scholarly journals A closed-loop anesthetic delivery system for real-time control of burst suppression

2013 ◽  
Vol 10 (4) ◽  
pp. 046004 ◽  
Author(s):  
Max Y Liberman ◽  
ShiNung Ching ◽  
Jessica Chemali ◽  
Emery N Brown
Keyword(s):  
Real Time ◽  
Delivery System ◽  
Closed Loop ◽  
Burst Suppression ◽  
Real Time Control ◽  
Time Control

scholarly journals Real-time Closed-loop Control in a Rodent Model of Medically Induced Coma Using Burst Suppression

2013 ◽  
Vol 119 (4) ◽  
pp. 848-860 ◽  
Author(s):  
ShiNung Ching ◽  
Max Y. Liberman ◽  
Jessica J. Chemali ◽  
M. Brandon Westover ◽  
Jonathan D. Kenny ◽  
...  
Keyword(s):  
Real Time ◽  
Delivery System ◽  
Closed Loop ◽  
Brain Injuries ◽  
Estimation Procedure ◽  
Burst Suppression ◽  
Real Time Control ◽  
Loop Control ◽  
Time Control ◽  
Proportional Integral Controller

Abstract Background: A medically induced coma is an anesthetic state of profound brain inactivation created to treat status epilepticus and to provide cerebral protection after traumatic brain injuries. The authors hypothesized that a closed-loop anesthetic delivery system could automatically and precisely control the electroencephalogram state of burst suppression and efficiently maintain a medically induced coma. Methods: In six rats, the authors implemented a closed-loop anesthetic delivery system for propofol consisting of: a computer-controlled pump infusion, a two-compartment pharmacokinetics model defining propofol’s electroencephalogram effects, the burst-suppression probability algorithm to compute in real time from the electroencephalogram the brain’s burst-suppression state, an online parameter-estimation procedure and a proportional-integral controller. In the control experiment each rat was randomly assigned to one of the six burst-suppression probability target trajectories constructed by permuting the burst-suppression probability levels of 0.4, 0.65, and 0.9 with linear transitions between levels. Results: In each animal the controller maintained approximately 60 min of tight, real-time control of burst suppression by tracking each burst-suppression probability target level for 15 min and two between-level transitions for 5–10 min. The posterior probability that the closed-loop anesthetic delivery system was reliable across all levels was 0.94 (95% CI, 0.77–1.00; n = 18) and that the system was accurate across all levels was 1.00 (95% CI, 0.84–1.00; n = 18). Conclusion: The findings of this study establish the feasibility of using a closed-loop anesthetic delivery systems to achieve in real time reliable and accurate control of burst suppression in rodents and suggest a paradigm to precisely control medically induced coma in patients.

Evaluation of a Low-Cost Microcontroller for Real-Time Control Education and Prototyping

2014 ◽  
Author(s):  
Ryan W. Krauss
Keyword(s):  
Feedback Control ◽  
Real Time ◽  
Closed Loop ◽  
Low Cost ◽  
Serial Communication ◽  
Real Time Control ◽  
Time Control ◽  
Active User ◽  
Bode Plots ◽  
Control Education

Arduino microcontrollers are popular, low-cost, easy-to-program, and have an active user community. This paper seeks to quantitatively assess whether or not Arduinos are a good fit for real-time feedback control experiments and controls education. Bode plots and serial echo tests are used to assess the use of Arduinos in two scenarios: a prototyping mode that involves bidirectional real-time serial communication with a PC and a hybrid mode that streams data in real-time over serial. The closed-loop performance with the Arduino is comparable to that of another more complicated and more expensive microcontroller for the plant considered. Some practical tips on using an Arduino for real-time feedback control are also given.

Is Deterministic Real Time Control Always Necessary? A Time Scales Perspective

2014 ◽  
Author(s):  
Dylan Poulsen ◽  
Ian Gravagne ◽  
John M. Davis
Keyword(s):  
Feedback Control ◽  
Real Time ◽  
Linear Systems ◽  
Time Scales ◽  
Closed Loop ◽  
Control Design ◽  
Real Time Control ◽  
Time Control ◽  
Real Time Computing ◽  
Sampling Times

Practitioners of feedback control design often must spend a great deal of time and effort dealing with the complexities of deterministic, or “real time” computing. In this paper, we argue that if certain conditions are met, stable feedback control is possible under non-deterministic conditions. In particular, certain classes of linear systems may be uniformly exponentially stabilized by placing the closed-loop poles within an “osculating circle” if the statistics of the controller’s sampling times are known.

Finite Element Analyses of Real-Time Stability Control in Sheet Forming Processes

1992 ◽  
Vol 114 (2) ◽  
pp. 180-188 ◽  
Author(s):  
H. B. Sim ◽  
M. C. Boyce
Keyword(s):  
Finite Element ◽  
Real Time ◽  
Deformation Process ◽  
Closed Loop ◽  
Real Time Control ◽  
Forming Process ◽  
Time Control ◽  
Control Schemes ◽  
Loop Feedback ◽  
Closed Loop Feedback

Sheet metal forming processes involve the plastic deformation of a sheet of material into a desired shape. In practice, the uncontrolled variation of boundary and material conditions have made the continual reproducibility of a sheet forming process a very difficult operation. Recently, real-time control schemes based on simplified models of “average” in-process stresses and/or strains have provided a repeatability of end product quality in terms of final shape, failure modes, and/or material state. The success of these control schemes have warranted a more detailed investigation into the complete physics of the deformation process. This study takes one such operation, the axisymmetric cup-forming process, and conducts an off-line detailed analysis using the finite element method in order to obtain information on the state of the material during the deformation process. In our analysis, actual closed-loop feedback control laws which have previously been applied in experiments have been numerically simulated with a novel method of modifying the boundary conditions based on current conditions. This has lead to further understanding of the role of the control law in optimizing draw failure height. Our further investigation and analysis directly incorporates the predicted localized nature of failure of this process into the feedback loop and has lead to the construction of an improved control algorithm which has the potential of dramatically increasing the failure height and which can be used in on-line control of the process. The study clearly demonstrates the utility and power of using off-line detailed analyses which incorporate closed-loop feedback laws to obtain a better understanding of the physics of the deformations which occur during processing, and thereby greatly improve upon the algorithms which are used for real time control of forming or other processing.

Optical mapping system with real-time control capability

2007 ◽  
Vol 293 (4) ◽  
pp. H2605-H2611 ◽  
Author(s):  
Shahriar Iravanian ◽  
David J. Christini
Keyword(s):  
Real Time ◽  
Cardiac Electrophysiology ◽  
Closed Loop ◽  
Optical Mapping ◽  
Cardiac Activity ◽  
Real Time Control ◽  
Optical Signals ◽  
Time Control ◽  
Time Operation ◽  
Mapping Techniques

Real-time, closed-loop intervention is an emerging experiment-control method that promises to provide invaluable new insight into cardiac electrophysiology. One example is the investigation of closed-loop feedback control of cardiac activity (e.g., alternans) as a possible method of preventing arrhythmia onset. To date, such methods have been investigated only in vitro using microelectrode systems, which are hindered by poor spatial resolution and are not well suited for atrial or ventricular tissue preparations. We have developed a system that uses optical mapping techniques and an electrical stimulator as the sensory and effector arms, respectively, of a closed-loop, real-time control system. The system consists of a 2,048 × 1 pixel line-scan charge-coupled device camera that records optical signals from the tissue. Custom-image processing and control software, which is implemented on top of a hard real-time operation system (RTAI Linux), process the data and make control decisions with a deterministic delay of <1 ms. The system is tested in two ways: 1) it is used to control, in real time, simulated optical signals of electrical alternans; and 2) it uses precisely timed, feedback-controlled initiation of antitachycardia pacing to terminate reentrant arrhythmias in an arterially perfused swine right ventricle stained with voltage-sensitive fluorescent dye 4{β-[2-(di- n-butylamino)-6-napathy]vinyl}pyridinium (di-4-ANEPPS). Thus real-time control of cardiac activity using optical mapping techniques is feasible. Such a system is attractive because it offers greater measurement resolution than the electrode-based systems with which real-time control has been used previously.

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