Impulsive Disturbances Research Articles

Mean square stability of discrete-time linear systems with random impulsive disturbances

Mean square stability of discrete-time linear systems with random impulsive disturbances

Sliding Mode Control for Linear Impulsive Systems With Matched Disturbances

This article develops the sliding mode control (SMC) strategy for linear impulsive systems with matched disturbances. Such systems describe dynamical systems that evolve according to continuous process most of the time with matched disturbances, but instantaneously exhibit discontinuities, i.e., impulsive disturbances. A suitable sliding surface function is proposed and the resulting sliding mode dynamics are a class of linear impulsive systems. Some sufficient conditions coupled with impulse time sequences are proposed to guarantee the reachability of the predesigned sliding surface and the stability of the reduced-order impulsive systems under sliding motion, respectively. We show how restrictions on the structure of the systems and impulses should be imposed to ensure the feasibility of the proposed SMC strategy in comparison with general SMC in continuous space. To show the effectiveness of the proposed approach, two simulation examples are presented at the end.

Benchmarking Dynamic Balancing Controllers for Humanoid Robots

This paper presents a comparison study of three control design approaches for humanoid balancing based on the Center of Mass (CoM) stabilization and body posture adjustment. The comparison was carried out under controlled circumstances allowing other researchers to replicate and compare our results with their own. The feedback control from state space design is based on simple models and provides sufficient robustness to control complex and high Degrees of Freedom (DoFs) systems, such as humanoids. The implemented strategies allow compliant behavior of the robot in reaction to impulsive or periodical disturbances, resulting in a smooth and human-like response while considering constraints. In this respect, we implemented two balancing strategies to compensate for the CoM deviation. The first one uses the robot’s capture point as a stability principle and the second one uses the Force/Torque sensors at the ankles to define a CoM reference that stabilizes the robot. In addition, was implemented a third strategy based on upper body orientation to absorb external disturbances and counterbalance them. Even though the balancing strategies are implemented independently, they can be merged to further increase balancing performance. The proposed strategies were previously applied on different humanoid bipedal platforms, however, their performance could not be properly benchmarked before. With this concern, this paper focuses on benchmarking in controlled scenarios to help the community in comparing different balance techniques. The key performance indicators (KPIs) used in our comparison are the CoM deviation, the settling time, the maximum measured orientation, passive gait measure, measured ankles torques, and reconstructed Center of Pressure (CoP). The benchmarking experiments were carried out in simulations and using the facility at Istituto Italiano di Tecnologia on the REEM-C humanoid robot provided by PAL robotics inside the EU H2020 project EUROBENCH framework.

High-speed collision dynamics of the tethered space net robot and parameter analysis to the collision disturbance

Tethered Space Net Robot (TSNR) is one of the efficient technologies in Active Debris Removal, it can maneuver in orbit automatically and capture multiple space debris continuously. However, the steady increase of the space debris greatly increases the collision risk of the TSNR in orbit. If threads of the net are broken by high-speed debris, the DOF of the TSNR will change and the maneuver of the TSNR will also be unstable. Moreover, TSNR is a classic underactuated system, the complex collision disturbance during the collision will increase more difficulty in controller design. Based on the improved net collision model, the collision dynamics of the TSNR with high-speed debris is studied, and a series of collision cases are designed to investigate the influence of the following three parameters, the collision position of the net, the size and mass of debris on collision disturbance. Results show that: TSNR is affected by several impulsive collision disturbances, which cause the rebound of the TSNR and the breakage of the local threads. The collision position of the net has a significant impact on the collision disturbance, and can be divided into three sensitive areas, central area, edge area and corner area, under the structure of the net and simulation results. The influence of both the size and the mass of the space debris on collision disturbance are piecewise and non-linear. This paper provides references for the structure design and dynamic control of the TSNR.

Formula omitted]th moment synchronization of stochastic impulsive neural networks with time-varying coefficients and unbounded delays

This article is devoted to the investigation of the pth moment synchronization problem for stochastic impulsive neural networks (SINNs) with time-varying coefficients and unbounded delays. First of all, one novel impulse generation rule is proposed, which generates the more general impulsive sequences. In order to cope with time-varying coefficients, unbounded delays and impulsive disturbances, some impulsive differential inequalities are developed by utilizing the comparison principle. With the help of the established impulsive inequalities, the synchronization of SINNs is analyzed in detail, and both pth moment exponential synchronization and asymptotical synchronization are realized by designing appropriate feedback controllers. Finally, several simulation examples are provided to illustrate the validity of the theoretical results.

Geomagnetic Disturbances That Cause GICs: Investigating Their Interhemispheric Conjugacy and Control by IMF Orientation

AbstractNearly all studies of impulsive geomagnetic disturbances (GMDs, also known as magnetic perturbation events MPEs) that can produce dangerous geomagnetically induced currents (GICs) have used data from the northern hemisphere. In this study, we investigated GMD occurrences during the first 6 months of 2016 at four magnetically conjugate high latitude station pairs using data from the Greenland West Coast magnetometer chain and from Antarctic stations in the conjugate AAL‐PIP magnetometer chain. Events for statistical analysis and four case studies were selected from Greenland/AAL‐PIP data by detecting the presence of >6 nT/s derivatives of any component of the magnetic field at any of the station pairs. For case studies, these chains were supplemented by data from the BAS‐LPM chain in Antarctica as well as Pangnirtung and South Pole in order to extend longitudinal coverage to the west. Amplitude comparisons between hemispheres showed (a) a seasonal dependence (larger in the winter hemisphere), and (b) a dependence on the sign of the By component of the interplanetary magnetic field (IMF): GMDs were larger in the north (south) when IMF By was >0 (<0). A majority of events occurred nearly simultaneously (to within ±3 min) independent of the sign of By as long as |By| ≤ 2 |Bz|. As has been found in earlier studies, IMF Bz was <0 prior to most events. When IMF data from Geotail, Themis B, and/or Themis C in the near‐Earth solar wind were used to supplement the time‐shifted OMNI IMF data, the consistency of these IMF orientations was improved.

Robust mean shift filter for mixed Gaussian and impulsive noise reduction in color digital images

Noise reduction is one of the most important topics of digital image processing and despite the fact that it has been studied for a long time it remains the subject of active research. In the following work, we present an extension of the Mean Shift technique, which is efficiently reducing the Gaussian noise, so that it is able to cope with the impulsive disturbances. Furthermore, the elaborated technique can be applied to enhance the images corrupted by a mixture of strong Gaussian and impulsive noise, severely decreasing the quality of color digital images. By means of our approach, which is based on a novel similarity measure between a pixel and a patch located in the center of the processing block, even heavily disturbed images can be effectively restored, which enables the success of further stages of the image processing pipeline. We evaluate the efficiency of the proposed method using a publicly available database of test color images and compare the restored images applying a set of standard quality metrics with the results delivered by state-of-the-art denoising methods. Additionally, we compare our method with the Medoid and Quick Shift techniques, accelerating the original Mean Shift algorithm, in terms of objective quality criteria and computational complexity. The results of the performed experiments indicate that the proposed technique is superior to the widely used denoising techniques and can be used as a robust extension of the Mean Shift procedure. In the paper, a particular emphasis is placed on the ability of the presented algorithm to preserve and enhance image edges. The performed experiments evaluated with the use of the Pratt’s index, quantitatively confirm the superiority of the proposed design over the Mean Shift and standard denoising methods. The preservation of edges and even their sharpening is a very important feature of our algorithm whereas the final goal is segmentation, playing a crucial role in various computer vision tasks. The proposed algorithm is intended for the mixed noise reduction in color images, but it can be also applied in multispectral imaging and clustering of multidimensional data. To enable the comparison of our method with the standard denoising techniques and to help applying it in other image processing fields, we made its code freely available.

Optimal extended state observer based control for vibration reduction on a flexible cantilever beam with using air thrust actuator

The idea of using air thrusts for vibration control of structures has gained attention since the 1990s. However, only discontinuous controllers and switching functions have been studied with these actuators. Therefore, the main motivation of this study is to investigate air thrusters with continuous control methods for vibration reduction on a flexible cantilever beam. First, the finite element model of the flexible cantilever beam is defined. The order of the model is reduced according to the effective mass participation factor using the mode displacement method to obtain a controllable and observable system. The fundamental dynamics of the air thrust actuator, such as time constant, delay time and bandwidth, have been determined by system identification and considered in the control system. In this study, optimal extended state observer-based control (optimal ESOBC) tuned by optimal control law and particle swarm optimization (PSO) is proposed and compared to linear quadratic Gaussian (LQG) and positive position feedback (PPF) controllers. The performance of the controllers has been evaluated under several experiments such as initial displacement, impulsive disturbance, structure uncertainty and actuator uncertainty. The effectiveness of the controllers is determined by the RMS value of the beam displacement and the total air consumption. The results show that the ESOBC controlled air thrust actuator has suppressed beam vibrations more successfully than LQG and PPF controllers. In addition, the proposed method is found to be effective for low-frequency vibration suppression on flexible structures.

Effect of saturation structure on finite-time stabilization of nonlinear systems with impulsive disturbance

This paper studies the finite-time stabilization (FTS) of nonlinear systems with impulsive disturbance, where the effect of saturation structure on the control input is fully considered. By establishing a potential relationship between saturation structure and impulsive disturbance, some FTS criteria are presented via a class of saturated control input, where estimations of domain of attraction and settling-time are derived. Compared with the control input without saturation structure, the constraints on impulse time sequence are strengthened to guarantee that the saturated control input has an effective stabilizing effect on the system. Based on such constraints, the system subjected to impulsive disturbance can still achieve FTS. Then theoretical results are applied to finite-time synchronization for a class of impulsive dynamical networks. Finally, two examples and their simulations are given to illustrate the effectiveness of the proposed results.

Синхронные глобально наблюдаемые ультракороткопериодные импульсы

We have studied the properties of impulsive geomagnetic disturbances, which are observed synchronously at the network of induction magnetometers of the Institute of Solar-Terrestrial Physics (ISTP SB RAS) and Canadian stations of the CARISMA project [Mann, et al., 2008]. A feature of the pulses we detected is that their frequency range (f~5–30 Hz) lies at the junction of the ranges of two known classes of electromagnetic oscillations: ultra-low-frequency (ULF) oscillations (f<5–10 Hz), or geomagnetic pulsations, and extra-low frequency (ELF) oscillations (f~30–300 Hz); therefore, the 5–30 Hz range is poorly studied. The work is of undoubted interest for physics of processes in the magnetosphere–ionosphere–atmosphere system. Morphological analysis of the pulses detected has been carried out using data from ISTP stations. As a result, we obtained statistical characteristics of the pulses, plotted their dynamic spectra, and determined a number of unusual properties that distinguish them, on the one hand, from geomagnetic pulsations of the pulsed type (irregular pulsations of the Pi1B type), and, on the other hand, from higher frequency ELF and VLF signals (atmospherics, whistlers, etc.). On the basis of the results, we have made an assumption that a source of the pulses under study can be electrical sprites caused by powerful thunderstorms at middle and low latitudes. Using the results obtained by Wang, et al. in 2019 on spatial and temporal fixation of sprites in North China, we have confirmed that ultra-short-period pulses occur following the emergence of sprites. Thunderstorm activity, both local and global, is considered to be one of the main sources of excitation of the ionospheric Alfvén resonator (IAR), which plays an important role in coupling the ionosphere and the magnetosphere. The pulsed oscillations of interest may be one of the agents through which the energy of thunderstorms is transferred to IAR, thereby including the atmosphere in the system considered.

Synchronous globally observable ultrashort-period pulses

We have studied the properties of impulsive geomagnetic disturbances, which are observed synchronously at the network of induction magnetometers of the Institute of Solar-Terrestrial Physics (ISTP SB RAS) and Canadian stations of the CARISMA project [Mann, et al., 2008]. A feature of the pulses we detected is that their frequency range (f~5–30 Hz) lies at the junction of the ranges of two known classes of electromagnetic oscillations: ultra-low-frequency (ULF) oscillations (f<5–10 Hz), or geomagnetic pulsations, and extra-low frequency (ELF) oscillations (f~30–300 Hz); therefore, the 5–30 Hz range is poorly studied. The work is of undoubted interest for physics of processes in the magnetosphere–ionosphere–atmosphere system. Morphological analysis of the pulses detected has been carried out using data from ISTP stations. As a result, we obtained statistical characteristics of the pulses, plotted their dynamic spectra, and determined a number of unusual properties that distinguish them, on the one hand, from geomagnetic pulsations of the pulsed type (irregular pulsations of the Pi1B type), and, on the other hand, from higher frequency ELF and VLF signals (atmospherics, whistlers, etc.). On the basis of the results, we have made an assumption that a source of the pulses under study can be electrical sprites caused by powerful thunderstorms at middle and low latitudes. Using the results obtained by Wang, et al. in 2019 on spatial and temporal fixation of sprites in North China, we have confirmed that ultra-short-period pulses occur following the emergence of sprites. Thunderstorm activity, both local and global, is considered to be one of the main sources of excitation of the ionospheric Alfvén resonator (IAR), which plays an important role in coupling the ionosphere and the magnetosphere. The pulsed oscillations of interest may be one of the agents through which the energy of thunderstorms is transferred to IAR, thereby including the atmosphere in the system considered.

Research of the influence of external the impact of impulse and shock disturbances during the damping of frictional self-oscillations in a two-mass oscillatory system

A two-mass oscillatory system under the action of external periodic impulse and shock disturbances is considered. To reduce the intensity of oscillations two force effects of a special structure were used simultaneously. The calculation options showed an effective damping in the oscillation amplitude.

СТАБИЛИЗАЦИЯ ДВИЖЕНИЯ КВАДРОКОПТЕРА ВДОЛЬ ЗАДАННОЙ ТРАЕКТОРИИ С ПОМОЩЬЮ СУБОПТИМАЛЬНОГО ЗАКОНА УПРАВЛЕНИЯ С -КРИТЕРИЕМ

The aim of the study is to construct a suboptimal controller with the -criterion that stabilizesthe deviation of the dynamic system from the given program trajectory. It is assumed that an impulsedisturbance will be applied to one input of the system, and an -disturbance to the second one.The -norm is equal to the maximum value of the -output norm for all - and impulse disturbancesvectors for which the sum of the quadratic form of the impulse disturbance vector with a givenweight matrix and the squared -norm of the second disturbance never greater than one. In this paper,it is required to demonstrate the process of calculating the -norm in terms of linear matrix inequalitiesfor a dynamical system and a system with uncertainty. An important role in the process ofcombining the -norm and the -norm in the -norm is played by the weight matrix includedin the definition of this norm. It should be noted that, unlike the -norm, the -norm is achievedin the sense of the worst - and impulse disturbances, where the maximum value of the -output normis reached. It is necessary to obtain and linearize the mathematical model of the quadcopter, build aprogrammed trajectory, and stabilize the deviations using a suboptimal control law with the -criterion in the presence of noise in the system. Linear matrix inequalities are used for suboptimal controlsearching. The object of this study is a quadcopter, which is an unmanned aerial vehicle with fourengines with propellers that create thrust. The axes of the propellers and the angles of the blades arefixed and only the speed of rotation is regulated, which greatly simplifies the design. Using the Newton-Euler equation, a nonlinear mathematical model of a quadcopter is obtained, and this model is linearized.In the MATLAB environment, using the applied package for modeling and optimization YALMIP,Sedumi toolbox, numerical modeling, and construction of quadcopter motion trajectories are performed.After that, in the Simulink environment, a control block that stabilizes the movement of thequadcopter along a given trajectory in the presence of - and impulse disturbances in the system isconstructed. At the end, a demonstration of the process of virtual visualization of the flight is made.

Adaptive algorithms for blind channel equalization in impulsive noise

The unsupervised adaptive mitigation of intersymbol interference in an additive impulsive noise environment, modeled as generalized Gaussian, is dealt in this work. The theory of statistical invariance, Wijsman’s theorem, is used to develop a maximal-invariant test to discriminate equally-likely pulsed signals against impulsive disturbance leading to an admissible cost function for blind equalization. The cost function is optimized to realize two adaptive equalizers capable of not only mitigating intersymbol interference but also robust to impulsive disturbance. Numerical simulations, obtained on a baseband digital microwave radio system for amplitude-phase shift keying signaling in an additive (generalized Gaussian and symmetric-alpha stable) impulsive environment, confirm the admissibility of the proposed equalizers in terms of robustness and steady convergence.

An Inverse Dynamics-Based Control Approach for Compliant Control of Pneumatic Artificial Muscles

Rehabilitation is an area of robotics in which human–robot collaboration occurs, requiring adaptation and compliance. Pneumatic artificial muscles (PAM) are soft actuators that have built-in compliance making them usable for rehabilitation robots. Conversely, compliance arises from nonlinear characteristics and generates obstructions in modeling and controlling actions. It is a critical issue limiting the use of PAM. In this work, multi-input single-output (MISO) inverse modeling and inverse dynamics model learning approaches are combined to obtain a novel nonlinear adaptive control scheme for single PAM-actuated 1-DoF rehabilitation devices, for instance, continuous passive motion (CPM) devices. The objective of the proposed system is to bring an alternative solution to the compliant operation of PAM while performing exercise trajectories, to satisfy requirements such as larger range of motion (ROM) and adaptability to external load impedance variations. The control system combines the operation of a nonlinear autoregressive network with exogenous inputs (NARX)-based inverse dynamics estimator used as a global range controller and cascade PIDs for local position and pressure loops. Implementation results demonstrated the efficacy of the introduced method in terms of compliant operation for dynamic external load variations as well as a stable operation in case of impulsive disturbances. To summarize, a simple but efficient method is illustrated to facilitate the common use of PAM.

Global asymptotic stability of delayed fractional-order complex-valued fuzzy cellular neural networks with impulsive disturbances

Global asymptotic stability of delayed fractional-order complex-valued fuzzy cellular neural networks with impulsive disturbances

ω-граничнi множини для iмпульсно-збуреного параболiчного рiвняння в просторi неперервних функцiй

We consider an important class of disturbed infinite-dimensional systems provided by evolutionary equations with impulsive effects. An impulsive dynamical system acting in the phase space H is a hybrid system described by an evolutionary equation together with impulsive disturbances which, in turn, are characterized by a closed set M ⊂ H (impulsive set) and a mapping I: M -> H (impulsive mapping). A solution of such a system, by definition, is a left-continuous function y satisfying evolutionary equation for all times t for which y(t) \notin M and jumping to a new state I(y(t)) at all times t for which y(t) reaches M. The main problem in the study of qualitative behavior of impulsive dynamical systems by classical methods is that solutions usually do not depend continuously on initial data. A number of examples illustrate already in the finite-dimensional case that new complex scenarios of possible limit behaviors of impulsive trajectories can occur, which are fundamentally impossible in the non-impulsive case. Results concerning attracting sets for infinite-dimensional impulsive systems have appeared only a few years ago. But all those results concern the limit behavior of impulsive semiflows in Hilbert space and the presence of scalar product played crucial role in those construction. In this paper we want to investigate ω-limit attracting sets for impulsive-disturbed parabolic system in the sup-norm of Banach space of continuous functions.

Robust finite-time stability of nonlinear systems involving hybrid impulses with application to sliding-mode control.

This paper is concerned with the robust finite-time stability and stabilization of impulsive systems subject to hybrid disturbances that consists of external disturbances and hybrid impulses with time-varying jump maps. First, the global finite-time stability and local finite-time stability of a scalar impulsive system are ensured by the analysis of cumulative effect of hybrid impulses. Then, asymptotic stabilization and finite-time stabilization of second-order system subject to hybrid disturbances are achieved by linear sliding-mode control and non-singular terminal sliding-mode control. It shows that the stable systems under control are robust to external disturbances and hybrid impulses with non-destabilizing cumulative effect. If the hybrid impulses have destabilizing cumulative effect, the systems are also capable of absorbing the hybrid impulsive disturbances by the designed sliding-mode control strategies. Finally, the effectiveness of theoretical results is verified by numerical simulation and the tracking control of linear motor.

Hybrid vibration control of an industrial CFRP composite robot-manipulator system based on reduced order model

This paper introduces a novel hybrid vibration control of an industrial flexible link manipulator (FLM) with carbon-fiber reinforced polymer (CFRP) composite material. The hybrid controller consists of a closed-loop direct strain feedback controller (DSFC) and a new open-loop input shaper (OLIS), and its performance is examined and compared by numerical simulation and experiment. Vibration attenuation is also verified by a spare sensor, an accelerometer. Thanks to the design of an analog isolator circuit, data acquisition of the real-time experiments are carried out noise-free from the servo driver. Reduced-order-model (ROM) is generated for the composite link with three different loading conditions and model for servo system is derived via system identification. Impulse force test hammer (IFTH) equipment is used to excite the system with force input and the results of the experiments/simulations confirm that the controller is robust against the impulse disturbances. As a result, a decrease of 88 ± 6.9 percent in vibration amplitudes and a decrease of 90 ± 7 percent in vibration duration confirms that the proposed controller is effective for vibration control of the flexible arm even under disturbance. Controller performance also enabled the FLM to work with payloads 16 times of its own weight.

Comparison of volcanic explosions in Japan using impulsive ionospheric disturbances

Using the ionospheric total electron content (TEC) data from ground-based Global Navigation Satellite System (GNSS) receivers in Japan, we compared ionospheric responses to five explosive volcanic eruptions 2004–2015 of the Asama, Shin-Moe, Sakurajima, and Kuchinoerabu-jima volcanoes. The TEC records show N-shaped disturbances with a period ~ 80 s propagating outward with the acoustic wave speed in the F region of the ionosphere. The amplitudes of these TEC disturbances are a few percent of the background absolute vertical TEC. We propose to use such relative amplitudes as a new index for the intensity of volcanic explosions.Graphical