Constrained and unconstrained modes - Some modeling aspects of flexible spacecraft

Hablani, Hari B.

doi:10.2514/3.19764

Cited by 52 publications

(20 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Using the continuum modal analysis approach, the characteristics of global modes of flexible spacecraft are investigated in great detail by Hughes [14][15][16] and Hablani [17][18][19][20]. In their researches, the global and assumed modes are denoted as unconstrained and constrained modes.…”

mentioning

confidence: 99%

Studies on global analytical mode for a three-axis attitude stabilized spacecraft by using the Rayleigh–Ritz method

2016

View full text Add to dashboard Cite

With extending the Rayleigh-Ritz procedure to study the hub-plate system, the characteristics of global analytical modes are addressed for a typical rigid-flexible coupling dynamic system, i.e., a threeaxis attitude stabilized spacecraft installed with a pair of solar arrays. The displacement field of the solar arrays is expressed as a series of admissible functions which is a set of characteristic orthogonal polynomials generated directly by employing Gram-Schmidt process. The rigid body motion of spacecraft is represented by the product of constant and generalized coordinate. Then, through Rayleigh-Ritz procedure, the eigenvalue equation of the three-axis attitude stabilized spacecraft installed with a pair of solar arrays is derived. Solving this eigenvalue equation, the frequencies and analytical expressions of global modes for the flexible spacecraft are obtained. To validate the present analysis, comparisons between the results of the present method and ANSYS software are performed and very good agreement is achieved. The convergence studies demonstrate the high accuracy, excellent convergence and high efficiency of the present approach. Finally, the method is applied to study the characteristics of global modes of the flexible spacecraft.

show abstract

mentioning

confidence: 99%

Studies on global analytical mode for a three-axis attitude stabilized spacecraft by using the Rayleigh–Ritz method

2016

View full text Add to dashboard Cite

show abstract

“…is applied to the central rigid body, the dynamical equations of the spacecraft with N append described by (The detail procedure of modelling can be found in other studies [16][17]. ): where I is an identity matrix and  denotes the number of selected vibration modes for each app of the spacecraft is very small, namely, consider the translational motion of on-orbit spacecraft, but is only concerned with the rotational motion of structure.…”

Section: Equation Description Of the Rigid-flexible Coupling Spacecraftmentioning

confidence: 99%

“…ere ( ) t x is the 1 n  dimensional state vector; ( ) t A and ( ) t B are the n n  system matrix and r input matrix respectively as follows:  dimensional control torque l rigid body, the dynamical equations of the spacecraft with N appendages are edure of modelling can be found in other studies [16][17]. ):…”

mentioning

confidence: 99%

See 1 more Smart Citation

Time-varying modal parameters identification of large flexible spacecraft using a recursive algorithm

Ni¹,

Wu²,

Wu³

2016

International Journal of Aeronautical and Space Sciences

View full text Add to dashboard Cite

In existing identification methods for on-orbit spacecraft, such as eigensystem realization algorithm (ERA) and subspace method identification (SMI), singular value decomposition (SVD) is used frequently to estimate the modal parameters. However, these identification methods are often used to process the linear time-invariant system, and there is a lower computation efficiency using the SVD when the system order of spacecraft is high. In this study, to improve the computational efficiency in identifying time-varying modal parameters of large spacecraft, a faster recursive algorithm called fast approximated power iteration (FAPI) is employed. This approach avoids the SVD and can be provided as an alternative spacecraft identification method, and the latest modal parameters obtained can be applied for updating the controller parameters timely (e.g. the self-adaptive control problem). In numerical simulations, two large flexible spacecraft models, the Engineering Test Satellite-VIII (ETS-VIII) and Soil Moisture Active/Passive (SMAP) satellite, are established. The identification results show that this recursive algorithm can obtain the time-varying modal parameters, and the computation time is reduced significantly.

show abstract

“…59, No. 3, 2016 with N appendages is described by (detailed modeling procedure can be found in other studies [16][17][18][19] ): …”

Section: Equation Description Of Rigid-flexible Coupling Satellitesmentioning

confidence: 99%

Identification of Time-varying Frequencies and Model Parameters for Large Flexible On-orbit Satellites Using a Recursive Algorithm

Tan

2016

Trans. Japan Soc. Aero. S Sci.

View full text Add to dashboard Cite

Today, the primary identification methods in time domain for spacecraft are based on singular value decomposition (SVD), such as the eigensystem realization algorithm (ERA) or stochastic subspace identification (SSI), which requires significant computation time. However, some control problems, such as self-adaptive control, need the latest modal parameters to update controller parameters online. To improve computational efficiency, the fast approximated power iteration (FAPI) recursive algorithm, which avoids SVD, is applied as an alternative method to identify the time-varying frequencies of large flexible satellites. Moreover, an improved recursive form is also proposed to obtain the time-varying input matrix in a state-space model by rewriting the relation of the input and output data. In numerical simulations, the time-varying model of the Engineering Test Satellite-VIII (ETS-VIII) is established. The results illustrate that this recursive algorithm can implement time-varying parameter online identification and it has a better computational efficiency than the SVD-based methods.

show abstract

Constrained and unconstrained modes - Some modeling aspects of flexible spacecraft

Cited by 52 publications

References 16 publications

Studies on global analytical mode for a three-axis attitude stabilized spacecraft by using the Rayleigh–Ritz method

Studies on global analytical mode for a three-axis attitude stabilized spacecraft by using the Rayleigh–Ritz method

Time-varying modal parameters identification of large flexible spacecraft using a recursive algorithm

Identification of Time-varying Frequencies and Model Parameters for Large Flexible On-orbit Satellites Using a Recursive Algorithm

Contact Info

Product

Resources

About