On Performance Recovery and Bumpless Switch of Disturbance Observer based Control

Li Sun,Donghai Li,Kwang Y. Lee 제어로봇시스템학회 2015 제어로봇시스템학회 국제학술대회 논문집 Vol.2015 No.10

The performance recovery ability of disturbance observer based control (DOBC) is revealed based on equivalent transfer function transformation. It is found that, with the help of DOB, the open-loop characteristics of perturbed condition can be reshaped as similar to the nominal one. A nonlinear fluidized bed combustor is used to validate the ability. To implement the DOBC in practice, the bumpless switch is necessary for safety. A practical bumpless switch strategy is first proposed based on MATLAB/SIMULINK. Finally, a bumpless DOB enhanced PI controller is configured in Ovation DCS.

전자기 구동 시스템을 이용한 능동 약물전달 마이크로로봇

LI DONGHAI 대한기계학회 2014 대한기계학회 춘추학술대회 Vol.2014 No.4-4

Disturbance Rejection of Superheated Steam Temperature in a Utility Boiler

Li Sun,Donghai Li,Yong Sun,Yali Xue,Kwang Y. Lee 제어로봇시스템학회 2016 제어로봇시스템학회 국제학술대회 논문집 Vol.2016 No.10

This paper derived a model for the superheated steam temperature based on the open-loop step response. A cascaded control structure based on disturbance observer (DOB) is proposed to accommodate the control difficulties. The simulation results show the great performance improvement compared with the conventional cascaded control structure. This paper is a preliminary research to the cascaded DOB control structure. Much improvement, theoretic analysis and experimental demonstration will be carried out in the future.

Probability-based Robust Optimal PI Control for Shell Gasifier in IGCC Power Plants

Li Sun,Donghai Li,Junyi Dong,Makeximu 제어로봇시스템학회 2013 제어로봇시스템학회 국제학술대회 논문집 Vol.2013 No.10

In order to achieve a robust control performance of the gasifier which has dynamic characteristics of multi-variable coupling, large inertia and multi-disturbance, an optimization method for decentralized PID/PI controller parameters based on probabilistic robustness is developed. First, the control structure and target of the Shell gasifier is analyzed and a crude model is introduced. Model uncertainties and other detailed industrial requirements could be considered at the same time in the method. The probability of satisfaction with the dynamic performance is computed statistically, and then it is presented as the objective function to optimize the controller parameters based on genetic algorithm. The Monte Carlo experiment was applied to test the robustness of the control system. In comparison with the tuning methods based on internal model control (IMC) and the optimization algorithm under the nominal model, simulation results show the method could exploit the potentialities of PID/PI controllers in a maximal probability.

Expression and Efficient Purification of Tag-cleaved Active Recombinant Human Insulin-like Growth Factor-II from Escherichia coli

Hongbo Li,Xiaoyan Hui,Peng Li,Aimin Xu,Shiwu Li,Shouguang Jin,Donghai Wu 한국생물공학회 2015 Biotechnology and Bioprocess Engineering Vol.20 No.2

Insulin-like growth factor-II (IGF2) is a growth factor for the control of cell proliferation and apoptosis. To explore the clinical use of human IGF2, an efficient method for production of a large amount of active recombinant hIGF2 is necessary. Human IGF2 cDNA was cloned into pET32 vector where it is under the control of an IPTGinducible T7 promoter. High level soluble thioredoxin (Trx)- hIGF2 fusion protein was produced at room temperature following IPTG induction, amounting up to 20% of the total soluble bacterial proteins. The recombinant TrxhIGF2 fusion protein was purified to an approximate 95% purity using Ni+-NTA affinity chromatography with an overall yield of 120 mg protein per liter of bacterial culture. After cleavage of the Trx fusion fragment by recombinant enterokinase, the tag-free recombinant hIGF2 protein (rhIGF2) was purified by passage through the Ni+-NTA affinity column again. Biological activity of the purified hIGF2 was determined by its ability to support NIH/3T3 cells proliferation and to activate AKT signaling pathways. Our results demonstrate that tag-free active rhIGF2 can easily be obtained for various applications from E. coli using the procedure described in this report.

Active Disturbance Rejection Control for Structural Vibration

Makeximu,Li Sun,Donghai Li,Min Zhu 제어로봇시스템학회 2014 제어로봇시스템학회 국제학술대회 논문집 Vol.2014 No.10

Construction vibration is a fast responding, multivariable coupled dynamic system. In this paper, an active disturbance rejection control (ADRC) solution is proposed and tested on a certain three-storey building model. The proposed system with a decentralized structure is free from complex decoupling which is hard to practice in actual application. Under ADRC framework, the influence of the entanglement between two control loops, the un-modeled, the higher order dynamics and the uncertainties are regarded as a single combined general disturbance, which could be actively compensated by the controller with the information obtained from the Extended State Observer(ESO). The simulation results indicate that the proposed strategy could attenuate structural vibration effectively when actual earthquake signal is added into the system. Since ADRC method is model free, strong controller robustness is well secured, and a single set of parameters is adequate in various situations. Due to the advantages in disturbance-rejection and structure simplicity and tuning easiness, ADRC provides an simple, practical alternative solution for structural vibration control in both earthquake and industrial application.

Clonging and Expression of Heparinase III Gene from Flavobacterium heparinum

( Ye Li ),( Donghai Su ),( Lihua Jin ),( Jingjun Wu ),( Xinhui Xing ) 조선대학교 공학기술연구원 2012 공학기술논문지 Vol.5 No.4

To enhance solubility of heparinase III when expressed in recombinant E. coli, the heparinase III gene (HepC) of 1980 bp from Flavobacterium heparinum was amplified by the PCR method, and then it was in inserted in the prokaryotic expression vector pMAL-c2x with the gene of maltose binding protein (MBP) which was identified by colony PCR, restriction enzyme digestion and gene sequencing. The results showed that the fusion strategy by using maltose binding protein (MBP) was effective to enhance solubility when induced at low temperatures, such as 15°C. By shake flask cultivation, the specific enzyme activity of MBP-hepC fusion protein could reach about 46.41 IU/mg which was higher than previous reported results. By one-­step affinity purification with amylose resin, the MBP-hepC fusion protein was easily purified to more than 95% purifty and the enzyme characteristics were studied. The optimum reaction pH value of MEP-hepC was 7.3. The optimum reaction temperature was 42-48°C, which was different from the native heparinase III from Flavobacterium heparinum. This enzymatic reaction to heparine followed Michaelis-Menten equation. The all above realize the process intergration of the enzyme production, separation, purification and applications in LMWH production for reducing the enzyme cost. The study laid the foundation for industrial production of low molecular weight heparin.

ADRC Applied in Chaotic Arrhythmic Heartbeats Control

Ting HE,Donghai LI 제어로봇시스템학회 2015 제어로봇시스템학회 국제학술대회 논문집 Vol.2015 No.10

Control arrhythmic heartbeats has always been an important issue in cardiology. In this work, the capability of active disturbance rejection control (ADRC) to suppress the chaotic arrhythmic heartbeats is studied. The modified Van der Pol model is employed as mathematical model to describe the normal and pathological heart rhythms. The ADRC method is applied in three channels of the chaotic cardiac model. Compared with the commonly used time-delayed feedback control method, the ADRC method manifests better performance, thus worth further investigation and development in the field of chaotic arrhythmic heart beats control.

Active Disturbance Rejection Control For Circulating Fluidized Bed Boiler

Yuqiong Zhang,Donghai Li,Yali Xue 제어로봇시스템학회 2012 제어로봇시스템학회 국제학술대회 논문집 Vol.2012 No.10

The Circulating Fluidized Bed Boiler (CFBB) is a multivariable coupled, long time-delay, large inertia system. In this paper, a decentralized control system using active disturbance rejection control (ADRC) strategy is proposed for a nonlinear CFBB model. The designed control system has a fully decentralized structure and it is free of complex decouplers, which is difficult to achieve in actual plants. With ADRC method, the interaction of two control loops, the higher orders, uncertainties and unmodeled dynamics are treated as general disturbance, which is estimated by Extended State Observer (ESO) and then actively compensated. Some simulation results illustrate that the designed control system has good performance when the power set point is varied in a wide range and a disturbance of the set point of main steam pressure is added into the CFBB system. Besides, the same parameters are adequate on varied operating points, indicating the strong robustness of the controller. The proposed decentralized control system has advantage in easy tuning procedure, simple structure and its disturbance-rejection capability.

Active Control of Combustion Oscillations Based on Desired Dynamic Equation

Yichao Hu,Donghai Li,Min Zhu,Tao Gu 제어로봇시스템학회 2010 제어로봇시스템학회 국제학술대회 논문집 Vol.2010 No.10

Combustion oscillations have become a major issue for propulsion systems and combustion chambers since it can cause structural damages. Active control provides a way of extending the systems’ stable operating range and numerous efforts have been made by engineers and researchers. In this paper, increment type PID controller with real differentiation based on Desired Dynamical Equation (DDE-PID) is applied in the control of combustion oscillations in Rijke tube when exist no disturbance, sinusoidal disturbances and white noise disturbances. Meanwhile, orthogonal experimental design is used to investigate effects of the DDE’s parameters and real differentiation. The experimental results show that DDE-PID is easy to tune and can suppress combustion oscillations effectively. Furthermore, simple structure, good performance robustness, and independent on the model of processes make DDE-PID more suitable for practical applications in suppressing combustion oscillations.