phd-nass-design/nass-design.org

Nano Hexapod - Obtained Design

• Introduction
• Mechanical Design
  • Struts
    • Introduction
    • Flexible joints
    • Piezoelectric Amplified Actuators
    • Encoder support
  • Plates
  • Finite Element Analysis
  • Obtained Design
• Multi-Body Model
  • Introduction
  • Flexible Joints
  • Amplified Piezoelectric Actuators
  • Encoders
• Conclusion
• Bibliography

Introduction   ignore

Design goals:

• Position bi and si
• Maximum height of 95mm
• As close as possible to "perfect" stewart platform: flexible modes at high frequency
• Easy mounting, easy change of strut in case of failure

Presentation of the obtained design:

• Fixation
• Section on: Complete strut
• Cable management
• Plates design
• FEM results
• Explain again the different specifications in terms of space, payload, etc..
• CAD view of the nano-hexapod
• Chosen geometry, materials, ease of mounting, cabling, …
• Validation on Simscape with accurate model?

Mechanical Design

<<sec:detail_design_mechanics>>

Struts

Introduction   ignore

Flexible joints

Flexible joints: X5CrNiCuNb16-4 (F16Ph)

• high yield strength: specified >1GPa using heat treatment
• high fatigue resistance

Piezoelectric Amplified Actuators

APA: modification for better mounting

Encoder support

All other parts are made of aluminum.

Plates

Plates: X30Cr13

• high hardness to not deform

• Maximize frequency of flexible modes (show FEM)
• Good tolerances for interfaces with flexible joints Positioning of bi and orientation si

The cylindrical component is located (or constrained) within the V-groove via two distinct line contacts.

Fixation of the flexible points to the nano-hexapod plates. Both top and bottom flexible joints are clamped to the plates as shown in (⊂ref{fig:detail_design_fixation_flexible_joints}). While the top flexible joint is in contact with the top plate for precise positioning of its center of rotation (⊂ref{fig:detail_design_location_top_flexible_joints}), the bottom joint is just oriented (⊂ref{fig:detail_design_location_bot_flex}).

Finite Element Analysis

• FEM of complete system
• Show modes of the struts

Obtained Design

• Alternative encoder position: on the plates
• Support made of aluminum

Finite Element Analysis of the encoder supports. Encoder inertia was taken into account.

Multi-Body Model

<<sec:detail_design_model>>

Multi body Model:

• Complete model: two plates, 6 joints, 6 actuators, 6 encoders
• Joint Model
• APA Model
• Encoder model
• Say that obtained dynamics was considered good + possible to perform simulations of tomography experiments with same performance as during the conceptual design

Introduction   ignore

Two configurations:

• Encoders fixed to the struts
• Encoders fixed to the plates

Flexible Joints

Amplified Piezoelectric Actuators

Encoders

Conclusion

<<sec:detail_design_conclusion>>

Bibliography   ignore