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Shuichi Okada,Hiroshi Tokutake,Shigeru Sunada 한국항공우주학회 2008 한국항공우주학회 학술발표회 논문집 Vol.- No.-
An observer-based disturbance estimation method was developed. The polynomial approximation of disturbance was introduced, and the observer gain was optimized so that the H-infinity norm of the estimation error was minimized. In this method, the estimated disturbance was adjusted using the estimated output error at several arbitrary time points. The proposed method was applied to aircraft dynamics and verified by numerical simulation.
Disturbance Prediction and Its Application to H<SUB>∞</SUB> Flight Control
Shuichi Okada,Hiroshi Tokutake,Shigeru Sunada 제어로봇시스템학회 2009 제어로봇시스템학회 국제학술대회 논문집 Vol.2009 No.8
An output-feedback H∞ preview controller is proposed. The controller predicts disturbance responses by considering the disturbance derivatives and generates the optimal control input that minimizeste H∞ norm of the closed-loop transfer function. By assuming a disturbance response with out a future control input, a design problem is for mulated as a standard H∞ problem. The disturbance information that the controller requires is obtained by a disturbance observer. The proposed controller is combined with the disturbance observer and applied to the flight control of the lifting-body airplane dynamics. Simulation results show the effectiveness of the proposed system.
Experimental Study on Autonomous Lifting-body Type Airplane in Osaka Prefecture University
Hiroshi Tokutake,Shuichi Okada,Shigeru Sunada 한국항공우주학회 2008 한국항공우주학회 학술발표회 논문집 Vol.- No.-
A lifting-body type reentry vehicle has several advantages; however, it lacks natural stability. Therefore, a high-performance night control system is required. Our research group working on an unmanned aerial vehicle in Osaka Prefecture University focused on the flight control system of a small lifting-body type airplane. The flight model was built and the night dynamics were modeled using wind tunnel testing. In addition, a small control board with functions for autonomous flight was developed. Next, a robust flight controller was designed, and the flight testing during landing verified the performance of the developed flight control system.
Kazuyuki Matsumoto,Hironari Kato,Shigeru Horiguchi,Takeshi Tomoda,Akihiro Matsumi,Yuki Ishihara,Yosuke Saragai,Saimon Takada,Shinichiro Muro,Daisuke Uchida,Hiroyuki Okada 거트앤리버 소화기연관학회협의회 2020 Gut and Liver Vol.14 No.5
Background/Aims: Endoscopic ultrasound (EUS)-guided fine needle aspiration (FNA; EUS-FNA) allows for diagnostic tissue specimens from various regions to be analyzed. However, diagnosing recurrent pancreaticobiliary cancer after surgery is sometimes difficult. We evaluated the efficacy of EUS-FNA in the diagnosis of local recurrence of pancreaticobiliary cancer and analyzed the factors associated with falsenegative results. Methods: Fifty-one consecutive patients who underwent EUS-FNA due to suspected recurrence of pancreaticobiliary cancer after surgery in an academic center were retrospectively analyzed. The criteria for EUS-FNA were a resected margin or remnant pancreas mass, round swollen lymph node (≥10 mm in diameter), and soft-tissue enhancement around a major artery. Patients with suspected liver metastasis or malignant ascites were excluded. Results: Thirty-nine of the 51 patients had pancreatic cancer; the remaining 12 had biliary cancer. The target sites for EUS-FNA were the soft tissue around a major artery (n=22, 43%), the resected margin or remnant pancreas (n=12, 24%), and the lymph nodes (n=17, 33%). The median size of the suspected recurrent lesions was 15 mm (range, 8 to 40 mm). The overall sensitivity, specificity and accuracy of EUS-FNA for the diagnosis of recurrence was 84% (32/38), 100% (13/13), and 88% (45/51), respectively. FNA of the soft tissue around major arteries (odds ratio, 8.23; 95% confidence interval, 1.2 to 166.7; p=0.033) was significantly associated with a falsenegative diagnosis in the multivariate analysis. Conclusions: EUS-FNA is useful for diagnosing recurrent cancer, even after pancreaticobiliary surgery. The diagnoses of recurrence at soft-tissue sites should be interpreted with caution.