In magnetically suspended rotor (MSR) systems, harmonic current mainly originates from rotor mass imbalance and sensor runout, which can generate multifrequency vibration. Repetitive control (RC) is an effective method to eliminate periodic disturbance from a control system. Conventional RC (CRC) method requires the exact knowledge of the period of the periodic signal. However, in some applications, the period may fluctuate or may not be available with sufficient accuracy, in which case the perf...
We demonstrate the application of the internal model principle in tracking a sequential cycloid trajectory to achieve video-rate atomic force microscope (AFM) imaging. To generate a sequential cycloid pattern, one axis of the nanopositioner traces a sinusoidal signal superimposed on a slow triangular wave. Discontinuities at turning points induce large peaks in the steady-state tracking error. To address this issue, a smooth trajectory is designed to reduce the magnitude of error by 60 nm compar...
#1Hui Xie(HIT: Harbin Institute of Technology)H-Index: 28
#2Yongbing Wen(HIT: Harbin Institute of Technology)H-Index: 5
Last. Lining Sun(HIT: Harbin Institute of Technology)H-Index: 24
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This paper presents a method that combines a robust controller (H _{\infty }) and an iterative learning controller (ILC) to control a low mechanical bandwidth nanopositioning stage for high-speed atomic force microscopy imaging. In conventional scanning configurations, the imaging speed of a low-resonance frequency scanner is limited to a few Hz. However, the images obtained using the proposed method have no obvious anamorphosis with a scan speed of up to 80 Hz. This method uses a sinusoidal ...
Last. Li-Min Zhu(SJTU: Shanghai Jiao Tong University)H-Index: 41
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The repetitive control (RC), capable of tracking periodic trajectories and rejecting periodic disturbances, is a promising technique to control the nanopositioning stages for high-speed raster scanning. In digital implementation of the RC scheme, the number of delay points has to be an integer, which implies that the sampling frequency should be an integer multiple of the desired tracking frequency. Clearly, this is a severe limitation on the range of the trajectory frequencies where the RC sche...
Last. Dawei Zhang(Ministry of Education)H-Index: 32
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This paper presents a novel actuator-internal two degree-of-freedom (2-DOF) micro/nano positioning stage actuated by piezoelectric (PZT) actuators, which can be used as a fine actuation part in dual-stage system. To compensate the positioning error of coarse stage and achieve a large motion stroke, a symmetrical structure with an arch-shape bridge-type amplifier based on single notch circular flexure hinges is proposed and utilized in the positioning stage. Due to the compound bridge arm configu...
Last. Da Min(Southwest Jiaotong University)H-Index: 2
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Rate-dependent hysteretic nonlinearity, which is an inherent characteristic of piezoelectric actuators (PEAs), causes a significant challenge in precise motion control of piezoelectric nanopositioning stages. In this paper, by assuming that the model of PEA takes a Hammerstein structure, a novel control strategy that combines iterative learning control (ILC) and the direct inverse of hysteresis is proposed to compensate for both nonlinearities and uncertainties of system simultaneously. Differen...
#1Xiaodong Chen(Liaoning University of Petroleum and Chemical Technology)H-Index: 3
#2Zilong Deng(Liaoning University of Petroleum and Chemical Technology)H-Index: 3
Last. Xingjun Gao(Liaoning University of Petroleum and Chemical Technology)H-Index: 3
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Abstract Aiming to address the problem of the low amplification ratio of traditional microgrippers, a two-stage microgripper based on the principle of combined amplification was designed with a high amplification ratio and large displacement, using a simple and compact structure. The relationship between theoretical input variables and output variables were first calculated by a projection theorem. Secondly, the performance of the microgripper was analyzed by finite element analysis (FEA). Final...
Last. Vicente Feliu(UCLM: University of Castilla–La Mancha)H-Index: 33
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Parameter uncertainty is a key challenge in the real-time control of nanopositioners employed in scanning probe microscopy. Changes in the sample to be scanned introduces changes in system resonances, requiring instantaneous online tuning of controller parameters to ensure stable, optimal scanning performance. This paper presents a method based on the frequency-domain algebraic derivative approach for the accurate online identification of the nanopositioner's parameters. The parameter estimates ...
Last. Li-Min Zhu(SJTU: Shanghai Jiao Tong University)H-Index: 41
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The repetitive control (RC) has been employed for high-speed tracking control of nanopositioning stages due to its abilities of precisely tracking periodic trajectories and rejecting periodic disturbances. However, in digital implementation, the sampling frequency should be integer multiple of the tracking frequency of the desired periodic trajectory. Otherwise, the rounding error would result in a significant degradation of the tracking performance, especially for the case of high input frequen...
This paper presents the design of a new compact one-degree-of-freedom (1-DOF) compliant stage driven by a piezoelectric actuator (PEA) for micro/nanopositioning in the vertical direction. An orthogonal compound bridge-type amplifier is introduced to amplify the displacement of the PEA. It significantly reduces the height of the stage and leads to a compact design. By analytical modeling of the mechanism, the design variables are determined, which are then optimized via the multiobjective genetic...
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