Decentralized DVDFB Control of Large Space Structures

Kobayashi, Yohji; Ikeda, Masao; Fujisaki, Yasumasa; Matsuda, Masayoshi; Kida, Takashi

doi:10.9746/sicetr1965.35.919

Cited by 7 publications

(5 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Depending on the histology and extent of disease, radiation options can range from localized fields to CSl. Stereotactic radiosurgery has been used for recurrent and newly diagnosed patients with good results (27)(28)(29).…”

Section: Pineal Tumorsmentioning

confidence: 99%

Stereotactic Radiosurgery for Brain Tumors in Pediatric Patients

Suh

Barnett

2003

Technol Cancer Res Treat

View full text Add to dashboard Cite

!3rain tumors represent the most common solid tumor in children. Fractionated radiation therapy has been an important treatment modality in the mUlti-disciplinary management of these tumors. Stereotactic radiosurgery is the precise delivery of a single fraction of radiation and has been an important treatment option for adult brain tumor patients. Although the use of stereotactic radiosurgery in pediatric brain tumors is much less frequent, it represents an important alternative for patients with recurrent, surgically inaccessible or radioresponsive tumors. This article will review the results and logistical issues of this modality in the management of pediatric brain tumors.Key words: Radiosurgery, pediatric brain tumors. IntroductionBrain tumors represent the most common solid tumor in children and account for approximately 20% of all childhood malignancies. Radiation therapy has been an important treatment modality in the multi-disciplinary management of these tumors.Stereotactic radiosurgery (SRS) is a conformal radiation technique that has been used frequently in adult patients to treat a variety of intracranial tumors, functional disorders, and vascular malformations. Unlike conventional radiotherapy, SRS enables the neurosurgeon and radiation oncologist to deliver a high, single dose of radiation to a precisely defined radiographic target to stop tumor growth while minimizing the dose to the surrounding normal tissue. The technique has been criticized, though, over concerns' about single fraction treatment and the potential for normal tissue damage. Given these concerns, the use of stereotactic radiotherapy or fractionated SRS has been advocated for some tumors based on histology, size and location. This approach combines the radiobiologic advantages of fractionation with the precision of radiosurgery.Based on the extensive literature regarding the use of SRS in adult patients, this modality has been used for some pediatric brain tumors. The use of SRS for such tumors is particularly appealing for patients with recurrent, surgicaIly inaccessible, or radioresponsive tumors. This article will review the results of SRS in pediatric patients with brain tumors. MedulloblastomasMedulloblastomas account for 15% to 20% of all primary pediatric central nervous system (CNS) tumors and 40% of all posterior fossa pediatric tumors. Following maximal surgical resection, optimal management includes cran-

show abstract

Section: Pineal Tumorsmentioning

confidence: 99%

Stereotactic Radiosurgery for Brain Tumors in Pediatric Patients

Suh

Barnett

2003

Technol Cancer Res Treat

View full text Add to dashboard Cite

show abstract

“…where I ni ∈ R ni×ni denotes an identity matrix of the n i -th order. Here, we should note that the closed-loop subsystem in which the augmented system (15) is controlled by feedback 7, is equivalent to the substructure controlled by the local proper controller (8). Now, we present the following theorem for optimality of the closed-loop subsystem composed of the augmented system (15) and the control law (7).…”

Section: Optimal Control Of Closed-loop Subsystemmentioning

confidence: 97%

“…5,8) They make closed-loop subsystems and an overall closed-loop system not only robustly stable against uncertainty of characteristic parameters such as mass, damping, and stiff-ness, but also optimal for quadratic cost functions. 4,8,9) However, for implementation of DVDFB, velocity sensors need to be added to displacement sensors. For reduction of cost, it is desired not to use such velocity sensors.…”

Section: Introductionmentioning

confidence: 99%

Decentralized Robust Optimal Control of Large Flexible Space Structures by Fourth Order Local Proper Controllers Using Displacement Output

Igawa

Kobayashi

2016

AEROSPACE TECHNOLOGY JAPAN

Self Cite

View full text Add to dashboard Cite

This paper considers position and attitude control of large flexible space structures composed of a number of subsystems(substructures) under the assumption of sensors and actuators collocation. The purpose of this paper is to propose a decentralized control scheme with fourth order local proper controllers using displacement/angle output, which makes both each closed-loop subsystem and an overall closed-loop system not only robustly stable but also optimal for quadratic cost functions. We first introduce a fourth order local proper controller for stabilizing each subsystem using only displacement/angle output. Then, we show each closedloop subsystem becomes not only robustly stable against uncertain characteristic parameters such as mass, damping, and stiffness, but also optimal for a quadratic cost function by choosing parameters of each local proper controller appropriately. After stabilizing and optimizing each subsystem, we interconnect the closed-loop subsystems by flexible links to obtain an overall closed-loop system, and we show the overall closed-loop system also becomes robustly stable and optimal for a quadratic cost function. Finally, numerical examples are presented to show effectiveness of the proposed method.

show abstract

“…As a method for position and attitude control of flexible space structures such as solar power satellites [1], direct velocity and displacement feedback (DVDFB) [2], [3] has been proposed under the assumption of sensors/actuators collocation. DVDFB can robustly stabilize a closed-loop system and make it optimal.…”

Section: Introductionmentioning

confidence: 99%

Robust optimal control of flexible space structures by a fourth-order proper controller using displacement output

Igawa

Kobayashi

2014

2014 IEEE/SICE International Symposium on System Integration

Self Cite

View full text Add to dashboard Cite

This paper considers robust optimal control of flexible space structures with collocated sensors and actuators. First, we introduce a fourth-order low-pass filter of which relative degree is 1 at each input channel. Then, we temporally feed back output of the filter, displacement and velocity output of the structure to input of the filter, so that we obtain a fourthorder proper controller using only displacement output. By choosing parameters of the proper controller as the controller becomes a phase lead compensator, the closed-loop system becomes robustly stable against uncertainty of characteristic parameters of the structures such as mass, damping, and stiffness. The purpose of this paper is to show the closed-loop system can be made not only robustly stable but also optimal for a quadratic cost function by making two feedback gains of the proper controller sufficiently large. I. INTRODUCTIONAs a method for position and attitude control of flexible space structures such as solar power satellites [1], direct velocity and displacement feedback (DVDFB) [2],[3] has been proposed under the assumption of sensors/actuators collocation. DVDFB can robustly stabilize a closed-loop system and make it optimal. However, both displacement sensors and velocity sensors are needed to implement DVDFB. For reduction of cost, it is desired not to use velocity sensors. To solve this issue, dynamic displacement feedback (DDFB) has been proposed [4] under the assumption that sensors and actuators are collocated. DDFB can also robustly stabilize a closed-loop system. However, DDFB has been proposed as a theoretical scheme in [4] so that it has not been shown how to determine quantitatively the parameters of a DDFB controller.The purpose of this paper is to propose a control method that makes a closed-loop system not only robustly stable but also optimal by introducing a fourth-order controller using only displacement output. We show the closed-loop system becomes robustly stable if the parameters of the proper controller are chosen to make the controller a phase lead compensator to resonant frequencies of the structure. Furthermore, we also show the closed-loop system becomes optimal for a quadratic cost function if two gains of the controller are chosen sufficiently large.

show abstract

Decentralized DVDFB Control of Large Space Structures

Cited by 7 publications

References 1 publication

Stereotactic Radiosurgery for Brain Tumors in Pediatric Patients

Stereotactic Radiosurgery for Brain Tumors in Pediatric Patients

Decentralized Robust Optimal Control of Large Flexible Space Structures by Fourth Order Local Proper Controllers Using Displacement Output

Robust optimal control of flexible space structures by a fourth-order proper controller using displacement output

Contact Info

Product

Resources

About