Nonlinear Stability Region Determination of Pilot-Aircraft Closed-Loop Based on Differential Manifold Theory

2021 ◽  
pp. 53-66
Author(s):  
Zehong Dong ◽  
Yinghui Li ◽  
Wuji Zheng ◽  
Chi Zhou ◽  
Haojun Xu ◽  
...  
Keyword(s):  
Nonlinear Stability ◽  
Stability Region ◽  
Closed Loop ◽  
Differential Manifold ◽  
Manifold Theory

scholarly journals Delay-Dependent Anti-Windup Loops for Enlarging the Stability Region of Time Delay Systems With Saturating Inputs

2003 ◽  
Vol 125 (2) ◽  
pp. 265-267 ◽  
Author(s):  
S. Tarbouriech ◽  
J. M. Gomes da Silva, ◽  
G. Garcia
Keyword(s):  
Stability Region ◽  
Closed Loop ◽  
Input Saturation ◽  
Delay Systems ◽  
Time Delay Systems ◽  
Closed Loop System ◽  
Regions Of Stability ◽  
The Stability ◽  
Delay Dependent

This paper addresses the problem of the determination of regions of stability for linear systems with delayed inputs and subject to input saturation through anti-windup strategies. Differently of the most anti-windup techniques, where the design of the anti-windup loop is introduced with the objective of minimizing the performance degradation, we are particularly interested in the synthesis of anti-windup gains in order to guarantee the stability of the closed-loop system for regions of admissible initial states as large as possible. With this aim, due to the presence of delay in the input we propose delay dependent results.

Interpreting Open- and Closed-Loop Transfer Relations Between Cardiorespiratory Parameters: Lessons Learned from a Computer Model of Beat-to-Beat Cardiovascular Regulation

1997 ◽  
Vol 36 (04/05) ◽  
pp. 237-240
Author(s):  
P. Hammer ◽  
D. Litvack ◽  
J. P. Saul
Keyword(s):  
Computer Model ◽  
Closed Loop ◽  
Computer Models ◽  
Cardiovascular Regulation ◽  
Cardiovascular Control ◽  
Lessons Learned ◽  
Multiple Systems ◽  
Response Characteristics ◽  
Similarities And Differences

Abstract:A computer model of cardiovascular control has been developed based on the response characteristics of cardiovascular control components derived from experiments in animals and humans. Results from the model were compared to those obtained experimentally in humans, and the similarities and differences were used to identify both the strengths and inadequacies of the concepts used to form the model. Findings were confirmatory of some concepts but contrary to some which are firmly held in the literature, indicating that understanding the complexity of cardiovascular control probably requires a combination of experiments and computer models which integrate multiple systems and allow for determination of sufficiency and necessity.

Nonlinear control for modular multilevel converters with enhanced stability region and arbitrary closed loop dynamics

2021 ◽  
Vol 126 ◽  
pp. 106590
Author(s):  
Guacira Costa de Oliveira ◽  
Gilney Damm ◽  
Renato Machado Monaro ◽  
Luís F.N. Lourenço ◽  
Miguel Jimenez Carrizosa ◽  
...  
Keyword(s):  
Nonlinear Control ◽  
Stability Region ◽  
Closed Loop ◽  
Multilevel Converters ◽  
Loop Dynamics ◽  
Modular Multilevel Converters ◽  
Enhanced Stability

In vitro evaluation of delays in the adjustment of the fraction of inspired oxygen during CPAP: effect of flow and volume

2020 ◽  
pp. fetalneonatal-2020-319058
Author(s):  
Christoph E. Schwarz ◽  
Gordon Lightbody ◽  
Ingo Müller-Hansen ◽  
Jörg Arand ◽  
Christian F. Poets ◽  
...  
Keyword(s):  
Gas Flow ◽  
Closed Loop ◽  
Volume Flow ◽  
Target Range ◽  
Equilibration Time ◽  
Ventilator Circuit ◽  
Fraction Of Inspired Oxygen ◽  
Inspired Oxygen

BackgroundAdjusting the fraction of inspired oxygen (FiO2) delivered to preterm infants to keep their oxygen saturation within target range remains challenging. Closed-loop automated FiO2 control increases the time infants spend within the assigned target range. The delay with which FiO2 adjustments at the ventilator result in a change in the inspired gas limits the performance of both manual and automated controls.ObjectiveTo evaluate the equilibration time (Teq) between FiO2 adjustments and changes in FiO2 reaching the patient.MethodsIn vitro determination of the delay in FiO2 adjustments at the ventilator at 5 and 8 L/min of gas flow and two different humidifier/ventilator circuit volumes (840 and 432 mL).ResultsTeq values were 31, 23, 20 and 17 s for the volume–flow combinations 840 mL+5 L/min, 840 mL+8 L/min, 432 mL+5 L/min and 432 mL+8 L/min, respectively.ConclusionThe identified delay seems clinically relevant and should be taken into account during manual and automatic control of FiO2.

Application of Self-Excited Machine-Tool Chatter Theory: Contribution to Machine-Tool Chatter Research—4

1965 ◽  
Vol 87 (4) ◽  
pp. 471-479 ◽  
Author(s):  
J. R. Lemon ◽  
P. C. Ackermann
Keyword(s):  
Machine Tool ◽  
Stability Region ◽  
High Stability ◽  
Closed Loop ◽  
Measured Data ◽  
Cutting Conditions ◽  
Machine Tool Chatter ◽  
The Subject ◽  
Cutting Speeds ◽  
Tool Chatter

This paper is one of a series of four being presented simultaneously on the subject of self-excited machine-tool chatter. It deals primarily with the applications of the closed-loop chatter theory to several actual machine-tool systems. In all cases the predicted chatter performance is compared with measured data and the correlation discussed. The predicted and measured onset of chatter compare reasonably well, in each example, when the complexities of the test setups are considered. The most serious discrepancy between experiments and the simplified chatter theory is the high-stability region at low cutting speeds. Dynamic specifications to assure the chatter-free performance of a machine tool for a given set of cutting conditions are discussed. The difficulties in arriving at such specifications are also pointed out.

An L1 adaptive closed-loop guidance law for an orbital injection problem

2009 ◽  
Vol 223 (6) ◽  
pp. 753-761 ◽  
Author(s):  
J Roshanian ◽  
M Zareh ◽  
H H Afshari ◽  
M Rezaei
Keyword(s):  
Closed Loop ◽  
Adaptive Strategy ◽  
Analytical Form ◽  
Open Loop ◽  
Control Input ◽  
Guidance Law ◽  
Non Linear ◽  
Non Linear System ◽  
Orbital Injection

The current paper presents the determination of a closed-loop guidance law for an orbital injection problem using two different approaches and, considering the existing time-optimal open-loop trajectory as the nominal solution, compares the advantages of the two proposed strategies. In the first method, named neighbouring optimal control (NOC), the perturbation feedback method is utilized to determine the closed-loop trajectory in an analytical form for the non-linear system. This law, which produces feedback gains, is in general a function of small perturbations appearing in the states and constraints separately. The second method uses an L1 adaptive strategy in determination of the non-linear closed-loop guidance law. The main advantages of this method include characteristics such as improvement of asymptotic tracking, guaranteed time-delay margin, and smooth control input. The accuracy of the two methods is compared by introducing a high-frequency sinusoidal noise. The simulation results indicate that the L1 adaptive strategy has a better performance than the NOC method to track the nominal trajectory when the noise amplitude is increased. On the other hand, the main advantage of the NOC method is its ability to solve a non-linear, two-point, boundary-value problem in the minimum time.

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