From 943bbe2601a93c6a571a2b5e43b704c246bbf1ed Mon Sep 17 00:00:00 2001 From: Thomas Dehaeze Date: Tue, 15 Apr 2025 17:20:12 +0200 Subject: [PATCH] Add conclusion for "experimental phase" --- phd-thesis.org | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) diff --git a/phd-thesis.org b/phd-thesis.org index 02f5d33..11e6820 100644 --- a/phd-thesis.org +++ b/phd-thesis.org @@ -12926,6 +12926,32 @@ Moreover, the systematic approach to system development and validation, along wi :END: <> +The experimental validation detailed in this chapter confirms that the Nano Active Stabilization System successfully augments the positioning capabilities of the micro-station, thereby enabling full utilization of the ESRF's new light source potential. +A methodical approach was employed—first characterizing individual components and subsequently testing the integrated system—to comprehensively evaluate the NASS performance. + +Initially, the Amplified Piezoelectric Actuators (APA300ML) were characterized, revealing consistent mechanical and electrical properties across multiple units. +The implementation of Integral Force Feedback was shown to add significant damping to the system. +Two models of the APA300ML were developed and validated: a simplified two degrees-of-freedom model and a more complex super-element extracted from finite element analysis. +Both models accurately represented the axial dynamics of the actuators, with the super-element model additionally capturing flexible modes. + +The flexible joints were examined for geometric accuracy and bending stiffness, with measurements confirming compliance with design specifications. +The experimental values demonstrated good agreement with finite element predictions, validating the joint design and enabling accurate modeling of their behavior within the system. + +The strut assembly process was optimized to ensure consistent performance across the six struts. +Dynamic testing revealed complex behavior in the transfer function from piezoelectric voltage to encoder displacement, attributed to misalignment between flexible joints and actuators. +This finding led to the strategic decision to mount encoders on the nano-hexapod plates rather than on the struts. + +The nano-hexapod was then assembled and mounted on a suspended table to characterize its dynamic behavior. +The measurement setup enabled isolation of the hexapod's dynamics from potential influence of complex support dynamics. +The experimental frequency response functions exhibited good correlation with the multi-body model, confirming that the model can be used for control system design. + +Finally, the complete NASS was validated on the ID31 beamline using a short-stroke metrology system. +The HAC-LAC control architecture successfully provided robust active damping of suspension modes and rejection of low-frequency disturbances across various payload conditions. +Comprehensive testing under typical experimental scenarios—including tomography scans, reflectivity scans, and diffraction tomography—demonstrated the NASS ability to maintain the positioning errors within specifications ($30\,\text{nm RMS}$ in lateral direction, $15\,\text{nm RMS}$ in vertical direction, and $250\,\text{nrad RMS}$ in tilt direction). +The system performed exceptionally well during vertical scans, though some limitations were identified during rapid lateral scanning and with heavier payloads. + +With the implementation of an accurate online metrology system, the NASS will be ready for integration into the beamline environment, significantly enhancing the capabilities of high-precision X-ray experimentation on the ID31 beamline. + * TODO Conclusion and Future Work <>