Enhancement of dynamic performance of wave energy converter by introducing a flow control

2022 ◽  
pp. 014233122110699
Author(s):  
Dazhou Geng ◽  
Qijuan Chen ◽  
Yang Zheng ◽  
Xuhui Yue ◽  
Donglin Yan
Keyword(s):  
Flow Control ◽  
Transient Process ◽  
Closed Loop ◽  
Control Method ◽  
Control Valve ◽  
Open Loop ◽  
Closed Loop Control ◽  
Flow Control Valve ◽  
Open Loop Control ◽  
Loop Control

The stabilization of power take-off (PTO) is imperative especially under circumstances of fluctuating input wave energy. In this paper, a flow control valve is introduced to optimize the transient process of the hydraulic PTO, which can contribute to a quicker adjustment and a stronger stability. Under variations of input power and load torque in transient process, an open-loop control method and a closed-loop control method are proposed as the opening law of the above valve, and the hydraulic motor speed, the pressure at the accumulator inlet and the generated power are chosen as indicators to examine the regulation performance. Then, the synergic effect of the flow control valve and the accumulator in the transient process is discussed. The effectiveness of the two presented control methods on the fluctuation suppression is respectively tested and compared in both regular wave and irregular wave situations via simulation. To validate the practical effectiveness of the proposed methods, field experiments are conducted. The results demonstrate that the open-loop control can only improve the damping ability of the hydraulic PTO in the speed raising stage, while the closed-loop control can improve the stability both in the speed raising stage and in the load increasing stage.

ADAPTIVE OPEN-PLUS-CLOSED-LOOP CONTROL METHOD OF MODIFIED FUNCTION PROJECTIVE SYNCHRONIZATION IN COMPLEX NETWORKS

2011 ◽  
Vol 22 (12) ◽  
pp. 1393-1407 ◽  
Author(s):  
HONGYUE DU
Keyword(s):  
Closed Loop ◽  
Control Method ◽  
Open Loop ◽  
Projective Synchronization ◽  
Closed Loop Control ◽  
Loop Control ◽  
Function Projective Synchronization ◽  
Advantages And Disadvantages ◽  
Modified Function Projective Synchronization ◽  
Loop Feedback

This paper investigates the modified function projective synchronization (MFPS) in drive-response dynamical networks (DRDNs) with different nodes, which means that systems in nodes are strictly different. An adaptive open-plus-closed-loop (AOPCL) control method is proposed, which is a practically realizable method and can overcome the model mismatched to achieve synchronization. It is well known that each of the close-loop and open-loop control method possesses some advantages and disadvantages. By combining their advantages, the open-plus-closed-loop (OPCL) control method was proposed by Jackson and Grosu. For arbitrary nonlinear dynamic systems, dx/dt = F(x,t), Jackson and Grosu proved that there exists solutions, x(t), in the neighborhood of any arbitrary goal dynamics g(t) that are entrained to g(t), through the use of an additive controlling action, K(g,x,t) = H(dg/dt,g) + C(g,t)(g(t) - x), which is the sum of the open-loop action, H(dg/dt,g), and a suitable linear closed-loop (feedback) action C(g,t). This method is a practically realizable method and robust to limited accuracy of data and effects of noise. The AOPCL control method preserve the merits of OPCL control method and its closed loop control part can be automatically adapted to suitable constants. Considering time-delays are always unavoidably in the practical situations, MFPS in DRDNs with time-varying coupling delayed is further investigated by the proposed method. Corresponding numerical simulations are performed to verify and illustrate the analytical results.

A New Close-Loop Control Method for an Inspection Robot Equipped with Electropermanent-Magnets

2016 ◽  
Vol 28 (2) ◽  
pp. 185-193 ◽  
Author(s):  
Pakpoom Kriengkomol ◽  
◽  
Kazuto Kamiyama ◽  
Masaru Kojima ◽  
Mitsuhiro Horade ◽  
...  
Keyword(s):  
Closed Loop ◽  
Control Method ◽  
Steel Structures ◽  
Open Loop ◽  
Closed Loop Control ◽  
Loop Control ◽  
Inspection Robot ◽  
Industrial Age ◽  
Set Up ◽  
Close Loop Control

[abstFig src='/00280002/09.jpg' width=""300"" text='ASTERISK use our proposed method to walk' ]Since the industrial age began, increasing numbers of manufacturing plants have been set up to serve economic growth demand. More bridges were built simultaneously to connect cities and to make transportation more convenient. As these facilities have aged, regular maintenance has increased. The limb mechanism project we started almost 20 years ago was to deliver new types of inspection and maintenance to industrial fields. Our first prototype, a six-limb robot called Asterisk, included such capabilities as walking on ceilings, climbing and descending stairs and ladders, walking tightropes, and transversing rough terrain. Asterisk's latest version uses electromagnets to work in antigravity environments such as steel structures. Unfortunately, this presented a major danger, requiring that we replace electromagnets with electropermanent magnets (EPMs). Limitations on EPMs, however, required a new control strategy. We propose and compare three control methods -- open-loop control, closed-loop control using torque feedback, and closed-loop control using angle feedback -- in the sections that follow. Our objective is to determine the best control for inspection robots having electropermanent magnets but not using additional sensors.

scholarly journals Closed-Loop Artificial Pancreas Using Subcutaneous Glucose Sensing and Insulin Delivery and a Model Predictive Control Algorithm: The Virginia Experience

2009 ◽  
Vol 3 (5) ◽  
pp. 1031-1038 ◽  
Author(s):  
William L. Clarke ◽  
Stacey Anderson ◽  
Marc Breton ◽  
Stephen Patek ◽  
Laurissa Kashmer ◽  
...  
Keyword(s):  
Type 1 Diabetes ◽  
Predictive Control ◽  
Insulin Infusion ◽  
Closed Loop ◽  
Artificial Pancreas ◽  
Open Loop ◽  
Closed Loop Control ◽  
Open Loop Control ◽  
Loop Control

Background: Recent progress in the development of clinically accurate continuous glucose monitors (CGMs), automated continuous insulin infusion pumps, and control algorithms for calculating insulin doses from CGM data have enabled the development of prototypes of subcutaneous closed-loop systems for controlling blood glucose (BG) levels in type 1 diabetes. The use of a new personalized model predictive control (MPC) algorithm to determine insulin doses to achieve and maintain BG levels between 70 and 140 mg/dl overnight and to control postprandial BG levels is presented. Methods: Eight adults with type 1 diabetes were studied twice, once using their personal open-loop systems to control BG overnight and for 4 h following a standardized meal and once using a closed-loop system that utilizes the MPC algorithm to control BG overnight and for 4 h following a standardized meal. Average BG levels, percentage of time within BG target of 70–140 mg/dl, number of hypoglycemia episodes, and postprandial BG excursions during both study periods were compared. Results: With closed-loop control, once BG levels achieved the target range (70–140 mg/dl), they remained within that range throughout the night in seven of the eight subjects. One subject developed a BG level of 65 mg/dl, which was signaled by the CGM trend analysis, and the MPC algorithm directed the discontinuance of the insulin infusion. The number of overnight hypoglycemic events was significantly reduced ( p = .011) with closed-loop control. Postprandial BG excursions were similar during closed-loop and open-loop control Conclusion: Model predictive closed-loop control of BG levels can be achieved overnight and following a standardized breakfast meal. This “artificial pancreas” controls BG levels as effectively as patient-directed open-loop control following a morning meal but is significantly superior to open-loop control in preventing overnight hypoglycemia.

Research on the Control System of Ecological Architecture

2012 ◽  
Vol 174-177 ◽  
pp. 3196-3201
Author(s):  
Bo Xia
Keyword(s):  
Control System ◽  
Closed Loop ◽  
Open Loop ◽  
Closed Loop Control ◽  
Open Loop Control ◽  
Loop Control ◽  
Closed Loop Control System ◽  
Loop Control System ◽  
Ecological Architecture ◽  
Building Control System

This paper proceeds from the basic conceptions of systematology and cybernetics and researches ecological architecture from one new angle. The paper divides the building control system into the open-loop control system and closed-loop control system, and further researches their principles.

Experimental Study of Laser Interferometry Based Motion Tracking of a Flexure-Based Mechanism

2013 ◽  
pp. 165-178
Author(s):  
Umesh Bhagat ◽  
Bijan Shirinzadeh ◽  
Yanling Tian
Keyword(s):  
Experimental Study ◽  
Motion Tracking ◽  
Closed Loop ◽  
Position Control ◽  
Laser Interferometry ◽  
Open Loop ◽  
Closed Loop Control ◽  
Open Loop Control ◽  
Loop Control ◽  
Model Based

This paper presents an experimental study of laser interferometry-based closed-loop motion tracking for flexure-based four-bar micro/nano manipulator. To enhance the accuracy of micro/nano manipulation, laser interferometry-based motion tracking control is established with experimental facility. The authors present and discuss open-loop control, model-based closed-loop control, and robust motion tracking closed-loop control for flexure-based mechanism. A comparative error analysis for closed-loop control with capacitive position sensor and laser interferometry feedback is discussed and presented. Model-based closed-loop control shows improvement in position and motion tracking over open-loop control. Robust control demonstrates high precise and accurate motion tracking of flexure-based mechanism compared to the model-based control. With this experimental study, this paper offers evidence that the laser interferometry-based closed-loop control can minimize positioning and tracking errors during dynamic motion, hence realizing high precision motion tracking and accurate position control.

CLOSED-LOOP CONTROL OF QUADRICEPS/HAMSTRING ACTIVATION FOR FES-INDUCED STANDING-UP MOVEMENT OF PARAPLEGICS

2001 ◽  
Vol 05 (03) ◽  
pp. 173-184 ◽  
Author(s):  
Nan-Ying Yu ◽  
Jia-Jin Jason Chen ◽  
Ming Shiang Ju
Keyword(s):  
Control System ◽  
Closed Loop ◽  
Mechanical Energy ◽  
Open Loop ◽  
Knee Extensors ◽  
Joint Control ◽  
Closed Loop Control ◽  
Open Loop Control ◽  
Loop Control ◽  
Standing Up

Functional electrical stimulation (FES) standing system can enable the paraplegics to achieve the standing position for functional activities in daily living. FES standing system is usually applied by stimulating the knee extensor muscles. The hip joints are in hyperextension and the ankle joints remain free. Therefore, the knee joint control is the key point of the FES standing control system. Traditional open-loop control often induces high knee end-velocity (KEV) when the subject reaches the upright position. In this work, the reducing of KEV by closed-loop control was addressed. An on/off feedback control based on mechanical energy conservation was developed to control the knee extensors and flexors. The result was compared to the open loop controlled standing up in a mechanically simulative experiment. It is concluded that the on/off control strategy can reduce the KEV more efficiently when compared to the open-loop control. Proportional-integral-derivative (PID) position controlled standing up was also studied and compared with the on/off control system. The PID controller was found to be capable of reducing KEV to a level lower than that of the on/off control, whereas its instability for knee control was also found.

Experimental Study of Laser Interferometry Based Motion Tracking of a Flexure-Based Mechanism

2011 ◽  
Vol 1 (3) ◽  
pp. 31-45 ◽  
Author(s):  
Bijan Shirinzadeh ◽  
Umesh Bhagat ◽  
Yanling Tian
Keyword(s):  
Experimental Study ◽  
Motion Tracking ◽  
Closed Loop ◽  
Position Control ◽  
Laser Interferometry ◽  
Open Loop ◽  
Closed Loop Control ◽  
Open Loop Control ◽  
Loop Control ◽  
Model Based

This paper presents an experimental study of laser interferometry-based closed-loop motion tracking for flexure-based four-bar micro/nano manipulator. To enhance the accuracy of micro/nano manipulation, laser interferometry-based motion tracking control is established with experimental facility. The authors present and discuss open-loop control, model-based closed-loop control, and robust motion tracking closed-loop control for flexure-based mechanism. A comparative error analysis for closed-loop control with capacitive position sensor and laser interferometry feedback is discussed and presented. Model-based closed-loop control shows improvement in position and motion tracking over open-loop control. Robust control demonstrates high precise and accurate motion tracking of flexure-based mechanism compared to the model-based control. With this experimental study, this paper offers evidence that the laser interferometry-based closed-loop control can minimize positioning and tracking errors during dynamic motion, hence realizing high precision motion tracking and accurate position control.

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