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ADAPTIVE FEEDFORWARD CONTROL OF A STEER-BY-WIRE SYSTEM BY ONLINE PARAMETER ESTIMATOR
Xiaodong Wu,Mingming Zhang,Min Xu,Yo Kakogawa 한국자동차공학회 2018 International journal of automotive technology Vol.19 No.1
The tracking control of the steer-by-wire (SBW) system to achevie desired steering motion is the core issue for the design of algorithm. Most of model-based tracking control assumed the constant parameters without the consideration of dynamic characteristics. The external disturbances and model nonlinearities can bring uncertainties of the system parameters. To reduce the influence of parameter uncertainties, an online estimator by output error identification method is proposed to estimate the dynamic parameters of a SBW system. Meanwhile, the parameter gradient projection method is applied to eliminate the parameter drift, while a full order state observer is developed to weaken the effects of noise disturbance during the parameter identification. Since the sensitivity of parameter uncertainties for the feedforward control, the online estimator is incorporated into the control model and improve the controlled robustness. The proposed adaptive feedforward controller is conducted by the real-time experiments to show the tracking performance.
Xiaodong Wu,Jiale Qin,Tao Shen,Weidong Fei,Lili Chen,Xing Xie,Weiguo Lu 대한부인종양학회 2020 Journal of Gynecologic Oncology Vol.31 No.4
Objective: To assess the outcomes and toxic effects of 5-day actinomycin D (Act-D) salvagetherapy and to explore the predictors of Act-D resistance in patients with low-risk gestationaltrophoblastic neoplasia (GTN)who failed 5-day methotrexate (MTX) chemotherapy. Methods: This retrospective study analyzed patients with low-risk GTN administered Act-Dsalvage therapy after failing MTX chemotherapy at Women's Hospital, School of MedicineZhejiang University between January 2000 and December 2015. The clinical parameters ofthese patients were collected and analyzed. Results: The final analysis included 89 cases. Of these, 73 cases (82.02%) responded tosalvage Act-D. The remaining 16 resistant cases were switched to etoposide, MTX, Act-D/cyclophosphamide, and vincristine chemotherapy and achieved complete remission. Serumhuman chorionic gonadotrophin levels before Act-D salvage therapy (hCGAct-D)in the Act-D resistant cases were significantly higher than those in the Act-D responders (median 605 vs. 103 IU/L, p=0.009). However, the range of hCGAct-D values in Act-D responders was wider thanthat in Act-D-resistant cases (5.76–16,664 IU/L vs. 11.43–6,732 IU/L). Thus, assigning a generalcut-off value was difficult considering the individual setting. Except for 2 cases requiring othersalvage regimens due to Act-D toxicity, 97.80% of cases (89/91) tolerated the toxicity. During atleast 1-year follow-up, the survival rate was 100.00% and no case developed recurrence. Conclusion: Based on the good therapeutic effect and tolerable toxicity, we recommendAct-D salvage therapy for all patients with low-risk GTN who fail primary MTX chemotherapy. The higher serum hCG levels before Act-D salvage therapy may be associated with resistanceto this treatment.
The Optimization of Truss Structures with Genetic Algorithms
Wu, Houxiao,Luan, Xiaodong,Mu, Zaigen 한국공간구조학회 2005 한국공간구조학회지 Vol.5 No.3
This paper investigated the optimum design of truss structures based on Genetic Algorithms (GA's). With GA's characteristic of running side by side, the overall optimization and feasible operation, the optimum design model of truss structures was established. Elite models were used to assure that the best units of the previous generation had access to the evolution of current generation. Using of non-uniformity mutation brought the obvious mutation at earlier stage and stable mutation in the later stage; this benefited the convergence of units to the best result. In addition, to avoid GA's drawback of converging to local optimization easily, by the limit value of each variable was changed respectively and the genetic operation was performed two times, so the program could work more efficiently and obtained more precise results. Finally, by simulating evolution process of nature biology of a kind self-organize, self-organize, artificial intelligence, this paper established continuous structural optimization model for ten bars cantilever truss, and obtained satisfactory result of optimum design. This paper further explained that structural optimization is practicable with GA's, and provided the theoretic basis for the GA's optimum design of structural engineering.
A Control Method to Make LQR Robust: A Planes Cluster Approaching Mode
Xiaodong Liu,Yunjie Wu,Yu Zhang,Song Xiao 제어·로봇·시스템학회 2014 International Journal of Control, Automation, and Vol.12 No.2
Linear quadratic regulator (LQR) is an optimal controller being used for linear systems, and it can minimize the comprehensive quadratic performance index (QPI) with respect to convergence error and control consumption. However, LQR lacks the robust property to cope with parameter perturbations and external disturbances. Aiming at the above deficiency of LQR, a robust LQR (RLQR) is proposed for linear systems under the guideline of planes cluster approaching mode (PCAM). In the proposed RLQR, one nonlinear item is introduced into control law, and it cooperates with the other linear item to guarantee the global asymptotic stability in the presence of equivalent disturbances. The conditions of global asymptotic stability are deduced by the method of Lyapunov function. Simulation results present that, the chosen LTI plant using RLQR possesses smaller QPI in the existence of time-varying disturbances, compared with the conventional LQR and sliding mode controller (SMC).
Genome-wide scan for runs of homozygosity identifies candidate genes in Wannan Black pigs
Wu Xudong,Zhou Ren,Zhang Wei,Cao Bangji,Xia Jingjing,Wang Caiyun,Zhang Xiaodong,ChuMing-Xing,Yin Zongjun,Ding Yueyun 아세아·태평양축산학회 2021 Animal Bioscience Vol.34 No.12
Objective: Runs of homozygosity (ROH) are contiguous lengths of homozygous genotypes that can reveal inbreeding levels, selection pressure, and mating schemes. In this study, ROHs were evaluated in Wannan Black pigs to assess the inbreeding levels and the genome regions with high ROH frequency.Methods: In a previous study, we obtained 501.52 GB of raw data from resequencing (10×) of the genome and identified 21,316,754 single-nucleotide variants in 20 Wannan Black pig samples. We investigated the number, length, and frequency of ROH using resequencing data to characterize the homozygosity in Wannan Black pigs and identified genomic regions with high ROH frequencies.Results: In this work, 1,813 ROHs (837 ROHs in 100 to 500 kb, 449 ROHs in 500 to 1,000 kb, 527 ROHs in >1,000 kb) were identified in all samples, and the average genomic inbreeding coefficient (FROH) in Wannan Black pigs was 0.5234. Sixty-one regions on chromosomes 2, 3, 7, 8, 13, 15, and 16 harbored ROH islands. In total, 105 genes were identified in 42 ROH islands, among which some genes were related to production traits.Conclusion: This is the first study to identify ROH across the genome of Wannan Black pigs, the Chinese native breed of the Anhui province. Overall, Wannan Black pigs have high levels of inbreeding due to the influence of ancient and recent inbreeding due to the genome. These findings are a reliable resource for future studies and contribute to save and use the germplasm resources of Wannan Black pigs. Objective: Runs of homozygosity (ROH) are contiguous lengths of homozygous genotypes that can reveal inbreeding levels, selection pressure, and mating schemes. In this study, ROHs were evaluated in Wannan Black pigs to assess the inbreeding levels and the genome regions with high ROH frequency. Methods: In a previous study, we obtained 501.52 GB of raw data from resequencing (10×) of the genome and identified 21,316,754 single-nucleotide variants in 20 Wannan Black pig samples. We investigated the number, length, and frequency of ROH using resequencing data to characterize the homozygosity in Wannan Black pigs and identified genomic regions with high ROH frequencies. Results: In this work, 1,813 ROHs (837 ROHs in 100 to 500 kb, 449 ROHs in 500 to 1,000 kb, 527 ROHs in >1,000 kb) were identified in all samples, and the average genomic inbreeding coefficient (FROH) in Wannan Black pigs was 0.5234. Sixty-one regions on chromosomes 2, 3, 7, 8, 13, 15, and 16 harbored ROH islands. In total, 105 genes were identified in 42 ROH islands, among which some genes were related to production traits. Conclusion: This is the first study to identify ROH across the genome of Wannan Black pigs, the Chinese native breed of the Anhui province. Overall, Wannan Black pigs have high levels of inbreeding due to the influence of ancient and recent inbreeding due to the genome. These findings are a reliable resource for future studies and contribute to save and use the germplasm resources of Wannan Black pigs.
Xiaodong Liu,Yunjie Wu,Baiting Liu 제어·로봇·시스템학회 2012 International Journal of Control, Automation, and Vol.10 No.5
Considering sliding mode control (SMC) method using the estimation of upper bound on disturbances in motor servo system, if the upper bound is underestimated, the position tracking precision is poor. Contrarily, the control input is overlarge and even chatters violently. To solve the above problems, an adaptive sliding mode controller (ASMC) is proposed. It utilizes a fuzzy decision maker (FDM), which exports the estimation of upper bound on disturbances according to the information of position tracking error and control input. The computer simulations on a dc motor present that the proposed method guarantees satisfactory position tracking accuracy and the chattering at control input is evidently suppressed. Moreover, the output of FDM is sensitive to the changes of disturbances real-timely and precisely. Subsequently, the proposed scheme possesses strong robust performance against disturbances in motor servo system.