scholarly journals Seismic source tracking with six degree‐of‐freedom ground motion observations

2021 ◽  
Author(s):  
Shihao Yuan ◽  
Kilian Gessele ◽  
Alice‐Agnes Gabriel ◽  
Dave A. May ◽  
Joachim Wassermann ◽  
...  
Keyword(s):  
Ground Motion ◽  
Seismic Source ◽  
Degree Of Freedom ◽  
Source Tracking ◽  
Six Degree Of Freedom

Six-degree-of-freedom ground-motion measurement

1994 ◽  
Vol 84 (5) ◽  
pp. 1665-1669
Author(s):  
Robert L. Nigbor
Keyword(s):  
Ground Motion ◽  
Strong Ground Motion ◽  
Rotational Velocity ◽  
Free Field ◽  
Degree Of Freedom ◽  
Digital Data ◽  
Vertical Acceleration ◽  
Data Logger ◽  
Six Degree Of Freedom ◽  
Strong Ground

Abstract True six-degree-of-freedom (6DOF) measurement of free-field strong ground motion has been accomplished using a prototype 6DOF accelerograph system. This system consists of a traditional triaxial translational accelerometer, three new rotational velocity sensors, and a digital data logger. Rotational and translational ground motions at a single free-field location were measured successfully during the recent NPE event, a very large (1 kton) chemical explosion. Peak vertical acceleration at the near-field measurement site exceeded 1g for this event; the peak measured rotational velocity was 2.2°/sec. Earthquake strong-ground-motion measurements are currently in progress.

Iterative feedback control based on frequency response model for a six-degree-of-freedom micro-vibration platform

2021 ◽  
pp. 107754632199731
Author(s):  
He Zhu ◽  
Shuai He ◽  
Zhenbang Xu ◽  
XiaoMing Wang ◽  
Chao Qin ◽  
...  
Keyword(s):  
Feedback Control ◽  
Frequency Response ◽  
Control Strategy ◽  
Degree Of Freedom ◽  
Small Displacement ◽  
Response Model ◽  
Parameter Uncertainties ◽  
Micro Vibration ◽  
Six Degree Of Freedom ◽  
Iterative Feedback

In this article, a six-degree-of-freedom (6-DOF) micro-vibration platform (6-MVP) based on the Gough–Stewart configuration is designed to reproduce the 6-DOF micro-vibration that occurs at the installation surfaces of sensitive space-based instruments such as large space optical loads and laser communications equipment. The platform’s dynamic model is simplified because of the small displacement characteristics of micro-vibrations. By considering the multifrequency line spectrum characteristics of micro-vibrations and the parameter uncertainties, an iterative feedback control strategy based on a frequency response model is designed, and the effectiveness of the proposed control strategy is verified by performing integrated simulations. Finally, micro-vibration experiments are performed with a 10 kg load on the platform. The results of these micro-vibration experiments show that after several iterations, the amplitude control errors are less than 3% and the phase control errors are less than 1°. The control strategy presented in this article offers the advantages of a simple algorithm and high precision and it can also be used to control other similar micro-vibration platforms.

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