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High-precision linear stages used for applications such as surface measurement in life sciences, semiconductor manufacturing and other industries often require two distinctly different modes of motion. A rapid mode usually is needed to change locations quickly in the workspace, which might then be followed by very slow motion for finer focusing and resolution. The traditional option for achieving dual-speed motion has been to stack one stage atop another. But a promising new development controls dual-speed motion with a single-stage configuration. Watch this webinar to learn: –About both types of linear positioning system configurations –How to determine the extent to which they satisfy design requirements for velocity, range of motion and compactness
Citation preview
Developments In Precision Positioning Stages with High Speed Range
This webinar will be available afterwards at
designworldonline.com & email
Q&A at the end of the presentation
Hashtag for this webinar: #DWwebinar
Before We Start
Moderator
Leslie Langnau Design World
Presenter
George Jaffe Steinmeyer
Finding A Precision Positioning Stage for
Applications with Extremely Large Velocity Range
1. Problem description
2. State of the art
3. New approach to the problem
4. Results of field tests
5. Some Applications
“Dual-Speed”- Drive for Nanopositioning with Ball Screws
• High dynamic velocity range (extremely slow to fast)
(Measurement, microelectronics, engineering,…)
• High system accuracies for positioning - in sub-micrometer range
• Repeatability < 100 nm
• Long travel - up to 300 mm and more
1. Problem description – some typical requirements for such a linear positioning stage
Speed from 1 km/h up to 300 km/h
Dynamic range = 3 x 102 : 1
Speed from 0.05 mm/s up to 100 mm/s
Dynamic range = 2 x 103 : 1
But suppose the . . .
Requirement is 10 nm/s up to 100 mm/s
Dynamic range = 1 x 107 : 1 ! !
Dr. Ing. h.c. F. Porsche AG
Another way to look at the issue . . .
Advantages Disadvantages
Ball screw /
DC-Motor/
Stepper motor
- horizontal and vertical application
- cost effective
- robust and tested principle
- low dynamic range
(1 : 2000)
Direct drives - relatively cost effective
- very high accel and velocities possible
- no drive wear
- vertical usage critical (brake)
- heat generation
Piezo stack - travels possible in submicrometer range - very short travel ranges
- closed loop difficult
- position drift
- high voltage
2. State of the art – generally 3 possibilities
Combination of ball screw/motor-drive and piezo stacks
Mad City Labs Inc.
XY-
Piezo.stack-
system
XY-
Ball.screw-
system
2. State of the art – or “if one stage doesn‘t work, use two!”
• 2 stages = discontinuous position (variable performance)
• due to series connection of drives -> low system stiffness
(low self frequency)
• 2 force generators / 2 measuring systems / 2 controllers
• piezo mechanism is sensitive to shock and overload
• high costs
2. Stacked stages – what are the limitations of this approach?
Combination DC-Motor with ball screw drive/rotating piezo motor
DC-motor
Rotating piezo-motor
Permanent-electromagnetic coupling
Bellows coupling
Incremental measuring system
Slide system
Rotational encoder
Fixed bearing
Support bearing
Ball screw
3. A New (and Patented) Approach to the Problem
Characteristics of the rotary piezo motor
3. A New Approach to the Problem
Characteristics of the measuring system
- Scale resolution programmable from 5 μm-5 nm
- Accuracy 1 μm
- Interpolation error
< ± 0.12 μm over a
scale period of 20 μm
3. A New Approach to the Problem – more details
Rotating piezo motor – Test assembly
Piezo motor
3. A New Approach to the Problem – test set-up
Positioning: 10µm steps
2005
4010
6015
8020
10025
0
[nm]
4. First results of field tests – 10 µm steps
Positioning: 1µm steps
1015
812
609
406
203
0
[nm]
4. First results of field tests – 1 µm steps
Positioning: 50nm steps
-13
0
13
26
39
52
65
[nm]
4. First results of field tests – 50 nm steps
So, by way of review . . . “Dual Speed” stage
• We now have the possibility to move extremely slowly or
quite rapidly in a single stage with a common drive
element
• We are no longer limited to only very small movements in
small increments
• Now to some applications . . .
e.g. Optical 3D measurement
Alicona Imaging - Graz
5. Optical 3D Tool
• Coarse adjustment, focussing and scanning with
combined drive system possible
• Measuring range not limited to piezo stack range as
with this instrument
Physik Instrumente (PI) GmbH & Co. KG.
5. Confocal Microscopy
Thanks for your attention!
Questions? Design World Leslie Langnau llangnau@wtwhmedia.com Phone: 440.234.4531 Twitter: @DW_RapidMfg
Steinmeyer George Jaffe gjaffe@steinmeyer.com Phone: 781.273.6220
Thank You
This webinar will be available at designworldonline.com & email
Tweet with hashtag #DWwebinar
Connect with
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LinkedIn: Design World Group
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