Sliding-mode Observers for Nonlinear Systems with Unknown Inputs and Measurement Noise

Junqi Yang,Fanglai Zhu,Wei Zhang 제어·로봇·시스템학회 2013 International Journal of Control, Automation, and Vol.11 No.5

This paper deals with the design of observers for Lipschitz nonlinear systems with not only unknown inputs but also measurement noise when the observer matching condition is not satisfied. First, an augmented vector is introduced to construct an augmented system, and an auxiliary output vector is constructed such that the observer matching condition is satisfied and then a high-gain sliding mode observer is considered to get the exact estimates of both the auxiliary outputs and their derivatives in a finite time. Second, for nonlinear system with both unknown inputs and measurement noise, an adaptive robust sliding mode observer is developed to asymptotically estimate the system’s states, and then an unknown input and measurement noise reconstruction method is proposed. Finally, a numerical simulation example is given to illustrate the effectiveness of the proposed methods.

An uncertainty representation based sampling method for metamodeling in auto-motive design applications

Junqi Yang,Zhenfei Zhan,Kai Zheng,Chong Chen,Jie Hu,Ling Zheng 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.10

Meta-model is frequently employed as the surrogate of high-fidelity finite element models in computer aided engineering. It helps to achieve the trade-off between computational efficiency and predictive accuracy. To improve the predictive capability of meta-models, we developed an uncertainty representation based sampling method to schedule Design of experiment (DOE) for meta-modeling. Several datasets were first generated through a modified Bootstrap method for datasets acquisition, then the influence of the input uncertainty on the output was quantified as weighting factors. The weighting factors were used to integrate the represented distributions into a single one for further sampling. Finally, the sampling results then served as the elements of the DOE matrix to construct meta-models. The proposed method was demonstrated through an analytical case and a real-world vehicle crashworthiness design problem.

Observer-based Stabilization of Uncertain Switched Linear Systems with Admissible Edge-dependent Switching Signals

Junqi Yang,Ying Qiao,Xuhui Bu,Zhiguo Hu 제어·로봇·시스템학회 2021 International Journal of Control, Automation, and Vol.19 No.8

This paper focuses on the stabilization of a class of uncertain switched linear systems with admissible edge-dependent (AED) switching signals, where disturbances exist in not only the state equation but also output equation. The performance of switchings from the current system mode to the other is shown by the concept of admissible transition edge-dependent weights (ATEWs). A special output transformation is adopted to construct a new system with the same states as the original system but different output, where the disturbance in measurement equation is decoupled. Then, a multiple-mode unknown input observer (UIO) with AED switching is proposed to simultaneously estimate the state and disturbance. Next, an observer-based controller is developed to stabilize the uncertain switched system, then the conditions ensuring the stability of the closed-loop system are provided. Finally, the validity of the proposed method is shown by an example.

Multiple-mode Adaptive State Estimator for Nonlinear Switched Systems

Junqi Yang,Yantao Chen,Lizhi Cui 제어·로봇·시스템학회 2017 International Journal of Control, Automation, and Vol.15 No.4

This paper deals with the issue of state estimator design for nonlinear switched systems. A multiplemodeadaptive estimator is proposed under mode-dependent average dwell time (MDADT) switching, and theswitching signal with MDADT constraint is also obtained to guarantee the exponential stability of estimation errordynamics, where the Lipschitz constant may be unknown since it is adaptively adjusted by designing an adaptationlaw. Based on both Lyapunov stable theory and the feasible solution of an optimization problem with linear matrixinequality constraint, the gain matrices and switching signals are provided, respectively. The sufficient conditionsof the existence of multiple-mode adaptive switched estimator are also derived. Meanwhile, the above methodsare also extended to the case of the average dwell time (ADT) switching, and an algorithm is given to summarizethe implementation of the proposed estimators. Finally, the effectiveness of the designed methods is illustrated bysimulation examples.

Robust Sliding-mode Observer-based Sensor Fault Estimation, Actuator Fault Detection and Isolation for Uncertain Nonlinear Systems

Junqi Yang,Fanglai Zhu,Xin Wang,Xuhui Bu 제어·로봇·시스템학회 2015 International Journal of Control, Automation, and Vol.13 No.5

This paper deals with the issues of sensor fault estimation, actuator fault detection and isolation for a class of uncertain nonlinear systems. By taking the sensor fault vector as a part of an extended state vector, the original system with sensor faults, actuator faults and unknown inputs is transformed into an augmented singular system which is just with actuator faults and unknown inputs. For the constructed singular system, a robust sliding-mode observer is developed to simultaneously estimate the states and sensor faults of original system, and the observer gain matrices are computed in terms of linear matrix inequalities by solving an optimization problem. Then an actuator fault detector is designed to detect actuator faults when ones occur, and multiple observers used as actuator fault isolators are proposed to identify which actuator is with fault. Finally, a simulation example is given to illustrate the effectiveness of the proposed methods.

Enhancing Performances of Polyamide 66 Short Fiber/Natural Rubber Composites via In Situ Vulcanization Reaction

Zhi Hao,Junqi Shen,Xiang Sheng,Zong Shen,Le Yang,Xuefeng Lu,Zhu Luo,Qiang Zheng 한국섬유공학회 2020 Fibers and polymers Vol.21 No.2

This paper details a new method for improving the interfacial bonding between PA66 short fiber (PSF) and natural rubber (NR) by reaction of the methacrylic acid (MAA)-grafting-modified PSF with rubber during vulcanization. Carboncarbon double bonds introduced to the SF surface by MAA grafting were opened, and a vulcanization reaction occurred between the modified PSF and rubber in the presence of sulfur. The chemical reactions were verified by FTIR and XPS. The processing rheological behaviors of the compounded composites were investigated by a rubber processing analyzer (RPA). The morphology of modified PSF was characterized by AFM and SEM. The improved interfacial bonding was confirmed by DMA, which enhanced deformational stress at definite elongation of the NR/PSF composites. The volume concentration of the MAA solution for grafting on the SF surface had a great influence on the interfacial bonding and mechanical properties of the composites; when the volume concentration was 30 %, the modified PSF-reinforced NR/CB had the best interfacial bonding and mechanical properties.

IL28B Is Associated with Outcomes of Chronic HBV Infection

Xiaodong Shi,Junqi Niu,Xiumei Chi,Yu Pan,Yanhang Gao,Wanyu Li,Chen Yang,Jin Zhong,Damo Xu,Manna Zhang,Gerald Minuk,Jing Jiang 연세대학교의과대학 2015 Yonsei medical journal Vol.56 No.3

Purpose: The role of IL28B gene variants and expression in hepatitis B virus (HBV) infections are not well understood. Here, we evaluated whether IL28B gene expression and rs12979860 variations are associated with HBV outcomes. Materialsand Methods: IL28B genetic variations (rs12979860) were genotyped by pyrosequencingof DNA samples from 137 individuals with chronic HBV infection [50 inactive carriers (IC), 34 chronic hepatitis B (CHB), 27 cirrhosis, 26 hepatocellular carcinoma (HCC)], and 19 healthy controls. IL28A/B mRNA expression in peripheralblood mononuclear cells was determined by qRT-PCR, and serum IL28B proteinwas measured by ELISA. Results: Patients with IL28B C/C genotype had greater IL28A/B mRNA expression and higher IL28B protein levels than C/T patients. Within the various disease stages, compared to IC and healthy controls, IL28B expression was reduced in the CHB, cirrhosis, and HCC cohorts (CHB vs. IC, p=0.02; cirrhosis vs. IC, p=0.01; HCC vs. IC, p=0.001; CHB vs. controls, p<0.01; cirrhosis vs. controls, p<0.01; HCC vs. controls, p<0.01). When stratified with respect to serum HBV markers in the IC and CHB cohorts, IL28B mRNA and protein levels were higher in HBeAg-positive than negative individuals (p=0.01). Logistic regression analysis revealed that factors associated with high IL28B proteinlevels were C/C versus C/T genotype [p=0.016, odds ratio (OR)=0.25, 95% confidence interval (CI)=0.08‒0.78], high alanine aminotransferase values (p<0.001, OR=8.02, 95% CI=2.64‒24.4), and the IC stage of HBV infection (p<0.001). Conclusion: Our data suggest that IL28B genetic variations may play an important role in long-term development of disease in chronic HBV infections.

Primary Invasive Mucinous Adenocarcinoma of the Lung: Prognostic Value of CT Imaging Features Combined with Clinical Factors

Wang Tingting,Yang Yang,Liu Xinyue,Deng Jiajun,Wu Junqi,Hou Likun,Wu Chunyan,She Yunlang,Sun Xiwen,Xie Dong,Chen Chang 대한영상의학회 2021 Korean Journal of Radiology Vol.22 No.4

Objective: To investigate the association between CT imaging features and survival outcomes in patients with primary invasive mucinous adenocarcinoma (IMA). Materials and Methods: Preoperative CT image findings were consecutively evaluated in 317 patients with resected IMA from January 2011 to December 2015. The association between CT features and long-term survival were assessed by univariate analysis. The independent prognostic factors were identified by the multivariate Cox regression analyses. The survival comparison of IMA patients was investigated using the Kaplan-Meier method and propensity scores. Furthermore, the prognostic impact of CT features was assessed based on different imaging subtypes, and the results were adjusted using the Bonferroni method. Results: The median follow-up time was 52.8 months; the 5-year disease-free survival (DFS) and overall survival rates of resected IMAs were 68.5% and 77.6%, respectively. The univariate analyses of all IMA patients demonstrated that 15 CT imaging features, in addition to the clinicopathologic characteristics, significantly correlated with the recurrence or death of IMA patients. The multivariable analysis revealed that five of them, including imaging subtype (p = 0.002), spiculation (p < 0.001), tumor density (p = 0.008), air bronchogram (p < 0.001), emphysema (p < 0.001), and location (p = 0.029) were independent prognostic factors. The subgroup analysis demonstrated that pneumonic-type IMA had a significantly worse prognosis than solitary-type IMA. Moreover, for solitary-type IMAs, the most independent CT imaging biomarkers were air bronchogram and emphysema with an adjusted p value less than 0.05; for pneumonic-type IMA, the tumors with mixed consolidation and ground-glass opacity were associated with a longer DFS (adjusted p = 0.012). Conclusion: CT imaging features characteristic of IMA may provide prognostic information and individual risk assessment in addition to the recognized clinical predictors.

Quantized H∞ Control for a Class of 2-D Systems with Missing Measurements

Xuhui Bu,Jiaqi Liang,Zhongsheng Hou,Junqi Yang 제어·로봇·시스템학회 2017 International Journal of Control, Automation, and Vol.15 No.2

In this paper, the problem of quantized H¥ control is investigated for a class of 2-D systems described byRoesser model with missing measurements. The measurement missing of system state is described by a sequenceof random variables obeying the Bernoulli distribution. Meanwhile, the state measurements are quantized by logarithmicquantizer before being communicated. By introducing a new 2-D Lyapunov-like function, a sufficientcondition is derived to guarantee stochastically stable and H¥ performance of the closed-loop 2-D system, wherethe method of sector-bounded uncertainties is utilized to deal with quantization error. Based on the condition, thequantized H¥ control can be designed by using linear matrix inequality technique. A simulation example is alsogiven to illustrate the proposed method.

A Mean Field Game-Theoretic Cross-Layer Optimization for Multi-Hop Swarm UAV Communications

Tong Li,Cong Li,Chungang Yang,Junqi Shao,Yue Zhang,Lei Pang,Lizhong Chang,Lingli Yang,Zhu Han 한국통신학회 2022 Journal of communications and networks Vol.24 No.1

Unmanned aerial vehicle (UAV) multi-hop communicationnetworks are foreseen to be widely employed inboth military and civilian scenarios. However, in ultra-densescenarios with swarm UAVs, nodes are highly dynamic mobile,ultra-dense deployment and non-centralized distribution. Thesecharacteristics make the centralized resource management policynot apply. Meanwhile, existing routing protocols can’t meetthe performance challenges of high dynamic, topology and linkfrequency changes of ultra-dense scenarios with swarm UAVs. Tosolve the above challenges of resource management and routingprotocol, a cross-layer optimization method is presented witha novel mean field game (MFG) in this paper. It is based onthe cross-layer design method of the MFG theory and jointlyconsiders the power resources in the physical layer, frequencyresources in the medium access control (MAC) layer, and routingresources in the network layer. By dividing into subproblems,the original problem is solved. Meanwhile, the optimal datatransmission path can be selected through the management andallocation of frequency resources and power resources. A crosslayerresource management dynamic source routing (CLRMDSR)protocol is designed based on that which adds link qualitymeasurement. The simulation results show that the presentedCLRM-DSR with the proposed resource management schemecan improve the data packet transmission rate, reduce end-toenddelay, and lower routing overhead for the multi-hop swarmUAV communication network.