scholarly journals The Trade-Off between the Controller Effort and Control Quality on Example of an Electro-Pneumatic Final Control Element

Actuators ◽  
2019 ◽  
Vol 8 (1) ◽  
pp. 23 ◽  
Author(s):  
Michał Bartyś ◽  
Bartłomiej Hryniewicki
Keyword(s):  
Control Element ◽  
Time To Failure ◽  
Level Control ◽  
Control Effort ◽  
Control Value ◽  
Embedded Controller ◽  
Pneumatic Transducer ◽  
And Control ◽  
Mean Time ◽  
Selection Of

For many years, the programmable positioners have been widely applied in structures of modern electro-pneumatic final control elements. The positioner consists of an electro-pneumatic transducer, embedded controller, and measuring instrumentation. Electro-pneumatic transducers that are used in positioners are characterized by a relatively short mean time-to-failure. The practical and economical method of a reasonable prolongation of this time is proposed in this paper. It is principally based on assessment and minimizing the effort of the embedded controller. For this purpose, some measures were introduced: The control value variability, mean-time, and the cumulative controller’s effort. The diminishing of controller effort has significant practical repercussions because it reduces the intensity of mechanical wear of the final control element components. On the other hand, the reduction of the cumulative effort is important in the context of process economy due to limitation of the consumption of energy of compressed air supplying the final control element. Therefore, the minimization of control effort indicators has an impact on the increase of the functional safety and economics of the controlled process. The simulations were performed in the Matlab-Simulink environment with the use of the liquid level control system in which a phenomenological model of a final control element was deployed. As a result of the performed simulations, the recommendations regarding the selection of the structure of positioner controller were elaborated.

scholarly journals The Trade-Off between the Controller Effort and Control Quality on Example of an Electro-Pneumatic Final Control Element

2019 ◽  
Author(s):  
Michał Bartyś ◽  
Bartłomiej Hryniewicki
Keyword(s):  
Control Element ◽  
Time To Failure ◽  
Quality Factors ◽  
Level Control ◽  
Control Value ◽  
Control Quality ◽  
Embedded Controller ◽  
Pneumatic Transducer ◽  
And Control ◽  
Mean Time

For many years, the programmable positioners have been widely applied in structures of modern electro-pneumatic final control elements. The positioner consists of an electro-pneumatic transducer, embedded controller and measuring instrumentation. Electro-pneumatic transducers that are used in positioners are characterized by a relatively short mean time-to-failure. The practical and economical method of a reasonable prolongation of this time is proposed in this paper. It is principally based on assessment and minimizing the effort of the embedded controller. For this purpose, were introduced: the control value variability, mean-time and the cumulative controller's effort. The diminishing of controller effort has significant practical repercussions, because it reduces the intensity of mechanical wear of the final control element components. On the other hand, the reduction of the cumulative effort is important in the context of process economy due to limitation of the consumption of energy of compressed air supplying the final control element. Therefore, the minimization of introduced effort factors has an impact on increasing the functional safety and economics of the controlled process. As a result of the performed simulations, the recommendations regarding the selection of the structure and tuning of positioner controller were elaborated. The simulations were performed in the Matlab-Simulink environment with the use of the liquid level control system in which a phenomenological model of a final control element was deployed. It has been proven that under appropriate conditions, it is possible to extend significantly the lifetime of the final control element and simultaneously enhance the control quality factors.

scholarly journals The Use of Statistical Inference in the Water Supply Network Managing Operation Process

2019 ◽  
Vol 49 (4) ◽  
pp. 221-244
Author(s):  
Izabela Piegdoń
Keyword(s):  
Water Supply ◽  
Time To Failure ◽  
Supply Network ◽  
Water Supply Network ◽  
Time Between Failures ◽  
Operation Process ◽  
Safety And Reliability ◽  
Mean Time ◽  
Operational Data ◽  
Selection Of

Abstract Based on operational data concerning the dates of failure of the water supply network, a mean time to failure was performed. The calculations were performed for the main network, distribution network and water supply connections. The hypothesis about exponential working time between failures was verified using the Pearson test (χ2). The presented analyses provide an attitude of further analyses related to modelling the work of renovation and repair teams, associated with the selection of their appropriate number, and also to ensure the required level of safety and reliability of water supply to the consumers.

scholarly journals DEGRADATION ANALYSIS OF PROBABILISTIC PARALLEL CHOICE SYSTEMS

2014 ◽  
Vol 21 (03) ◽  
pp. 1450012
Author(s):  
AVINASH SAXENA ◽  
SHRISHA RAO
Keyword(s):  
Complete System ◽  
System Failure ◽  
Time To Failure ◽  
Probabilistic Choice ◽  
Mean Time Between Failures ◽  
System Parameters ◽  
Time Between Failures ◽  
Degradation Analysis ◽  
Mean Time ◽  
Selection Of

Degradation analysis is used to analyze the useful lifetimes of systems, their failure rates, and various other system parameters like mean time to failure (MTTF), mean time between failures (MTBF), and the system failure rate (SFR). In many systems, certain possible parallel paths of execution that have greater chances of success are preferred over others. Thus we introduce here the concept of probabilistic parallel choice. We use binary and n-ary probabilistic choice operators in describing the selections of parallel paths. These binary and n-ary probabilistic choice operators are considered so as to represent the complete system (described as a series-parallel system) in terms of the probabilities of selection of parallel paths and their relevant parameters. Our approach allows us to derive new and generalized formulae for system parameters like MTTF, MTBF, and SFR. We use a generalized exponential distribution, allowing distinct installation times for individual components, and use this model to derive expressions for such system parameters.

Modeling and Robust Low Level Control of an Omnidirectional Mobile Robot

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Ramon Comasolivas ◽  
Joseba Quevedo ◽  
Teresa Escobet ◽  
Antoni Escobet ◽  
Juli Romera
Keyword(s):  
Mobile Robot ◽  
Pi Controller ◽  
Control Technique ◽  
Level Control ◽  
Parameter Uncertainties ◽  
Control Effort ◽  
Friction Forces ◽  
Low Level ◽  
Stability And Control ◽  
And Control

This paper presents the modeling and robust low-level control design of a redundant mobile robot with four omnidirectional wheels, the iSense Robotic (iSRob) platform, that was designed to test safe control algorithms. iSRob is a multivariable nonlinear system subject to parameter uncertainties mainly due to friction forces. A multilinear model is proposed to approximate the behavior of the system, and the parameters of these models are estimated from closed-loop experimental data applying Gauss–Newton techniques. A robust control technique, quantitative feedback theory (QFT), is applied to design a proportional–integral (PI) controller for robust low-level control of the iSRob system, being this the main contribution of the paper. The designed controller is implemented, tested, and compared with a gain-scheduling PI-controller based on pole assignment. The experimental results show that robust stability and control effort margins against system uncertainties are satisfied and demonstrate better performance than the other controllers used for comparison.

Electromigration in Thin Films of Au on GaAs

1989 ◽  
Vol 167 ◽  
Author(s):  
P. F. Tang ◽  
A. G. Milnes ◽  
C. L. Bauer ◽  
S. Mahajan
Keyword(s):  
Thin Films ◽  
Grain Boundary ◽  
Time To Failure ◽  
Triple Junctions ◽  
Flux Divergence ◽  
Boundary Triple ◽  
Log Normal ◽  
Mean Time ◽  
Selection Of ◽  
Good Agreement

AbstractEvolution of the fractional change of electrical resistance ΔR/R in thin films of Au on (001) substrates of semi-insulating GaAs has been investigated as a function of time t, temperature T, and current density j. Initially, ΔR/R increases linearly with increasing t for constant T and j, and exponentially with increasing T for constant t and j, characterized by an activation energy of 0.73 eV. An analytical model is developed to evaluate ΔR/R for the early stages of electromigration. This model is based on flux divergence at grain boundary triple junctions resulting from variations of grain boundary inclination and/or diffusivity. Using a Monte Carlo method, conducting lines containing a prescribed number of random triple junctions are simulated, wherein distribution of mass flux divergence determines initial values of ΔR/R. Moreover, by selection of an appropriate failure criterion, the sequence of cumulative failures is characterized by a log-normal-like distribution, which defines mean time to failure and corresponding standard deviation. In general, the model is in good agreement with experimental observations.

MODEL OF SOCIAL POTENTIAL OF CHILDHOOD IN THE RUSSIAN REGIONS: THE RESULTS OF EXPERIMENTS

2019 ◽  
pp. 152-162
Author(s):  
A.G. Filipova ◽  
A.V. Vysotskaya
Keyword(s):  
Third Wave ◽  
Russian Regions ◽  
The Third ◽  
Control Factors ◽  
Social Potential ◽  
System Input ◽  
Optimal Values ◽  
Fixed Ideal ◽  
And Control ◽  
Selection Of

The article presents the results of mathematical experiments with the system «Social potential of childhood in the Russian regions». In the structure of system divided into three subsystems – the «Reproduction of children in the region», «Children’s health» and «Education of children», for each defined its target factor (output parameter). The groups of infrastructure factors (education, health, culture and sport, transport), socio-economic, territorial-settlement, demographic and en-vironmental factors are designated as the factors that control the system (input parameters). The aim of the study is to build a model îf «Social potential of childhood in the Russian regions», as well as to conduct experiments to find the optimal ratio of the values of target and control factors. Three waves of experiments were conducted. The first wave is related to the analysis of the dynam-ics of indicators for 6 years. The second – with the selection of optimal values of control factors at fixed ideal values of target factors. The third wave allowed us to calculate the values of the target factors based on the selected optimal values of the control factors of the previous wave.

POSSIBILITY TO REDUCE THROMBOCYTOPENIA AFTER CHEMORADIOTHERAPY IN ONCOLOGICAL PATIENTS

2017 ◽  
Vol 63 (3) ◽  
pp. 466-469
Author(s):  
Luiza Korytova ◽  
Aleksey Meshechkin ◽  
Oleg Korytov ◽  
V. Krasnikova
Keyword(s):  
Combined Treatment ◽  
Treated Group ◽  
Median Number ◽  
Blood Analysis ◽  
Control Group ◽  
Level Control ◽  
Normal Range ◽  
Oncological Patients ◽  
Level Increase ◽  
And Control

Objective was to establish efficiency of sodium nucleospermat in correcting thrombocytopenia after chemoradiotherapy in oncological patients. Methods and materials. The study included data on 32 patients that had undergone combined treatment from January till May 2016. After detecting thrombocytopenia patients were randomized into two groups (16 patients in each): treated group, where patients received sodium nucleospermat, and control group, where sodium nucleospermat was not used. Thrombocyte level control was done on 5th, 10th and 15th day after treatment was over. Results and discussion. All 16 patients showed positive dynamics in increasing thrombocyte level after Sodium nucleospermat injection course was finished. This was proven by first (5th day) blood analysis. On average thrombocyte level after sodium nucleospermat treatment has risen to normal, at 161х109/1. Only 3 patients from this group had to pause radiotherapy for 5 days. Control group patients, which did not receive sodium nucleospermat, showed evidence of thrombocyte level recovery by 10th day only. On average thrombocyte level increase was insignificant, and median number was 111*109/l. Low thrombocyte level was main reason to pause radiotherapy for 11 (69%) patients in control group. Conclusion. Sodium nucleospermat allowed raising thrombocyte level to the lower normal range, which surpassed by 40%-50% in control group patients. Use of sodium nucleospermat did not show any cases of allergic reactions, toxicity or complications in oncological patients.

An LQ Approach to Active Control of Vibrations in Helicopters

1996 ◽  
Vol 118 (3) ◽  
pp. 482-488 ◽  
Author(s):  
Sergio Bittanti ◽  
Fabrizio Lorito ◽  
Silvia Strada
Keyword(s):  
Optimal Control ◽  
Active Control ◽  
Linear Quadratic ◽  
Control Effort ◽  
Vibration Effect ◽  
Suitable Definition ◽  
Lq Optimal Control ◽  
The One ◽  
Definition Of ◽  
And Control

In this paper, Linear Quadratic (LQ) optimal control concepts are applied for the active control of vibrations in helicopters. The study is based on an identified dynamic model of the rotor. The vibration effect is captured by suitably augmenting the state vector of the rotor model. Then, Kalman filtering concepts can be used to obtain a real-time estimate of the vibration, which is then fed back to form a suitable compensation signal. This design rationale is derived here starting from a rigorous problem position in an optimal control context. Among other things, this calls for a suitable definition of the performance index, of nonstandard type. The application of these ideas to a test helicopter, by means of computer simulations, shows good performances both in terms of disturbance rejection effectiveness and control effort limitation. The performance of the obtained controller is compared with the one achievable by the so called Higher Harmonic Control (HHC) approach, well known within the helicopter community.

scholarly journals Surveillance System in Smart Cities: A Dependability Evaluation Based on Stochastic Models

Electronics ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 876
Author(s):  
Igor Gonçalves ◽  
Laécio Rodrigues ◽  
Francisco Airton Silva ◽  
Tuan Anh Nguyen ◽  
Dugki Min ◽  
...  
Keyword(s):  
Surveillance System ◽  
Smart Cities ◽  
Heterogeneous Data ◽  
Time To Failure ◽  
Video Streams ◽  
Dependability Evaluation ◽  
The Mean ◽  
Mean Time ◽  
The Internet Of Things

Surveillance monitoring systems are highly necessary, aiming to prevent many social problems in smart cities. The internet of things (IoT) nowadays offers a variety of technologies to capture and process massive and heterogeneous data. Due to the fact that (i) advanced analyses of video streams are performed on powerful recording devices; while (ii) surveillance monitoring services require high availability levels in the way that the service must remain connected, for example, to a connection network that offers higher speed than conventional connections; and that (iii) the trust-worthy dependability of a surveillance system depends on various factors, it is not easy to identify which components/devices in a system architecture have the most impact on the dependability for a specific surveillance system in smart cities. In this paper, we developed stochastic Petri net models for a surveillance monitoring system with regard to varying several parameters to obtain the highest dependability. Two main metrics of interest in the dependability of a surveillance system including reliability and availability were analyzed in a comprehensive manner. The analysis results show that the variation in the number of long-term evolution (LTE)-based stations contributes to a number of nines (#9s) increase in availability. The obtained results show that the variation of the mean time to failure (MTTF) of surveillance cameras exposes a high impact on the reliability of the system. The findings of this work have the potential of assisting system architects in planning more optimized systems in this field based on the proposed models.

scholarly journals The dynamic of body and brain co-evolution

2021 ◽  
pp. 105971232199468
Author(s):  
Paolo Pagliuca ◽  
Stefano Nolfi
Keyword(s):  
Morphological Traits ◽  
The Body ◽  
Morphological Variations ◽  
And Control ◽  
Selection Of

We introduce a method that permits to co-evolve the body and the control properties of robots. It can be used to adapt the morphological traits of robots with a hand-designed morphological bauplan or to evolve the morphological bauplan as well. Our results indicate that robots with co-adapted body and control traits outperform robots with fixed hand-designed morphologies. Interestingly, the advantage is not due to the selection of better morphologies but rather to the mutual scaffolding process that results from the possibility to co-adapt the morphological traits to the control traits and vice versa. Our results also demonstrate that morphological variations do not necessarily have destructive effects on robots’ skills.

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