Trajectory sensitivity analysis of first order and second order on position control system of highly integrated valve-controlled cylinder

Xiangdong Kong,Kaixian Ba,Bin Yu,Yuan Cao,Liujie Wu,Lingxiao Quan 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.10

A Highly-integrated valve-controlled cylinder (HIVC) that has the advantage of large power weight ratio and fast response is widelyapplied in many fields. To ensure high performance of HIVC, control strategy selection and structure parameters optimization are essential;thus, performance-influenced main parameters and secondary parameters should be well-grasped to target control compensation andstructure optimization. Trajectory sensitivity analysis (TSA), a branch of sensitivity analysis, can be adapted to research on the effects ofcontrol and structure parameter variation on system performance; the analysis conclusions can be used to improve system performanceand the analysis has been applied in many applications in various fields. In this paper, based on the mathematical model of the First-ordertrajectory sensitivity analysis (FOTSA), the mathematical model of Second trajectory sensitivity analysis (SOTSA) is further derived; thegeneral expression of the second-order trajectory sensitivity equations and the special expression that is applicable to each system parametersensitivity analysis of HIVC are built respectively. Furthermore, based on the position control system of the nonlinear mathematicalmodel of HIVC involved with servo valve dynamic characteristics, flow-pressure nonlinearity, initial piston position of servocylinder, and friction nonlinearity, the coefficient items and the free items matrices of the special expression are calculated. Moreover, theFirst-order trajectory sensitivity function (FOTSF) and the Second trajectory sensitivity function (SOTSF) of the 17 main parameters inHIVC are computed on the MATLAB/Simulink platform under nine typical working conditions of the displacement step response. Then,the dynamic change rules and the differences and similarities of each parameter sensitivity analysis results are obtained through FOTSAand SOTSA under different working conditions with different parameter variations; each parameter sensitivity variation histogram basedon the two kinds of sensitivity indexes, including the maximum value of the percentage absolute value and the absolute value summationwithin the sampling time, are given. Furthermore, differences and similarities of each parameter sensitivity index change rule and valueare quantitatively analyzed. Finally, the sensitivity index change rules and values of the four parameters in the position control system ofHIVC, including system supply oil pressure, proportion gain, initial piston position of servo cylinder, and load are experimentally verified. All above studies indicate that each parameter SOTSA result of HIVC vary under different working conditions. When parametervariation is significant, the differences in certain parameter sensitivity analysis between FOSTA and SOTSA are relatively significant;and SOTSA results are more similar to the test results, which illustrates that SOTSA results are more accurate.

Autophagy and regulation of aquaporins in the kidneys

Guo Xiangdong,Kong Yonglun,권태환,李春玲,Wang Weidong 대한신장학회 2023 Kidney Research and Clinical Practice Vol.42 No.6

Aquaporins (AQPs) are water channel proteins that facilitate the transport of water molecules across cell membranes. To date, seven AQPs have been found to be expressed in mammal kidneys. The cellular localization and regulation of the transport properties of AQPs in the kidney have been widely investigated. Autophagy is known as a highly conserved lysosomal pathway, which degrades cytoplasmic components. Through basal autophagy, kidney cells maintain their functions and structure. As a part of the adaptive responses of the kidney, autophagy may be altered in response to stress conditions. Recent studies revealed that autophagic degradation of AQP2 in the kidney collecting ducts leads to impaired urine concentration in animal models with polyuria. Therefore, the modulation of autophagy could be a therapeutic approach to treat water balance disorders. However, as autophagy is either protective or deleterious, it is crucial to establish an optimal condition and therapeutic window where autophagy induction or inhibition could yield beneficial effects. Further studies are needed to understand both the regulation of autophagy and the interaction between AQPs and autophagy in the kidneys in renal diseases, including nephrogenic diabetes insipidus.

Modification of surface/neuron interfaces for neural cell-type specific responses: a review

Chen, Cen,Kong, Xiangdong,Lee, In-Seop Institute of Physics Publishing Ltd 2016 Biomedical Materials Vol.11 No.1

<P>Surface/neuron interfaces have played an important role in neural repair including neural prostheses and tissue engineered scaffolds. This comprehensive literature review covers recent studies on the modification of surface/neuron interfaces. These interfaces are identified in cases both where the surfaces of substrates or scaffolds were in direct contact with cells and where the surfaces were modified to facilitate cell adhesion and controlling cell-type specific responses. Different sources of cells for neural repair are described, such as pheochromocytoma neuronal-like cell, neural stem cell (NSC), embryonic stem cell (ESC), mesenchymal stem cell (MSC) and induced pluripotent stem cell (iPS). Commonly modified methods are discussed including patterned surfaces at micro- or nanoscale, surface modification with conducting coatings, and functionalized surfaces with immobilized bioactive molecules. These approaches to control cell-type specific responses have enormous potential implications in neural repair.</P>

The Dynamic Compliance and Its Compensation Control Research of the Highly Integrated Valve-controlled Cylinder Position Control System

Kaixian Ba,Bin Yu,Xiangdong Kong,Hua-Long Zhao,Jin-Song Zhao,Qi-Xin Zhu,Chun-He Li 제어·로봇·시스템학회 2017 International Journal of Control, Automation, and Vol.15 No.4

The highly integrated valve-controlled cylinder (HIVC) is the joint driver in the hydraulic drive leggedrobot motion process, with the inner-loop-control-based outer loop dynamic compliance control method of the hydraulicsystem adopted. Yet the dynamic compliance of the HIVC position inner loop control has effects on theaccuracy of the outer loop dynamic compliance control. Therefore, the dynamic compliance parallel compositiontheory of the HIVC position inner loop control is presented and its dynamic compliance is analyzed in this paper,based on the HIVC position control nonlinear mathematical model. Moreover, the multiple parallel branch dynamiccompliance compound compensation control method is also designed and the dynamic compliance parallel compositionis rearranged. The experimental results indicate that adopting the compensation control method can decreasethe dynamic compliance of the HIVC position control system dramatically, which would provide the inner loopdynamic compliance compensation control method of the robot with high accuracy and high robustness.

Immobilizing osteogenic growth peptide with and without fibronectin on a titanium surface: effects of loading methods on mesenchymal stem cell differentiation

Chen, Cen,Li, Han,Kong, Xiangdong,Zhang, Sheng-Min,Lee, In-Seop Dove Medical Press 2015 INTERNATIONAL JOURNAL OF NANOMEDICINE Vol.10 No.-

<P>In this study, to improve the osseointegration of implants, osteogenic growth peptide (OGP) and fibronectin (FN) were loaded within mineral, which was formed on titanium, through adsorption and coprecipitation methods. The release profiles of OGP loaded by either adsorption or coprecipitation and the effects of the loading methods to immobilize OGP with and without FN on rat mesenchymal stem cell (rMSC) osteogenic differentiation were studied. The coprecipitation approach slightly reduced the initial burst release, while the adsorption approach provided a more sustained release. Dual loading of OGP and FN further improved cell attachments compared with either OGP or FN alone. Dually loaded OGP and FN also had a positive impact on rMSC proliferation and osteogenic differentiation. The difference in methods of loading OGP with and without FN also had some effects on osteogenic differentiation. Compared with coprecipitated OGP alone, adsorbed OGP enhanced later differentiation, such as osteocalcin secretion and matrix mineralization. Simultaneously adsorbed OGP and FN led to higher proliferation and higher osteogenic differentiation in both early and late stages compared with sequentially loaded OGP and FN. rMSC culture clearly indicated that simultaneously adsorbed OGP and FN could improve osseointegration, and this treatment represents a potential method for effective surface modification of dental and orthopedic implants.</P>

Displacement and dual-pressure compound control for fast forging hydraulic system

Jing Yao,Bin Liu,Xiangdong Kong,Fang Zhou 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.1

The poor energy efficiency is a big issue in the conventional electro-hydraulic proportional valve controlled fast forging system due tothe huge throttling losses and overflow losses. Aimed to address this problem, a new compound control strategy of displacement anddual-pressure was proposed in this study. Firstly, the mathematic model of the main components was built, and the compound controlstrategy was designed depending on the different working conditions. Then, the overall control system was integrated for both downstrokestage and return-stroke stage. The proposed control strategy was tested and evaluated in a 0.6 MN fast forging press. Results indicatedthat the input energy was reduced by 50% and energy loss decreased dramatically while control performance is good. Results alsoshow that control performance and energy saving is significantly affected by the variation of △p and pb. Overall, the proposed new controlstrategy could be used for the fast forging press with high energy efficiency.

Laminin functionalized biomimetic apatite to regulate the adhesion and proliferation behaviors of neural stem cells

Luo, Dandan,Ruan, Shichao,Liu, Aiping,Kong, Xiangdong,Lee, In-Seop,Chen, Cen Dove Medical Press 2018 International journal of nanomedicine Vol.13 No.-

<P><B>Background</B></P><P>Functionalizing biomaterial substrates with biological signals shows promise in regulating neural stem cell (NSC) behaviors through mimicking cellular microenvironment. However, diverse methods for immobilizing biological molecules yields promising results but with many problems. Biomimetic apatite is an excellent carrier due to its non-toxicity, good biocompatibility, biodegradability, and favorable affinity to plenty of molecules. Therefore, it may provide a promising alternative in regulating NSC behaviors.</P><P><B>Methods</B></P><P>Biomimetic apatite immobilized with the extracellular protein – laminin (LN) was prepared through coprecipitation process in modified Dulbecco’s phosphate-buffered saline (DPBS) containing LN. The amount of coprecipitated LN and their release kinetics were examined. The adhesion and proliferation behaviors of NSC on biomimetic apatite immobilized with LN were investigated.</P><P><B>Results</B></P><P>The coprecipitation approach provided well retention of LN within biomimetic apatite up to 28 days, and supported the adhesion and proliferation of NSCs without cytotoxicity. For long-term cultivation, NSCs formed neurosphere-like aggregates on non-functionalized biomimetic apatite. A monolayer of proliferated NSCs on biomimetic apatite with coprecipitated LN was observed and even more stable than the positive control of LN coated tissue-culture treated polystyrene (TCP).</P><P><B>Conclusion</B></P><P>The simple and reproducible method of coprecipitation suggests that biomimetic apatite is an ideal carrier to functionalize materials with biological molecules for neural-related applications.</P>

Adaptive extraction method for trend term of machinery signal based on extreme-point symmetric mode decomposition

Yong Zhu,Wan-lu Jiang,Xiangdong Kong 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.2

In mechanical fault diagnosis and condition monitoring, extracting and eliminating the trend term of machinery signal are necessary. In this paper, an adaptive extraction method for trend term of machinery signal based on Extreme-point symmetric mode decomposition (ESMD) was proposed. This method fully utilized ESMD, including the self-adaptive decomposition feature and optimal fitting strategy. The effectiveness and practicability of this method are tested through simulation analysis and measured data validation. Results indicate that this method can adaptively extract various trend terms hidden in machinery signal, and has commendable self-adaptability. Moreover, the extraction results are better than those of empirical mode decomposition.

Biomimetic apatite formed on cobalt-chromium alloy: A polymer-free carrier for drug eluting stent

Chen, Cen,Yao, Chenxue,Yang, Jingxin,Luo, Dandan,Kong, Xiangdong,Chung, Sung-Min,Lee, In-Seop Elsevier 2017 Colloids and surfaces Biointerfaces Vol.151 No.-

<P><B>Abstract</B></P> <P>In this study, sirolimus (SRL) was loaded within biomimetic apatite formed on cobalt-chromium (Co-Cr) alloy, which has been reported for the first time, to inhibit the in-stent restenosis. Two different groups of loading SRL within biomimetic apatite were prepared: Group A (mono-layer of apatite/SRL) and Group B (bi-layer of apatite/SRL). Group A and Group B showed the biphasic pattern of SRL release up to 40 and 90days, respectively. The attachment of human artery smooth muscle cell (HASMC) for both Group A and Group B was significantly inhibited, and proliferation dramatically decreased with the release of SRL. Noteworthily, biomimetic apatite alone also suppressed the SMC proliferation. The porous biomimetic apatite uniformly covered Co-Cr stent without crack or webbings. After balloon expansion, the integrity of biomimetic apatite was sufficient to resist delamination or destruction. Thus, this study demonstrated that biomimetic apatite is a promising drug carrier for potential use in stents.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Biomimetic apatite is formed on Co-Cr alloy as a polymer-free drug carrier. </LI> <LI> To inhibit in-stent restenosis, sirolimus is loaded within apatite in two ways. </LI> <LI> Porous and biodegradable biomimetic apatite releases of sirolimus over 40days. </LI> <LI> Integrity of biomimetic apatite is sufficient for clamping and balloon expansion. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

A Nonlinear Model-based Variable Impedance Parameters Control for Position-based Impedance Control System of Hydraulic Drive Unit

Kaixian Ba,Guo-liang Ma,Bin Yu,Zheng-guo Jin,Zhi-peng Huang,Jun-xiao Zhang,Xiangdong Kong 제어·로봇·시스템학회 2020 International Journal of Control, Automation, and Vol.18 No.7

In this paper, aimed at the problem of control accuracy when the traditional position-based impedance control is applied in the hydraulic drive unit (HDU) of legged robot, a kind of nonlinear model-based variable impedance parameters controller (MVIPC) is designed. First, the mathematical model of position-based impedance control for HDU is given. Second, the performance of traditional position-based impedance control is tested on the HDU performance test platform under different working conditions, and the experimental results show that the control accuracy of this control method needs to be improved greatly. Thirdly, the control idea of MVIPC is described, and the theoretical derivation is deduced. MVIPC considers the high-order dynamic characteristics of servo valve, pressure-flow nonlinearity of servo valve, oil compressibility and load characteristics. Finally, the control performance of MVIPC is verified on the HDU performance test platform. The experimental results show that MVIPC can significantly improve the performance of traditional position-based impedance control, and have an excellent adaptability under different working conditions. This research can provide an underlying control method of hydraulic systems during the robot locomotion.