Performance simulation of an adaptive optics system with liquid crystal corrector under closed-loop and open-loop control

2010 ◽  
Vol 283 (10) ◽  
pp. 2017-2019 ◽  
Author(s):  
Quanquan Mu ◽  
Zhaoliang Cao ◽  
Zenghui Peng ◽  
Yonggang Liu ◽  
Lifa Hu ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Adaptive Optics ◽  
Closed Loop ◽  
Open Loop ◽  
Open Loop Control ◽  
Performance Simulation ◽  
Loop Control ◽  
Adaptive Optics System

Modeling of a Hydraulic Elevator Driven by an Open-Loop Control

2009 ◽  
Author(s):  
Roberto Strada ◽  
Alberto Oldani
Keyword(s):  
Power Generation ◽  
Closed Loop ◽  
Open Loop ◽  
The Other ◽  
Open Loop Control ◽  
Proportional Valve ◽  
Loop Control ◽  
Complete Knowledge ◽  
Motion Time ◽  
Loop Control System

Electro-hydraulic elevators are widely used systems, especially in low level buildings, due to their very good ratio between power generation and dynamic response. Generally, the goal of an elevator system is just to reach the floor with a precision enough to be comfortable for the passengers, without the need to follow a specific law of motion; hence an open-loop control system could be enough. Otherwise such a kind of solution reduces the number of components, bringing down the costs of production. On the other hand a complete knowledge of the mechanical system’s behaviour is required. In this work we deal with the analysis of the behaviour of a commercial hydraulic elevator driven by an open loop control that monitors the downstream pressure of the proportional valve supplying the cylinder. At the end of the paper, a closed loop solution based on the pressure measurement and on the motion time is proposed.

Optimal Performance of Cylinder-by-Cylinder and Fuel Bank Controllers for a CIDI Engine

2009 ◽  
Author(s):  
Ming Fang ◽  
Shawn Midlam-Mohler ◽  
Rajaram Maringanti ◽  
Fabio Chiara ◽  
Marcello Canova
Keyword(s):  
Closed Loop ◽  
Open Loop ◽  
Optimal Performance ◽  
Combustion Control ◽  
Open Loop Control ◽  
Loop Control ◽  
Engine Model ◽  
Engine Combustion ◽  
Performance Gains ◽  
Near Future

At present, Diesel engine combustion in most production engines is controlled via open-loop control. Increasing pressure from tightening emissions standards and on-board diagnosis requirements has made closed-loop combustion a possibility for production engines in the near future. For new combustion concepts, such as Homogeneous Charge Compression Ignition and other low NOx regimes, the need for closed-loop combustion control is very strong. In this work, the applicability of closed-loop combustion control for controlling the variability between cylinders in conventional Diesel combustion is explored through the use of a high-fidelity engine model. The problem is formulated such that the optimal performance of two different closed-loop control concepts can be evaluated through optimization rather than via control design. It is found that, for the types of disturbances occurring in a non-faulty engine, that control of individual cylinders leads to small performance gains compared to fuel bank control.

Progress of liquid crystal adaptive optics for applications in ground-based telescopes

2020 ◽  
Vol 494 (3) ◽  
pp. 3536-3540
Author(s):  
Xingyun Zhang ◽  
Zhaoliang Cao ◽  
Quanquan Mu ◽  
Dayu Li ◽  
Zenghui Peng ◽  
...  
Keyword(s):  
Energy Efficiency ◽  
Liquid Crystal ◽  
Adaptive Optics ◽  
Low Cost ◽  
Response Speed ◽  
Open Loop ◽  
Loop Control ◽  
Compact Size ◽  
Control Scheme ◽  
Resolution Imaging

ABSTRACT Liquid crystal (LC) adaptive optics systems (AOS) can potentially be used in ground-based large aperture telescopes, because of their high spatial resolution, low cost and compact size. However, their disadvantages, such as low energy efficiency and slow response speed, still hinder their application. In this paper, we demonstrate solutions to these problems. With newly synthesized fast nematic LC material and using an overdriving technique, the response time of a LC wavefront corrector was reduced to 0.75 ms. Under an open-loop control scheme, a novel optical system was designed to improve the energy efficiency of LC AOS. With those problems resolved, a LC AOS was built for a 1.23-m telescope. This system has a disturbance rejection bandwidth of 80 Hz, and could fully use the energy of 400–900 nm wavebands. Observation results showed that the diffraction limit resolution imaging of the telescope could be obtained after correction, which indicates that the LC AOS is ready to be used in ground-based telescopes for visible waveband imaging.

Liquid Crystal Adaptive Optics System for Retinal Imaging Operated on Open-Loop and Double-Pulse Mode

2012 ◽  
Vol 32 (1) ◽  
pp. 0111002
Author(s):  
孔宁宁 Kong Ningning ◽  
李大禹 Li Dayu ◽  
夏明亮 Xia Mingliang ◽  
齐岳 Qi Yue ◽  
宣丽 Xuan Li
Keyword(s):  
Liquid Crystal ◽  
Adaptive Optics ◽  
Retinal Imaging ◽  
Pulse Mode ◽  
Open Loop ◽  
Double Pulse ◽  
Adaptive Optics System

scholarly journals Optimal energy-splitting method for an open-loop liquid crystal adaptive optics system

2012 ◽  
Vol 20 (17) ◽  
pp. 19331 ◽  
Author(s):  
Zhaoliang Cao ◽  
Quanquan Mu ◽  
Lifa Hu ◽  
Yonggang Liu ◽  
Zenghui Peng ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Adaptive Optics ◽  
Splitting Method ◽  
Open Loop ◽  
Energy Splitting ◽  
Optimal Energy ◽  
Adaptive Optics System

scholarly journals Closed-loop adaptive optics system with a single liquid crystal spatial light modulator

2014 ◽  
Vol 22 (14) ◽  
pp. 17216 ◽  
Author(s):  
Kainan Yao ◽  
Jianli Wang ◽  
Xinyue Liu ◽  
Wei Liu
Keyword(s):  
Liquid Crystal ◽  
Adaptive Optics ◽  
Spatial Light Modulator ◽  
Closed Loop ◽  
Light Modulator ◽  
Adaptive Optics System
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