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Add introduction to the second chapter

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Thomas Dehaeze 2025-04-15 23:10:53 +02:00
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@ -360,7 +360,7 @@ From the measured frequency response functions (FRF), the model can be tuned to
#+name: fig:uniaxial_ustation_first_meas_dynamics #+name: fig:uniaxial_ustation_first_meas_dynamics
#+caption: Experimental setup used for the first dynamical measurements on the Micro-Station. Geophones are fixed to different stages of the micro-station. #+caption: Experimental setup used for the first dynamical measurements on the Micro-Station. Geophones are fixed to different stages of the micro-station.
#+attr_nlatex: :width \linewidth #+attr_latex: :width \linewidth
[[file:figs/uniaxial_ustation_first_meas_dynamics.jpg]] [[file:figs/uniaxial_ustation_first_meas_dynamics.jpg]]
**** Measured dynamics **** Measured dynamics
@ -5526,11 +5526,29 @@ As anticipated by the control analysis, some performance degradation was observe
:UNNUMBERED: t :UNNUMBERED: t
:END: :END:
#+name: fig:chapter2_overview Following the validation of the Nano Active Stabilization System concept in the previous chapter through simulated tomography experiments, this chapter addresses the refinement of the preliminary conceptual model into an optimized implementation.
#+caption: Figure caption The initial validation utilized a nano-hexapod with arbitrary geometry, where components such as flexible joints and actuators were modeled as ideal elements, employing simplified control strategies without consideration for instrumentation noise.
#+attr_org: :width 800px This detailed design phase aims to optimize each component while ensuring none will limit the system's overall performance.
#+attr_latex: :width \linewidth
[[file:figs/chapter2_overview.png]] This chapter begins by determining the optimal geometric configuration for the nano-hexapod (Section\nbsp{}ref:sec:detail_kinematics).
To this end, a review of existing Stewart platform designs is first presented, followed by an analysis of how geometric parameters influence the system's properties—mobility, stiffness, and dynamical response—with a particular emphasis on the cubic architecture.
The chapter concludes by specifying the chosen nano-hexapod geometry and the associated actuator stroke and flexible joint angular travel requirements to achieve the desired mobility.
Section\nbsp{}ref:sec:detail_fem introduces a hybrid modeling methodology that combines finite element analysis with multi-body dynamics to optimize critical nano-hexapod components.
This approach is first experimentally validated using an Amplified Piezoelectric Actuator, establishing confidence in the modeling technique.
The methodology is then applied to two key elements: the actuators (Section\nbsp{}ref:sec:detail_fem_actuator) and the flexible joints (Section\nbsp{}ref:sec:detail_fem_joint), enabling detailed optimization while maintaining computational efficiency for system-level simulations.
The control strategy is refined in Section\nbsp{}ref:sec:detail_control, where three critical aspects are addressed.
First, various approaches for optimally combining multiple sensors are examined, with particular emphasis on sensor fusion techniques.
Second, different decoupling strategies for parallel manipulators are compared—an analysis notably lacking in the literature.
Third, the optimization of controllers for decoupled plants is discussed, introducing a novel method for shaping closed-loop transfer functions using complementary filters.
Section\nbsp{}ref:sec:detail_instrumentation focuses on instrumentation selection using a dynamic error budgeting approach to establish maximum acceptable noise specifications for each component.
The selected instrumentation is then experimentally characterized to verify compliance with these specifications, ensuring that the combined effect of all noise sources remains within acceptable limits.
# TODO - Refine this part when the corresponding section is fully written
The chapter concludes with a concise presentation of the obtained optimized nano-hexapod design in Section\nbsp{}ref:sec:detail_design, summarizing how the various optimizations contribute to a system that balances the competing requirements of precision positioning, vibration isolation, and practical implementation constraints.
With the detailed design completed and components procured, the project advances to the experimental validation phase, which will be addressed in the subsequent chapter.
** Optimal Geometry ** Optimal Geometry
<<sec:detail_kinematics>> <<sec:detail_kinematics>>
@ -6470,6 +6488,7 @@ The diagram confirms that the required workspace fits within the system's capabi
#+name: fig:detail_kinematics_nano_hexapod_mobility #+name: fig:detail_kinematics_nano_hexapod_mobility
#+caption: Specified translation mobility of the Nano-Hexapod (grey cube) and computed Mobility (red volume). #+caption: Specified translation mobility of the Nano-Hexapod (grey cube) and computed Mobility (red volume).
#+attr_latex: :scale 0.9
[[file:figs/detail_kinematics_nano_hexapod_mobility.png]] [[file:figs/detail_kinematics_nano_hexapod_mobility.png]]
**** Required Joint angular stroke **** Required Joint angular stroke
@ -6500,6 +6519,7 @@ For the nano-hexapod design, a key challenge was addressing the wide range of po
This led to a practical design approach where struts were oriented more vertically than in cubic configurations to address several application-specific needs: achieving higher resolution in the vertical direction by reducing amplification factors and better matching the micro-station's modal characteristics with higher vertical resonance frequencies. This led to a practical design approach where struts were oriented more vertically than in cubic configurations to address several application-specific needs: achieving higher resolution in the vertical direction by reducing amplification factors and better matching the micro-station's modal characteristics with higher vertical resonance frequencies.
** Component Optimization ** Component Optimization
<<sec:detail_fem>>
*** Introduction :ignore: *** Introduction :ignore:
During the nano-hexapod's detailed design phase, a hybrid modeling approach combining finite element analysis with multi-body dynamics was developed. During the nano-hexapod's detailed design phase, a hybrid modeling approach combining finite element analysis with multi-body dynamics was developed.