Control of a Non-uniform Flexible Beam: Identification of First Two Modes

Phuong-Tung Pham,Gyoung-Hahn Kim,Quoc Chi Nguyen,Keum-Shik Hong 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.11

This paper presents an experimental study implementing the input shaping control of the first two modes of the vibration of a non-uniform flexible cantilever beam having a translating base. Examples of a moving cantilever beam appear in many industrial systems. Vibration suppression of the beam has important implications for improving the effectiveness of such systems. The equations of motion of the cantilever beam, including the moving base, are developed using the extended Hamilton principle. The partial differential equation representing the beam’s dynamics is then transformed into a finite-dimensional model using the Galerkin method. Accordingly, the modal parameter identification procedure is established based on experimental modal analysis. Under the estimated modal parameters, including the natural frequency and damping ratio, single- and two-mode input shaping controllers of three different types (zero vibration, zero vibration derivative, and zero vibration derivative-derivative) are designed for vibration suppression of the beam. Experimental results are discussed, reporting that the two-mode shaper’s vibration suppression was superior to the single-mode shaper. In contrast, the two-mode shaper’s settling time has slightly increased compared to that of the single-mode shaper.

Adaptive Control of a Flexible Varying-length Beam with a Translating Base in the 3D Space

Phuong-Tung Pham,Quoc Chi Nguyen,Junghan Kwon,Keum-Shik Hong 제어·로봇·시스템학회 2023 International Journal of Control, Automation, and Vol.21 No.3

This paper investigates a control scheme for a variable-length beam attached to a translating base under an unknown boundary disturbance. The axial beam motion is assumed pre-defined. A hybrid system consisting of a gantry, a trolley, and an expandible cantilever beam attached to the trolley is considered. Two control forces are applied to the trolley and the gantry, respectively, to position them and suppress the vibration of the beam. According to Hamilton’s principle, a nonlinear mathematical model is developed describing the dynamics of the transverse and lateral oscillations of the beam, trolley, and gantry. Based on this dynamic model, a robust adaptive control law is developed to handle the closed-loop stability of the axially moving system with unknown disturbances. Stability analysis using the Lyapunov method proves that the closed-loop system under the proposed control law is uniformly ultimately bounded. Finally, numerical simulations verify the proposed control laws’ effectiveness.

Fuzzy Inference System for Improving the Input Shaping Control for a Flexible Beam

Phuong-Tung Pham,Quoc Chi Nguyen,So-Hyeon Yoo,Keum-Shik Hong 제어로봇시스템학회 2023 제어로봇시스템학회 국제학술대회 논문집 Vol.2023 No.10

Ideal Topographic Simulations for Null Measurement Data

Yan-Jen Su,Chi-Hong Tung,Leh-Rong Chang,Jin-Liang Chen,Calvin Chang 한국정밀공학회 2008 International Journal of Precision Engineering and Vol.9 No.4

A method is described for ideally reconstructing the profile from a surface profiling measurement containing a reasonable amount of null measurement data. The proposed method can conjecture lost information and rectify irregular data that result due to bad measuring environments. signal transmission noise. or instrument-induced errors. The method adopts the concept 0/ computer graphics and consists of several processing steps. First, a search for valid data in the neighborhood of the null data is performed. The valid data are then grouped and their contours are extracted. By analyzing these contours, a bounding box can be obtained and the general distribution of the entire area encompassing the valid and null data is determined. Finally, em ideal surface model is overlaid onto the measurement results based on the bounding box, generating a complete reconstruction of the calculations. A surface-profiling task on a liquid crystal display photo spacer is used to verify the proposed method. The results are compared to those obtained through the use of a scanning electron microscope to demonstrate the accuracy of the proposed method.

Ideal Topographic Simulations for Null Measurement Data

Su, Yan-Jen,Tung, Chi-Hong,Chang, Leh-Rong,Chen, Jin-Liang,Chang, Calvin Korean Society for Precision Engineering 2008 International Journal of Precision Engineering and Vol.9 No.4

A method is described for ideally reconstructing the profile from a surface profiling measurement containing a reasonable amount of null measurement data. The proposed method can conjecture lost information and rectify irregular data that result due to bad measuring environments, signal transmission noise, or instrument-induced errors, The method adopts the concept of computer graphics and consists of several processing steps. First, a search for valid data in the neighborhood of the null data is performed. The valid data are then grouped and their contours are extracted. By analyzing these contours, a bounding box can be obtained and the general distribution of the entire area encompassing the valid and null data is determined Finally, an ideal surface model is overlaid onto the measurement results based on the bounding box, generating a complete reconstruction of the calculations, A surface-profiling task on a liquid crystal display photo spacer is used to verify the proposed method. The results are compared to those obtained through the use of a scanning electron microscope to demonstrate the accuracy of the proposed method.

Impact of Obesity on a Chinese Population with Erosive Esophagitis and Barrett`s Esophagus

( Shou-wu Lee ),( Han-chung Lien ),( Teng-yu Lee ),( Chun-fang Tung ),( Hong-zen Yeh ),( Chi-sen Chang ) 대한간학회 2017 Gut and Liver Vol.11 No.3

Background/Aims: The aim of this study was to investigate the associations between obesity and erosive esophagitis (EE) or Barrett`s esophagus (BE) in a Chinese population. Methods: Data from subjects were retrospectively collected from 2006 to 2009. Individuals with BE were identified and age- and sex-matched at a 1:2 ratio with normal esophagocardial junction and EE patients. The subjects were stratified into two groups: the normal weight group and overweight/ obesity group (body mass index ≥25 mg/m2) or the normal waist group and abdominal obesity group (waist circumference ≥90 cm for men and ≥80 cm for women). Results: Overall, 45%, 72%, and 52% were overweight/obese and 23%, 65%, and 18% had abdominal obesity in the normal, EE, and BE groups, respectively. Positive associations were identified between EE and overweight/obesity (odds ratio [OR], 3.14; 95% confidence interval [CI], 1.75 to 5.66) and abdominal obesity (OR, 6.22; 95% CI, 3.34 to 11.57); however, the associations were nonsignificant between BE and overweight/obesity (OR, 1.32; 95% CI, 0.67 to 2.61) or abdominal obesity (OR, 0.73; 95% CI, 0.31 to 1.73). Female BE patients had a significantly increased rate of being overweight/obese. Conclusions: Obesity is a contributing factor in EE. The association of BE and obesity was not significant, with the exception of female BE cases. (Gut Liver 2017;11:377-382)

Multimorbidity Pattern and Risk for Mortality Among Patients With Dementia: A Nationwide Cohort Study Using Latent Class Analysis

Che-Sheng Chu,Shu-Li Cheng,Ya-Mei Bai,Tung-Ping Su,Shih-Jen Tsai,Tzeng-Ji Chen,Fu-Chi Yang,Mu-Hong Chen,Chih-Sung Liang 대한신경정신의학회 2023 PSYCHIATRY INVESTIGATION Vol.20 No.9

Objective Individuals with dementia are at a substantially elevated risk for mortality; however, few studies have examined multimorbidity patterns and determined the inter-relationship between these comorbidities in predicting mortality risk.Methods This is a prospective cohort study. Data from 6,556 patients who were diagnosed with dementia between 1997 and 2012 using the Taiwan National Health Insurance Research Database were analyzed. Latent class analysis was performed using 16 common chronic conditions to identify mortality risk among potentially different latent classes. Logistic regression was performed to determine the adjusted association of the determined latent classes with the 5-year mortality rate.Results With adjustment for age, a three-class model was identified, with 42.7% of participants classified as “low comorbidity class (cluster 1)”, 44.2% as “cardiometabolic multimorbidity class (cluster 2)”, and 13.1% as “FRINGED class (cluster 3, characterized by FRacture, Infection, NasoGastric feeding, and bleEDing over upper gastrointestinal tract).” The incidence of 5-year mortality was 17.6% in cluster 1, 26.7% in cluster 2, and 59.6% in cluster 3. Compared with cluster 1, the odds ratio for mortality was 9.828 (95% confidence interval [CI]=6.708–14.401; p<0.001) in cluster 2 and 1.582 (95% CI=1.281–1.953; p<0.001) in cluster 3.Conclusion Among patients with dementia, the risk for 5-year mortality was highest in the subpopulation characterized by fracture, urinary and pulmonary infection, upper gastrointestinal bleeding, and nasogastric intubation, rather than cancer or cardiometabolic comorbidities. These findings may improve decision-making and advance care planning for patients with dementia.