Feedforward control with rate-dependent hysteresis compensator for piezoelectric micro stage (Conference Presentation)

2019 ◽  
Author(s):  
Jongnam Kim ◽  
Hyeong Geon Kim ◽  
Il-Kwon Oh
Keyword(s):  
Feedforward Control ◽  
Rate Dependent

scholarly journals Inverse Rate-Dependent Rayleigh Model Based Feedforward Control for Piezoelectric-Driven Mechanism

IEEE Access ◽  
2020 ◽  
Vol 8 ◽  
pp. 194808-194819
Author(s):  
Meng Zhang ◽  
Zhigang Liu ◽  
Yu Zhu
Keyword(s):  
Feedforward Control ◽  
Model Based ◽  
Rate Dependent

Tracking control of a 3-dimensional piezo-driven micro-positioning system using a dynamic Prandtl–Ishlinskii model

2021 ◽  
pp. 1045389X2110482
Author(s):  
Wei Zhu ◽  
Feifei Liu ◽  
Fufeng Yang ◽  
Xiaoting Rui
Keyword(s):  
Power Amplifier ◽  
Dynamic Characteristics ◽  
Tracking Control ◽  
Feedforward Control ◽  
Positioning System ◽  
Hysteresis Model ◽  
Tracking Accuracy ◽  
Simple Method ◽  
3 Dimensional ◽  
Rate Dependent

A controller composed of a feed-forward loop based on a novel dynamic Prandtl–Ishlinskii (P-I) model and a PID feedback control loop is developed to support a 3-dimensional piezo-driven micro-positioning system for high-bandwidth tracking control. By considering the dynamic characteristics of the power amplifier, the dynamic P-I model can accurately describe the rate-dependent hysteresis of piezoelectric stack actuators (PSAs). To ensure that the hysteresis model is independent of system load, the P-I hysteresis operator in that model characterizes the relationship between the output force and the input voltage of PSAs. The dynamics equation of the mechanical is established by using the cutoff modal method. The feedforward control is designed based on the dynamic hysteresis model to reduce the rate-dependent hysteresis. The PID control is incorporated with the feedforward control to increase the tracking accuracy. Experimental results indicate that the controller can overcome the hysteresis efficiently and preserve good positioning accuracy in 1–100 Hz bandwidth. Just by introducing the dynamic characteristics of the power amplifier, which can be expressed as a first-order differential equation, the P-I model can accurately describe the rate-dependent hysteresis of the PSA, which provides a simple method to describe and control piezoelectric actuators and piezo-driven systems in a wide frequency.

scholarly journals Tracking Control of a Galfenol-Actuated Nanopositioning Stage Using Feedforward Control with a Disturbance Observer

2019 ◽  
Vol 2019 ◽  
pp. 1-9
Author(s):  
Shiping Jiang ◽  
Bin Xu ◽  
Shuxin Liu ◽  
Wei Zhu
Keyword(s):  
Tracking Control ◽  
Disturbance Observer ◽  
Control Method ◽  
Feedforward Control ◽  
Unmodeled Dynamics ◽  
Output Displacement ◽  
Hysteresis Compensation ◽  
Rate Dependent ◽  
Main Challenge ◽  
Compensation Error

The main challenge of the galfenol actuator for high-precision positioning is the inherent nonsmooth hysteresis, which may lead to undesirable inaccuracies or oscillations and even instability. The primary aim of this study is to develop a tracking control method to precisely control the output displacement of a galfenol-actuated nanopositioning stage using feedforward control with a disturbance observer. In order to accurately describe the rate-dependent hysteresis, considering the dynamic behavior of the power amplifier, a novel dynamic model is put forward. Then, a developed controller is designed. In this controller, a feedforward control is developed to compensate the rate-dependent hysteresis, and a disturbance observer is employed to restrain disturbances, high-order unmodeled dynamics, and hysteresis compensation error. The comparative experimental results show that the proposed control method can significantly improve the positioning accuracy and suppress disturbances. This research can be applied in various micro and nanopositioning and vibration control fields.

Evaluation of Freezing Methods by Low Temperature X-Ray Diffraction

1977 ◽  
Vol 35 ◽  
pp. 330-333
Author(s):  
T. Gulik-Krzywicki ◽  
M.J. Costello
Keyword(s):  
Biological Materials ◽  
Molecular Organization ◽  
X Ray Diffraction ◽  
Glass Capillary ◽  
X Ray ◽  
Rate Dependent ◽  
Before And After ◽  
Freeze Etching ◽  
Diffraction Patterns ◽  
Set Up

Freeze-etching electron microscopy is currently one of the best methods for studying molecular organization of biological materials. Its application, however, is still limited by our imprecise knowledge about the perturbations of the original organization which may occur during quenching and fracturing of the samples and during the replication of fractured surfaces. Although it is well known that the preservation of the molecular organization of biological materials is critically dependent on the rate of freezing of the samples, little information is presently available concerning the nature and the extent of freezing-rate dependent perturbations of the original organizations. In order to obtain this information, we have developed a method based on the comparison of x-ray diffraction patterns of samples before and after freezing, prior to fracturing and replication.Our experimental set-up is shown in Fig. 1. The sample to be quenched is placed on its holder which is then mounted on a small metal holder (O) fixed on a glass capillary (p), whose position is controlled by a micromanipulator.

Dysarthria Profiles in Adults With Hereditary Ataxia

2019 ◽  
Vol 28 (2S) ◽  
pp. 915-924 ◽  
Author(s):  
Kristie A. Spencer ◽  
Mallory Dawson
Keyword(s):  
Rating Scales ◽  
Feedforward Control ◽  
Hereditary Ataxia ◽  
Severity Rating ◽  
Visual Analog Scales ◽  
Speech Characteristics ◽  
Ataxic Dysarthria ◽  
Preliminary Study

Purpose This preliminary study examined whether speech profiles exist for adults with hereditary ataxia based on 2 competing frameworks: a pattern of instability/inflexibility or a pattern of differential subsystem involvement. Method Four dysarthria experts rated the speech samples of 8 adults with dysarthria from hereditary ataxia using visual analog scales and presence/severity rating scales of speech characteristics. Speaking tasks included diadochokinetics, sustained phonation, and a monologue. Results Speech profiles aligned with the instability/inflexibility framework, with the pattern of instability being the most common. Speech profiles did not emerge for the majority of speakers using the differential subsystem framework. Conclusions The findings extend previous research on pure ataxic dysarthria and suggest a possible framework for understanding the speech heterogeneity associated with the ataxias. The predominance of the instability profile is consistent with the notion of impaired feedforward control in speakers with cerebellar disruption.

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