scholarly journals Stability of digital feedback control systems

2018 ◽  
Vol 161 ◽  
pp. 02004
Author(s):  
Eugene Larkin ◽  
Alexey Bogomolov ◽  
Sergey Feofilov
Keyword(s):  
Control Method ◽  
Linear Part ◽  
Computer Experiment ◽  
Lag Time ◽  
Order System ◽  
Von Neumann ◽  
Semi Markov Process ◽  
System Functioning ◽  
Method Of Evaluation ◽  
Complexity Of Algorithm

Specific problems arising, when Von Neumann type computer is used as feedback element, are considered. It is shown, that due to specifics of operation this element introduce pure lag into control loop, and lag time depends on complexity of algorithm of control. Method of evaluation of runtime between reading data from sensors of object under control and write out data to actuator based on the theory of semi- Markov process is proposed. Formulae for time characteristics estimation are obtained. Lag time characteristics are used for investigation of stability of linear systems. Digital PID controller is divided onto linear part, which is realized with a soft and pure lag unit, which is realized with both hardware and software. With use notions amplitude and phase margins, condition for stability of system functioning are obtained. Theoretical results are confirm with computer experiment carried out on the third-order system.

Modified Posicast Control Design Method Based on the Parameters of a Fractional Order System

2021 ◽  
Vol 143 (4) ◽  
Author(s):  
Erhan Yumuk ◽  
Müjde Güzelkaya ◽  
İbrahim Eksin
Keyword(s):  
Real Time ◽  
Fractional Order ◽  
Control Method ◽  
Design Method ◽  
Order System ◽  
Half Cycle ◽  
Empirical Formulas ◽  
Real Time System ◽  
Novel Design ◽  
Better Than

Abstract In this study, a novel design method for half-cycle and modified posicast controller structures is proposed for a class of the fractional order systems. In this method, all required design variable values, namely, the input step magnitudes and their application times are obtained as functions of fractional system parameters. Moreover, empirical formulas are obtained for the overshoot values of the compensated system with half-cycle and modified posicast controllers designed utilizing this method. The proposed design methodology has been tested via simulations and ball balancing real-time system. It is observed that the derived formulas are in coherence with outcomes of the simulation and real-time application. Furthermore, the performance of modified posicast controller designed using proposed method is much better than other posicast control method.

The Study of Optimal Fuzzy PID-Smith Control Based on Genetic Algorithm

2013 ◽  
Vol 313-314 ◽  
pp. 448-452
Author(s):  
Dian Ting Liu ◽  
Hai Xia Li
Keyword(s):  
Genetic Algorithm ◽  
Simulation Model ◽  
Control Method ◽  
Order System ◽  
Membership Functions ◽  
Fuzzy Pid ◽  
Improved Genetic Algorithm ◽  
Simulation Results ◽  
The Stability ◽  
Better Than

In this paper, the improved genetic algorithm is applied to optimize the quantization factors and the scaling factors of fuzzy control, and the optimized rule table and membership functions is obtained according to certain performances. Then a kind of optimal fuzzy PID-Smith control method based on genetic algorithm is proposed and its simulation model is built in this paper, a second-order system is simulated and analyzed. The results show that requirements of deterministic performances of the new control method are better than the conventional methods through the simulation results in the stability, rapidity and robustness.

Research on the Hydraulic Actuator Control of the Quadruped Robot Based Dual-Loop

2012 ◽  
Vol 569 ◽  
pp. 533-538
Author(s):  
En Chao Yang ◽  
Qing Wei ◽  
Run Bin Cai ◽  
Hong Xu Ma
Keyword(s):  
Position Control ◽  
Control Method ◽  
Quadruped Robot ◽  
Order System ◽  
Control Loop ◽  
Hydraulic Actuator ◽  
Loop Control ◽  
Actual Force ◽  
Target Force ◽  
Actuator Control

This paper presents modeling and dual-loop control of a non-linear hydraulic actuator applied on the quadruped robot. The pure position control of the actuator is hard to achieve because it’s a three-order system. So we propose the dual-loop control method to decompose it. The controller structure of the system is composed of two loops namely outer position control loop and inner force control loop. Outer loop controller is used to calculate the optimum target force to reject the errors of the position control, while, the inner loop controller is used to keep the actual force close to this desired force.

Reduced Order Controller Design for Nonlinear Systems With Periodic Coefficients

2009 ◽  
Author(s):  
Amit P. Gabale ◽  
Subhash C. Sinha
Keyword(s):  
Controller Design ◽  
Linear Part ◽  
Eigenvalue Decomposition ◽  
Order System ◽  
Time Varying ◽  
Periodic Coefficients ◽  
Reduced Order ◽  
Periodic Linear ◽  
Time Invariant ◽  
Time Periodic

This study provides a methodology for reduced order controller design for nonlinear dynamic systems with time-periodic coefficients. System equations are represented by quasi-linear differential equations in state space, containing a time-periodic linear part and nonlinear monomials of states with periodic coefficients. The Lyapunov-Floquet (L-F) transformation is used to transform the time-varying linear part of the system into a time-invariant form. Eigenvalue decomposition of the time-invariant linear part can then be used to identify the dominant/ non-dominant dynamics of the system. The non-dominant states of the system are expressed as a nonlinear, time-periodic, manifold relationship in terms of the dominant states. As a result, the original large system can be expressed as a lower order system represented only by the dominant states. A reducibility condition is derived to provide conditions under which a nonlinear order reduction is possible. Then a proper coordinate transformation and state feedback can be found under which the reduced order system is transformed into a linear, time-periodic, closed-loop system. This permits the design of a time-varying feedback controller in linear space to guarantee the stability of the system. The proposed methodology is illustrated by designing a reduced order controller for a 4-dof, inverted pendulum subjected to a periodic follower force. Treatment for the time-invariant case is also included as a subset of the problem.

scholarly journals Water needs of interplanted crops on rice irrigation systems

2020 ◽  
pp. 102-111
Author(s):  
A. M. Rokochinskiy ◽  
V. O. Turcheniuk ◽  
P. P. Volk ◽  
R. M. Koptyuk ◽  
N. V. Prykhodko ◽  
...  
Keyword(s):  
Climate Change ◽  
Crop Rotation ◽  
Computer Experiment ◽  
Climatic Conditions ◽  
Rice Crop ◽  
Water Regulation ◽  
Total Evaporation ◽  
Technological Efficiency ◽  
System Functioning ◽  
Irrigated Lands

Relevance of research. Recent studies of  weather and climatic conditions of the rice-growing zone of Ukraine indicate a steady tendency to increase the aridity of the climate in the region. Further increase in air temperature and decrease in natural water availability of these territories will lead to the increase in total evaporation and water needs for irrigation of the crops of rice crop rotation. Under such conditions a significant exacerbation of the existing problem of water deficit is expected in the region. The availability of water resources directly affects the efficiency of agricultural production on the irrigated lands of rice systems. In this regard, there is an objective need to adapt agricultural production on the irrigated lands of rice systems to the existed and predicted climate change, which, first of all, requires the assessment of water needs for irrigation both the leading crop of flooded rice and the interplanted  crops of rice crop rotation. Aim of the study is to estimate the  changes in water needs for irrigation of the interplanted crops of rice crop rotation in the variable natural-agro-reclamation conditions of rice system functioning. To achieve this goal, the authors implemented a large-scale computer experiment, based on a complex of predictive-simulation models, which basing on  a long-term forecast, allow to estimate weather and climatic conditions, water regime, water regulation technologies and the productivity of reclaimed lands. During the experiment the conditions of total evaporation formation were investigated, the water needs of different types of interplanted crops of rice crop rotation were determined for the technology and regime of water regulation on the irrigated lands of rice systems for the typical groups of vegetation periods of target years in view of general heat and moisture provision. It was evaluated technological efficiency of irrigation of the interplanted crops of rice crop rotation in the variable natural-agro-reclamation conditions of rice system functioning and obtained results with the actual production data were compared.   Research methods. The research methods were based on the application of system theory along with the systematic approach, system analysis and modeling oriented on widespread use of computers and related software in the developing of modern approaches to substantiate of technical and technological solutions for water regulation on the drained lands in the conditions of climate change. The object of the study is the Danube rice irrigation systems in Odessa region, design, natural and reclamation conditions of which are typical for the most of rice systems in Ukraine.   Results of the study and the main conclusions. During the computer experiment the conditions of total evaporation formation were investigated, the water needs of different types of interplanted crops of rice crop rotation were determined for the technology and regime of water regulation on the irrigated lands of rice systems for the typical groups of vegetation periods of target years in view of general heat and moisture provision. Technological efficiency of irrigation of the interplanted crops of rice crop rotation in the variable natural-agro-reclamation conditions of rice system functioning was evaluated and the obtained results with the actual production data were compared. This approach makes it possible to evaluate and predict water needs for irrigation of the interplanted crops of rice crop rotation in the variable natural-agro-reclamation conditions of rice system functioning. Prospects. The obtained results can be effectively used for justification of regime and technological decisions in the projects of reconstruction and modernization of existing rice systems and developing adaptive measures to the predicted climate change in the region. 

scholarly journals Approach to analysis of technical -organizational system functioning on the base of semi-markov process theory

2018 ◽  
Vol 7 (2.23) ◽  
pp. 1
Author(s):  
Aleksey Gavrilin ◽  
Tatiana Gorbunova ◽  
Marina Tumanova ◽  
Oleg Ratnikov
Keyword(s):  
Complex System ◽  
Markov Process ◽  
Temporal Analysis ◽  
Process Theory ◽  
Normal Operation ◽  
Adequate Description ◽  
Organizational System ◽  
The Status ◽  
Semi Markov Process ◽  
System Functioning

Relevance of the present task lays in optimization of control over complex systems considering probabilistic and temporal nature of their functioning. Allocated some generic States of the system's normal operation and consider destabilizing situations when the continued functioning of the element in the system becomes difficult, impossible. Including the status when it is necessary to conduct full diagnostic and restoring of the system with explicit damage which makes it impossible for the system to operate in the acceptable mode into the model is described in the work. The proposed solution to this task is based on the mathematical modelling. Considering the general case of nonexponential time of system residence in its own status, the proposed functioning model displays relations between system statuses and probable parameters of its functioning on the base of semi-Markov process theory. Because of this work the explanation of an adequate description of complex system functioning at probabilistic and temporal analysis was presented.  

Nonlinear Control of a Transient Inductrack System Using State Feedback

2021 ◽  
Author(s):  
Ruiyang Wang ◽  
Bingen Yang
Keyword(s):  
Feedback Control ◽  
Nonlinear Control ◽  
Dynamic Modeling ◽  
State Feedback ◽  
Permanent Magnets ◽  
Control Method ◽  
Linear Part ◽  
Control Design ◽  
Nonlinear Part ◽  
Highly Nonlinear

Abstract The concept of Inductrack refers to the magnetic levitation technology achieved by Halbach arrays of permanent magnets. In an Inductrack system, the dynamic behaviors involved with transient responses are difficult to capture due to the highly nonlinear, time-varying, electromagnetic-mechanical couplings. In the literature, dynamic modeling of Inductrack systems that aims to analyze the transient behaviors has been widely addressed. However, one common issue with the previous investigations is that most of the dynamic models either partly or completely adopted certain steady-state and ideal case assumptions. These assumptions are extremely difficult to maintain in a transient scenario, if not impossible. Therefore, while providing good understanding of Inductrack systems, the previous results in dynamic modeling have a limited utility in providing guidance for feedback control of Inductrack systems. Recently, a benchmark transient Inductrack model was created for characterizing the transient time response of the system with fidelity, which enables model-based feedback control design. In this work, based on the transient model, a new control method for the Inductrack dynamic system is developed. The proposed control method consists of a linear part and a nonlinear part. The linear part is devised based on a state feedback configuration; the nonlinear part is accomplished by fitting a nonlinear “force-current” mapping function. With this nonlinear feedback controller, the levitation gap of the Inductrack vehicle can be effectively stabilized at both constant and time-dependent traveling speed. The proposed control law is demonstrated in numerical examples. The nonlinear control design is potentially extensible to more complicated Inductrack systems with higher degrees of freedom.

Synchronization and Antisynchronization of a Class of Chaotic Systems With Nonidentical Orders and Uncertain Parameters

2014 ◽  
Vol 10 (1) ◽  
Author(s):  
Diyi Chen ◽  
Weili Zhao ◽  
Xinzhi Liu ◽  
Xiaoyi Ma
Keyword(s):  
Chaotic Systems ◽  
Control Method ◽  
Sliding Mode ◽  
Order System ◽  
Theory Analysis ◽  
Integer Order ◽  
Uncertain Chaotic Systems ◽  
Hyperchaotic Systems ◽  
Fractional Orders ◽  
Good Agreement

In this paper, we study the synchronization of a class of uncertain chaotic systems. Based on the sliding mode control and stability theory in fractional calculus, a new controller is designed to achieve synchronization. Examples are presented to illustrate the effectiveness of the proposed controller, like the synchronization between an integer-order system and a fraction-order system, the synchronization between two fractional-order hyperchaotic systems (FOHS) with nonidentical fractional orders, the antisynchronization between an integer-order system and a fraction-order system, the synchronization between two new nonautonomous systems. The simulation results are in good agreement with the theory analysis and it is noted that the proposed control method is of vital importance for practical system parameters are uncertain and imprecise.

Motion control with robust string stability of mobile-rack vehicles in autonomous logistics

2020 ◽  
pp. 095440622095317
Author(s):  
Boc Minh Hung ◽  
Sam-Sang You ◽  
Bui Duc Hong Phuc ◽  
Hwan-Seong Kim
Keyword(s):  
Control Method ◽  
Order System ◽  
Robust Controller ◽  
String Stability ◽  
Storage And Retrieval ◽  
Working Space ◽  
Vehicle System ◽  
Efficient Storage ◽  
Control Stability ◽  
Safe Working

In order to reduce costs for a larger warehouse or expand the floor space of a small warehouse, it is impossible to implement this with a traditional warehouse, which is characterized as poorly utilized space. For the efficient storage and retrieval, the smart warehouse system with autonomous mobile-rack vehicles can optimize the space utilization by providing only a few open aisles at a time for accessing the racks with minimal intervention. This paper deals with designing the vehicle robust controller for maintaining safe spacing with collision avoidance in the fully automated warehouse. The compact vehicle dynamics are presented for the interconnected string of vehicles. Next, the string stability with safe working space of the mobile-rack vehicles has been described for guaranteeing complete autonomous logistics in smart warehouse. In addition, the controller order has been significantly reduced to a low-order system without performance degradation for real implementation. This control method can guarantee control stability as well as performances of mobile-rack vehicles against unavoidable uncertainties, disturbances, and noises for warehouse automation in the extremely cold environment without rail rack. Finally, the autonomous mobile-rack vehicle system is to become the promising vision of future smart warehouse technology in autonomous logistics.

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