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 1

 Evaluation strategies of fractional order controllers discretization methods

[期刊]
,
2007, 41(7): 842846
EI
SCOPUS
CSCD
PKU

摘要To solve the difficulties of the discretization and application of fractional order controllers (FOC), evaluation strategies of digital realization of FOC are investigated. The realization principle and process of various discretization methods are discussed. One position control system is introduced as the objective controlled by FOC. Based on MittagLeffler function, the fractional order control system with full memory length is adopted as evaluation criterion, and an approximation performance function of discretization methods is proposed. Analyzing the time domain error and approximation performance, the investigation to various discretization methods is carried out comparatively in detail. The result verifies that the discrete model with power series direct discretization method requires 100 memory length to obtain the better approximation, while one with continued fraction direct discretization method requires only 10 order. Thus the continued fraction direct discretization method is preferable to digital realization of fractional order control algorithms in engineering applications.
 2

 FractionalOrder Control of Pneumatic Position Servosystems
 [期刊] , 2011, (): EI SCIE SCOPUS 0.777
 被引用 1 (Web of Science℠)

摘要A fractionalorder control strategy for pneumatic position servosystem is presented in this paper. The idea of the fractional calculus application to control theory was introduced in many works, and its advantages were proved. However, the realization of fractionalorder controllers for pneumatic position servosystems has not been investigated. Based on the relationship between the pressure in cylinder and the rate of mass flow into the cylinder, the dynamic model of pneumatic position servo system is established. The fractionalorder controller for pneumatic position servo and its implementation in industrial computer is designed. The experiments with fractionalorder controller are carried out under various conditions, which include sine position signal with different frequency and amplitude, step position signal, and variety inertial load. The results show the effectiveness of the proposed scheme and verify their fine control performance for pneumatic position servo system.
 3

 Design and kinematic modeling of a planar piezoactuated multistage compliant mechanism

[其他]
12th IEEE/ASME International Conference on Mechatronic and Embedded Systems and Applications (MESA),
2016 :
EI
CPCIS
SCOPUS
 被引用 0 (Web of Science℠)

摘要Multistage compliant mechanisms have been widely investigated in recent decades oweing to their multiplying displacement amplification and compact structure. This paper presents a new planar multistage compliant mechanism with no assembly errors, relatively high frequency response and large range. By defining an impedance factor to describe the hindering effect of the second layer on the preceding one, the combined displacement amplification ratio of the proposed multistage compliant mechanism is theoretically modeled based on the elastic beam theory and the principle of conservation of energy. Initial prototype is monolithically fabricated and experimentally tested. It exhibits a natural frequency of 987Hz and displacement of more than 260 mu m, which agrees well with the finite elemental results and the theoretical predictions. The accuracy of the proposed model and the vibration modal is also verified, which may be a versatile tool for designing.关键词compliant , bridgetype , Piezoelectric actuator , displacement amplifier , flexure hinge
 4

 A new hybrid piezoactuated compliant mechanism with selftuned flexure arm
 [其他] , 2017 : EI SCOPUS CPCIS
 被引用 0 (Web of Science℠)

摘要© 2017 SPIE. Recent interests and demands for developing videorate atomic force microscopes, highthroughput probebased nanofabrication and highfrequency vibration generator for assistedmachining are increasingly posing new challenges for designing highbandwidth and largerange piezoactuated compliant mechanisms. The previous studies mainly focused on making the tradeoff between natural frequency and motion range by designing a proper topology. Differing from the previous works, this paper attempts to break the deadlock by employing both piezostacks and piezoelectric patches to actuate compliant mechanisms. In this method, piezostacks provide an actuating force similar to the traditional way, while piezoelectric patches are bonded on the surface of the flexure arms in compliant mechanisms. These 'active' laminaes are used to further actuate the hosting flexural beam by inducing strains on the interface and then give additional bending moments to the flexural arms, which enlarge the output displacement of the compliant mechanism while without the sacrifice of natural frequency. An analytical formulation is established to illustrate the new driving principle and the compound static behaviour of a specific hybrid piezoactuated multistage compliant mechanism. Initial prototype is also manufactured and experimentally testing is conducted to verify the feasibility of the method.关键词compliant mechanism  flexure hinge  Piezoelectric actuator
 5

 An improved comprehensive SOC prediction method based on adaptive particle filter
 [其他] , 2017 : 70237028 EI SCOPUS CPCIS
 被引用 0 (Web of Science℠)

摘要© 2017 IEEE. It's important for battery safe use and performance of the play to predict the capacity changes and the state of charge (SOC) of the battery accurately. However, accuracy of SOC forecast is affected by SOC definition, battery model and algorithm. In this paper, the factors which affect battery capacity are analyzed based on experiment. Storage capacity decay, recycling capacity fade and dynamic changes of the current effect are modeled, considering the influences of temperature, current ratio and so on. Based on the models, the definition of SOC was modified from the perspective of capacity. Besides, prediction algorithm is a key factor affecting the accuracy of SOC prediction. Compared with other SOC prediction methods, Particle Filter (PF) is a complete nonlinear filter. Due to the large amount of computation, the practicability of Particle Filter is limited. Thus, in order to take into account the calculation quantity and accuracy, adaptive particle filter based on KullbackLeibler distance (KLD) sampling is introduced. Finally, the new method based on modified SOC definition and adaptive particle filter is verified by experimental data of federal urban driving schedule (FUDS) condition.关键词Capacity attenuation model  KLDSampling  Particle Filter  SOC
 6

 Development of selfpowered smart bearing for health condition monitoring

[其他]
IEEE/ASME International Conference on Advanced Intelligent Mechatronics (AIM),
2018 : 786791
CPCIS
Scopus
 被引用 0 (Web of Science℠)

摘要The bearing is the key part to keep continuous work in many important machines and it is of great significance for industrial manufacture. However, the bearing is most likely to be vulnerable. During the working process of the bearing, it can be wear failure to be damaged, due to the effects of work fatigue, lack of lubrication and impact of external impact. The smart bearing is the development trend in the future, which can realize the monitoring of working performance and prediction of fault degree for bearing by detecting the health condition signals of the bearing online. The smart bearing mainly contains wireless sensor module and power supply module. The wireless sensor module is arranged into the bearing to detect the real time signal data and send the data to the upper computer for process. The power supply module is responsible to provide energy for wireless sensor modules. In the early stages of many bearing failures, the fault information can be recognized from physical signals such as load, temperature, rotational speed and vibration. The wireless sensor module can detect these subtle abnormal signals to predict the failure. According to the monitoring information of smart bearing, the bearing can be maintained in time, so that it can extend the life of bearing and reduce the loss resulting from the faults of bearing. This paper reviews the recent develop of the smart bearing. The detecting signal of bearing, the power supply method, the interface circuits and the arrangement layout are discussed.
 7

 Fuzzy fractional order controller based on fractional calculus

[期刊]
,
2005, 39(11): 12461249+1253
EI
SCOPUS
CSCD
PKU

摘要A novel fuzzy fractional order proportional integral derivative (FFPID) controller based on fractional calculus is presented. Fractional calculus performs more effectively for the controller design than integer order calculus with arbitrary integral and derivative orders of real number. Combined the fractional proportional integral derivative controller with fuzzy control logic, the unit of fractional proportional integral derivative replaces the unit of proportional integral derivative in conventional fuzzy PID controllers to establish the structure of FFPID. The operational process of FFPID controllers is realized with the method of Tustin discretization and fuzzy logic reasoning. To demonstrate better control characteristics of the FFPID controllers, a numerical simulation with a detailed comparative analysis under individual conditions is carried out. The results verify the fine robust performance for the nonlinearity and parameter uncertainty.
 8

 NONLINEAR DYNAMIC ANALYSIS OF A CRACKED ROTORBEARING SYSTEM WITH FRACTIONAL ORDER DAMPING

[其他]
ASME Internationl Design Engineering Technical Conferences / Computers and Information in Engineering Conference (IDETC/CIE),
2012 : 179184
CPCIS
 被引用 0 (Web of Science℠)

摘要Fatigue cracking of the rotor shaft is an important fault observed in rotating machinery of key industry, which can lead to catastrophic failure. Nonlinear dynamics of a cracked rotor system with fractional order damping is investigated by using a responsedependent breathing crack model. The fourth order RungeKutta method and tenth order CFEEuler (Continued Fraction ExpansionEuler) method are introduced to simulate the proposed system equation of fractional order cracked rotors. The effects of derivative order of damping, rotating speed ratio, crack depth, orientation angle of imbalance relative to the crack direction and mass eccentricity on the system dynamics are demonstrated by using bifurcation diagram, Poincare map and rotor trajectory diagram. The results show that the rotor system displays chaotic, quasiperiodic and periodic motions as the fractional order increases. It is also found that the imbalance eccentricity level, crack depth, rotational speed, fractional damping and crack angle all have considerable influence on the nonlinear behavior of the cracked rotor system.
 9

 Nonlinear dynamics of Duffing system with fractional order damping

[期刊]
,
2009, 43(3): 5054
EI
SCOPUS
CSCD
PKU

摘要Nonlinear dynamics of Duffing system with fractional order damping is investigated. The equations of fractional order damped Duffing system are established. The fourorder RungeKutta method and tenorder CFEEuler methods are performed to solve the fractional order Duffing equations. The effects of fractional order on the system dynamics are proposed with phase diagrams, bifurcation diagrams and Poincare map. The bifurcation diagram is utilized to analyze the effect of excitation amplitude and frequency on Duffing system with fractional order damping. The analysis shows that the fractional order damped Duffing system exhibits period motion, chaos, period motion, chaos, period motion one by one when the fractional order change from 0.1 to 2.0. A period doubling route to chaos is appeared clearly. The numerical results verify the significant effect of fractional order on system dynamics. It is necessary to consider the fractional order of damping in the design and analysis of system dynamics.
 10

 A linearelement coupled nonlinear energy harvesting system
 [其他] , 2015 : EI SCOPUS

摘要This paper presents a linearspring coupled nonlinear energy harvesting system, which contains linear piezoelectric energy harvesters coupled by linear springs. Although every element of the system is linear, the system will present nonlinear characteristics when it is subjected to excitations because of the geometric nonlinearity induced by coupled motions. Three nonuniform crosssection linear harvesters with the same total length and the different thickness are selected to form the proposed system. Based on EulerBernoulli beam assumptions and the geometrical relationship among each element, a detailed modeling process of the proposed system is presented. In order to verify the broadband characteristics, the comparison of the proposed system and its linear counterparts is provided. Under harmonic excitations, the proposed system has much better energy harvesting capacity compared with its linear counterparts. What's more, the energy harvesting performance of the proposed system is a little better than its linear counterparts under random excitations. The results demonstrate that the advantage of the proposed system is enhanced along with increased excitation level. In addition, such nonmagnetic nonlinear energy harvesting system can be used in the areas where magnets are forbidden, such as inside the human body. © Copyright 2015 by ASME.关键词Intelligent materials , Intelligent systems , Structural health monitoring , Broadband characteristics , Different thickness , Energy harvesting systems , Euler Bernoulli beams , Geometric nonlinearity , Geometrical relationship , Nonlinear characteristics , Piezoelectric energy harvesters
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