Nonlinear adaptive guidance considering target uncertainties and control loop dynamics

2001 ◽  
Author(s):  
Jin Young Choi ◽  
DongKyoung Chwa ◽  
Heum-Pil Cho
Keyword(s):  
Control Loop ◽  
Loop Dynamics ◽  
Adaptive Guidance ◽  
And Control

Optimizing anaerobic co-digestion plants: MIR online instrumentation and dynamic real-time substrate feed optimization

2015 ◽  
Vol 63 (7) ◽  
Author(s):  
Daniel Gaida ◽  
Christian Wolf ◽  
Robin Eccleston ◽  
Michael Bongards
Keyword(s):  
Predictive Control ◽  
Closed Loop ◽  
Closed Loop Control ◽  
Control Loop ◽  
Loop Control ◽  
Plant Operation ◽  
Novel Approaches ◽  
The One ◽  
Middle Infrared ◽  
And Control

AbstractClosed-loop control of the substrate feed as well as the application of online instrumentation are important to achieve optimal biogas plant operation. Therefore, this paper presents two novel approaches for online instrumentation and control to achieve optimal AD plant operation based on middle-infrared spectroscopy on the one hand and nonlinear model predictive control on the other hand. At present, research into both techniques is being performed separately, with the intention that in the future the spectroscopic measurements will be integrated into the control loop.

Aeroelastic Vehicle Sensor Placement for Feedback Control Applications Using Gain Stability

2000 ◽  
Author(s):  
Abdul G. Al-Shehabi ◽  
Brett Newman
Keyword(s):  
Flight Control ◽  
Optimization Method ◽  
Stability Criteria ◽  
Control Loop ◽  
Aircraft Structure ◽  
Design Constraints ◽  
Optimal Approach ◽  
And Control ◽  
Vehicle Sensor ◽  
Structural Mode

Abstract Optimal positions for aeroelastic vehicle feedback sensors, which meet design constraints and control requirements, are difficult to determine. This paper introduces a systematic and optimal approach for choosing sensor locations based on gain stability criteria. A steepest descent optimization method with constraints is used to minimize such objective criteria, which are based on the dipole magnitudes for each aeroelastic mode appearing in a traditional Evans diagram for a scalar control loop. Each dipole magnitude term is multiplied by a weight parameter. Rigid-body augmentation characteristics are implicitly accounted for in the type of input-output pairs utilized and in predefined loop compensation structure. Constraints enforcing minimum phase zeros in the transfer function are also considered. A flexible aircraft structure is used as an example to demonstrate this procedure. Results indicate flight control and structural mode control characteristics can be effectively balanced.

Absolute Stability Analysis Using the Liénard Equation: A Study Derived From Control of Fuel Cell Ultracapacitor Hybrids

2016 ◽  
Vol 138 (3) ◽  
Author(s):  
William Nowak ◽  
Daniel Geiyer ◽  
Tuhin Das
Keyword(s):  
Closed Loop ◽  
Operating Mode ◽  
Liénard Equation ◽  
Nonlinear Characteristics ◽  
Load Following ◽  
Systems And Control ◽  
Loop Dynamics ◽  
Variable Power ◽  
Lienard Equation ◽  
And Control

Load-following in solid oxide fuel cells (SOFCs), hybridized with an ultracapacitor for energy storage, refers to an operating mode where the fuel cell's generated power follows the variable power demand, delivering the total demanded power at steady-state. Implementing this operating mode presents a rich set of problems in dynamical systems and control. This paper focuses on state-of-charge (SOC) control of the ultracapacitor during load-following, under transient constraints, and in the presence of an unknown nonlinearity. The problem is generalized to stabilization of a plant containing a cascaded connection of a driver and a driven dynamics, where the former is nonlinear and largely unknown. Closed-loop stability of the system is studied as a Lur'e problem and via energy-based Lyapunov equations, but both impose conservative conditions on the nonlinearity. An alternate approach is developed, where the closed-loop dynamics are formulated as a class of Liénard equations. The corresponding analysis, which is based on the nonlinear characteristics of the Liénard equation, yields more definitive and less conservative stability criteria. Additional conditions that lead to limit cycles are also derived, and a bifurcation pattern is revealed. The generality of the proposed approach indicates applicability to a variety of nonlinear systems.

Faulty measurement substitution and control reconfiguration by using a multivariate flow control loop

2014 ◽  
Vol 53 (2) ◽  
pp. 568-577
Author(s):  
Sergio R.P. Perillo ◽  
Belle R. Upadhyaya ◽  
J. Wesley Hines
Keyword(s):  
Flow Control ◽  
Control Loop ◽  
Control Reconfiguration ◽  
And Control

How to design externally positive feedback loops – an open problem of control theory

2020 ◽  
Vol 68 (5) ◽  
pp. 301-311
Author(s):  
Alexander Schwab ◽  
Jan Lunze
Keyword(s):  
Open Problem ◽  
Closed Loop ◽  
Design Procedure ◽  
Positive Control ◽  
Feedback Loops ◽  
Positive Systems ◽  
Control Loop ◽  
Output Variable ◽  
Control Loops ◽  
Loop Dynamics

AbstractThis paper addresses the properties of externally positive systems and summarises existing conditions and design approaches that achieve externally positive closed-loop dynamics. The output variable of such systems is always nonnegative for any nonnegative input which is a very useful property in various control tasks. This paper investigates the problem of rendering control loops externally positive by an appropriate choice of a feedback. It shows that there is currently no general design procedure for that purpose and the question of when such a controller exists has not been clarified yet. It is also shown that there are plants for which there is no controller that leads to an externally positive control loop.

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