Design and Testing of a Nanometer Positioning System

2010 ◽  
Vol 132 (2) ◽  
Author(s):  
Lu Lihua ◽  
Liang Yingchun ◽  
Guo Yongfeng ◽  
Shimokohbe Akira
Keyword(s):  
Closed Loop ◽  
Single Step ◽  
Ball Screw ◽  
Dual Model ◽  
Positioning System ◽  
Positioning Error ◽  
Precision Positioning ◽  
Screw Mechanism ◽  
Point Positioning ◽  
Point To Point

This paper presents the design and implementation of a positioning system with a dc servomotor and ball-screw mechanism used to realize high-precision positioning over a wide travel range with nanometer level positioning error and near zero overshoot. Instead of the popular dual-model control strategy and friction compensation, a high-gain proportional-integral-derivative controller is used to realize a single-step point-to-point positioning. The controller parameters are obtained by placing closed-loop poles according to the macrodynamics of a ball-screw mechanism only to avoid identification of microdynamics and friction modeling. In order to suppress the overshoot caused by actuator saturation in long-stroke positioning, a trajectory planning method is applied to calculate the input of the closed-loop system. Experimental and simulation results demonstrate that single-step precision positioning responses to different size commands are achieved without producing any large overshoot. In point-to-point positioning from 100 mm down to 10 nm, the positioning error is within 2 nm and the response dynamics is satisfactory.

scholarly journals Experiment-based thermal behavior research about the feed drive system with linear scale

2018 ◽  
Vol 10 (11) ◽  
pp. 168781401881235
Author(s):  
Yang Li ◽  
Jun Zhang ◽  
Dongxu Su ◽  
Changxing Zhou ◽  
Wanhua Zhao
Keyword(s):  
Closed Loop ◽  
Great Influence ◽  
Drive System ◽  
Ball Screw ◽  
Heat Sources ◽  
Positioning Error ◽  
Thermally Induced ◽  
Feed Drive ◽  
Feed Drive System ◽  
Screw Feed

Positioning error of the feed drive system has great influence of the machining quality. In order to guarantee the positioning accuracy, the linear grating scale is adopted to form a full-closed loop. However, due to the inner heat sources and environmental temperature variations, the linear grating scale could expand and the thermally induced positional deviation is generated. In this article, temperatures and positional deviations of the ball screw feed drive system and the linear motor feed drive system equipped with linear scales were tested. The factors that affect the positioning error were analyzed. Then, the temperatures and positioning coordinates were used as inputs to build the thermally induced positional deviation model of full closed-loop feed drive system. Based on the model, coordinate values of the machine tool were adjusted and the compensation was implemented. The testing results verified that after compensation, the positional deviations were greatly reduced.

Nanometer Positioning System Based on Ball Screw

2006 ◽  
Vol 315-316 ◽  
pp. 710-714
Author(s):  
Li Hua Lu ◽  
Ying Chun Liang ◽  
H. Tachikawa ◽  
Yong Feng Guo ◽  
Akira Shimokohbe
Keyword(s):  
Pid Controller ◽  
Friction Model ◽  
Pole Placement ◽  
Ball Screw ◽  
Positioning System ◽  
Loop Gain ◽  
Response Characteristics ◽  
High Loop ◽  
Simulation Results ◽  
Point To Point

This paper deals with nanometer positioning in the presence of friction. The object researched is a ball-screw-driven and linear-ball-guide-supported table system. For such system, models that do not account for friction can only be applicable to describe the macrodynamic behavior which is significantly different from the microdynamic one. A PID controller is designed with high-loop gain to suppress the effect of friction. The controller parameters are calculated by pole placement according to macrodynamics, no identification of friction and friction model are necessary. Experiment and simulation results indicate that nanometer positioning can be realized in this system by the controller. In point-to-point (PTP) positioning for step heights from 0.1μm to 1mm, the positioning error is within ±5 nm and the response characteristics are satisfactory.

Control Methods for Energy-Efficient Pneumatic Servos Employing Asymmetric Cylinders

Volume 2 ◽  
2004 ◽  
Author(s):  
Aaimin Yang ◽  
Junsheng Pu ◽  
C. B. Wong ◽  
Philip Moore
Keyword(s):  
Energy Efficiency ◽  
Energy Efficient ◽  
Energy Use ◽  
Pneumatic Cylinder ◽  
Positioning System ◽  
Control Methods ◽  
Pneumatic Actuation ◽  
Improved Stability ◽  
Point Positioning ◽  
Point To Point

Pneumatic drives or actuators are most widely used in industry, in comparison to their hydraulic and electrical counterparts. However, they are low in energy efficiency and have typically been used in performing simple actuation tasks. This paper investigates the use of pneumatic actuation for point-to-point positioning applications in the context of employing asymmetric cylinders. The focus of this research is to study appropriate control methods, aiming for improved energy efficiency in the use of pneumatic servo positioning system. Relevant mathematical models and stability analysis will be presented in this paper, with results from simulation and experimental verification. In particular, a hydraulic circuit (rapid motion circuit) is adopted in the case for pneumatic actuation. For point-to-point positioning application, in the forward moving phase, the inlet and outlet chambers will be connected via by-pass valve allowing exhausted compress air to be reused. In comparison with the conventional way in controlling the motion of an asymmetric pneumatic cylinder, a portion of the compressed can be re-used leading to an enhancement in energy-efficiency. The results show that some 15% saving in energy use can be acquired with improved stability while the settling time of the positioning system is maintained. Relevant design and applications issues will be outlined and discussed in this paper as well.

Nanometer Positioning in the Presence of Friction

2007 ◽  
Vol 339 ◽  
pp. 217-222
Author(s):  
Li Hua Lu ◽  
Yong Feng Guo ◽  
H. Tachikawa ◽  
Ying Chun Liang ◽  
Akira Shimokohbe
Keyword(s):  
Pid Controller ◽  
Step Height ◽  
Ball Screw ◽  
Positioning Error ◽  
Loop Gain ◽  
Response Dynamics ◽  
High Loop ◽  
Micro Motion ◽  
Simulation Results ◽  
Point To Point

This paper deals with nanometer positioning in the presence of friction. The object studied is a ball-screw-driven and linear-ball-guide-supported table system. For this system, the friction dominates the resulting performance for micro-motion and the system exhibits microdynamic characteristic which is rather different from macrodynamics. Inherently a controller with high loop-gain is needed to suppress the effect of friction. A PID controller is designed for the table system for step height smaller than 10μm. Experiment and simulation results indicate that the PID controller can provide a sufficiently high-loop gain and effect of friction is suppressed. In point-to-point(PTP) positioning for step heights from 10μm down to 10nm, the positioning error is within ±2 nm and the response dynamics is satisfactory.

scholarly journals Fast Precision Positioning of a Ball Screw Mechanism Based on Practical NCTF Control

2009 ◽  
Vol 3 (3) ◽  
pp. 233-240 ◽  
Author(s):  
Kaiji Sato ◽  
◽  
Guilherme Jorge Maeda
Keyword(s):  
Control Theory ◽  
High Speed ◽  
Step Height ◽  
Ball Screw ◽  
Precision Positioning ◽  
Exact Model ◽  
Step Movement ◽  
Object Movement ◽  
Screw Mechanism ◽  
Trajectory Following

We discuss improvements in a practical nominal characteristic trajectory-following (NCTF) controller for fast positioning. The NCTF controller consists of a nominal characteristic trajectory (NCT) as the movement reference and a PI compensator making object movement follow the NCT. It is easily designed without an exact model, known parameters, or much control theory knowledge. The step speed of NCTF control depends on the NCT. We introduce two ways to construct the NCT for high-speed step movement, - fast positioning is introduced and the performances by two NCTs thus constructed are compared to clarify a more suitable way using two ball screw mechanisms. Experiments in positioning with the NCT by the suitable way are evaluated, whose results show that the NCT increases step speed while preserving the robustness of feature step height and movable mass changes.

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