A Novel Micro-Positioning Stage With Large-Stroke and Adjustable Stiffness

2021 ◽  
Author(s):  
Zhijun Yang ◽  
Bingyu Cai ◽  
Ruiqi Li ◽  
Hao Peng ◽  
Youdun Bai
Keyword(s):  
Large Deformation ◽  
Control Strategies ◽  
Operating Conditions ◽  
Flexure Hinge ◽  
Pid Algorithm ◽  
Wide Range ◽  
Non Linear ◽  
Micro Motion ◽  
Motion Stage ◽  
Application Requirements

Abstract The existing micro-motion stage based on flexure hinge can hardly meet the requirements of a high-precision stage with large stroke and variable operating conditions (especially variable frequency operation). In this paper, a flexible hinge micro-motion stage with adjustable stiffness is presented. A wide range of stiffness and frequency adjustments are realized by changing the length of the flexure hinge through the movement of the support. However, the change on the stiffness of the flexure hinge is non-linear when is in large deformation. It is difficult to use the traditional PID algorithm to control such nonlinear system without the complete mathematical model, and much more complicated control strategies are required to deal with the condition of large deformation of the flexure hinge. In this paper, the active disturbance rejection control (ADRC) strategy is adopted to solve the above non-linear control problem without relying on the complete system model. A novel model-compensated ADRC based on the dynamic characteristics is proposed to further improve the performance of the micro-motion stage. Experiments show that the ADRC with model compensation (MADRC) can achieve high positioning and tracking precision faster than the conventional ADRC. The presented micro-motion stage based on stiffness-adjustable flexure hinges and MADRC design is capable to meet the industrial application requirements of large stroke or variable working conditions.

scholarly journals Data–Driven Control Techniques for Renewable Energy Conversion Systems: Wind Turbine and Hydroelectric Plants

2019 ◽  
Author(s):  
Silvio Simani ◽  
Stefano Alvisi ◽  
Mauro Venturini
Keyword(s):  
Renewable Energy ◽  
Energy Conversion ◽  
Wind Turbine ◽  
Control Strategies ◽  
Operating Conditions ◽  
Renewable Energy Resources ◽  
Control Techniques ◽  
Wide Range ◽  
Energy Conversion Systems ◽  
Hydroelectric Plants

The interest on the use of renewable energy resources is increasing, especially towards wind and hydro powers, which should be efficiently converted into electric energy via suitable technology tools. To this aim, data--driven control techniques represent viable strategies that can be employed for this purpose, due to the features of these nonlinear dynamic processes working over a wide range of operating conditions, driven by stochastic inputs, excitations and disturbances. Some of the considered methods, such as fuzzy and adaptive self--tuning controllers, were already verified on wind turbine systems, and similar advantages may thus derive from their appropriate implementation and application to hydroelectric plants. These issues represent the key features of the work, which provides some guidelines on the design and the application of these control strategies to these energy conversion systems. The working conditions of these systems will be also taken into account in order to highlight the reliability and robustness characteristics of the developed control strategies, especially interesting for remote and relatively inaccessible location of many installations.

Optimum control of an automotive direct injection diesel engine for low exhaust emissions

2001 ◽  
Vol 215 (11) ◽  
pp. 1225-1236 ◽  
Author(s):  
M Capobianco
Keyword(s):  
Diesel Engine ◽  
Control Strategies ◽  
Direct Injection ◽  
Experimental Information ◽  
Operating Conditions ◽  
Pollutant Emissions ◽  
Control Variables ◽  
Wide Range ◽  
Di Diesel Engine ◽  
Definition Of

The paper presents the latest results of a wide investigation performed at the University of Genoa on the control of automotive direct injection (DI) diesel engines. A dedicated procedure was developed which enables analysis of the behaviour of engine operating parameters as a function of two control variables with a limited amount of experimental information and the definition of proper control strategies. A first application of the procedure is presented in the paper with reference to a typical turbocharged DI diesel engine for automotive applications. The exhaust gas recirculation (EGR) rate and the position of the turbocharger waste-gate regulating valve were assumed as control variables and the behaviour of the most important engine parameters was analysed in a wide range for 15 steady state operating conditions related to the European driving cycle. Particular attention was paid to the most significant pollutant emissions and to the exhaust boundary conditions for the application of a low temperature lean de-NOx catalyst. Two different control strategies were also developed by which the catalyst conversion efficiency and the NOx engine tail pipe emission were individually optimized, taking account of some operating limits for specific parameters.

Stick-Slip and Bit-Bounce Interaction in Oil-Well Drillstrings

2006 ◽  
Vol 128 (4) ◽  
pp. 268-274 ◽  
Author(s):  
Ahmet S. Yigit ◽  
Andreas P. Christoforou
Keyword(s):  
Control Strategies ◽  
Operating Conditions ◽  
Oil Well ◽  
Axial Motion ◽  
Stick Slip ◽  
Well Drilling ◽  
Wide Range ◽  
Equipment Failures ◽  
Drilling Operations ◽  
Major Factors

Drillstring vibrations and in particular stick-slip and bit-bounce are detrimental to oil-well drilling operations. Controlling these vibrations is essential because they may cause equipment failures and damage to the oil-well. A simple model that adequately captures the dynamics is used to simulate the effects of varying operating conditions on stick-slip and bit-bounce interactions. It is shown that the conditions at the bit/formation interface, such as bit speed and formation stiffness, are major factors in shaping the dynamic response. Due to the varying and uncertain nature of these conditions, simple operational guidelines or active rotary table control strategies are not sufficient to eliminate both stick-slip and bit-bounce. It is demonstrated that an additional active controller for the axial motion can be effective in suppressing both stick-slip and bit-bounce. It is anticipated that if the proposed approach is implemented, smooth drilling will be possible for a wide range of conditions.

scholarly journals Design and Simulation of the Control System for Inverter-fed Permanent Magnet Synchronous Motor Drive

2018 ◽  
Vol 12 (3) ◽  
pp. 958
Author(s):  
Ramana Pilla ◽  
Santukumari Killari ◽  
K.B.Madhu Sahu
Keyword(s):  
Control System ◽  
Permanent Magnet ◽  
Control Strategies ◽  
Permanent Magnet Synchronous Motor ◽  
Cost Effective ◽  
Synchronous Motor ◽  
Operating Conditions ◽  
Variable Speed ◽  
Linear Controller ◽  
Non Linear

<p>Development in the field of power electronics, cost effective DSP’s and microprocessors have opened a new era in the design and implement modern control strategies for variable speed drives.<strong> </strong>This paper presents the design of a control system which includes a non-linear controller and observer for inverter fed Permanent Magnet Synchronous Motor (PMSM) Drive. The entire design is carried out by designing of Speed Controller, Non-linear controller (NLC), State feedback controller (SFC), H<sub>∞</sub> controller as well as Non-linear full order observer (NFO). The proposed control scheme is extensively simulated under various conditions using MATLAB/Simulink, which shows better performance under all operating conditions for variable speed PMSM drive.</p>

scholarly journals Self--Tuning Control Techniques for Wind Turbine and Hydroelectric Plant Systems

2018 ◽  
Author(s):  
Silvio Simani ◽  
Stefano Alvisi ◽  
Mauro Venturini
Keyword(s):  
Energy Conversion ◽  
Wind Turbine ◽  
Hydroelectric Plant ◽  
Control Strategies ◽  
Operating Conditions ◽  
Renewable Energy Resources ◽  
Control Techniques ◽  
Wide Range ◽  
Energy Conversion Systems ◽  
Self Tuning

The interest on the use of renewable energy resources is increasing, especially towards wind and hydro powers, which should be efficiently converted into electric energy via suitable technology tools. To this aim, self--tuning control techniques represent viable strategies that can be employed for this purpose, due to the features of these nonlinear dynamic processes working over a wide range of operating conditions, driven by stochastic inputs, excitations and disturbances. Some of the considered methods were already verified on wind turbine systems, and important advantages may thus derive from the appropriate implementation of the same control schemes for hydroelectric plants. This represents the key point of the work, which provides some guidelines on the design and the application of these control strategies to these energy conversion systems. In fact, it seems that investigations related with both wind and hydraulic energies present a reduced number of common aspects, thus leading to little exchange and share of possible common points. This consideration is particularly valid with reference to the more established wind area when compared to hydroelectric systems. In this way, this work recalls the models of wind turbine and hydroelectric system, and investigates the application of different control solutions. The scope is to analyse common points in the control objectives and the achievable results from the application of different solutions. Another important point of this investigation regards the analysis of the exploited benchmark models, their control objectives, and the development of the control solutions. The working conditions of these energy conversion systems will be also taken into account in order to highlight the reliability and robustness characteristics of the developed control strategies, especially interesting for remote and relatively inaccessible location of many installations.

Damping Performance of Axial Turbine Stages With Loosely Assembled Friction Bolts: The Non-Linear Dynamic Assessment — Part II

2007 ◽  
Author(s):  
J. Szwedowicz ◽  
Th. Secall-Wimmel ◽  
P. Du¨nck-Kerst
Keyword(s):  
Contact Stiffness ◽  
Contact Condition ◽  
Operating Conditions ◽  
Friction Forces ◽  
Linear Dynamic ◽  
Resonance Frequencies ◽  
Contact Behaviour ◽  
Wide Range ◽  
Dynamic Analyses ◽  
Non Linear

An entire family of twisted and tapered low pressure steam turbine SK-blades with pinned radial root and loosely assembled conical bolts is designed by scaling of the aerodynamic and mechanical properties of the smallest airfoil. For SK-blades operating with variable speed, the friction bolts, mounted in the upper airfoil part, provide either damping or coupling capabilities for the blades with respect to resonance conditions. The damping and coupling performance have been proved experimentally in the test rig of the real turbine. The measurements of the smallest SK-disc assembly under different operating conditions have allowed understanding the dynamic and damping behaviour of the bolts that are either friction dampers or coupling devices for the vibrating blades depending on the excitation level. In this paper, non-linear dynamic analyses of the smallest and large SK-turbine stage are performed and compared with the experimental data. The modal blade dynamics is defined by 30 complex FE mode shapes of the freestanding blades coupled by the disc whereby the bolt’s motion is described by 6 rigid body modes. The sticking contact condition between the blades and bolts is represented by the normal and tangential contact stiffness. These values are firstly estimated analytically with the Hertz’s formulas for the FE reaction forces and contact areas. More realistic contact stiffness values are obtained from the iterative process, in which the resonance frequencies are calculated with the steady-state simulations and compared to the FE nodal diameter curves for sticking contact conditions that meet the experimental frequencies very well (GT2007-27502). In non-linear simulations, in case of exceeding the sticking contact condition, the induced friction forces are linearized by the Harmonic Balance Method. In this manner, the micro-slipping and sticking contact behaviour at all contact points are calculated iteratively for the specified excitation amplitudes, friction coefficient, contact roughness and aerodamping values that are known from the experiment. The computed results of the tuned smallest SK-blades agree with the experimental resonance stresses of 12 measured blades. Differences between the computed and measured stresses are caused by mistuning, which was not quantified in the experiment. The non-linear dynamic analyses provide evidence of good damping performance for the smallest and large SK-blades with respect to wide range of excitation forces, different friction coefficients and various aerodynamic damping values. For the analyzed resonances of the 8th engine order, the scalability of damping performance is found for the SK-blades of different sizes.

Optimal Structural Design of Micro-Motion Stage with Stiffness Constraints Using Topology and Sizing Optimization Method

2016 ◽  
Vol 679 ◽  
pp. 55-58
Author(s):  
You Dun Bai ◽  
Zhi Jun Yang ◽  
Xin Chen ◽  
Meng Wang
Keyword(s):  
Compliant Mechanisms ◽  
Optimization Methods ◽  
Flexure Hinge ◽  
Leaf Spring ◽  
Element Analysis ◽  
Sizing Optimization ◽  
Flexure Hinges ◽  
Spring Type ◽  
Micro Motion ◽  
Motion Stage

Flexure hinge is widely used in the compliant mechanisms for precision engineering. Generally, compliant mechanisms with flexure hinges are designed using the analytical stiffness formulas, which increases the design complexity. As the development of finite element analysis (FEA) and optimization methods, it is likely to design the flexure hinges directly using the FEA based numerical optimization methods. This paper developed a leaf spring type flexure hinge based micro-motion stage with specific stiffness constraints. Both topology and sizing optimization methods are used in the design of motion stage. The proposed methods is apply to optimal design formed the leaf spring type flexure hinge for a micro motion stage which serves as a guidance mechanism. Further numerical result shows the good stiffness stability of the refined stage.

Fatigue Life Prediction and Optimal Design of a Flexure Based Micro-Motion Stage

2013 ◽  
Author(s):  
Qiliang Wang ◽  
Xianmin Zhang
Keyword(s):  
Fatigue Life ◽  
Fatigue Strength ◽  
Optimal Design ◽  
Life Prediction ◽  
Design Method ◽  
Fatigue Life Prediction ◽  
Flexure Hinge ◽  
Flexure Hinges ◽  
Micro Motion ◽  
Motion Stage

This paper presents a fatigue-based method for optimal design of a flexure based 3-RRR compliant micro-motion stage, which is driven by three piezoelectric actuators (PZT). As this compliant stage obtains motions from the deflection of its flexure hinges, fatigue failure becomes its major failure mode. The aim of this paper is to provide a method to predict the fatigue life of the stage and redesign it by considering fatigue strength. Firstly, the motion transformation matrix, which reveals the relation between output displacement vector of moving platform and three input displacements of PZT actuators, is established by using the finite element method. Then, the force vectors of all the twelve flexure elements in the stage can be derived. Secondly, the fatigue properties of circular flexure hinge are discussed by considering the effects of flexure dimension parameters, non-zero mean stress, surface conditions and et al. Combined with the material stress life curve and the fatigue strength of the flexure hinges, fatigue life prediction of the micro-motion stage can be carried out by utilizing the nominal stress approach. The aforementioned micro-motion stage, which is optimized based on maximum stress constraint, is presented as an example to illustrate the fatigue life prediction procedure. And the predicted results of fatigue lives in specified condition indicate that fatigue lives of all flexure hinges in the stage differ drastically. In this condition, the stage will fail prematurely due to the most vulnerable hinge. So, the design method based on static strength may lead to unsafe or uneconomic design of the stage. Finally, a fatigue based optimal design method is introduced to redesign the flexure based micro-motion stage. The stage dimensions and the flexure hinge geometry are considered as design variables. The maximum motion range is set as the objective function. And the fatigue strength of flexures is taken as constraint, as well as the natural frequency of the stage and the input force capacity of PZT actuators. A micro-motion stage with optimal dimension parameters is obtained at last. Numerical results show that the optimal stage has a good comprehensive properties and can endure a infinite cycles.

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