Mode Disturbance Research Articles

The Lateral and Directional Stability Behavior for Two Aircraft Models

The current study looks at flight behavior in lateral and directional motion.The investigation involves setting up the aircraft under an equilibrium condition with a small disturbance applied to it. Plotting the side slip angle, roll angle, and yaw angle with respect to time in the presence of disturbances can be used to investigate flight behavior in lateral and directional motion. Here the disturbance can be simulated by the movement of the aileron or rudder, in which these two control surfaces can be designed to move in a single impulse or multiple impulse disturbance mode. These two disturbance modes are used on the Beechcraft 99 and Cessna T37 aircraft. Both impulse disturbance models are used for the aileron and the rudder. However, in the current work, the Beechcraft 99 receives a single impulse, whereas the Cessna T37 receives multiple impulses. The implementation of such disturbances found that the Beechcraft 99 represented the aircraft that would be able to go back to its initial condition in response to a single impulse disturbance modewhile the Cessna T37 aircraft requires a little more time to return to its original yaw angle. Following the implementation of these twotypes of disturbances, it was discovered that each aircraft has the ability to return to its initial condition, but at varying times to reach its steady state solution.

Composite Terminal Guidance Law for Supercavitating Torpedoes with Impact Angle Constraints

A novel composite terminal guidance law with impact angle constraints is proposed for supercavitating torpedoes to intercept maneuvering warships. Based on an adaptive super-twisting algorithm and nonsingular terminal sliding mode (NTSM), the proposed guidance law can guarantee the finite-time convergence of line-of-sight (LOS) angle error and the LOS angular rate error. The new guidance law is a combination of finite-time stability theory, sliding mode control (SMC), tracking differentiator (TD), disturbance observer (DO), and dynamic surface control. A high-order sliding mode TD is used for denoising, tracking, and differentiating the measured target heading angle. A novel DO, with its finite-time stability proved, is designed to estimate the target lateral acceleration for feedforward compensation to attenuate chattering in control input. In the case of a first-order-lag autopilot, a new kind of tracking differentiator is adopted to compute the first-order time derivative of the virtual control command, which can improve the accuracy of dynamic surface control and avoid the “explosion of items” problem encountered with the backstepping control. Finally, numerical simulation results are presented to validate the effectiveness and superiority of the proposed TD, DO, and the composite guidance law.

A Novel Frequency Regulation in Islanded Microgrid using Sliding Mode Control with Disturbance Observers considering Storages and EVs

A variation in load on a microgrid (MG) system has a significant impact on the MG's frequency. In addition, wind and photovoltaic power sources are significantly affected by weather fluctuations; thus, the system experiences frequent oscillations. This paper proposes an integral sliding mode control system that incorporates a disturbance observer (ISMCDO) for establishing a power balance and frequency regulation in a MG system. MATLAB/ Simulink is used to compare the results of this method and those of integral sliding mode controller (ISMC) and disturbance observer-based controller (DOBC). In addition, their performance indices are compared as well, where the results can verify the superiority of ISMCDO method in comparison with other techniques. Consequently, Utilizing the ISMCDO controller, the secondary controller performances in the MG system may be improved, which will ensure stability, flexibility, quick response, and maintenance of the load balance when sudden changes in loads and weather conditions occur.

Immunity of CAN, CAN FD and Automotive Ethernet 100/1000BASE-T1 to Crosstalk From Power Electronic Systems

Reliable and fast data exchange is essential for many vehicle functions. For this purpose, special communication systems were introduced during the last years, e.g., LIN, CAN, or Automotive Ethernet. At the same time, more and more power electronic systems are integrated, e.g., for electric driving, causing electromagnetic disturbances. Because of the extended cable harness and short distances between the cables as well as the electrical devices, electromagnetic coupling between power electronic systems and communication systems is more likely. It may affect the reliability of data transmission. This article analyzes and compares the robustness of the automotive communication systems CAN, CAN FD, and Automotive Ethernet (100BASE-T1 and 1000BASE-T1) against common and differential mode disturbances from cable and PCB coupling. Simulations and measurements are shown to identify critical coupling configurations. The EMC performance of the different bus systems is discussed.

Synchronous control system of virtual main-axis based on extended sliding mode disturbance observer

A synchronous control system of virtual main-axis based on extended sliding mode disturbance observer is designed to solve some problems that coupling of multi-axis synchronous control of electronic gears is low and has poor anti-interference ability, and a large amount of synchronization error callback overshoot in bag-making machines. First, a velocity compensator is designed in order to establish the coupling relationship between the virtual and traction motor. Second, a nonsingular terminal sliding mode controller and a disturbance observer are used to enhance the anti-disturbance capability of the system. Finally, by using MATLAB/Simulink simulation, the viability and superiority of the method in multi-axis synchronous control are proved. The simulation results demonstrate that the control method decreases the synchronization error and the callback overshoot between the traction motors, and enhances the coupling performance and anti-interference ability of the system, which has a more significant impact on the high-performance synchronization control for the multi-traction motor system of the bag-making machine.

Fixed-time observer-based control of DFIG-based wind energy conversion systems for maximum power extraction

To extract maximum power from the available wind energy, it is necessary that the doubly-fed induction generator (DFIG) based wind energy conversion system (WECS) outputs that maximum power at each instant of time for different wind speeds. This can be achieved by controlling the rotor voltage of the DFIG. To make it possible, a novel maximum power point tracking (MPPT) controller in combination with state and disturbance observers and fixed-time stability notion is proposed in this paper. The sliding mode control (SMC) method is used to design the observer-based controller and ensure the robustness. The sliding mode state observer is designed while only the measurement of the stator reactive power and rotor speed is required. The modelling uncertainties and external disturbances are estimated by the sliding mode disturbance observer without information about their upper bounds in advance. Then, the combinatorial effect of uncertainties and disturbances are fully compensated by the designed controller. The fixed-time convergence issue is addressed where the bound on the settling time is user-defined using design parameters regardless of initial conditions. The elimination of chattering issue is considered in the design of the SMC laws. The stability analysis of the closed-loop system is obtained via the Lyapunov stability theory. The validity and robustness of the proposed method is tested in Simulink/MATLAB for a DFIG under two different scenarios of wind speed modelling. The proposed fixed-time method is also compared with a classical finite-time method. Comparing the results demonstrate that the proposed method outperforms the other method.

Fixed-Time Disturbance Observer-Based Control for Quadcopter Suspension Transportation System

By considering the under-actuated characteristics of the quadcopter suspension transportation system and the external disturbance, the effective tracking control of the quadrotor transportation system faces great difficulties and challenges. An adaptive hierarchical sliding mode control (HSMC) scheme based on fixed-time sliding mode disturbance observer (FTSMDO) is developed for the anti-disturbance tracking control of under-actuated quadcopter suspension transportation system (UQSTS). The HSMC is used to deal with the under-actuated characteristics of the UQSTS, and the external disturbance is estimated by designing the FTSMDO. Synchronously, the disturbance estimation error is processed by designing the adaptive law. The stability analysis based on Lyapunov is applied to verify the uniform ultimate boundedness of the closed-loop system. Finally, the comparison of physical experiment upshots shows the effectiveness and potential of the proposed new control techniques.

Hybrid Adaptive Dynamic Inverse Compensation for Hypersonic Vehicles with Inertia Uncertainty and Disturbance

This paper studies an intelligent hybrid compensation scheme for the uncertain parameter and disturbance of hypersonic flight vehicles (HFV). For the longitudinal model of HFV with modeling errors, a nominal nonlinear dynamic inverse (NDI) controller ensures that the system output can accurately track the reference command. In the presence of rotational inertia uncertainty, a multi-learning law adaptive NDI controller is proposed to directly compensate for its impact on tracking performance, making the system robust to the uncertainty and reducing high maneuvering attitude angles and velocities vibration. Then, an improved adaptive NDI controller with a sliding mode disturbance observer is designed to actively compensate for the elastic mode disturbance, and continuously ensure the system’s anti-disturbance flight quality. Ultimately, this active–passive hybrid control scheme compensates for both high maneuvering inertia uncertainty and global disturbance. The Lyapunov functions prove the system’s stability, and the semi-physical simulation platform verifies the effectiveness of the method.

Super-Twisting Sliding Mode Control with SVR Disturbance Observer for PMSM Speed Regulation

Sliding mode control and disturbance compensation techniques are applied to a nonlinear speed control algorithm for a permanent magnet synchronous motor (PMSM). Optimizing the speed control performance of PMSM systems with various disturbances and uncertainties is challenging. To achieve a satisfactory performance, a sliding mode control method based on the super-twisting algorithm reaching law (STRL) is presented. STRL can adapt dynamically to the variations of a controlled system. The STRL maintains a high tracking performance of the controller and allows the control input to eliminate chattering. To estimate the uncertainties and compensate for disturbances, a support vector regression-disturbance observer (SVR-DOB) is presented. The estimated uncertainties were used to minimize modeling errors and improve the disturbance rejection. A controller using SVR-DOB achieves a high precision, and the simulation results demonstrated the validity of the proposed control approach.

Continuous fixed-time synchronization control for uncertain industrial master-slave robotics system with improved transparency

Industrial telerobotics system (ITS) enables robots to implement remote, dangerous, and complicated manufacturing tasks by incorporating human intelligence. Higher requirements are put forward for the working speed and performance of ITS. However, for ITS, only asymptotic convergence can be realized by existing control strategies, which have poor robust performance. In view of these theoretical and practical problems, this article addresses fixed-time synchronization control issue for a class of ITS with unknown parametric/nonparametric uncertainties and external disturbances. Satisfactory force and position performance can be achieved with the designed novel control algorithms. Firstly, based on the impedance control frame, two reference models are constructed for the master and slave robots by considering force and position signals transmission between master and slave, respectively. Then, a new adaptive sliding mode disturbance observer (ASMDO) is developed to realize the estimation of external disturbances and system uncertainties in higher speed and higher precision under relaxed assumption. Moreover, a novel continuous fixed-time control (CFTC) scheme is developed to guarantee good position and force synchronization performances, simultaneously. Finally, the effectiveness of the suggested control method is validated with simulations and experimental results.

Global Ionospheric Disturbance Propagation and Vertical Ionospheric Oscillation Triggered by the 2022 Tonga Volcanic Eruption

The Tonga volcano erupted on 15 January 2022, at 04:15:45 UTC, which significantly influenced the atmosphere and space environment, at the same time, an unprecedented opportunity to monitor ionospheric anomalies is provided by its powerful eruption. In current studies of traveling ionospheric disturbance (TID) triggered by the 2022 Tonga volcanic eruption, the particular phenomenon of ionospheric disturbances in various parts of the world has not been reasonably explained, and the vertical ionospheric disturbances are still not effectively detected. In this paper, we calculate the high-precision slant total electron content (STEC) from more than 3000 ground-based GPS stations distributed around the world, then we obtain the radio occultation (RO) data from near-field COSMIC-2 profiles and investigate the horizontal TID and the vertical ionospheric disturbances by the singular spectrum analysis (SSA). Horizontal TID propagation captured by GPS STEC results indicates that acoustic-gravity waves dominate the energy input at the beginning of the ionospheric disturbance with an approximate speed of 1050 m/s initially. With the dissipation of the shock energy, lamb waves become a dominant mode of ionospheric disturbances, moving at a more stable speed of about 326 m/s to a range of 16,000 km beyond the far-field. Local characteristics are evident during the disturbance, such as the ionospheric conjugation in Australia and the rapid decay of TID in Europe. The shock-Lamb-tsunami waves’ multi-fluctuation coupling is recorded successively from the COSMIC-2 RO observation data. The shock and Lamb waves can perturb the whole ionospheric altitude. In contrast, the disturbance caused by tsunami waves is much smaller than that of acoustic-gravity waves and Lamb waves. In addition, influenced by the magnetic field, the propagation speed of TID induced by Lamb waves is higher towards the northern hemisphere than towards the southern hemisphere.

Robust tracking control for dynamic positioning ships subject to dynamic safety constraints

This paper addresses the dynamic safety constraint problem for the Dynamic Positioning (DP) ship subject to model uncertainties and unknown environmental disturbances. To guarantee the dynamic safety constraints, a new constraint technique based on the unified barrier function (UBF) is used to convert the original constrained DP system into an equivalent “non-constrained” one. By blending the new coordinate transformation into backstepping design, the position and velocity of the DP ship keep within the given constraints. In addition, a bioinspired neurodynamics model (BNDM) is developed to solve the traditional differential explosion problem of the virtual control law and limit the output in a certain range. Further, a sliding mode disturbance observer (SMDO) is introduced to estimate the model uncertainties and unknown environmental disturbances with minor chattering and rapid convergence. Finally, the effectiveness of the proposed controller and observer of the DP ship is illustrated by numerical simulations.

Research progress on the influence of forest fire on the eco-stoichiometric characteristics of carbon, nitrogen and phosphorus in forest ecosystem

Forest fire can change the eco-stoichiometric characteristics of forest ecosystem elements, reflect the biogeochemical cycle change mode of forest ecosystem environment after fire, and clarify the eco-stoichiometric characteristics of carbon (C), nitrogen (N), phosphorus (P) in forest ecosystem under forest fire disturbance, which is very important for understanding the response mechanism of forest ecosystem to forest fire disturbance. By consulting a large number of relevant literatures, the author summarized and analyzed the impact mode of forest fire disturbance on the C–N–P eco-stoichiometric characteristics of forest ecosystem, as well as the impact of forest fire disturbance on the C–N–P eco-stoichiometric characteristics of plants, C–N–P eco-stoichiometric characteristics of litter, and C–N–P eco-stoichiometric characteristics of soil. It is considered that the C–N–P eco-stoichiometric characteristics of forest ecosystem are mainly affected by fire factors (fire intensity, fire frequency, recovery time after fire), vegetation types and soil properties. In view of the scientific problems that forest fire urgently needs to be solved in the study of forest ecosystem eco-stoichiometry, three aspects: the impact mechanism of forest fire disturbance on the homeostasis of plant eco-stoichiometry, the study of multi-element eco-stoichiometry under forest fire disturbance, the establishment of the eco-chemometrics relationship of the plant–litter–soil composite system under the interference of forest fire are proposed, in order to deeply understand the plant regulation strategy under the interference of forest fire, clarify the mutual coupling mechanism between multiple chemical elements after the interference of forest fire, and improve the relationship between the input and output of aboveground and underground nutrients with the plant–litter–soil as a composite whole, which is of great significance for a deep understanding of the nutrient cycle and balance of the forest ecosystem under the background of global climate change, and reasonable formulation of forest fire management measures.

STRENGTH AND STABILITY ASSESSMENT OF NPP REINFORCED CONCRETE STRUCTURES REGARDING THE RESULTS OF VIBRATION ANALYSIS

Introduction . The article outlines methodological stages when assessing the resource of nuclear power plant (NPP) operation units with regard to degradation in the dynamic characteristics of reinforced concrete structures obtained by means of vibration analysis methods on the example of hot cells of nuclear installations. Aim : to improve the method currently used for assessing the stress-stain behavior and strength of NPP structures regarding the aging process of reinforced concrete elements under various environmental exposures. Materials and methods . A methodology is proposed for assessing the strength (loading capacity) and stability of NPP structures where significant variations in the properties of reinforced concrete elements have taken place under the action of continuous operation and thermal mode disturbances, thus weakening the element stiffness and, as a result, reducing their strength and stability. Therefore, in order to evaluate the stress-stain behavior and strength of hot cells, calculations should be carried out taking into account the history of structure loading and the process of crack development over the entire operation period. However, no analysis of the history of thermal loading has been performed during the operation period of the NPP under study. In addition, there is a lack of suitable software packages for nonlinear dynamic analysis certified by Rostechnadzor capable of considering the loading history and crack development in reinforced concrete structures. In order to eliminate the mentioned shortcomings, a vibration analysis of the walls and floors of hot cells should be performed to determine the following dynamic characteristics: natural vibration frequency and mode, logarithmic decrement of damping, deformation modulus and Poisson ratio for each wall and floor. Further, based on the obtained experimental data, the stress-stain behavior and strength of hot cells should be calculated using experimental data as calculation input information. The calculation methodology is based on a nonclassical method of modal superposition using the ABAQUS, ANSYS, and Nastran software packages. In order to verify the correctness of the results obtained by vibration analysis, an assessment of floor dynamic characteristics at the point +13.450 in the “П”–“Ж” rows was conducted. Results . The values of deformation modulus and natural vibration frequency obtained in the conducted experiment were found to agree with the calculated values. Conclusions . A methodology for assessing the strength of NPP structures regarding the aging of reinforced concrete under various environmental exposures was presented. The validity of dynamic characteristics obtained using vibration analysis was evaluated.

Model-free robust adaptive control of overhead cranes with finite-time convergence based on time-delay control

In this paper, a model-free robust adaptive control scheme with finite-time convergence based on time-delay control is proposed for anti-sway and positioning control of two-dimensional underactuated overhead cranes. First, the whole overhead cranes system is simplified to an ultra-local model for time delay estimation (TDE). TDE brings a direct and effective model-free property but also an estimation error. Second, a sliding mode disturbance observer is designed to estimate and compensate for the TDE error. Third, sliding mode control (SMC) is used to enhance the robustness of the controller. An adaptive integral sliding surface is then designed to accelerate the sliding surface convergence rate and shorten the convergence time. To further optimize the selection of parameters, the parameter estimation is integrated to enhance the performance of model-free control. In the final analysis of the simulation, data yield that the introduction of parameter estimation increases the control performance by more than 20% on average, and the above facts verify the effectiveness of the scheme. Finally, the stability of the closed-loop control system is analyzed by using Lyapunov stability theory, and the effectiveness and robustness of the control scheme are verified through computer simulation results.

Sliding Mode Disturbance Observer-Based Adaptive Dynamic Inversion Fault-Tolerant Control for Fixed-Wing UAV

Unmanned aerial vehicles (UAVs) have been widely applied over the past decades, especially in the military field. Due to the unpredictability of the flight environment and failures, higher requirements are placed on the design of the control system of the fixed-wing UAV. In this study, a sliding mode disturbance observer-based (SMDO) adaptive dynamic inversion fault-tolerant controller was designed, which includes an outer-loop sliding mode observer-based disturbance suppression dynamic inversion controller and an inner-loop real-time aerodynamic identification-based adaptive fault-tolerant dynamic inversion controller. The sliding mode disturbance observer in the outer-loop controller was designed based on the second-order super-twisting algorithm to alleviate chattering. The aerodynamic identification in the inner-loop controller adopts the recursive least squares algorithm to update the aerodynamic model of the UAV online, thereby realizing the fault-tolerant control for the control surface damage. The effectiveness of the proposed SMDO enhanced adaptive fault-tolerant control method was validated by mathematical simulation.

Sliding mode disturbance observer and Q learning-based bilateral control for underwater teleoperation systems

For underwater environments, it is difficult to acquire accurate contact force vectors between the end effecter and the object by multidimensional force sensors. Precise force measurement is the key point for accurate teleoperation tasks. However, existing force estimations are rarely concerned with multidimensional force vector estimations. Therefore, the transparency of the teleoperation system may be attenuated, even resulting in stability or task failure in practical engineering. In this paper, we focus on analyzing the contact force vector in three dimensions. A sliding mode disturbance observer is designed to estimate the contact force. A Q learning process is used to find the optimal multidimensional contact force. Furthermore, a bilateral controller is proposed based on the sliding mode disturbance observer and Q learning-based method for underwater teleoperation systems. The stability is analyzed by Lyapunov functions. Numerical simulations and real robot experiments are performed to verify the effectiveness of the proposed method.

Compensated Deadbeat Predictive Current Control Considering Disturbance and VSI Nonlinearity for In-Wheel PMSMs

In this article, a compensated deadbeat predictive current control (CDPCC) based on composite sliding mode disturbance observer (CSMDO) is proposed in response to the detrimental disturbance. Above all, the parameter variation and external load change are regarded as a lumped disturbance to build the PMSM mathematical model. Based on this model, a CSMDO is constructed to estimate the lumped disturbance in both speed and current loops. Then, the estimated disturbances are applied as compensations for the double loops to increase the speed robustness and current tracking accuracy. Furthermore, a voltage space vector compensation method is introduced to reduce the current distortion resulting from the added dead time in the three-phase full-bridge voltage source inverter. In the end, the effectiveness of the CDPCC method is validated by experiments through an in-wheel PMSM drive.

Two-Level Hierarchical-Interaction-Based Group Formation Control for MAV/UAVs

Cooperative group formation control of manned/unmanned aircraft vehicles (MAV/UAVs) using a hierarchical framework can be more efficient and flexible than centralized control strategies. In this paper, a two-level hierarchical-interaction-based cooperative control strategy is proposed for the MAV/UAVs group formation. At the upper level, combined with the nonlinear disturbance observer (NDO) and dynamic surface control (DSC) algorithm, a trajectory tracking problem with external disturbances for MAV is formulated. At the lower level, the leader-following formation controller is utilized to deal with the sub-formation keeping control problem for UAVs, based on the sliding mode disturbance observer and fast terminal sliding mode control law, and the robust performance and control accuracy are effectively improved. Moreover, the overall stability of the MAV/UAVs system is demonstrated using Lyapunov theory. The proposed approach is evaluated by simulation under the ground penetration combat mission for MAV/UAVs, and the performance is compared with that of other control strategies.

Finite-Time Extended State Observer-Based Fixed-Time Attitude Control for Hypersonic Vehicles

A finite-time extended, state-observer-based, fixed-time backstepping control algorithm was designed for hypersonic flight vehicles. To enhance the robustness of the controller, two novel finite-time extended state observers were introduced to compensate for the negative effects of lumped disturbances such as uncertainties and external disturbances. Two hyperbolic sine tracking differentiators were used to approximate the derivatives of the virtual control signals and guidance commands, thereby alleviating the computational burden associated with traditional backstepping control. Furthermore, a fixed-time backstepping attitude controller was used to guarantee that the tracking errors converged to a small neighbor of the origin in fixed time. According to the simulation results, the proposed controller outperformed a fixed-time sliding mode disturbance, observer-based, finite-time backstepping controller in terms of the tracking precision and convergence rate. Moreover, the proposed controller was noted to be robust in simulations involving lumped disturbances.