Low Chattering Trajectory Tracking Control of Non-singular Fast Terminal Sliding Mode Based on Disturbance Observer

Jiqing Chen,Chaoyang Zhao,Qingsong Tang,Xu Liu,Zhikui Wang,Chengzhi Tan,Jiahua Wu,Teng Long 제어·로봇·시스템학회 2023 International Journal of Control, Automation, and Vol.21 No.2

The improvement of the performance of the multi-joint manipulator control system is of great significance to improve the level of industrial automation. The existing sliding mode control methods are difficult to ensure the high-precision and fast-tracking of joints of a manipulator to the desired trajectory under low chattering control input. Therefore, a non-singular fast terminal sliding mode control method based on a nonlinear disturbance observer is proposed. In addition, a new non-singular fast terminal sliding mode surface is designed. The performance comparison method of the sliding mode surface proves its better control quality. Aiming at the problem of serious chattering, the nonlinear disturbance observer technology, and saturation function method are introduced to effectively weaken the chattering. Finally, taking the 3-DOF manipulator as the research object, a comparative simulation experiment is carried out in the MATLAB / Simulink environment. The results show that under the uncertainty of modeling error, external disturbance, and joint friction, the designed control method not only solves the problems of singular control input and serious chattering but also realizes the high-precision and fast-tracking of each joint to the desired trajectory. Thus, the effectiveness and feasibility of the design method are verified. The improvement of the performance of the multi-joint manipulator control system is of great significance to improve the level of industrial automation. The existing sliding mode control methods are difficult to ensure the high-precision and fast-tracking of joints of a manipulator to the desired trajectory under low chattering control input. Therefore, a non-singular fast terminal sliding mode control method based on a nonlinear disturbance observer is proposed. In addition, a new non-singular fast terminal sliding mode surface is designed. The performance comparison method of the sliding mode surface proves its better control quality. Aiming at the problem of serious chattering, the nonlinear disturbance observer technology, and saturation function method are introduced to effectively weaken the chattering. Finally, taking the 3-DOF manipulator as the research object, a comparative simulation experiment is carried out in the MATLAB / Simulink environment. The results show that under the uncertainty of modeling error, external disturbance, and joint friction, the designed control method not only solves the problems of singular control input and serious chattering but also realizes the high-precision and fast-tracking of each joint to the desired trajectory. Thus, the effectiveness and feasibility of the design method are verified.

Quality Evaluation and Optimization of Confusion Network for LVCSR

Huanliang Wang,Jiqing Han,Tieran Zheng 한국어정보학회 2006 한국어정보학 Vol.8 No.1

Confusion network (CN) is an aligned and compact representation form of word lattice that stores median results of decoding procedure and connects the acoustic decoding and succeeding process steps. The quality of confusion network is very important for multi‐pass decoding based recognition method. Three new quality evaluation measures are proposed for confusion network in this paper. The first is called confusion network word error rate (CWER), which gives a lower bound of recognition word error rate. The second is used to measure the size of confusion set, called confusion word density (CWD). The third is word confusion probability (WCP), which can measure average distinguishability between words in a confusion set. Based on the proposed measures, we present a new method of quality optimization for confusion network, called as confusion probability based pruning algorithm. The experiments, carried out on a large vocabulary Chinese continuous speech recognition system, demonstrate that the new method leads to a significant reduction in CWD and WCP without an increase of CWER.

Quality evaluation and optimization of confusion network for LVCSR

Huanliang Wang,Jiqing Han,Tieran Zheng 한국어정보학회 2005 국제학술대회 Vol.2005 No.08

Speaker Recognition via Block Sparse Bayesian Learning

Wei Wang,Jiqing Han,Tieran Zheng,Guibin Zheng,Mingguang Shao 보안공학연구지원센터 2015 International Journal of Multimedia and Ubiquitous Vol.10 No.7

In order to demonstrate the effectiveness of sparse representation techniques for speaker recognition, a dictionary of feature vectors belonging to all speakers is constructed by total variability i-vectors. Each feature vector from unknown utterance is expressed as linear weighted sum of a dictionary. The weights are calculated using Block Sparse Bayesian Learning (BSBL) where the sparsest solution can be obtained. By exploiting the speech signal’s block structure and intra-block correlation, the system performance is improved. The experimental results validate that our method outperforms the baseline systems and the system using Orthogonal Matching Pursuit (OMP) algorithm on the typical corpus and realizes the identity validation function.

SURFACE PLASMON COUPLING EFFECTS ON THE FUNDAMENTAL MODES IN THE NANOWIRE

HUIBING MAO,JIQING WANG 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2014 NANO Vol.9 No.4

The degeneracy of the two fundamental modes HE 11 of the nanowire (NW) is removed due to thecoupling of surface plasmon (SP). For the coupled mode 1 of HE 11 the electric ¯eld is con-centrated between the metal sphere and the NW because of the coupling of the metal sphere. Thecoupling intensity depends on the relative position of the metal sphere. There is no ¯eld con-centration phenomenon for the coupled mode 2 of HE 11 , and the coupling only a®ects the dis-tribution of the local ¯eld in the NW. For the coupled mode 2 of HE 11 , both the mode volume andthe Purcell factor do not have obvious change. However, for the coupled mode 1 of HE 11 both themode volume and the Purcell factor have a fundamental change. The mode volume increases withthe increase of the metal sphere distance from the point of maximum ¯eld intensity of the Fabry –Perot standing wave. The Purcell factor decreases with the increase of the metal sphere distancefrom the point of maximum ¯eld intensity of the Fabry – Perot standing wave.

Facile Synthesis, Morphology Evolution and Tunable Luminescence of NaGdF4:Yb,Er Nanorods with Various Aspect Ratios

Shasha Gai,Jiqing Jiao,Wei Wei,Yao Li,Lihua Liu,Yi Liu,Baize Lv,Yao Wang,Laurence A. Bel¯ore,Jianguo Tang 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2018 NANO Vol.13 No.08

The well-defined NaGdF4:Yb,Er nanorods (NRs) with various aspect ratios were synthesized using a facile hydrothermal method. The morphology and crystal phase of NRs could be controlled by reaction conditions. NaGdF4:Yb,Er NRs with various aspect ratios could be synthesized and their upconversion (UC) luminescence was tuned. It is displayed that the NRs with aspect ratios about 5 exhibited the strongest UC luminescence among samples. The growth mechanism and morphology transition of NRs had been deduced by schematic diagram. And UC mechanism had been determined by energy level diagrams. Compared with previous reports, the work provided a facial method for UCNRs with various aspect ratios at lower temperature.

Stem Rot on Adzuki Bean (Vigna angularis) Caused by Rhizoctonia solani AG 4 HGI in China

Suli Sun,Changjian Xia,Jiqing Zhang,Canxing Duan,Xiaoming Wang,Xiaofei Wu,이석하,Zhendong Zhu 한국식물병리학회 2015 Plant Pathology Journal Vol.31 No.1

During late August and early September 2011, stem rotsymptoms were observed on adzuki bean plants (Vignaangularis) growing in fields located in Beijing and HebeiProvince, China, respectively. In this study, four isolateswere obtained from infected stems of adzuki beanplants. Based on their morphology, and sequence andpolymerase chain reaction-restriction fragment lengthpolymorphism (PCR-RFLP) analyses of the ribosomalDNA internal transcribed spacers (rDNA-ITS) region,the four isolates were identified as Rhizoctonia solaniin anastomosis group (AG) 4 HGI. Pathogenicity testsshowed that all isolates were strongly pathogenic to adzukibean and resulted in serious wilt symptoms whichwas similar to observations in the fields. Additionally,the isolates infected several other crops and inducedrelated rot on the roots and basal stems. To our knowledge,this is the first report of Rhizoctonia solani AG 4HGI causing stem rot on adzuki bean.

Effect of the scanning speed of laser cladding on microstructure and mechanical properties of WC/Ni composite coatings

Wenqiang Sun,Deqiang Zhang,Xiang Chen,Keyan Wang,Jiqing Zhang,Yunjie Jia 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.2

Cold work dies (of Cr12MoV) surface of the WC/Ni composite coating prepared by laser cladding can be used to quickly repair worn areas of dies. The composition, hardness, fracture morphology, microstructure, and shear strength of the coating were characterized by microhardness tester, universal tensile testing machine, XRD, EDS, and SEM. The results show that the main phase of the coating is composed are M 23 C 6 , FeNi 3 , Cr 7 C 3 , WC, W 2 C, Cr 2 B, Fe 2 B, and W 2 B. The change of scanning speed only changes the diffraction peak, but has little effect on the internal structure and strengthening mechanism of the coating. With the decrease of scanning speed, the powder deposition density per unit time increases, and a large number of pores and unmelted particles are mixed in the coating, which weakens the bonding strength between the coating and the substrate, and the fracture mechanism of the coating changes from quasi-cleavage fracture to brittle fracture.

Fluorination of dichlorodifluoromethane to synthesize tetrafluoromethane over Cr_2O_3–AlF_3 catalyst

Wenzhi Jia,Mengfei Luo,Lingyun Jin,Yuejuan Wang,Jiqing Lu 한국공업화학회 2011 Journal of Industrial and Engineering Chemistry Vol.17 No.3

A series of Cr_2O_3–AlF_3 catalysts with different Cr_2O_3 contents were prepared by a deposition–precipitation method for the fluorination of dichlorodifluoromethane (CCl_2F_2) to synthesize tetrafluoromethane (CF4). The highest activity was obtained on the Cr_2O_3–AlF_3 catalyst containing 61.2 wt.% of Cr_2O_3, with the CF_4 yield of 94% at 400℃. X-ray diffraction (XRD) and Raman spectroscopy results indicated the presence of bulk Cr_2O_3 and a-AlF_3 phases in the catalysts. Ammonia temperature programmed desorption (NH3-TPD) and Fourier transformation infrared spectroscopy (FTIR) of pyridine chemisorption revealed strong Lewis acidity of the catalysts. The Cr species and Lewis acid in the Cr_2O_3–AlF_3 catalysts were the active sites of fluorination and dismutation reaction of CCl_2F_2, respectively. This indicated bi-function catalytic performance of Cr_2O_3–AlF_3 catalysts for fluorination and dismutation reaction.

Stem Rot on Adzuki Bean (Vigna angularis) Caused by Rhizoctonia solani AG 4 HGI in China

Sun, Suli,Xia, Changjian,Zhang, Jiqing,Duan, Canxing,Wang, Xiaoming,Wu, Xiaofei,Lee, Suk-Ha,Zhu, Zhendong The Korean Society of Plant Pathology 2015 Plant Pathology Journal Vol.31 No.1

During late August and early September 2011, stem rot symptoms were observed on adzuki bean plants (Vigna angularis) growing in fields located in Beijing and Hebei Province, China, respectively. In this study, four isolates were obtained from infected stems of adzuki bean plants. Based on their morphology, and sequence and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analyses of the ribosomal DNA internal transcribed spacers (rDNA-ITS) region, the four isolates were identified as Rhizoctonia solani in anastomosis group (AG) 4 HGI. Pathogenicity tests showed that all isolates were strongly pathogenic to adzuki bean and resulted in serious wilt symptoms which was similar to observations in the fields. Additionally, the isolates infected several other crops and induced related rot on the roots and basal stems. To our knowledge, this is the first report of Rhizoctonia solani AG 4 HGI causing stem rot on adzuki bean.