design and control of a compact ultra- precision machine ...€¦ · design and control of a...
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Design and Control of a Compact Ultra-Precision Machine for High Dynamic
Performance
Why High-Dynamic Performance?
Ref: Fang et al., 2013
Ref: Fang et al., 2013
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Electronics cabinet
What is a compact UP machine? µ4 machine
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What is the “problem”? “stiff frame”
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Linear motor & encoder
Air bearing
Frame
Carriage
What is the “problem”? “flexible frame”
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What is the research hypothesis?
Improving position control of a linear stage based on real time measurements from array of accelerometers
F
X
k
c
Xf
framem
loadm
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What are the aims & objectives?
Capabilities: • sub-micrometre accuracy
• high jerk (>500m/s3)
Aims: • Machine modelling
• Technological solutions for improving control for
“flexible frame”
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What is the contribution?
combining the apparent antagonistic requirements of a compact machine and high dynamic performance into one solution
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F
X
k
c
Xf
framem
loadm
What is the methodology?
Problem definition
Analysis &
Optimisation
Proof of concept
System Identification
Sensors placement Mechanical design
Goals and requirements
Implementation
Validation
Control design
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What is the setup?
Frame Air bearing Slave side
Air bearing Master side
Encoder Rail Carriage
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CAD Test rig
Air bearing
Frame
Carriage
System identification: methodology
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Plate Frame
Frame & guide-ways Motion module
System identification: experimental equipment
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Frame - “free-free” support Motion module – operational measurements
System identification: modal measurements results
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459Hz Measured
473Hz Simulated
? =
593Hz Measured
647Hz Simulated
? =
System identification: correlation: FEM & modal measurements
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FEM – 473Hz Modal measurements – 459Hz
System identification: correlation: FEM & modal measurements
FEM – 473Hz Modal measurements – 459Hz
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FEM – 647Hz Modal measurements – 593Hz
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System identification: correlation: FEM & modal measurements
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System identification: correlation: FEM & modal measurements
System identification: control & modal measurements
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Encoder signal
Accelerometers signal(s)
Motion module
What are the conclusions?
•Bottom-up system identification methodology was adopted
• System identification – different techniques showed a good correlation
•FEM-modal measurements correlation – input for mechanical design improvements
•Modal measurements analysis – input for control design
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What’s next?
• Control techniques for “flexible frame”: Adaptive? Acceleration Feedforward / Feedback?
•Optimal sensor placement: Number, Location, Specification
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Thank you
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