Dynamic Nonlinear Feedback Control Applied to Improve Butanol Production by Clostridium acetobutylicum

2017 ◽  
Vol 15 (6) ◽  
Author(s):  
H. I Velázquez-Sánchez ◽  
G. Lara-Cisneros ◽  
R. Femat ◽  
R. Aguilar-López
Keyword(s):  
Clostridium Acetobutylicum ◽  
Numerical Experiments ◽  
Closed Loop ◽  
Open Loop ◽  
Feedback Signal ◽  
Butanol Production ◽  
Nonlinear Feedback ◽  
Operational Conditions ◽  
Continuous Bioreactor ◽  
Control Scheme

Abstract The goal of this work is to present a closed-loop operational strategy in order to improve the butanol production in an anaerobic continuous bioreactor for the called Acetone-Butanol-Ethanol (ABE) process. The proposed control scheme considers a class of feedback signal which includes a nonlinear bounded function of the regulation error. The control scheme is applied to a phenomenological unstructured kinetic model obtained from an experimental and metabolic study of butanol production by Clostridium acetobutylicum, which allows the proposed structure to predict several operational conditions from batch and continuous regimes. Numerical experiments using the proposed model considering continuous operation were performed in order to find a feasible operating region for maximum butanol production at open-loop regime. The proposed methodology is applied to regulate the product concentration, manipulating the dilution rate to lead to a higher butanol productivity. The closed-loop behaviour of the bioreactor is analysed, finding that the proposed controller minimizes the response time of the system and allows it to achieve a productivity gain of 55 % over open-loop operation. Further numerical experiments show the satisfactory closed-loop performance of the proposed methodology in comparison with a PI controller.

scholarly journals Controlling continuous bioreactor via nonlinear feedback: modelling and simulations approach

2016 ◽  
Vol 64 (1) ◽  
pp. 235-241 ◽  
Author(s):  
R. Aguilar-López ◽  
I. Neria-González
Keyword(s):  
Numerical Experiments ◽  
Closed Loop ◽  
Lyapunov Theory ◽  
Nonlinear Feedback ◽  
Input Flow ◽  
Nonlinear Controller ◽  
Stirred Tank Bioreactor ◽  
Sulfate Reducing ◽  
Continuous Bioreactor ◽  
Continuous Stirred Tank

Abstract The aim of this work is to present a class of nonlinear controller with an exponential-type feedback in order to regulate the sulfate mass concentration via the input flow in a continuous stirred tank bioreactor of an anaerobic sulfate-reducing process. The corresponding kinetic terms in the bioreactor’s modeling are modeled by unstructured modeling approach, which was experimentally corroborated. A sketch of proof of the closed-loop stability of the considered system is done under the framework of Lyapunov theory. Numerical experiments are conducted to show the performance of the proposed methodology in comparison with a well-tuned sigmoid controller.

scholarly journals Automatic locking of a parametrically resonating, base-excited, nonlinear beam

2021 ◽  
Author(s):  
Nir Ben Shaya ◽  
Izhak Bucher ◽  
Amit Dolev
Keyword(s):  
Relative Phase ◽  
Closed Loop ◽  
Dynamical Behavior ◽  
Open Loop ◽  
Vibration Modes ◽  
Nonlinear Structure ◽  
Nonlinear Beam ◽  
Loop Control ◽  
Control Scheme ◽  
Slender Beams

AbstractDescribed is a closed-loop control scheme capable of stabilizing a parametrically excited nonlinear structure in several vibration modes. By setting the relative phase between the spatially filtered response and the excitation, the open-loop unstable solution branches are stabilized under a 2:1 parametric excitation of a chosen mode of vibration. For a given phase, the closed-loop automatically locks on a limit cycle, through an Autoresonance scheme, at any desired point on the solution branches. Axially driven slender beams and nanowires develop large transverse vibration under suitable amplitudes and frequency base-excitation that are sensitive to small potential coupled field. To utilize such a structure as a sensor, stable and robust operation are made possible by the control scheme. In addition, an optimal operating point with large sensitivity to the sensed potential field can be set using phase as a tunable parameter. Detailed analysis of the dynamical behavior, experimental verifications, and demonstrations sheds light on some features of the system dynamics.

scholarly journals Open-closed Iterative Learning Control Algorithm for Exoskeleton Rehabilitation Purposes

2019 ◽  
Vol 292 ◽  
pp. 01010
Author(s):  
Mihailo Lazarević ◽  
Nikola Živković ◽  
Darko Radojević
Keyword(s):  
Iterative Learning Control ◽  
Control Algorithm ◽  
Closed Loop ◽  
Learning Control ◽  
Open Loop ◽  
Iterative Learning ◽  
Control Law ◽  
Exact Linearization ◽  
Outer Loop ◽  
Control Scheme

The paper designs an appropriate iterative learning control (ILC) algorithm based on the trajectory characteristics of upper exosk el eton robotic system. The procedure of mathematical modelling of an exoskeleton system for rehabilitation is given and synthesis of a control law with two loops. First (inner) loop represents exact linearization of a given system, and the second (outer) loop is synthesis of a iterative learning control law which consists of two loops, open and closed loop. In open loop ILC sgnPDD2 is applied, while in feedback classical PD control law is used. Finally, a simulation example is presented to illustrate the feasibility and effectiveness of the proposed advanced open-closed iterative learning control scheme.

scholarly journals Design of Ship Course-Keeping Autopilot using a Sine Function-Based Nonlinear Feedback Technique

2015 ◽  
Vol 69 (2) ◽  
pp. 246-256 ◽  
Author(s):  
Xian-ku Zhang ◽  
Guo-qing Zhang
Keyword(s):  
Control Strategies ◽  
Feedback Signal ◽  
Sine Function ◽  
Nonlinear Feedback ◽  
Control Effect ◽  
Control Error ◽  
Closed Loop Systems ◽  
Automatic Navigation ◽  
Feedback Scheme ◽  
Control Scheme

Course keeping for ships is the core of automatic navigation in sea transportation. Much work has concentrated on developing novel control strategies for closed loop systems. We have turned our attention the other way to improve the control performance of marine autopilots in this work by “modulating” the control error using a sine function while the construction of the controller is not changed. The nonlinear feedback signal thus obtained is sent to the controller to replace the control error itself, which used to be the deviation between the output response and the reference input of the system. Such a control scheme is called “nonlinear feedback control” hereafter. Theoretical analysis by using a describing function and robust control theory shows that the same control quality is guaranteed with minor control actions for the nonlinear feedback scheme. Simulation experiments were carried out for the ship Yulong of Dalian Maritime University. It is shown that the method postulated in this paper has advantages of safety and energy saving in navigation; the maximum initial rudder angle is reduced by 31·2% with satisfactory control effect.

scholarly journals Open Loop and Closed Loop Power Control Analysis on LTE

2018 ◽  
Vol 10 (4) ◽  
pp. 195
Author(s):  
Norma Amalia ◽  
Eka Setia Nugraha ◽  
Muntaqo Alfin Amanaf
Keyword(s):  
Power Control ◽  
Multiple Access ◽  
Closed Loop ◽  
Open Loop ◽  
Control Analysis ◽  
Transmit Power ◽  
Control Scheme ◽  
Loop Condition ◽  
High Level ◽  
Loop Scheme

LTE downlink is using Orthogonal Frequency Division Multiple Access (OFDMA) multiple access system which have high invulnerability from multipath problem. One of the weakness of OFDM system is the high level from Peak to Average Power Ratio (PAPR) that was required higher level transmit power for maintaining the Bit Error Rate (BER) requirement. Using uplink scheme with Single Carrier FDMA (SC-FDMA) which is OFDMA modification, will be offered better level of PAPR than its conventional OFDM. The main problem of using OFDMA is the high level of PAPR, while using SC-FDMA the problem is intra-cell interference. Intra-cell or inter-cell interference is the common problem that can reduce the LTE performance. Minimizing received power for each users (UE) which is still at acceptable tolerance parameter, can be used for reducing the interference problem to another UE. Power control is the appropriate solution for minimizing the interference level. In this paper will be analyzed the power control using open loop and closed loop scheme at LTE network. The simulation result show that without power control schemes, the transmit power of UE is 23 dBm. While, after applying power control scheme, the transmit power is 18.8 dBm at ?=0.4 of open loop condition and 9.05 dBm at closed loop condition. Using this transmit power value as the UE power can improve the SINR performance. The SINR average value without power control scheme is only 20.38 dB which is lower than using open loop scheme is achieved 22.44 dB and 24.02 dB at closed loop scheme.

Computer Control of on-off Electrothermal Processes

1973 ◽  
Vol 6 (4) ◽  
pp. 161-166
Author(s):  
J. L. Murgatroyd ◽  
D. Goodman
Keyword(s):  
Closed Loop ◽  
Computer Control ◽  
Open Loop ◽  
Performance Characteristics ◽  
Temperature Drift ◽  
Switching Sequence ◽  
Control Scheme ◽  
Electrothermal Process

A control scheme is described for improving the performance characteristics of an on/off electrothermal process by means of a model of the process. A /though the process itself operates on open loop, the switching sequence is closely controlled by the operation of a closed loop incorporating the model and the process controller. The temperature drift may be virtually eliminated by representing the model electronically. The scheme proves useful when the process has a large inherent delay or when it is not convenient to derive transduced signals from the output temperature for the purpose of control.

Measurement Errors in Closed-Loop Frequency Response Estimates

1980 ◽  
Vol 102 (1) ◽  
pp. 13-20
Author(s):  
P. W. Davall ◽  
P. N. Nikiforuk
Keyword(s):  
Frequency Response ◽  
Measurement Errors ◽  
Closed Loop ◽  
Power Spectra ◽  
Open Loop ◽  
Feedback Signal ◽  
Single Input Single Output ◽  
Closed Loop Systems ◽  
Single Output ◽  
Single Input

The sampling distributions associated with frequency response estimates of single input, single output closed-loop systems are derived for the case where both the output and feedback signal measurements are subject to added noise. This work is an extension of that done by Goodman [1-3] and Akaike [4, 5] on open-loop systems. Conditions for response estimate bias are investigated and approximate distributions for the power spectra estimates of the added noise terms are derived.

Towards the Design of a Fully Actuated Invertible Flying Quadrotor MAV

2013 ◽  
Author(s):  
Andreas Gelardos ◽  
David J. Cappelleri
Keyword(s):  
Closed Loop ◽  
Mechanical Design ◽  
Low Cost ◽  
Open Loop ◽  
Transmission Mechanism ◽  
Micro Aerial Vehicle ◽  
Loop Control ◽  
Minimal Weight ◽  
Control Scheme ◽  
Aerial Vehicle

In this paper, we present the transmission mechanism design for a fully actuated Invertible Flying Quadrotor (IFQ) micro aerial vehicle (MAV). At the heart of the mechanism is a gearbox which couples and counter rotates two pairs of shafts that have the quadrotor propellers mounted at their ends. This mechanism will allow for the IFQ to follow aggressive maneuvers, hover at an arbitrary attitude, and have sustained inverted flight capabilities. The paper presents the mechanical design challenges and solutions in designing such a transmission mechanism with minimal weight along with low cost and easy manufacturing. The dynamic model for the IFQ MAV is presented along with an optimal open loop trajectory control scheme and related simulations. An approach for a full closed loop control scheme is also discussed. A prototype of the mechanism has been manufactured and functionally tested. The entire transmission mechanism was able to be prototyped with a weight of only approximately 100 grams.

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