Online payload estimation for the control of underactuated mechanical systems

Yu-Sheng Lu,Hua-Hsu Chiu 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.7

This paper presents a payload estimation scheme for underactuated robotic manipulators with passive joints that are not driven by actuators. In the proposed scheme, only the payload, which can be quite uncertain when a robot performs various tasks, is estimated, becausethe manipulator’s electrical and other mechanical parameters are generally known in advance. In comparison to other adaptiveschemes for underactuated robotic manipulators, the proposed scheme produces satisfactory transient performance and also reduces thecomputational burden in real-time implementation. The proposed estimation law is also based on the theory of Variable Structure Systems. In contrast to existing adaptation laws that have an integral form, the proposed law estimates uncertain payload using lowpass filteringof a switching signal that is always bounded, which avoids the parameter-drifting problem that is often encountered when using theprevious integral laws. Real-time experiments are conducted using an inverted pendulum and the experimental results demonstrate thefeasibility and effectiveness of the proposed scheme.

Path Loss Exponent Estimation for Indoor Wireless Sensor Positioning

( Yu-sheng Lu ),( Chin-feng Lai ),( Chia-cheng Hu ),( Yueh-min Huang ),( Xiao-hu Ge ) 한국인터넷정보학회 2010 KSII Transactions on Internet and Information Syst Vol.4 No.3

Rapid developments in wireless sensor networks have extended many applications, hence, many studies have developed wireless sensor network positioning systems for indoor environments. Among those systems, the Global Position System (GPS) is unsuitable for indoor environments due to Line-Of-Sight (LOS) limitations, while the wireless sensor network is more suitable, given its advantages of low cost, easy installation, and low energy consumption. Due to the complex settings of indoor environments and the high demands for precision, the implementation of an indoor positioning system is difficult to construct. This study adopts a low-cost positioning method that does not require additional hardware, and uses the received signal strength (RSS) values from the receiver node to estimate the distance between the test objects. Since many objects in indoor environments would attenuate the radio signals and cause errors in estimation distances, knowing the path loss exponent (PLE) in an environment is crucial. However, most studies preset a fixed PLE, and then substitute it into a radio propagation loss model to estimate the distance between the test points; such method would lead to serious errors. To address this problem, this study proposes a Path Loss Exponent Estimation Algorithm, which uses only four beacon nodes to construct a radio propagation loss model for an indoor environment, and is able to provide enhanced positioning precision, accurate positioning services, low cost, and high efficiency.

An improved backstepping design for the control of an underactuated inverted pendulum

Yu-Sheng Lu,Hua-Hsu Chiu,Shu-Fen Lien 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.3

This paper presents an improved backstepping design (IBD) for the control of a new type of underactuated inverted pendulum. The characteristics and possible applications of the inverted pendulum are presented. Nonlinear models and a linearized model are given for a straightforward explanation of its dynamic features. The conventional backstepping design (CBD) is revisited for this plant. The IBD is then used to reduce the complexity of the design and to allow the specification of transient characteristics, to improve the system’s performance. Experimental studies are conducted to investigate the effectiveness of the proposed scheme.

Low-Frequency Compensation of Piezoelectric Accelerometers for Motion Control Systems

Lu Yu-Sheng,Lu Chun-Wei 대한전기학회 2021 Journal of Electrical Engineering & Technology Vol.16 No.4

This paper describes how piezoelectric accelerometers can be applied to motion control systems for performance enhancements. Piezoelectric accelerometers are known for their wide frequency ranges to sense dynamic acceleration. However, they are unable to measure static and quasi-static acceleration. Since positional sensors generally exist in motion control systems, this paper presents two acceleration observers that fuse piezoelectric accelerometers and positional sensors and are able to achieve high-quality observation of acceleration, including static and quasi-static components. The proposed observers are applied to a robotic manipulator, and experimental results confi rm feasibility and eff ectiveness of the proposed acceleration observers.

A Stability-Guaranteed Integral Sliding Disturbance Observer for Systems Suffering from Disturbances with Bounded First Time Derivatives

Yu-Sheng Lu,Chien-Wei Chiu 제어·로봇·시스템학회 2011 International Journal of Control, Automation, and Vol.9 No.2

This paper presents an integral sliding disturbance observer (I-SDOB) to compensate for unknown disturbances for a class of nonlinear systems. To guarantee the existence of a sliding mode for disturbance estimation, the proposed I-SDOB needs only a small switching gain compared with conventional sliding disturbance observers, which leads to further alleviation of chatter. Moreover, the stability analysis of the controller-observer system is given based on the Lyapunov theory. Applica-tions of the proposed scheme to a two-link robotic manipulator have been conducted, and experimental results confirm the effectiveness of the proposed scheme.

Silencing of PDK1 Gene Expression by RNA Interference Suppresses Growth of Esophageal Cancer

Yu, Jing,Chen, Kui-Sheng,Li, Ya-Nan,Yang, Juan,Zhao, Lu Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.8

The current study was conducted to explore the inhibitory effects of a small interfering RNA (siRNA) on 3-phosphoinositide-dependent protein kinase 1 (PDK1) expression in esophageal cancer 9706 (EC9706) cells and the influence on their biological behavior. After transfection of a synthesized PDK1 siRNA, PDK1 mRNA and protein expression and the phosphorylation level of the downstream Akt protein were assessed using RT-PCR and Western blot analysis. Proliferation, apoptosis, cell invasion and in vivo tumor formation capacity were also investigated using MTT, flow cytometry, Transwell invasion trials, and nude mouse tumor transplantion, respectively. PDK1 siRNA effectively suppressed PDK1 mRNA and protein expression, and down-regulated the phosphorylation level of the Akt protein in the EC9706 cells (P < 0.05). It also inhibited cell proliferation and invasion, and promoted apoptosis; such effects were particularly obvious at 48 h and 72 h after transfection (P < 0.05). Growth of transplanted tumors was inhibited in nude mice, with decreased PDK1 expression in tumor tissues. PDK1 may be closely correlated with proliferation, apoptosis and invasion of esophageal cancer cells and thus may serve as an effective target for gene therapy.

The Stability Issue of the Voltage Regulators Using a Ripple-Based Constant On-Time Controller with DC Offset-Correction Circuit

Yu-Hsuan Lu,Dan Chen,Sheng-Fu Hsiao,Ching-Jan Chen,Hung-Shou Nien 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

In recent years, the ripple-based constant on-time (RBCOT) control scheme for voltage regulators has been adopted in many applications because of its high efficiency feature under light-load conditions. However, a RBCOT control suffers from output-voltage offset problem. Therefore, an offset correction circuit (OC) is often added to the basic RBCOT scheme to correct the problem. In the OC circuit, there is a RC filter. The size of this RC filter not only affects the circuit stability and converter transient responses but also directly affects the controller chip size/cost. The main focus of the present paper is to investigate the relationship between the RC filter value and the feedback stability so that RC value can be minimized while avoiding circuit instability. A time-domain analysis approach is proposed to model OCRBCOT scheme for a buck converter configuration. Experimental and simulation results are given for verification.

Promoting effect of the Maillard reaction products produced during the stir-frying process of Hordei Fructus Germinatus on the intestinal absorption of active ingredients in Hordei Fructus Germinatus

Lu Wu,Li Xia Tan,Fen Fang Gong,Yu Xia,Rui Ge Chu,Hua Sheng Yang 한국식품과학회 2021 Food Science and Biotechnology Vol.30 No.5

This study was designed to evaluate theabsorption promoting capacity of Maillard Reaction Products(MRPs) produced during the stir-frying process ofHordei Fructus Germinatus on catechin, ferulic acid,quercetin and kaempferol by the ex vivo rat everted gut sacmodel, in situ single-pass intestinal perfusion model andthe whole animal model. Moreover, verapamil, EDTA andmannitol were used for determining the transport mechanismof catechin, ferulic acid, quercetin and kaempferol. The tight junction (TJ) proteins including zonula occudens-1(ZO-1) and claudin-1 were chosen to investigate thepromoting mechanism of MRPs by quantitative real-timePCR (qRT-PCR) and western blot analyses. The resultsshowed that the MRPs produced during the stir-fryingprocess of Hordei Fructus Germinatus could improve theintestinal absorption of catechin, ferulic acid, quercetin andkaempferol. And the absorption-promoting effect of MRPswas related to chelating effect and the reduced expressionof claudin-1 and ZO-1. Our results suggested that MRPscould be promising oral absorption promoters, which mightbe another processing mechanism of Hordei FructusGerminatus.

Effect of Portal Vein Chemotherapy on Liver Metastasis after Surgical Resection of Colorectal Cancer

Yu, Dong-Sheng,Li, Ying,Huang, Xin-En,Lu, Yan-Yan,Wu, Xue-Yan,Liu, Jin,Cao, Jie,Xu, Xia,Xiang, Jin,Wang, Guo-Ping Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.9

Objective: To explore the effect of portal vein chemotherapy on liver metastasis after surgical resection of colorectal cancer. Methods: Patients fulfilling the eligibility criteria were assigned to receive either surgery plus 1-week continuous infusion of 5-FU (study group) or surgery alone (observational group). Patients in the study group received portal vein chemotherapy, whereby 5-FU (1000 mg/d) and heparin (5000 IU/d) infusion was initiated from the day of surgery and lasted for 7 consecutive days. Liver metastasis was monitored during five years follow-up postoperatively. Results: Sixty four patients were recruited and assigned to the study group (12 with colon and 20 with rectal cancer) or the control group (10 with colon and 22 with rectal cancer). Liver metastasis rate was 12.5% in study and 25.0% in observational group, the difference being significant (P<0.01). Conclusion: Portal vein chemotherapy could be an effective treatment in preventing liver metastasis after surgical resection of colorectal cancer.

A High-efficiency Method to Suppress Transformer Core Imbalance in Digitally Controlled Phase-shifted Full-bridge Converter

Yu, Juzheng,Qian, Qinsong,Sun, Weifeng,Zhang, Taizhi,Lu, Shengli The Korean Institute of Power Electronics 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.3

A high-efficiency method is proposed to suppress magnetic core imbalance in phase-shifted full-bridge (PSFB) converters. Compared with conventional solutions, such as controlling peak current mode (PCM) or adding DC blocking capacitance, the proposed method has several advantages, such as lower power loss and smaller size, because the additional current sensor or blocking capacitor is removed. A time domain model of the secondary side is built to analyze the relationship between transformer core imbalance and cathode voltage of secondary side rectifiers. An approximate control algorithm is designed to achieve asymmetric phase control, which reduces the effects of imbalance. A 60 V/15 A prototype is built to verify the proposed method. Experimental results show that the numerical difference of primary side peak currents between two adjacent cycles is suppressed from 2 A to approximately 0 A. Meanwhile, compared with the PCM solution, the efficiency of the PSFB converter is slightly improved from 93% to 93.2%.