Internal Disturbance Research Articles

Fractional Order PID Control mechanism for Helicopter Gearbox Test Control with internal and External Disturbance

Fractional order PID (FOPID) controller is a special kind of PID controller which it’s derivative and integral order are fractional rather than integer and has five parameters. Using this control improves the control results in accuracy and speed. Statistics show that using this controller for systems with high sensitivity is more practical and safe. Mechanical closed loop test rig acts an important role in aviation industry. Fault diagnosis in gearboxes and other critical components of the airplane and helicopters is the most important part of this industry. More over testing rotating equipment is very important for system security verification. There are several testing technics and many important testing parameters. One of these essential factors is gearbox security test technique. What’s more, mechanical closed-loop system is a very cost effective method. For financial, energy consumption and maintenance reasons, using a system with the ability of energy regeneration is suggested. In this paper mechanical close loop with energy regeneration mechanism is used for testing the helicopter gearbox. Two kinds of controllers are used for keeping the closed-loop’s torque in the constant value. The result of paper shows the behavior of PID and FOPID controller methods in controlling torque circulating in this mechanical closed loop. Beside the overshoot and settling time is considerable.

Los estados de excepción en el régimen constitucional colombiano

From a juridical analysis about the regulation of states of emergency in the Colombian juridical system and the assessment conducted by the Constitutional Court, this article is intended to show that, thanks to the 1991 Colombian Constitution, today there is a state of emergency system in Colombia which holds strong warranties and controls to protect human rights. For this reason, a historical journey will be made on such figure, establishing the most important aspects currently active in current regulation on emergency powers. Finally, the article will address the study of each state of emergency: state of foreign war (article 212 of the Political Constitution); state of internal disturbance (article 213 of the Political Constitution; and state of economic, social, and ecologic emergency (article 215 of the Political Constitution), clearly defining nature, limitations, and budgets of each one, which will allow us to demonstrate the Copernican turn with respect to the former state of siege.

Output tracking for a class of nonlinear systems with mismatched uncertainties by active disturbance rejection control

In this paper, we apply active disturbance rejection control, an emerging control technology, to achieve practical output tracking for a class of nonlinear systems in the presence of vast matched and mismatched uncertainties including unknown internal system dynamic uncertainty, external disturbance, and uncertainty caused by the deviation of control parameter from its nominal value. The total disturbance influencing the performance of controlled output is refined first and then estimated by an extended state observer (ESO). Under the assumption that the inverse dynamics of the uncertain systems are bounded-input-bounded-state stable, a constant high gain ESO based output feedback is constructed to guarantee that the state is bounded and the output tracks practically a given reference signal. A time-varying gain ESO is also discussed to reduce the peaking value near the initial stages of ESO caused by constant high gain. Numerical simulations are presented to demonstrate the effectiveness of the proposed output-feedback control scheme.

Dynamic model and ADRC of a novel water-air unmanned vehicle for water entry with in-ground effect

The class of vehicles that can move both in the air and underwater has been of great interest for decades. A novel water-air unmanned vehicle with double quadrotor structure is designed in this study. The air power mechanism works when the vehicle flies in the air, whereas the water power mechanism works when it moves underwater. The water entry process of water-air unmanned vehicle requires accurate attitude and height control, or the vehicle may bounce off or overturn. However, a force resisting its descent known as in-ground effect will affect its stability. The in-ground effect formula of the water entry process is derived by experiments, and the water entry dynamic model is improved at the same time. An active disturbance rejection controller (ADRC) is designed for the control of water entry attitude and height. Experimental results obtained from the comparison of the ADRC and a proportional-integral-derivative (PID) controller show that the ADRC designed in this study is more robust than the PID controller for the internal coupling and external disturbance on the vehicle. Moreover, the ADRC can meet the requirements of rapid attitude adjustment and accurate height control.

Unifying dynamical and structural stability of equilibria.

We exhibit a fundamental relationship between measures of dynamical and structural stability of linear dynamical systems-e.g. linearized models in the vicinity of equilibria. We show that dynamical stability, quantified via the response to external perturbations (i.e. perturbation of dynamical variables), coincides with the minimal internal perturbation (i.e. perturbations of interactions between variables) able to render the system unstable. First, by reformulating a result of control theory, we explain that harmonic external perturbations reflect the spectral sensitivity of the Jacobian matrix at the equilibrium, with respect to constant changes of its coefficients. However, for this equivalence to hold, imaginary changes of the Jacobian's coefficients have to be allowed. The connection with dynamical stability is thus lost for real dynamical systems. We show that this issue can be avoided, thus recovering the fundamental link between dynamical and structural stability, by considering stochastic noise as external and internal perturbations. More precisely, we demonstrate that a linear system's response to white-noise perturbations directly reflects the intensity of internal white-noise disturbance that it can accommodate before becoming stochastically unstable.

Extended state observer for uncertain lower triangular nonlinear systems subject to stochastic disturbance

The extended state observer (ESO) is the most important part of an emerging control technology known as active disturbance rejection control to this day, aiming at estimating “total disturbance” from observable measured output. In this paper, we construct a nonlinear ESO for a class of uncertain lower triangular nonlinear systems with stochastic disturbance and show its convergence, where the total disturbance includes internal uncertain nonlinear part and external stochastic disturbance. The numerical experiments are carried out to illustrate effectiveness of the proposed approach.

An MEF-Based Localization Algorithm against Outliers in Wireless Sensor Networks.

Precise localization has attracted considerable interest in Wireless Sensor Networks (WSNs) localization systems. Due to the internal or external disturbance, the existence of the outliers, including both the distance outliers and the anchor outliers, severely decreases the localization accuracy. In order to eliminate both kinds of outliers simultaneously, an outlier detection method is proposed based on the maximum entropy principle and fuzzy set theory. Since not all the outliers can be detected in the detection process, the Maximum Entropy Function (MEF) method is utilized to tolerate the errors and calculate the optimal estimated locations of unknown nodes. Simulation results demonstrate that the proposed localization method remains stable while the outliers vary. Moreover, the localization accuracy is highly improved by wisely rejecting outliers.

Downscaling and disaggregating NAO-conflict nexus in pre-industrial Europe

Recently, the desiccation effect of the North Atlantic Oscillation (NAO) is found to be positively correlated with violent conflict in pre-industrial Europe, with agricultural shrinkage and its subsequent economic shocks to be their causal link. However, it remains unexplored whether the correlation persists if the study period is extended backward in time, a different definition of violent conflict is applied, or the relationship is examined at lower geographic levels. In this study, we based on 835 internal disturbance incidents in Europe during 1049–1800 to conduct long-temporal and multi-scalar examination on the NAO-conflict nexus. ′Time-series′ and ′panel data′ disaggregation approaches, together with Granger Causality, Multiple Regression, and Survival Analyses were applied to verify the nexus quantitatively. Results show that the positive NAO-conflict correlation was significant at the continent and physiographic zone levels. During the positive NAO phases, the annual probability of internal disturbance outbreak increased by 70.0% in the southern Europe and the Mediterranean, a zone most affected by the NAO-induced desiccation effect. Yet, the NAO-conflict correlation was rather inconsistent when it was downscaled to the sub-regional level. Moreover, the NAO-conflict correlation was inflated under the time-series approach, while the panel data approach demonstrated the region-specific nature of the NAO forcing more clearly. The associated implications in examining climate-conflict nexus are discussed. Our findings may be crucial in examining violent conflict in the northwestern Africa, a highly agricultural region affected by the NAO.

Concept of Recognition in International Law and Instances of its Breach by Powerful Nations

As international law struggles with the question of sovereignty, it also suffers from the question of recognition. So, it is very important to understand the various kinds of recognition which are concurrent to the question of sovereignty. Even after 65 years since the establishment of United Nations and various conventions, International community is again and again blanked by the question of ‘Recognition’. Incidents of civil war in Rwanda, Sierra Leone or question of recognition of Chinese Taipei, Hong Kong, Palestine as independent state, or internal disturbance like Naxalism in India, LTTE in Sri Lanka, or Secession demand by the states like Chechnya, Tibet recurrently imposes the question mark on the effectiveness of International Law.Answering this question is important but first it is necessary to discuss the need of recognition. Why it is required? In simple terms, Recognition is required as it signifies that the entity has attained the required qualifications[1] for state and is entitled for privileges and immunities within the domestic legal order[2].This research paper will try to analyse aforementioned issue in context of various types of recognition. Recognition in International Law is divided into 8 types, which are:a) Recognition of States; b) Recognition of Government; c) De Facto and De Jure recognition; d) Premature recognition; e) Implied recognition; f)Conditional recognition; g) Collective recognition; h) Withdrawal of recognition.Subsequent to the above discussion, paper will also dwelve upon the idea of Non-Recognition and Legal consequences of recognition and non-recognition.[1] Nurullah Yamali, “What is Meant by State Recognition in International Law”, General Directorate of International Law and Foreign Affairs,Turkey, http://www.justice.gov.tr/e-journal/pdf/LW7081.pdf[2] International Law, “Recognition”, http://web.wits.ac.za/NR/rdonlyres/E0A48346-CB0B-4BEC-95B1-DD3FD4DEDD58/0/Overhead15.doc

Distributed tracking control of the Schrödinger equation with internal disturbance

Distributed tracking control of the Schrödinger equation with internal disturbance

Adaptive Terminal Sliding Mode NDO-Based Control of Underactuated AUV in Vertical Plane

The depth tracking issue of underactuated autonomous underwater vehicle (AUV) in vertical plane is addressed in this paper. Considering the complicated dynamics and kinematics model for underactuated AUV, a more simplified model is obtained based on assumptions. Then a nonlinear disturbance observer (NDO) is presented to estimate the external disturbance acting on AUV, and an adaptive terminal sliding mode control (ATSMC) based on NDO is applied to enhance the depth tracking performance of underactuated AUV considering both internal and external disturbance. Compared with the traditional sliding mode controller, the static error and chattering problem of the depth tracking process have been clearly improved by adopting NDO-based ATSMC. The stability of control system is proven to be guaranteed according to Lyapunov theory. In the end, simulation results imply that the proposed controller owns strong robustness and satisfied control effectiveness in comparison with the traditional controller.

Dynamic Modeling and Chaotic Analysis of Gear Transmission System in a Braiding Machine with or without Random Perturbation

This paper is aimed at analyzing the dynamic behavior of the gear transmission system in a braiding machine. In order to observe the nonlinear phenomenon and reveal the time-varying gear meshing mechanism, a mathematical model with five degrees-of-freedom gear system under internal and external random disturbance of gear system is established. With this model, bifurcation diagrams, Poincare maps, phase diagrams, power spectrum, time-process diagrams, and Lyapunov exponents are used to identify the chaotic status. Meanwhile, by these analytical methods, spur gear pair with or without random perturbation are compared. The numerical results suggest that the vibration behavior of the model is consistent with that of Clifford system. The chaotic system associated parameters are picked out, which can be helpful to the design and control of braiding machines.

Sliding mode control of photoelectric tracking platform based on the inverse system method

In order to improve the photoelectric tracking platform tracking performance, an integral sliding mode control strategy based on inverse system decoupling method is proposed. The electromechanical dynamic model is established based on multi-body system theory and Newton-Euler method. The coupled multi-input multi-output (MIMO) nonlinear system is transformed into two pseudo-linear single-input single-output (SISO) subsystems based on the inverse system method. An integral sliding mode control scheme is designed for the decoupled pseudo-linear system. In order to eliminate system chattering phenomenon caused by traditional sign function in sliding-mode controller, the sign function is replaced by the Sigmoid function. Simulation results show that the proposed decoupling method and the control strategy can restrain the influences of internal coupling and disturbance effectively, and has better robustness and higher tracking accuracy.

ESO Based LQR Controller for Ball and Beam System

Abstract This paper presents an ESO based Control design for ball and beam system which is one of the most sought after problem for control engineering students. The system comprises a long beam which is moved by using servo motor and a ball on which it rolls with respect to Beam motion. In this design, estimation of a virtual state (“disturbance”) is carried out online with state observer and these states are used in controller to nullify the effects of actual disturbances and uncertainties in the plant. While designing controller, simpler model is used, thus avoiding accurate modeling of the system. Any nonlinear term and unknown parameter in the plant can be considered as internal or external disturbance. This is the peculiar feature of automatic disturbance rejection control or ESO based control scheme. Hence, linearized model of ball and Beam is considered. All simulations have been carried out with the help of MATLAB and SIMULINK. Using this algorithm, controller shows very good disturbance rejection capability and it has been shown with simulation results.

Permanent magnet brushless motor control based on ADRC

Permanent magnet brushless motor is a nonlinear system with multiple variables, the mathematical model of Permanent magnet brushless motor is difficult to establish, and since that the classic PID control is hard to precisely control the motor. Active disturbance rejection control (ADRC) technique is a new nonlinear controller which does not depend on the system model. It is starting from the classic PID control, and establishing the loop control system by error negative feedback, the ESO(extended state observer) observing system which comes from the observer theory of modern control theory to observe internal and external perturbations. ADRC inherits the advantages of PID with little overshoot, high convergence speed, high accuracy, strong anti-interference ability and other characteristics, and it has a strong disturbance adaptability and robustness as for the uncertainty perturbation and their internal disturbance of control objects. Therefore, This paper attempts to use Active disturbance rejection control(ADRC), in order to improve the control of permanent magnet brushless motor. In this design of control system, the simulation of the system is realized based on MATLAB, and then the discrete control algorithm is transplanted to the embedded system to control the permanent magnet brushless DC motor (PMBLDCM). The control system is implemented on the DSP-F28335 digital signal processor, and the DSP also provides the functions like voltage and current AD sampling, PWM driver generation, speed and rotor position calculation, etc. The simulation and experiment results indicate that, the system has good dynamic performance and anti-disturbance performance.

Soft sliding mode controller design for uncertain delta operator systems

Aiming at high-speed signal sampling system with internal parameter perturbation and external disturbance, a novel delta operator saturated variable rate reaching law based on sigmoid function is presented, and soft sliding mode controller design is addressed for delta operator systems with uncertainties in the paper. The structural feature of uncertain delta operator system is concerned. Soft sliding mode controller design for continuous-time system and discrete-time system can be converted to the case of delta operator system. The stability of uncertain delta operator soft sliding mode control (SMC) system is guaranteed by Lyapunov stability theory. Soft sliding mode controller design for uncertain delta operator systems is achieved by the proposed reaching law under a certain matching condition. It is illustrated that delta operator soft SMC system by the proposed reaching law in a simulation example can not only reach the scope of the switching plane in limited time, but also reduce system chattering effectively. The system on stability and process steady is better than that of delta operator exponential reaching law and delta operator variable rate reaching law. At the same time, the system has a good completely robustness compared with delta operator statured reaching law.

Ideological symbols of Heavenly Kingdom's Dress

Heavenly Kingdom was known for their strict discipline and law as well as their anti-corruption practices and for putting up unconventional ideas to rule its kingdom. They became weak as their leadership was split along with the power struggles that occurred within their kingdom. Heavenly Kingdom’s style of dress also ended during this period, but their philosophy continues to influence the style of dress. Taiping rebellion was modern China’s biggest internal disturbance which prior studies included political ideals, gender equality and the peasant movement. My research is to associate Heavenly Kingdom’s ideas and their dress style by analyzing its relations. Their form of clothing was similar to the Qing Dynasty but the same. They wanted to restore their identity of the Han( 漢) while their ideology was oriented in creating a large enough military power to go against the corrupt Qing Dynasty as seen in their military uniform. This research is to analyze about Heavenly Kingdom``s ideology with regard to their style of dress but because of their short existence, there are only small remains of artifacts and clothing available which limits this research. This research has to developing further research as I gather more additional data.

내부 모델 기반 외란 관측기를 이용한 수직 1축 머니퓰레이터의 속도 제어기 설계

This paper deals with a robust speed control problem of a vertical one-link manipulator in the presence of parameter uncertainties and unknown input disturbance. Uncertain load weight causes an additional sinusoidal disturbance in the rotation of the link. In order to improve the robustness against parameter uncertainties and external input disturbances, this paper employs an internal model-based disturbance observer approach. Comparative computer simulations are performed to test the performance of the proposed controller. The simulation results show the enhanced performance of the proposed method.

Controller dynamic linearisation‐based model‐free adaptive control framework for a class of non‐linear system

Without the explicit process identification, the authors propose a model-free adaptive control framework for unknown plant by using the concept of equivalent dynamic linearisation controller. The controller has linear incremental structure and its local dynamics is equivalent to the ideal controller in theory. Hence, the problem of determining the structure of candidate controller is transformed to the problem of finding a sequence of local dynamic controllers to approximate the ideal controller. With the help of gradient information extracted from input and output (I/O) data of the plant, the optimal controller parameter sequence is generated by minimising a user-defined control criterion. This method gives a solution on how to determine the candidate controller structure. The controller design, parameter tuning and controller validation are based on I/O data of the plant. Hence, it could reduce the influence of internal disturbance or unmodelled dynamics. The effectiveness of the proposed method is illustrated by the simulation of a continuous polymerisation reaction process in a jacketed continuous stirred tank reactor system. Meanwhile, a simulation comparison is carried out to show the superiority of neural network data model in model-free adaptive control framework.

Robust Speed Control of Induction Motor Drives Using First-Order Auto-Disturbance Rejection Controllers

A novel robust control scheme employing three first-order auto-disturbance rejection controllers (ADRCs) is presented for the speed control of induction motor drives. Compared with the existing high-order ADRC-based speed control structures, the proposed method does not need to estimate the rotor flux. As a result, the implementation of the proposed scheme on a digital signal processor (DSP) is easier, and the runtime of the proposed ADRC control algorithm is shorter. The simulation results show that the proposed control scheme can cope with the internal disturbance and external disturbance, such as the motor's parameter variations, the load disturbances, etc. A TMS320F2812 DSP-based prototype using the proposed control scheme was developed. The comparative experimental results show that the robustness of the proposed ADRC system is obviously better than the conventional proportional-integral system when various disturbances occur, and the scheme is feasible and effective.