Moment Disturbance Research Articles

Adaptive position control of a cart moved by a DC motor using integral controller tuned by Jaya optimization with Balloon effect

This study suggests an adaptive linear position control of a car moved by an armature-controlled DC motor. In this study, Jaya optimization algorithm supported by Balloon effect (BE) is used to tune the parameters of the controller of the car position. BE is introduced to improve response of the classical Jaya algorithm in face of the external disturbance and system parameters changes. In the suggested technique, an objective function (OF) of the modified Jaya depends on the updated values of the controller gains and identified value of the motor open loop transfer function. System with the suggested controller has been evaluated in case of step load disturbance and motor parameters changes. Simulation and experimental results supported that suggested adaptive controller using modified Jaya improved the total system performance at moments of load disturbance and uncertainties of system parameters.

Multiple observers based anti-disturbance control for a quadrotor UAV against payload and wind disturbances

This paper presents a multiple observers based anti-disturbance control (MOBADC) scheme against multiple disturbances for a quadrotor unmanned aerial vehicle (UAV). The quadrotor UAV dynamics can be represented by the Newton’s second law and Lagrange–Euler formalism. The proposed control scheme consists of disturbance observer (DO) based controller and extended state observer (ESO) based controller, which are utilized in the position loop to mainly eliminate the cable suspended payload disturbance with partially known information and mitigate the wind disturbance with bounded variation. What is more, in order to reject the model uncertainty and disturbance moment, another ESO based controller is designed for the attitude loop. Using the proposed control scheme, the anti-disturbance performance can be significantly enhanced. Experimental results in the presence of wind disturbance, payload oscillating disturbance, and hybrid disturbances illustrate the robustness and effectiveness of the proposed method compared to the classical PID method.

Идентификация параметров дискретных стохастических систем методом обратных итераций

Получены условия глобальной сходимости алгоритмов, основанных на обратных итерациях в переменной метрике, в задаче идентификации параметров дискретной стохастической системы с возмущениями в невязке уравнения и наблюдениях процессов. Доказана сходимость оценок параметров к истинному значению при увеличении объема выборки наблюдений истинного процесса. Приведены примеры расчетов The article addresses the problem of identifying parameters of discrete stochastic systems with perturbations in the residual of the equation and observation of variables. The identification functional in the problem has a complex nature of isosurfaces, which is why universal minimization algorithms based on estimates of the first and second derivatives have a small radius of convergence. It is proposed to employ efficient computational identification algorithms with inverse iterations in a variable metric for solving the convergence problem for two classes of systems with simple correspondence between matrix elements and parameters of equivalent systems without state variables. These algorithms are used for systems without state variables due to the large radius and high convergence rate since the 1970s. At first, a theorem on the conditions for convergence of inverse iterations from almost any initial approximation to a small neighborhood of the global minimum of the identification functional was proved. Secondly, a theorem on the convergence of the points of the global minimum of the identification functional to the desired true value with an increase in the sample size of observations is taken into account. Assumption of a zero first and restricted second moments of stochastic disturbances in the residual of the equation and observation of variables was made. The convergence of inverse iterations is shown numerically in a model example with significant values of disturbances. The result of the article is new theorems on the conditions of global convergence of computational algorithms with inverse iterations in the problem with mixed disturbances and the justification of possibility of using these algorithms to identify the parameters for discrete stochastic systems of two classes with a simple correspondence between matrix elements and parameters of equivalent systems without state variables

Stable control of the high-speeding magnetically suspended rotor based on extended state observer and two-degree freedom internal model control for control moment gyros with serious moving-gimbal effects

For a magnetically suspended control moment gyro (MSCMG), which is an ideal attitude actuator for its large outputting control moment and fast response, the moving-gimbal effects due to the coupling between the moving gimbal and high-speeding rotor will make the magnetically suspended rotor (MSR) unstable. To improve control precision, both the dynamic model of MSR and the feedback linearization control are done to decouple tilting motion, and poles of the system are reconfigured to reduce control error. To suppress the varying disturbance moments caused by moving-gimbal effects, an extended state observer (ESO) is originally designed to estimate and compensate them timely and accurately. To improve system robustness, a two-degree freedom internal model control (2-DOF IMC) is researched to suppress model error. Compared with existing proportional integral derivative (PID) control method, simulations done on a single gimbal MSCMG with 200 N.m.s angular momentum indicated that this presented control method with ESO and 2-DOF IMC can suppress the moving-gimbal effects more effectively and make the rotor suspension more stable.

Stability analysis of rubber-supported thrust bearing in a rotor-bearing system used in marine thrusters under disturbing moments

The transient model of a rotor-bearing system in marine thrusters was established, including 5-DOF model of the rotor and 3-DOF model of the rubber-supported water lubricated thrust bearing. In the model, mixed-TEHD was coupled and the damping of the rubber was characterized by damping loss factor. Furthermore, the responses of the system and the lubrication performance of the thrust bearing were studied under external disturbing moments. The simulation results show that with the increase of the disturbing moments, deflection angle of the thrust collar increases and the rubber-supported pads of the thrust bearing present the problem of insufficient mobility. The contact pressure near inner diameter of bearing pad increase dramatically, which may lead to the risk of friction. In addition, experiments were also carried out. The experimental results show that the thrust bearing appeared worn with the increase of deflection angle of the thrust collar, which is accordant to the simulation results.

Stability analysis of random nonlinear systems with time-varying delay and its application

This paper studies a class of random nonlinear systems with time-varying delay, in which the r-order moment of the random disturbance is finite. Firstly, some general conditions are proposed to guarantee the existence and uniqueness of the global solution to random nonlinear time-delay systems. Secondly, some criteria on noise-to-state stability in the moment sense and in probability sense are given by Lyapunov method respectively. Finally, an adaptive output feedback regulation controller is constructed for a class of random nonlinear time-delay systems and the effectiveness of the proposed recursive procedure is demonstrated by a simulation example.

Prediction of surface subsidence and deformations due to the underground coal mining

Throughout its historical development, mining has faced the problem of moral and material responsibility due to various types of endangerment and damage to the environment. As a result of the underground coal exploitation, a movement of the rock massif above the coal seam, and changes on the terrain surface due to the process of massif stabilizing take place. The process occurs in space and time, from the moment of balance disturbance in the massif, i.e., the beginning of excavation, during excavation, and after the final excavation of deposit, when the equilibrium state is reestablished in the massif. The character and intensity of these movements and principles according to which they are performed, depend on numerous natural and mining-technological conditions, and are specific to each individual coal deposit. Deformations on the terrain surface in the sinkhole occur in the horizontal and vertical directions. Their values serve to determine the vulnerability level of individual objects on the terrain surface. On the basis of the Patarić-Stojanović stochastic method for the predictive subsidence and deformations calculation, an original MITSOUKO program package, supported by the spatial analyses in the Geographic Information System (GIS), was designed. A case study in Sladaja village influenced by the underground exploitation in the coal mine "Rembas"-Resavica, one of the biggest Serbian coal mines, has been chosen. The data processed in the GIS provided determining the module, sense, and direction of the displacements, sinking velocity, and possible effects of subsidence on facilities.

A novel multiple impact factors based accuracy analysis approach for power quality disturbance detection

Nowadays, power quality problems are affecting people's daily life and production activities. With the aim to improve disturbance detection accuracy, a novel analysis approach based on multiple impact factors is proposed in this paper. First, a multiple impact factors analysis is implemented in which two perspectives, i.e., the wavelet analysis and disturbance features are considered simultaneously. Five key factors, including wavelet function, wavelet decomposition level, redundant algorithm, event type and disturbance intensity, start and end moment of disturbance, have been considered. Next, an impact factors based accuracy analysis algorithm is proposed, through which each factor's potential impact on disturbance location accuracy is investigated. Three transforms, i.e., the classic wavelet, lifting wavelet and redundant lifting wavelet are employed, and their superiority on disturbance location accuracy is investigated. Finally, simulations are conducted for verification. Through the proposed method, the wavelet based parameters can be validly selected in order to detect power quality disturbance accurately.

Control Law Design for MISO System in the Presence of Actuator Position Limit Constraint

This article is about including the actuator position limit constraint while designing PD controller based on output feedback pole placement methodology for a multi-input-single-output (MISO) system. While designing control law for MISO system, designer has additional degrees of freedom which can be utilized in many ways to achieve different time and frequency domain specifications. One such goal can be to maximize the control availability at any instant of time in the presence of growing disturbance moment. In the paper it is shown that if the proportional path gains of all the loops are constrained to be in the ratio of the maximum value (actuator saturation limit) of control input of respective loops, then at steady state, total control demand will always be distributed to different control power plants in the ratio of their maximum control availability. Designing control law with the inclusion of actuator saturation limit, as constraint on proportional path gains, helps in ensuring the stability of the whole closed loop system by postponing saturation to higher disturbance values. Efficacy of the proposed method is demonstrated on a real life problem of attitude control law design for a typical launch vehicle.

Algorithm for Spacecraft Angular and Translational Motion Control with use of Orientation Thrusters

The paper discusses the algorithm of spacecraft orientation and docking thrusters control for simultaneous spatial and angular motion. The solution of control velocity formation problem and the problem of required engines configuration determination along with the optimization of control vector execution accuracy are considered. The formation of control velocity is carried out using a phase plane with switching lines and a zone of inactivity. The calculation of thrusters working duration time is based on the method of least squares with non-negative resulting solution vector and additional boundary conditions. In the paper, the necessary control parameters were chosen to ensure the necessary accuracy of spacecraft stabilization. To demonstrate the developed algorithm, mathematical modelling of various considered spacecraft's orbital flight stages was executed, including damping of initial angular velocities, spatial motion, and stabilization under the influence of continuous perturbations. The simulation took into account the disturbing moments acting on the spacecraft, thrusters mounting errors and the characteristics of the angular velocity meter. The elastic characteristics of the structure were not taken into account. The results of mathematical modelling showed that the proposed algorithm coped well with the task, and was able to ensure the movement of the spacecraft center of masses in a given direction and simultaneous angular stabilization with required accuracy.

Fluctuation-dissipation phenomena in the Earth pole oscillations

Earth pole oscillations at the Chandler frequency are studied taking into account nonlinear fluctuation-dissipative moments of forces and disturbances at the Chandler frequency and those close to it. For the stationary mode, the dependence of the external perturbation amplitude at the Chandler frequency on the dissipation coefficients is found. It is shown that the amplitude of the Chandler wobble is sensitive to the difference between the Chandler and close to it frequencies and nonlinear dissipation coefficients.

Біоморфологічна структура відновлюваного рослинного покриву луків Лісостепу України

Due to the influence of the anthropogenic factor and as a result of vegetation autogenesis, on the floodplains and abandoned lands with restored meadow vegetation, adaptive ecologically conditioned species conglomerates has been formed. Therefore, the study of the biomorphological structure of the different groups of plant species of restored meadow vegetation allows using quantitative relations between plants belonging to different life forms to reveal significant indices for the analysis of the flow of demutations, eventually expanding the representation of the occurrence of demotion processes on floodplains and abandoned lands with restored meadow vegetation. The features of plant life forms and the morphology of their vegetative organs are one of the determining factors for spatial structure of plant communities. The relevance of the study is due to the correlation between the biomorphological structure of the flora, ecology of the plant communities and their dynamic trends. The research is based on the results of five-year investigation on the abandoned lands with restored vegetation cover of meadows in the Forest-Steppe of Ukraine (2013–2017). The biomorphological analysis of a floral structure of restored meadow vegetation cover according to the classification of plant life forms by K. Raunkiaer has been conducted. The predominant group is hemicryptophytes (amount 358 species or 58.8 %), the second position belongs to terophytes (115 species or 18.6 %), cryptophytes occupy the third position with 66 species (10.7 %), there are the 42 species (6.8 %) of mesophanerophytes, nanophanerophytes and hamephytes containing 38 plant species (6.1%). The direct proportional relationship between the fraction of hemicryptophytes and terophytes in the structure of restoration stages enable quantifying changes of the ratio value from the first to the fourth stages of demutation. Formation of the main zonal and typological features of restoring of a meadow vegetation cover were detected on the third restoration stage, which corresponds to a period of 15 years from the moment of disturbance. The results of research allow establishing the provisions of the revisions in the system of restoration stages and optimizing the restoration of vegetation in the Forest-Steppe of Ukraine. Keywords: life forms, restoration, abandoned lands, meadow vegetation.

Model Reference Adaptive Control (MRAC) of a Small Satellite in the Presence of Parameters Uncertainties

An accurate control algorithm for small satellites is critical to the mission's success. In this paper, a novel discrete-time Model Reference Adaptive Control algorithm (MRAC) is developed based on unified approach for attitude control of a three-axis stabilized nonlinear satellite model. The linearized model of satellite with unknown dynamic parameters is derived and Recursive Least Squares (RLS) algorithm is used to identify the linear model’s unknown parameters. In order to take into account the nonlinear model of satellite dynamics, the proposed MRAC strategy is used considering the linear model, the estimation error; and the difference between the actual nonlinear system and the linear model outputs. The actual nonlinear model of satellite includes moments of inertia uncertainties, external disturbances, and sensor noise on the outputs. The introduced controller performance is compared with a conventional discrete -time MRAC which demonstrates excellent simultaneous regulation and tracking capabilities.

Nonlinear torsional vibrations of electromechanical coupling of diesel engine gear system and electric generator

New approach for analysis and detuning of nonlinear torsional vibrations of diesel electric generator gear system is suggested. Nonlinear magnetic field of the generator is calculated by finite element method to obtain the disturbing moments, which act on the gear system. Moreover, others disturbing moments, which arise due to operation in diesel engine cylinders, are accounted. Essential nonlinear model of torsional vibrations with sixteen degrees-of- freedom is derived. This model accounts the nonlinear moments of two elastic clutches and the backlashes of gear pairs. The comparison of the numerical simulations data with experimental results is performed to verify the obtained model. The approach for essential nonlinear free torsional vibrations calculations is suggested. The harmonic balanced method is the basis of this approach. Sensitivity theory is used to detune the nonlinear forced torsional vibrations from resonances. The results of nonlinear torsional vibrations analysis are discussed.

Application research of high-precision laser beam pointing technology in airborne aiming pod

Airborne aiming pod is mainly used for searching, capturing and tracking the target indicated by the laser, and then dropping the laser-guided weapons precisely to complete the close-range support attack or dual-aircraft cooperative instruction/attack. High-precision laser beam pointing technology is the core of the airborne aiming pod, and the accuracy of it is fatal for the realization of the final tactical index. In this paper, the factors affecting the beam pointing accuracy based on the research of airborne aiming pod platform are analyzed. At first, the composition of the pod system and the motion coupling of the composite axis pod are introduced; and then the beam pointing algorithm under the external guidance combined with aircraft disturbance and the effects of atmospheric turbulence and atmospheric attenuation on beam quality, including optical axis drift, beam spread and intensity distribution variation are discussed. Finally, the performance of the pod servo system is simulated and verified in Simulink. The simulation result of the real flight situation with disturbance moment shows that the pointing accuracy of the airborne aiming pod can reach 0.0075 degrees. The data analyzed in this paper can provide technical reference for other aiming photoelectric platforms.

机载光电稳瞄平台的线性自抗扰控制

In order to improve disturbance rejection capability and dynamic response characteristics of airborne photoelectric stability platform, the improved control method study was conducted on platform based on Linear Active Disturbance Rejection Control (LADRC). The Model-assisted Reduced-order Linear Extended State Observer (MRLESO) was used by the improved Linear Active Disturbance Rejection Controller (ILADRC), and used output of system and differential of output were used to generate the control quantity,which not only reduced phase lag and burden of observer, improved ability of estimation of observer, but also reduced the negative effects of observer with lag and estimation error of control law. The simulation experimental results show that the ILADRC had better frequency domain characteristics in the low-middle frequency band, ILADRC had better dynamic response characteristics in step response experiment, under the conditions of system had no input, sine wave moment disturbance and sine wave angular velocity disturbance with amplitude are and frequency of 2.5 Hz were applied to the system, the residual peak value of system output based LADRC were 0.175()/s and 0.566()/s. The residual peak value of system output based ILADRC were 0.175 ()/s and 0.566 ()/s. The simulation results demonstrate the validity of improved control method.

Satellites Autonomous Navigation With an Extended State and Disturbance Sliding Mode Observer Method

This paper considers the satellites autonomous navigation problem with an extended sliding mode observer method. First, on consideration that the relative dynamic equation of chaser and target spacecrafts refers to a nonlinear time-varying system, a transformation is performed on the original relative dynamic equation to obtain a linear time-invariant system with a nonlinear part. Second, an augmentation strategy is made on the new system to obtain a descriptor system. A new extended sliding mode observer is then designed for the descriptor system which can generate the simultaneous estimation of state and output measurement noise. Based on the observer estimates, the equivalent output error injection approach is used to estimate the space disturbance moment. Finally, an example is presented to demonstrate the effectiveness of the developed satellites autonomous navigation observer method.

Research on a six-degree-of-freedom disturbance force and moment simulator for space micro-vibration experiments

A six-degree-of-freedom disturbance force and moment simulator that reproduces the disturbance forces and moments that are generated by a reaction wheel assembly is presented. The simulator has considerable application potential in ground-based micro-vibration experiments. The detailed structure of the proposed simulator is first introduced and the simulator model is then established. Using this model, the dynamic relationships between the actuator forces and the disturbance forces and moments can be derived. Because of parameter uncertainties, a closed-loop iterative control method based on a dynamic model is developed, and the effectiveness of this control strategy is demonstrated through integrated simulations. Finally, the disturbance forces and moments reproduced by the simulator are tested using a six-component test platform, and the experimental results show that the maximum relative error between the measured value and the target value is 3.33%, thus demonstrating that the simulator can reproduce the disturbance forces and moments well.

Gust Perturbation Alleviation Control of Small Unmanned Aerial Vehicle Based on Pressure Sensor

A gust perturbation alleviation control method based on a real-time pressure sensor is proposed. Pressure measurement provides phase-advance information on external disturbance, while the conventional inertial measurement cannot. Two pairs of pressure sensors embedded on the main wing surfaces are employed to estimate the disturbance of gust-induced rolling moment. The estimated rolling moment is incorporated into a traditional flight controller as an additional feedforward channel. The simulation results show that the additional information on flow field is helpful and that the composite controller’s architecture is more effective for alleviating gust perturbation than the conventional ones.

The Numerical Investigation of Optical Error Compensation for Dynamic Target by FSM in Photoelectric Mast

In this paper, firstly, based on the basic control equations of fluid mechanics, the effects of the fluid on force and vortex induced vibration around underwater submarine model are studied and discussed, employing the finite volume method by hierarchy grids. Secondly, the structural characteristics, transfer functions and control strategies of Steering Mirror Fast (FSM) are analyzed and obtained. The disturbance of moment also has been resolved to optical axis coordinate system. Finally, take the optical model of submarine as the research background, the effects of the FSM on the stability improvement of photoelectric tracking system are discussed. The results show that the disturbance of submarine moments mainly origin from the vortex induced vibration. The dynamic target tracking error could be suppressed. This research explores vortex induced vibration control in optical filter. Therefore, it holds certain scientific significance and practical value.