Integrated modeling methodology validation using the micro-precision interferometer testbed: assessment of closed-loop performance prediction capability

1997 ◽  
Author(s):  
J.W. Melody ◽  
G.W. Neat
Keyword(s):  
Performance Prediction ◽  
Closed Loop ◽  
Integrated Modeling ◽  
Modeling Methodology ◽  
Prediction Capability

Preliminary Optical Performance Analysis of the Space Interferometer Mission Using an Integrated Modeling Methodology

2000 ◽  
Author(s):  
Ipek Basdogan ◽  
Robert Grogan ◽  
Andy Kissil ◽  
Norbert Sigrist ◽  
Lisa Sievers
Keyword(s):  
System Design ◽  
System Modeling ◽  
Experimental Studies ◽  
Integrated Modeling ◽  
Optical Performance ◽  
Reaction Wheel ◽  
Space Interferometer ◽  
Modeling Methodology ◽  
Reference Design ◽  
The Impact

Abstract The Space Interferometer Mission (SIM) scheduled for launch in 2008, is one of the premiere missions in the Origins Program, NASA’s endeavor to understand the origins of the galaxies, of planetary systems around distant stars, and perhaps the origins of life itself. The precise tolerance required by the SIM instrument facilitates the investigation of many design options, trades, and methods for minimizing interaction between the actively controlled optics and the structure. One of the activities that addresses these technological challenges is the integrated modeling methodology development and validation at Jet Propulsion Laboratory (JPL). The methodology integrates structural, optical, and control system modeling into a common computational environment and enables end-to-end performance evaluation of complex optomechanical systems. This paper provides an overview of the integrated modeling methodology and introduces the most recent SIM Reference Design model. The SIM integrated model is used in system requirement trade studies and performance analyses to support the overall system design and ongoing error budget efforts. Optical performance in interferometry is typically measured in terms of optical pathlength difference (OPD) and differential wavefront tilt (DWT). This paper focuses on the OPD performance metric and investigates the OPD jitter resulting from reaction wheel assembly (RWA) disturbances. The RWA is the largest anticipated disturbance source on the spacecraft. Therefore, assessing the impact of the wheel disturbance frequency content and magnitude levels on the optical performance is essential for the success of the mission. Broadband and discrete frequency models of a reaction wheel are used to perform the disturbance analysis. The overall system design can benefit from such analysis results by identifying the critical regions in the frequency domain and decoupling the dynamics of the optical and structural components from the disturbance spectrum and the control bandwidth. The preliminary performance results show that the current SIM Reference Design meets the mission requirements with respect to RWA induced disturbances. However, some of the modeling assumptions and component models must be validated by experimental studies before the subsystem requirements are finalized.

scholarly journals Full-Closed-Loop Time-Domain Integrated Modeling Method of Optical Satellite Flywheel Micro-Vibration

2021 ◽  
Vol 11 (3) ◽  
pp. 1328
Author(s):  
Yang Yu ◽  
Xiaoxue Gong ◽  
Lei Zhang ◽  
Hongguang Jia ◽  
Ming Xuan
Keyword(s):  
Time Domain ◽  
Closed Loop ◽  
Modeling Method ◽  
Integrated Modeling ◽  
Frequency Error ◽  
Vibration Source ◽  
Loop Model ◽  
Model Framework ◽  
Ground Experiment ◽  
Micro Vibration

Due to the micro-vibration of flywheels, the imaging quality of a high-resolution optical remote sensing satellite will be deteriorated, and the micro-vibration effect on the payload is complicated, so it is essential to establish a reasonable and accurate theoretical simulation model for it. This paper presents a method of full-closed-loop time-domain integrated modeling to estimate the impacts of micro-vibration generated by flywheels on optical satellites. The method consists of three parts. First, according to the satellites’ micro-vibration influence mechanism in orbit, this paper establishes a full-closed-loop model framework. The overall model input is the instructions received and the output is the image shift. Second, in order to meet the requirements of time-domain simulation, this paper proposes a time-domain vibration source subsystem model in the form of cosine harmonic superposition, and it integrates vibration source, structural, control, and optical subsystem models to create a full-closed-loop time-domain analysis model that can obtain the responses of micro-vibration in time and frequency domains. Lastly, the author designs a ground experiment and compares simulation results with experiment results. Compared with the ground experiment, frequency error is less than 0.4% at typical responses. Although the amplitude error is large at some typical responses, the mean root square error is less than 35%. Based on the data, the proposed integrated modeling method can be considered as an accurate methodology to predict the impacts of micro-vibration.

scholarly journals Modeling Web Client and System Behavior

Information ◽  
2020 ◽  
Vol 11 (6) ◽  
pp. 337
Author(s):  
Tomasz Rak
Keyword(s):  
Performance Prediction ◽  
Production Systems ◽  
Performance Model ◽  
Enterprise Performance ◽  
Performance Models ◽  
Modeling Methodology ◽  
System Behaviour ◽  
Simulation Based ◽  
Significant Effort ◽  
Web Systems

Web systems are becoming more and more popular. An efficiently working network system is the basis for the functioning of every enterprise. Performance models are powerful tools for performance prediction. The creation of performance models requires significant effort. In the article, we want to present various performance models of customer and Web systems. In particular, we want to examine a system behaviour related to different flow routes of clients in the system. Therefore we propose Queueing Petri Nets, the new modeling methodology for dealing with performance issues of production systems. We follow the simulation-based approach. We consider 25 different models to check performance. Then we evaluate them based on the proposed metrics. The validation results show that the model is able to predict the performance with a relative error lower than 20%. Our evaluation shows that prepared models can reduce the effort of production system preparation. The resulting performance model can predict the system behaviour in a particular layer at the indicated load.

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