in this paper for the dual manipulator cooperative system, the proposed dynamic path tracking cross-coupled sliding mode controller (PTCSMC) scheme can realize dynamic paths correction while executing the pre-planned paths. In addition, for the cross-coupled technology to be applied into the proposed control algorithm for dynamic path tracking based on the real-time feedback of the highly repeatable 3D visual measurement instrument (VMI), the tracking and synchronous errors of the dual manipulators converge synchronously to zero. Finally, the stability of proposed control algorithm is proven by the Lyapunov method. In the end, the real-time line and circle path tracking experimental results using two industrial manipulators demonstrate the effectiveness of the proposed algorithm.

Fault Detection for Unmanned Marine Vehicles Under Replay Attack

This paper investigates the fault detection problem of unmanned marine vehicles (UMV) under the influence caused by replay attacks. Firstly, the dynamics of UMV are modeled by a T-S fuzzy system with an unknown membership function, which includes the nonlinear coupling of the internal state of the system, the environmental multi-source disturbance as well as the potential thruster failure on UMV. Then, the possible replay attack from the sensor to the shore-based center is considered, and a switching-type attack tolerant fault detection filter is designed. Sufficient conditions are given to ensure that the filtering augmented system is stable and with stochastic finite frequency <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$H_{\infty }$</tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$H_{-}$</tex-math></inline-formula> performances, which reflect the robustness to the disturbance and sensitivity to the fault. On this basis, through a series of mathematical processing, the linear solvable conditions for the design of fault detection filters are obtained. Finally, the effectiveness of the proposed algorithm is verified by simulations.

Torque Ripple Minimization of Low-Speed Gimbal Servo System Using Parameter-Optimized ESO

Torque ripple of permanent magnet synchronous motor (PMSM) and load disturbances are the main influencing factors which restrict the application of PMSM in low speed tracking system. In order to improve the speed tracking precision of gimbal servo system in control moment gyro (CMG) with multi-source disturbances, this paper proposes a composite control method based on parameter-optimized extended state observers (ESOs) with sliding mode control in the speed loop and PI control with a feed-forward compensation in the current loop. Three ESOs are employed to estimate the disturbances on d-axis current, q-axis current and the load torque, so that the controller can have the corresponding parts to compensate for the disturbances. In particular, aiming at the contradiction between the estimation quality of the observer and the sensitivity to the measurement noise, an appropriate cost function is designed to take a compromise between the lumped disturbances and measurement noise and optimize the parameters of the ESOs. Finally, simulation and experimental results on the gimbal servo system of magnetically suspended control moment gyroscope (MSCMG) show the effectiveness of the proposed methods.

Reinforcement learning based-adaptive tracking control for a class of semi-markov non-Lipschitz uncertain system with unmatched disturbances

A reinforcement learning based-adaptive tracking control method has been proposed for a class of semi-markov non-Lipschitz uncertain system with unmatched disturbances. Not only does the considered system contain unknown nonlinear functions and multisource disturbances, but parameter matrix in the system varies with the semi-Markov progress, which create difficulties in the design of the controller. Firstly, to handle the non-Lipschitz nonlinear terms, an adaptive control law based on reinforcement learning has been designed. Secondly, according to the reinforcement learning result, an adaptive disturbance observer has been constructed to offset the adverse influence generated by the multiple disturbances in the considered system. Finally, aiming at the parameter matrixes in the system varying with semi-Markov progress, a novel adaptive tracking controller integrating the reinforcement learning approximation, the adaptive disturbance observer and the tracking control law, has been proposed. With the given adaptive tracking control law based on reinforcement learning, through the Lyapunov direct method, it has been proven that the closed-loop system are stable and convergent and the tracking errors are ultimately uniformly bounded. In addition, several numerical experiments are provided to illustrate the feasibility and effectiveness of the proposed reinforcement learning based adaptive tracking control law.

Appointed-Time Control for Flexible Hypersonic Vehicles with Conditional Disturbance Negation

This paper investigates the anti-disturbance control design for flexible air-breathing hypersonic vehicles (FAHVs) with appointed-time prescribed tracking performances. The challenging issues include multisource disturbances, cross-coupling effects of the vehicle dynamics, and asymmetric amplitude and rate saturations. To address these issues, we propose an appointed-time prescribed performance control scheme for FAHVs via conditional disturbance negation technique. In contrast to existing disturbance rejection approaches, the proposed control scheme not only estimates the disturbances first in a fixed time, but also evaluates the estimated disturbances and selectively conducts compensation actions according to the insight of the FAHV dynamic characteristics. To further enhance convergence rate, the composite appointed-time prescribed performance controllers are designed for FAHVs via time-varying barrier Lyapunov function and nonsmooth backstepping technique, which ensure satisfactory transient response and steady-state performances. In addition, the asymmetric amplitude and rate saturation problem of actuators are dealt with by introducing unified approximation dynamics. It is rigorously proved that the practical appointed-time convergence of the tracking errors and the fixed-time convergence of all signals in the resultant FAHV closed-loop system can be achieved under the proposed control scheme. Finally, extensive comparative simulations are provided to demonstrate the feasibility and superiority of the proposed approach.

Soil methane emission suppression control using unmanned aircraft vehicle swarm application of biochar mulch - A simulation study

In this paper, we present a soil methane emissions suppression approach using swarms of unmanned aerial vehicles (UAVs), by spreading biochar mulch on top of the detected methane emissions area/source. Soil microorganisms can produce methane and release it into the atmosphere causing climate change such as global warming. However, people lack methods to manage soil methane emissions, especially quantification of methane emissions from the soil. Current measurement and suppression of methane methods are often limited due to the maintenance, installation, and calibration requirements of these sensing systems. To overcome these drawbacks, we present a new method called FADE-MAS2D (Fractional Advection Diffusion Mobile Actuator and Sensor) in which swarming UAVs are applied as optimal coverage control actuators to various methane release scenarios (from single to multi-source disturbances) utilizing an anomalous diffusion model with different time, and space fractional orders subject to wind fields. This strategy is based on the premise that methane diffusion can be modeled as an anomalous diffusion equation, and swarming UAVs can be applied to tackle the optimal coverage control issue. To simulate methane diffusion under the wind, we utilize the fractional calculus to solve the anomalous diffusion equation and define wind force with the drag equation. In addition, we integrated emissions control, UAV control efforts, and UAV location error in our cost function. Finally, we evaluated our approach using simulation experiments with methane diffusion and multiple methane emission sources in the time and space domain, respectively. The results show that when α ​= ​0.8 and β ​= ​1.8, the shape and emissions of methane perform well. Furthermore, our approach resulted in great control performance with multiple methane emission sources and different wind velocities and directions.