ham-sas fabrication weekly caltech, 4/26/06 v. boschi, v. sannibale ham-sas mechanical model present...
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HAM-SAS fabrication weekly CALTECH, 4/26/06
V. Boschi, V. Sannibale
HAM-SAS Mechanical ModelPresent Status
HAM-SAS fabrication weekly CALTECH, 4/26/06
HAM-SAS Mechanical Model
We have developed a state-space model model of HAM-SAS mechanical structure using Maple
Let’s summarize the approximations used in the model:
• Lumped system, i.e. rigid body approximation
• Elastic elements are approximated using quadratic potentials, i.e. small oscillation regime
• Dissipation mechanisms are accounted using viscous damping which approximate structural/hysteretic damping in the small oscillation regime
•The system is considered symmetric enough to separate horizontal displacements x, y, and yaw from pitch, roll and vertical displacement z
•Internal modes of the mechanical structures are not accounted
Approximations
HAM-SAS fabrication weekly CALTECH, 4/26/06
HAM-SAS Mechanical Model
GAS filter representation IP representation
Horizontal and Vertical stages
HAM-SAS fabrication weekly CALTECH, 4/26/06
Horizontal stage Model Results: Trasmissibilities
HAM-SAS Mechanical Model
Transmissibility for the horizontal (blue) and yaw (red) degrees of freedom
30 mHz
IP frequency
1.2 Hz
Horizontal GAS frequency
110 Hz
Resonance frequency due to the little pendulum
30 Hz
Horizontal GAS notch frequency
HAM-SAS fabrication weekly CALTECH, 4/26/06
Vertical stage Model Results: TrasmissibilitiesHAM-SAS Mechanical Model
Transmissibility for the vertical (blue), pitch (red) and roll (green) degrees of freedom
30 mHz
GAS resonance frequency
2 Hz
GAS notch frequency
HAM-SAS fabrication weekly CALTECH, 4/26/06
Triple pendulum Model
HAM-SAS Mechanical Model
Upper mass
Intermediate mass
Test mass
HAM-SAS fabrication weekly CALTECH, 4/26/06
Triple pendulum model Results: x Trasmissibility
HAM-SAS Mechanical Model
HAM-SAS fabrication weekly CALTECH, 4/26/06
Triple pendulum model Results: z Trasmissibility
HAM-SAS Mechanical Model
HAM-SAS fabrication weekly CALTECH, 4/26/06
Triple pendulum model Results: comparison
HAM-SAS Mechanical Model
We can compare our results with a previous (2003) Mathematica model made by M. Burton
Test mass Intermediate mass Upper mass
HAM-SAS fabrication weekly CALTECH, 4/26/06
HAM-SAS Mechanical ModelTriple pendulum + Horizontal stage model Results: Trasmissibilities
HAM-SAS fabrication weekly CALTECH, 4/26/06
HAM-SAS Mechanical Model
The next steps are
• Introduce structural damping in the Triple pendulum models
• Connect the Vertical stage model to the Triple pendulum model
• Rerun our control simulations with the new models in order to optimize the feedback loops
Further developments