scholarly journals Ultrasensitive molecular controllers for quasi-integral feedback

2018 ◽  
Author(s):  
Christian Cuba Samaniego ◽  
Elisa Franco
Keyword(s):  
Computational Models ◽  
Closed Loop ◽  
Reaction Network ◽  
Robust Tracking ◽  
Closed Loop System ◽  
System Equilibrium ◽  
Molecular Reaction ◽  
Unknown Disturbances ◽  
Integral Controller ◽  
The Impact

AbstractFeedback control has enabled the success of automated technologies by mitigating the effects of variability, unknown disturbances, and noise. Similarly, feedback loops in biology reduce the impact of noise and help shape kinetic responses, but it is still unclear how to rationally design molecular controllers that approach the performance of controllers in traditional engineering applications, in particular the performance of integral controllers. Here, we describe a strategy to build molecular quasi-integral controllers by following two design principles: (1) a highly ultrasensitive response, which guarantees a small steady-state error, and (2) a tunable ultrasensitivity threshold, which determines the system equilibrium point (reference). We describe a molecular reaction network, which we name Brink motif, that satisfies these requirements by combining sequestration and an activation/deactivation cycle. We show that if ultrasensitivity conditions are satisfied, this motif operates as a quasi-integral controller and promotes homeostatic behavior of the closed-loop system (robust tracking of the input reference while rejecting disturbances). We propose potential biological implementations of Brink controllers and we illustrate different example applications with computational models.

Pseudo-random binary sequence closed-loop system identification error with integration control

2009 ◽  
Vol 223 (6) ◽  
pp. 877-884 ◽  
Author(s):  
Z Ren ◽  
G G Zhu
Keyword(s):  
System Identification ◽  
Closed Loop ◽  
Binary Sequence ◽  
Open Loop ◽  
Loop System ◽  
Loop Model ◽  
Closed Loop System ◽  
Identification Error ◽  
Closed Loop Identification ◽  
Integral Controller

This paper studies the closed-loop system identification (ID) error when a dynamic integral controller is used. Pseudo-random binary sequence (PRBS) q-Markov covariance equivalent realization (Cover) is used to identify the closed-loop model, and the open-loop model is obtained based upon the identified closed-loop model. Accurate open-loop models were obtained using PRBS q-Markov Cover system ID directly. For closed-loop system ID, accurate open-loop identified models were obtained with a proportional controller, but when a dynamic controller was used, low-frequency system ID error was found. This study suggests that extra caution is required when a dynamic integral controller is used for closed-loop system identification. The closed-loop identification framework also has significant effects on closed-loop identification error. Both first- and second-order examples are provided in this paper.

Energetically-Optimal Discrete and Continuous Stabilization of the Rimless Wheel With Torso

2019 ◽  
Author(s):  
Wankun Sirichotiyakul ◽  
Aykut C. Satici ◽  
Eric S. Sanchez ◽  
Pranav A. Bhounsule
Keyword(s):  
Closed Loop ◽  
Estimation Method ◽  
Linear Quadratic Regulator ◽  
Region Of Attraction ◽  
Closed Loop System ◽  
Linear Quadratic ◽  
Walking Gait ◽  
Rimless Wheel ◽  
The Impact ◽  
Discrete Controller

Abstract In this work, we discuss the modeling, control, and implementation of a rimless wheel with torso. We derive and compare two control methodologies: a discrete-time controller (DT) that updates the controls once-per-step and a continuous-time controller (CT) that updates gains continuously. For the discrete controller, we use least-squares estimation method to approximate the Poincaré map on a certain section and use discrete-linear-quadratic-regulator (DQLR) to stabilize a (closed-form) linearization of this map. For the continuous controller, we introduce moving Poincaré sections and stabilize the transverse dynamics along these moving sections. For both controllers, we estimate the region of attraction of the closed-loop system using sum-of-squares methods. Analysis of the impact map yields a refinement of the controller that stabilizes a steady-state walking gait with minimal energy loss. We present both simulation and experimental results that support the validity of the proposed approaches. We find that the CT controller has a larger region of attraction and smoother stabilization as compared with the DT controller.

scholarly journals A Circular Light Bulb Economy: Framework for Sustainable End-of-life Management of Modern Light Bulb

2019 ◽  
pp. 1-9
Author(s):  
S. Selvam ◽  
Shivinder Singh Chandok ◽  
Harsh Singh
Keyword(s):  
Pilot Study ◽  
Best Practices ◽  
Circular Economy ◽  
Closed Loop ◽  
Relevant Literature ◽  
Light Bulb ◽  
Closed Loop System ◽  
Comprehensive Review ◽  
The Impact

This paper presents a framework that focuses on transitioning from a linear light bulb economy to a circular light bulb economy by developing a closed-loop system of reuse. The conceptual framework is based on a pilot study conducted in India and strengthened by a comprehensive review and analysis of relevant literature. Accordingly, the proposed paradigms are a result of best practices identified during the pilot study. The results demonstrate the financial viability of the pilot study conducted over a period of three years. Additionally, the results provide evidence of the impact of the circular economy on economic growth, employment opportunity, and reduction in environmental waste. The discussion also identifies the barriers to the adoption of a circular economy framework including the role of attitude towards the environment and the skill gap in labor.

scholarly journals A synthetic integral feedback controller for robust tunable regulation in bacteria

2017 ◽  
Author(s):  
Gabriele Lillacci ◽  
Stephanie Aoki ◽  
David Schweingruber ◽  
Mustafa Khammash
Keyword(s):  
Closed Loop ◽  
Protein Pair ◽  
General Purpose ◽  
Proof Of Concept ◽  
Feedback Control System ◽  
Genetic Circuits ◽  
Closed Loop System ◽  
The Face ◽  
Integral Controller ◽  
Integral Feedback

AbstractWe report on the first engineered integral feedback control system in a living cell. The controller is based on the recently published antithetic integral feedback motif [1] which has been analytically shown to have favorable regulation properties. It is implemented along with test circuitry in Escherichia coli using seven genes and three small-molecule inducers. The closed-loop system is highly tunable, allowing a regulated protein of interest to be driven to a desired level and maintained there with precision. Realized using a sigma/anti-sigma protein pair, the integral controller ensures that regulation is maintained in the face of perturbations that lead to the regulated protein’s degradation, thus serving as a proof-of-concept prototype of integral feedback implementation in living cells. When suitably optimized, this integral controller may be utilized as a general-purpose robust regulator for genetic circuits with unknown or partially-known topologies and parameters.

scholarly journals Integration of a Commercial Barcode-Assisted Medication Dispensing System in a Teaching Hospital

2019 ◽  
Vol 10 (04) ◽  
pp. 615-624
Author(s):  
Sarah Berdot ◽  
Abdelali Boussadi ◽  
Aurélie Vilfaillot ◽  
Mathieu Depoisson ◽  
Claudine Guihaire ◽  
...  
Keyword(s):  
Teaching Hospital ◽  
Closed Loop ◽  
Medication Administration ◽  
Loop System ◽  
Control Group ◽  
Closed Loop System ◽  
Technical Problems ◽  
The Impact ◽  
Dispensing Error ◽  
Medication Dispensing

Objectives A commercial barcode-assisted medication administration (BCMA) system was integrated to secure the medication process and particularly the dispensing stage by technicians and the administration stage with nurses. We aimed to assess the impact of this system on medication dispensing errors and barriers encountered during integration process. Methods We conducted a controlled randomized study in a teaching hospital, during dispensing process at the pharmacy department. Four wards were randomized in the experimental group and control group, with two wards using the system during 3 days with dedicated pharmacy technicians. The system was a closed loop system without information return to the computerized physician order entry system. The two dedicated technicians had a 1-week training session. Observations were performed by one observer among the four potential observers previously trained. The main outcomes assessed were dispensing error rates and the identification of barriers encountered to expose lessons learned from this study. Results There was no difference between the dispensing error rate of the control and experimental groups (7.9% for both, p = 0.927). We identified 10 barriers to pharmacy barcode-assisted system technology deployment. They concerned technical (problems with semantic interoperability interfaces, bad user interface, false errors generated, lack of barcodes), structural (poor integration with local information technology), work force (short staff training period, insufficient workforce), and strategic issues (system performance problems, insufficient budget). Conclusion This study highlights the difficulties encountered in integrating a commercial system in current hospital information systems. Several issues need to be taken into consideration before the integration of a commercial barcode-assisted system in a teaching hospital. In our experience, interoperability of this system with the electronic health record is the key for the success of this process with an entire closed loop system from prescription to administration. BCMA system at the dispensing process remains essential to purchase securing medication administration process.

The Impact of Visual Feedback Type on the Mastery of Visuo-Motor Transformations

2012 ◽  
Vol 220 (1) ◽  
pp. 3-9 ◽  
Author(s):  
Sandra Sülzenbrück
Keyword(s):  
Empirical Research ◽  
Visual Feedback ◽  
Closed Loop ◽  
Motor Planning ◽  
Visual Input ◽  
Closed Loop Control ◽  
Loop Control ◽  
Feedback Type ◽  
Effective Use ◽  
The Impact

For the effective use of modern tools, the inherent visuo-motor transformation needs to be mastered. The successful adjustment to and learning of these transformations crucially depends on practice conditions, particularly on the type of visual feedback during practice. Here, a review about empirical research exploring the influence of continuous and terminal visual feedback during practice on the mastery of visuo-motor transformations is provided. Two studies investigating the impact of the type of visual feedback on either direction-dependent visuo-motor gains or the complex visuo-motor transformation of a virtual two-sided lever are presented in more detail. The findings of these studies indicate that the continuous availability of visual feedback supports performance when closed-loop control is possible, but impairs performance when visual input is no longer available. Different approaches to explain these performance differences due to the type of visual feedback during practice are considered. For example, these differences could reflect a process of re-optimization of motor planning in a novel environment or represent effects of the specificity of practice. Furthermore, differences in the allocation of attention during movements with terminal and continuous visual feedback could account for the observed differences.

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