Robust Control of Piezo Actuator for Active Error Compensation in Diamond Turning

2000 ◽  
Author(s):  
Jianming Yu ◽  
C. James Li
Keyword(s):  
Control Strategy ◽  
Error Compensation ◽  
Diamond Turning ◽  
Piezo Actuator ◽  
Turning Process ◽  
Robust Controller ◽  
Error Sources ◽  
Hysteresis Nonlinearity ◽  
Order Of Magnitude ◽  
Magnitude Improvement

Abstract This paper describes a new control strategy for the micro positioning system used in a diamond turning process to improve workpiece geometry in spite of hysteresis nonlinearity and guideway/spindle errors. The control strategy consists of two nested loops. The inner loop is a model-based robust controller, which compensates for the hysteresis nonlinearity associated with piezo actuators, and the outer loop is a P-integrator learning controller which eliminates the unmodeled error sources such as guideway and spindle errors. This control strategy was applied to the error compensation in a diamond turning process. Cutting tests were conducted and showed an order of magnitude improvement in the workpiece form accuracy from 10 μm to 1μm on an aluminum alloy disk.

A Method for Estimating and Compensating Quasistatic Errors of Machine Tools

1993 ◽  
Vol 115 (1) ◽  
pp. 149-159 ◽  
Author(s):  
P. M. Ferreira ◽  
C. Richard Liu
Keyword(s):  
Parameter Estimation ◽  
Error Compensation ◽  
Machine Tools ◽  
Experimental Results ◽  
Compensation Scheme ◽  
Order Of Magnitude ◽  
Magnitude Improvement

Quasistatic errors are the major contributors to positioning inaccuracies of machine tools. These errors, estimated to account for 70 percent of the errors of the machine, have been observed to be as high as 70 to 120 μm for production class machining centers. In this paper, a model for these errors is developed. Further, it is shown that the parameters for this model can be estimated by the observation of a few (nine) error vectors in the machine’s workspace. These two results form the basis for a viable error compensation scheme; the model for error compensation and the parameter estimation for updating the model. Experimental results verify the validity of the approach. An order-of-magnitude improvement in the accuracy of the machine, with respect to a calibration frame, was observed.

High-Density Memristor-CMOS Ternary Logic Family

2020 ◽  
Author(s):  
Xiaoyuan Wang ◽  
Pengfei Zhou ◽  
Jason Eshraghian ◽  
Chih-Yang Lin ◽  
Herbert Ho-Ching Iu ◽  
...  
Keyword(s):  
Indium Tin Oxide ◽  
Practical Implementation ◽  
Switching Speed ◽  
High Data ◽  
Fast Switching ◽  
Data Density ◽  
Order Of Magnitude ◽  
High Transconductance ◽  
Logic Functions ◽  
Magnitude Improvement

<div>This paper presents the first experimental demonstration</div><div>of a ternary memristor-CMOS logic family. We systematically</div><div>design, simulate and experimentally verify the primitive</div><div>logic functions: the ternary AND, OR and NOT gates. These are then used to build combinational ternary NAND, NOR, XOR and XNOR gates, as well as data handling ternary MAX and MIN gates. Our simulations are performed using a 50-nm process which are verified with in-house fabricated indium-tin-oxide memristors, optimized for fast switching, high transconductance, and low current leakage. We obtain close to an order of magnitude improvement in data density over conventional CMOS logic, and a reduction of switching speed by a factor of 13 over prior state-of-the-art ternary memristor results. We anticipate extensions of this work can realize practical implementation where high data density is of critical importance.</div>

scholarly journals Incremental Construction of Generalized Voronoi Diagrams on Pointerless Quadtrees

2014 ◽  
Vol 2014 ◽  
pp. 1-14 ◽  
Author(s):  
Quanjun Yin ◽  
Long Qin ◽  
Xiaocheng Liu ◽  
Yabing Zha
Keyword(s):  
Voronoi Diagrams ◽  
Surrounding Area ◽  
Repair Mechanism ◽  
Local Repair ◽  
Order Of Magnitude ◽  
Generalized Voronoi Diagrams ◽  
Incremental Construction ◽  
Coarse To Fine ◽  
Multiple Granularities ◽  
Magnitude Improvement

In robotics, Generalized Voronoi Diagrams (GVDs) are widely used by mobile robots to represent the spatial topologies of their surrounding area. In this paper we consider the problem of constructing GVDs on discrete environments. Several algorithms that solve this problem exist in the literature, notably the Brushfire algorithm and its improved versions which possess local repair mechanism. However, when the area to be processed is very large or is of high resolution, the size of the metric matrices used by these algorithms to compute GVDs can be prohibitive. To address this issue, we propose an improvement on the current algorithms, using pointerless quadtrees in place of metric matrices to compute and maintain GVDs. Beyond the construction and reconstruction of a GVD, our algorithm further provides a method to approximate roadmaps in multiple granularities from the quadtree based GVD. Simulation tests in representative scenarios demonstrate that, compared with the current algorithms, our algorithm generally makes an order of magnitude improvement regarding memory cost when the area is larger than210×210. We also demonstrate the usefulness of the approximated roadmaps for coarse-to-fine pathfinding tasks.

scholarly journals The Array of Long Baseline Antennas for Taking Radio Observations from the Sub-Antarctic

2020 ◽  
Vol 09 (04) ◽  
pp. 2050019
Author(s):  
H. C. Chiang ◽  
T. Dyson ◽  
E. Egan ◽  
S. Eyono ◽  
N. Ghazi ◽  
...  
Keyword(s):  
Low Frequency ◽  
Neutral Hydrogen ◽  
Radio Frequency Interference ◽  
Marion Island ◽  
Radio Observations ◽  
Long Baseline ◽  
Galactic Emission ◽  
Operating Frequency Range ◽  
Order Of Magnitude ◽  
Magnitude Improvement

Measurements of redshifted 21[Formula: see text]cm emission of neutral hydrogen at [Formula: see text][Formula: see text]MHz have the potential to probe the cosmic “dark ages,” a period of the universe’s history that remains unobserved to date. Observations at these frequencies are exceptionally challenging because of bright Galactic foregrounds, ionospheric contamination, and terrestrial radio-frequency interference. Very few sky maps exist at [Formula: see text][Formula: see text]MHz, and most have modest resolution. We introduce the Array of Long Baseline Antennas for Taking Radio Observations from the Sub-Antarctic (ALBATROS), a new experiment that aims to image low-frequency Galactic emission with an order-of-magnitude improvement in resolution over existing data. The ALBATROS array will consist of antenna stations that operate autonomously, each recording baseband data that will be interferometrically combined offline. The array will be installed on Marion Island and will ultimately comprise 10 stations, with an operating frequency range of 1.2–125[Formula: see text]MHz and maximum baseline lengths of [Formula: see text][Formula: see text]km. We present the ALBATROS instrument design and discuss pathfinder observations that were taken from Marion Island during 2018–2019.

Error Compensation Based on Differential Operators and Electro-Optical Collimation

2010 ◽  
Vol 44-47 ◽  
pp. 1568-1572 ◽  
Author(s):  
Lin Hong ◽  
Yan Shu Liang ◽  
Meng Cong
Keyword(s):  
Error Compensation ◽  
Differential Operators ◽  
Three Dimension ◽  
Parallel Mechanisms ◽  
Linear Calibration ◽  
Error Sources ◽  
Collimation System ◽  
Simulation And Experiment ◽  
Movable Platform ◽  
Calibration Techniques

Theoretical analysis and experiment study on the pose error compensations of parallel mechanisms have been presented. A method for error compensations by means of differential operators and electro-optical collimation system is discussed. Compensation quantities oriented to main error sources from position coordinates of joints on the movable platform can be obtained through mathematic models. Compensation quantities provided by driving legs can be realized precisely by linear calibration techniques. Orientation angles can be measured by means of electro-optical collimation system and a three-dimension turning table, which is centrally positioned and can complete multi-direction inverse adjusting. Numerical example relevant to Stewart platform has been given. Simulation and experiment results indicate the feasibility of the method.

Piezo Actuator Hybrid Modeling for Nonlinear Inverse Control in Diamond Turning

1999 ◽  
Author(s):  
Dongwoo Song ◽  
C. James Li
Keyword(s):  
Pid Control ◽  
Inverse Dynamics ◽  
Feedforward Control ◽  
Diamond Turning ◽  
Piezo Actuator ◽  
Positioning System ◽  
Preisach Model ◽  
Hysteresis Model ◽  
Inverse Control ◽  
Spring Mechanism

Abstract This paper describes a micro-positioning system based on piezo actuators and a spring mechanism, and a hybrid hysteresis model integrating a neural network and Preisach model to identify the inverse dynamics of the micro-positioning system. To improve the workpiece form accuracy in diamond turning, feedforward control using the hybrid inverse model and feedback PID control were applied individually and in combination. The performance of these controllers are compared in actual cutting tests.

ESCV cutting method during infrared crystal single point diamond turning process

2019 ◽  
Vol 48 (7) ◽  
pp. 742001
Author(s):  
王 朋 Wang Peng ◽  
薛栋柏 Xue Dongbai ◽  
张 昊 Zhang Hao ◽  
杨 坤 Yang Kun ◽  
李伟皓 Li Weihao ◽  
...  
Keyword(s):  
Single Point ◽  
Diamond Turning ◽  
Turning Process ◽  
Cutting Method

Effects of Machining Parameters on Surface Roughness when Ultra-High Precision Diamond Turning RSA443 Optical Aluminum

2019 ◽  
Vol 287 ◽  
pp. 30-34
Author(s):  
Zwelinzima Mkoko ◽  
Khaled Abou-El-Hossein
Keyword(s):  
Surface Roughness ◽  
Silicon Content ◽  
Cutting Speed ◽  
Cutting Parameters ◽  
Diamond Turning ◽  
Machining Parameters ◽  
Turning Process ◽  
Optical Components ◽  
Box Behnken Design ◽  
Factors Influencing

In the globally competitive environment, surface roughness and finer tolerances are becoming stringent and certainly most critical for optical components. The aim of this study is to determine the effects of diamond turning process parameters on surface finish when diamond turning RSA 443 alloy having high silicon content. This alloy is a new grade of aluminum that has a potential to be used for production of various optical components. The experiments were conducted based on the Box-Behnken design with three diamond-turning parameters varied at three levels. A mathematical regression model was developed for predicting surface roughness. Further, the analysis of variance was used to analyze the influence of cutting parameters and their interaction in machining. The developed prediction model reveals that cutting speed and feed rate are the most dominant diamond turning factors influencing surface roughness.

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