The mathematical model of a transport aircraft would be subjected to a sudden change when heavy cargo is dropped off in airdropping, which exerts serious influences upon the safety of the aircraft. A variable structur...The mathematical model of a transport aircraft would be subjected to a sudden change when heavy cargo is dropped off in airdropping, which exerts serious influences upon the safety of the aircraft. A variable structure controller is specially designed for handling the airdrop process. The nonlinear system is linearized by input-output feedback linearization using differential geometry theories. On this basis, an inner loop system for velocity and attitude tracking control is designed by using the exponentially approaching rule of the variable structure theory. The whole flight control system is integrated with the outer loop flight altitude control. Digital simulation evidences the applicability of the system to potentially catastrophic course in airdropping heavy cargo and provides robustness against system parameter perturbation.展开更多
This paper introduces the basic idea and provides the mathematical formulation of the delayed feedback control （DFC） methodology, which has been widely used in chaos control. Stability analysis including the well-kn...This paper introduces the basic idea and provides the mathematical formulation of the delayed feedback control （DFC） methodology, which has been widely used in chaos control. Stability analysis including the well-known odd number linfitation of the DFC is reviewed. Some new developments in characterizing the limitation of the DFC are presented. Various modified DFC methods, which are developed in order to overcome the odd number limitation, are also described. Finally, some open problems in this research field are discussed.展开更多
In this paper, an adaptive fuzzy robust feedback control approach is proposed for a class of single-input and singleoutput （SISO） strict-feedback nonlinear systems with unknown nonlinear functions, time delays, unkn...In this paper, an adaptive fuzzy robust feedback control approach is proposed for a class of single-input and singleoutput （SISO） strict-feedback nonlinear systems with unknown nonlinear functions, time delays, unknown high-frequency gain sign, and without the measurements of the states. In the backstepping recursive design, fuzzy logic systems are employed to approximate the unknown smooth nonlinear functions, K-filters is designed to estimate the unmeasured states, and Nussbaum gain functions are introduced to solve the problem of unknown sign of high-frequency gain. By combining adaptive fuzzy control theory and adaptive backstepping design, a stable adaptive fuzzy output feedback control scheme is developed. It has been proven that the proposed adaptive fuzzy robust control approach can guarantee that all the signals of the closed-loop system are uniformly ultimately bounded and the tracking error can converge to a small neighborhood of the origin by appropriately choosing design parameters. Simulation results have shown the effectiveness of the proposed method.展开更多
Achieving stability is the essential issue in the control system design. In this paper, four approaches that can be used to calculate the stability margin of the interval plant family are summarized and compared. The ...Achieving stability is the essential issue in the control system design. In this paper, four approaches that can be used to calculate the stability margin of the interval plant family are summarized and compared. The μ approach gives the bounds of the stability margin, and good estimation can be obtained with the numerical method. The eigenvalue approach yields accurate value, and the MATLAB＇s function robuststab sometimes provides wrong results. Since the eigenvalue approach is both accurate and computationally efficient, it is recommended for the calculation of the stability margin, while utilization of the function robuststab should be avoided due to the unreliable results it gives.展开更多
A structure of central air conditioning system in building and its running pattern are proposed in order to perform optimum energy saving strategy. The design of room temperature controller is taken as an example to d...A structure of central air conditioning system in building and its running pattern are proposed in order to perform optimum energy saving strategy. The design of room temperature controller is taken as an example to discuss the design of fuzzy controller using common microprogrammed control unit (MCU) in detail. Based on fuzzy theory the query control tables fixed in read only memory (ROM) of MCU are established to realize the energy saving in the room temperature controller and the reasoning procedure is analyzed. The diagram of hardware design and the flow chart of software of room temperature controller are presented. The results show that the proposed method is practical and effective to achieve the energy saving goal.展开更多
In order to improve the efficiency of the combustion of boilers, an approach named self-optimizing which takes the temperature of furnace as the major signal to control the ratio between the wind and coal input is use...In order to improve the efficiency of the combustion of boilers, an approach named self-optimizing which takes the temperature of furnace as the major signal to control the ratio between the wind and coal input is used. Our goal is to save energy. This method can be used to replace the one which uses zirconia as the monitor, so as to avoid its shortcomings, like expensive, ephemeral, and hysteresis. Equal step by step self-optimizing algorithm and variant step algorithm is also introduced. And the intelligent self-optimizing control algorithm is discussed. This intelligent algorithm is realized by utilizing fuzzy logic estimation method.展开更多
In order to solve the problems that make the orientation of pneumatic rotary actuator inaccurate, a newly intelligent PID control algorithm is proposed. Pneumatic rotary actuator angle servo-system uses electropneumat...In order to solve the problems that make the orientation of pneumatic rotary actuator inaccurate, a newly intelligent PID control algorithm is proposed. Pneumatic rotary actuator angle servo-system uses electropneumatic proportional valve as control device, which changes the pressure of cavity and then pushes the actuator to revolve to the expected position. Using intelligent PID control algorithm, several special methods were put forward to overcome the connatural shortcomings of pneumatic system and make the rotary actuator track the expected value timely and accurately. Experimental results have shown that by using this intelligent algorithm, the performance index of system was improved greatly.展开更多
The integrated control system of vehicle ABS/ASR/ACC has been developed using the MC9S12DP256 single chip, which is the new Motorola 16-bit product in HSC12 family. The system including the main control module, the da...The integrated control system of vehicle ABS/ASR/ACC has been developed using the MC9S12DP256 single chip, which is the new Motorola 16-bit product in HSC12 family. The system including the main control module, the data collection module and the drive and fault diagnosis module is demonstrated and its data collection function is presented in detail. The system designed by the modularization can supervise the data, drive the valves and pump. The program can be debugged on line, which is steady and reliable validated by the large numbers of vehicle road tests.展开更多
Based on the current structural theories of intelligent control,a new structural theory,the four-element intersection structure of intelligent control,has been proposed after study-ing the features and relationships a...Based on the current structural theories of intelligent control,a new structural theory,the four-element intersection structure of intelligent control,has been proposed after study-ing the features and relationships among the related disciplines.The reasons for adding in-formatics into the structure have been discussed and emphasized,and the relationships a-mong the four subsets are explained.展开更多
ADAPTIVE control is a proven method for learning feedback controllers for systems with unknown dynamic models,exogenous disturbances,nonzero setpoints,and unmodeled nonlinearities.Adaptive control has been applied for...ADAPTIVE control is a proven method for learning feedback controllers for systems with unknown dynamic models,exogenous disturbances,nonzero setpoints,and unmodeled nonlinearities.Adaptive control has been applied for years in process control,industry,aerospace systems。展开更多
BACKGROUND Hepatocellular carcinoma(HCC)in segments VII and VIII poses technical challenges for both liver resection and radiofrequency ablation(RFA).Robotic-assisted techniques may enhance safety and precision,but co...BACKGROUND Hepatocellular carcinoma(HCC)in segments VII and VIII poses technical challenges for both liver resection and radiofrequency ablation(RFA).Robotic-assisted techniques may enhance safety and precision,but comparative evidence remains limited.AIM To compare the clinical outcomes of robotic liver resection(R-LR)and robotic intraoperative RFA(RIO-RFA)for HCC located in liver segments VII and VIII.METHODS We retrospectively analyzed 93 HCC patients in segments VII/VIII with de novo(n=57)or first recurrent(n=36).HCC who underwent R-LR or RIO-RFA between 2015 and 2024.Propensity score matching was performed to reduce selection bias.Primary outcomes were overall survival(OS)and recurrence-free survival(RFS).Kaplan-Meier curves,log-rank tests,and Cox regression were used to identify prognostic factors for OS and RFS.RESULTS In the de novo group,OS and RFS did not differ significantly between R-LR and RIO-RFA before or after propensity score matching.In contrast,the recurrent group showed significantly improved OS and RFS with R-LR(P=0.005 and P=0.012,respectively).Subgroup analyses revealed that low-risk de novo patients with smaller tumors achieved superior OS after R-LR,whereas carefully selected low-risk recurrent patients undergoing RIO-RFA(smaller tumors,absence of complications)achieved outcomes comparable to R-LR.Platelet count,tumor size,and postoperative complications constituted key prognostic factors.CONCLUSION For HCC in challenging liver segments VII and VIII,R-LR and RIO-RFA achieve comparable outcomes in de novo cases,whereas R-LR confers superior survival in recurrent disease.R-LR should be prioritized for small de novo HCCs and for recurrent disease overall;RIO-RFA may serve as an effective alternative in carefully selected lowrisk recurrent patients.Tumor size,platelet count,and postoperative complications are key prognostic indicators to guide individualized treatment.展开更多
Sensor management plays an important role in data fusion system, and this paper presents an algorithm of sensor management that can be used in target detection, identification and tracking. First, the basic concept, r...Sensor management plays an important role in data fusion system, and this paper presents an algorithm of sensor management that can be used in target detection, identification and tracking. First, the basic concept, rule, range and function of sensor management are introduced. Then, the quantifying problems of target priority and sensor (or combination)-target pairing in multisensor management are discussed and the efficiency and waste functions are established based on the functions of target priority and sensor-target pairing. On this basis, a distribution algorithm of multi-sensor resources is given, which is optimized by the principle of maximum synthesis efficiency in the multisensor system and constrained by sensor maximum tracking power and what target must be scanned. In addition, the waste measure of sensor resources is introduced to improve the algorithm. Finally, a tactical task that includes three sensors and ten targets is set, and the simulation results show that the algorithm is feasible and effective.展开更多
Based on nominal model, a novel global sliding mode controller （GSMC） with a new control scheme is proposed for a practical uncertain servo system. This control scheme consists of two combined controllers, One is th...Based on nominal model, a novel global sliding mode controller （GSMC） with a new control scheme is proposed for a practical uncertain servo system. This control scheme consists of two combined controllers, One is the global sliding mode controller for practical plant, the other is the integral backstepping controller for nominal model. Modeling error between practical plant and nominal model is used to design GSMC. The steady-state control accuracy can be guaranteed by the integral backstepping control law, and the global robustness can be obtained by GSMC. The stability of the proposed controller is proved according to the Lyapunov approach. The simulation results both of sine signal and step signal tracking for 3-axis flight table are investigated to show good position tracking performance and high robustness with respect to large and parameter changes over all the response time.展开更多
To reduce the variations of the production process in penicillin cultivations, a rolling multivariate statis-tical approach based on multiway principle component analysis (MPCA) is developed and used for fault diagnos...To reduce the variations of the production process in penicillin cultivations, a rolling multivariate statis-tical approach based on multiway principle component analysis (MPCA) is developed and used for fault diagnosis of penicillin cultivations. Using the moving data windows technique, the static MPCA is extended for use in dy-namic process performance monitoring. The control chart is set up using the historical data collected from the past successful batches, thereby resulting in simplification of monitoring charts, easy tracking of the progress in each batch run, and monitoring the occurrence of the observable upsets. Data from the commercial-scale penicillin fer-mentation process are used to develop the rolling model. Using this method, faults are detected in real time and the corresponding measurements of these faults are directly made through inspection of a few simple plots (t-chart, SPE-chart, and T2-chart). Thus, the present methodology allows the process operator to actively monitor the data from several cultivations simultaneously.展开更多
A novel vibration isolation device called the nonlinear energy sink(NES)with NiTiNOL-steel wire ropes(NiTi-ST)is applied to a whole-spacecraft system.The NiTi-ST is used to describe the damping of the NES,which is cou...A novel vibration isolation device called the nonlinear energy sink(NES)with NiTiNOL-steel wire ropes(NiTi-ST)is applied to a whole-spacecraft system.The NiTi-ST is used to describe the damping of the NES,which is coupled with the modified Bouc-Wen model of hysteresis.The NES with NiTi-ST vibration reduction principle uses the irreversibility of targeted energy transfer(TET)to concentrate the energy locally on the nonlinear oscillator,and then dissipates it through damping in the NES with NiTi-ST.The generalized vibration transmissibility,obtained by the root mean square treatment of the harmonic response of the nonlinear output frequency response functions(NOFRFs),is first used as the evaluation index to analyze the whole-spacecraft system in the future.An optimization analysis of the impact of system responses is performed using different parameters of NES with NiTi-ST based on the transmissibility of NOFRFs.Finally,the effects of vibration suppression by varying the parameters of NiTi-ST are analyzed from the perspective of energy absorption.The results indicate that NES with NiTi-ST can reduce excessive vibration of the whole-spacecraft system,without changing its natural frequency.Moreover,the NES with NiTi-ST can be directly used in practical engineering applications.展开更多
To improve the accuracy of strapdown inertial navigation system(SINS) for long term applications,the rotation technique is employed to modulate the errors of the inertial sensors into periodically varied signals,and,a...To improve the accuracy of strapdown inertial navigation system(SINS) for long term applications,the rotation technique is employed to modulate the errors of the inertial sensors into periodically varied signals,and,as a result,to suppress the divergence of SINS errors.However,the errors of rotation platform will be introduced into SINS and might affect the final navigation accuracy.Considering the disadvantages of the conventional navigation computation scheme,an improved computation scheme of the SINS using rotation technique is proposed which can reduce the effects of the rotation platform errors.And,the error characteristics of the SINS with this navigation computation scheme are analyzed.Theoretical analysis,simulations and real test results show that the proposed navigation computation scheme outperforms the conventional navigation computation scheme,meanwhile reduces the requirement to the measurement accuracy of rotation angles.展开更多
Rotating machinery is important to industrial production. Any failure of rotating machinery, especially the failure of rolling bearings, can lead to equipment shutdown and even more serious incidents. Therefore, accur...Rotating machinery is important to industrial production. Any failure of rotating machinery, especially the failure of rolling bearings, can lead to equipment shutdown and even more serious incidents. Therefore, accurate residual life prediction plays a crucial role in guaranteeing machine operation safety and reliability and reducing maintenance cost. In order to increase the forecasting precision of the remaining useful life(RUL) of the rolling bearing, an advanced approach combining elastic net with long short-time memory network(LSTM) is proposed, and the new approach is referred to as E-LSTM. The E-LSTM algorithm consists of an elastic mesh and LSTM, taking temporal-spatial correlation into consideration to forecast the RUL through the LSTM. To solve the over-fitting problem of the LSTM neural network during the training process, the elastic net based regularization term is introduced to the LSTM structure.In this way, the change of the output can be well characterized to express the bearing degradation mode. Experimental results from the real-world data demonstrate that the proposed E-LSTM method can obtain higher stability and relevant values that are useful for the RUL forecasting of bearing. Furthermore, these results also indicate that E-LSTM can achieve better performance.展开更多
In this paper, a new adaptive hierarchical sliding mode control scheme for a 3D overhead crane system is proposed. A controller is first designed by the use of a hierarchical structure of two first-order sliding surfa...In this paper, a new adaptive hierarchical sliding mode control scheme for a 3D overhead crane system is proposed. A controller is first designed by the use of a hierarchical structure of two first-order sliding surfaces represented by two actuated and un-actuated subsystems in the bridge crane. Parameters of the controller are then intelligently estimated, where uncertain parameters due to disturbances in the 3D overhead crane dynamic model are proposed to be represented by radial basis function networks whose weights are derived from a Lyapunov function. The proposed approach allows the crane system to be robust under uncertainty conditions in which some uncertain and unknown parameters are highly difficult to determine. Moreover, stability of the sliding surfaces is proved to be guaranteed. Effectiveness of the proposed approach is then demonstrated by implementing the algorithm in both synthetic and reallife systems, where the results obtained by our method are highly promising.展开更多
文摘The mathematical model of a transport aircraft would be subjected to a sudden change when heavy cargo is dropped off in airdropping, which exerts serious influences upon the safety of the aircraft. A variable structure controller is specially designed for handling the airdrop process. The nonlinear system is linearized by input-output feedback linearization using differential geometry theories. On this basis, an inner loop system for velocity and attitude tracking control is designed by using the exponentially approaching rule of the variable structure theory. The whole flight control system is integrated with the outer loop flight altitude control. Digital simulation evidences the applicability of the system to potentially catastrophic course in airdropping heavy cargo and provides robustness against system parameter perturbation.
基金Supported by National High Technology Research and Development Program of China （863 Program） （2006AA04Z183）, National Nat- ural Science Foundation of China （60621001, 60534010, 60572070, 60774048, 60728307）, and the Program for Changjiang Scholars and Innovative Research Groups of China （60728307, 4031002）
文摘This paper introduces the basic idea and provides the mathematical formulation of the delayed feedback control （DFC） methodology, which has been widely used in chaos control. Stability analysis including the well-known odd number linfitation of the DFC is reviewed. Some new developments in characterizing the limitation of the DFC are presented. Various modified DFC methods, which are developed in order to overcome the odd number limitation, are also described. Finally, some open problems in this research field are discussed.
基金Supported by National Natural Science Foundation of China （60805039） and Nanjing University of Posts and Telecommunications r Introduced Talents （NY207028） The author would like to thank Professor Tian Yu-Ping. for fruitful discussions and his helpful remarks that improved the presentation of the paper.
文摘追踪 nonholonomic 的控制问题的输出锁住形式系统在这份报纸被学习，没有坚持的刺激，全球指数的输出追踪者被介绍或对零不收敛在参考书轨道上。首先，变化时间的并列转变被介绍避免操作指数地收敛的信号。在串联系统和线性使不安的系统的理论的帮助下，然后，全球指数的产量追踪者成功地被获得。没有坚持的刺激的流行条件，建议控制器的新特征是追踪 nonholonomic 的控制问题的输出锁住形式系统的 A 也是可溶解的在以前的工作在引用信号上收敛到零。建议方法与一辆大蓬车借助于 nonholonomic 被示威并且讨论活动机器人和汽车。
基金supported by National Natural Science Foundation of China (No. 61074014)the Outstanding Youth Funds of Liaoning Province (No. 2005219001)Educational Department of Liaoning Province (No. 2006R29, No. 2007T80)
文摘In this paper, an adaptive fuzzy robust feedback control approach is proposed for a class of single-input and singleoutput （SISO） strict-feedback nonlinear systems with unknown nonlinear functions, time delays, unknown high-frequency gain sign, and without the measurements of the states. In the backstepping recursive design, fuzzy logic systems are employed to approximate the unknown smooth nonlinear functions, K-filters is designed to estimate the unmeasured states, and Nussbaum gain functions are introduced to solve the problem of unknown sign of high-frequency gain. By combining adaptive fuzzy control theory and adaptive backstepping design, a stable adaptive fuzzy output feedback control scheme is developed. It has been proven that the proposed adaptive fuzzy robust control approach can guarantee that all the signals of the closed-loop system are uniformly ultimately bounded and the tracking error can converge to a small neighborhood of the origin by appropriately choosing design parameters. Simulation results have shown the effectiveness of the proposed method.
基金supported by the National Natural Science Foundation of China (No.69574003, 69904003)the Research Fund for the Doctoral Program of the Higher Education (RFDP) (No.1999000701)was partly supported by the Advanced Weapons Research Supporting Fund(No.YJ0267016)
文摘Achieving stability is the essential issue in the control system design. In this paper, four approaches that can be used to calculate the stability margin of the interval plant family are summarized and compared. The μ approach gives the bounds of the stability margin, and good estimation can be obtained with the numerical method. The eigenvalue approach yields accurate value, and the MATLAB＇s function robuststab sometimes provides wrong results. Since the eigenvalue approach is both accurate and computationally efficient, it is recommended for the calculation of the stability margin, while utilization of the function robuststab should be avoided due to the unreliable results it gives.
文摘A structure of central air conditioning system in building and its running pattern are proposed in order to perform optimum energy saving strategy. The design of room temperature controller is taken as an example to discuss the design of fuzzy controller using common microprogrammed control unit (MCU) in detail. Based on fuzzy theory the query control tables fixed in read only memory (ROM) of MCU are established to realize the energy saving in the room temperature controller and the reasoning procedure is analyzed. The diagram of hardware design and the flow chart of software of room temperature controller are presented. The results show that the proposed method is practical and effective to achieve the energy saving goal.
文摘In order to improve the efficiency of the combustion of boilers, an approach named self-optimizing which takes the temperature of furnace as the major signal to control the ratio between the wind and coal input is used. Our goal is to save energy. This method can be used to replace the one which uses zirconia as the monitor, so as to avoid its shortcomings, like expensive, ephemeral, and hysteresis. Equal step by step self-optimizing algorithm and variant step algorithm is also introduced. And the intelligent self-optimizing control algorithm is discussed. This intelligent algorithm is realized by utilizing fuzzy logic estimation method.
文摘In order to solve the problems that make the orientation of pneumatic rotary actuator inaccurate, a newly intelligent PID control algorithm is proposed. Pneumatic rotary actuator angle servo-system uses electropneumatic proportional valve as control device, which changes the pressure of cavity and then pushes the actuator to revolve to the expected position. Using intelligent PID control algorithm, several special methods were put forward to overcome the connatural shortcomings of pneumatic system and make the rotary actuator track the expected value timely and accurately. Experimental results have shown that by using this intelligent algorithm, the performance index of system was improved greatly.
基金Ford-China Research and Development Fund Project(50122148)
文摘The integrated control system of vehicle ABS/ASR/ACC has been developed using the MC9S12DP256 single chip, which is the new Motorola 16-bit product in HSC12 family. The system including the main control module, the data collection module and the drive and fault diagnosis module is demonstrated and its data collection function is presented in detail. The system designed by the modularization can supervise the data, drive the valves and pump. The program can be debugged on line, which is steady and reliable validated by the large numbers of vehicle road tests.
基金Supported by National Natural Science Foundation of China.
文摘Based on the current structural theories of intelligent control,a new structural theory,the four-element intersection structure of intelligent control,has been proposed after study-ing the features and relationships among the related disciplines.The reasons for adding in-formatics into the structure have been discussed and emphasized,and the relationships a-mong the four subsets are explained.
文摘ADAPTIVE control is a proven method for learning feedback controllers for systems with unknown dynamic models,exogenous disturbances,nonzero setpoints,and unmodeled nonlinearities.Adaptive control has been applied for years in process control,industry,aerospace systems。
基金Supported by Feng Chia University/Chung Shan Medical University,No.FCU/CSMU 112-001Taiwan National Science and Technology Council,No.NSTC 114-2221-E-035-036.
文摘BACKGROUND Hepatocellular carcinoma(HCC)in segments VII and VIII poses technical challenges for both liver resection and radiofrequency ablation(RFA).Robotic-assisted techniques may enhance safety and precision,but comparative evidence remains limited.AIM To compare the clinical outcomes of robotic liver resection(R-LR)and robotic intraoperative RFA(RIO-RFA)for HCC located in liver segments VII and VIII.METHODS We retrospectively analyzed 93 HCC patients in segments VII/VIII with de novo(n=57)or first recurrent(n=36).HCC who underwent R-LR or RIO-RFA between 2015 and 2024.Propensity score matching was performed to reduce selection bias.Primary outcomes were overall survival(OS)and recurrence-free survival(RFS).Kaplan-Meier curves,log-rank tests,and Cox regression were used to identify prognostic factors for OS and RFS.RESULTS In the de novo group,OS and RFS did not differ significantly between R-LR and RIO-RFA before or after propensity score matching.In contrast,the recurrent group showed significantly improved OS and RFS with R-LR(P=0.005 and P=0.012,respectively).Subgroup analyses revealed that low-risk de novo patients with smaller tumors achieved superior OS after R-LR,whereas carefully selected low-risk recurrent patients undergoing RIO-RFA(smaller tumors,absence of complications)achieved outcomes comparable to R-LR.Platelet count,tumor size,and postoperative complications constituted key prognostic factors.CONCLUSION For HCC in challenging liver segments VII and VIII,R-LR and RIO-RFA achieve comparable outcomes in de novo cases,whereas R-LR confers superior survival in recurrent disease.R-LR should be prioritized for small de novo HCCs and for recurrent disease overall;RIO-RFA may serve as an effective alternative in carefully selected lowrisk recurrent patients.Tumor size,platelet count,and postoperative complications are key prognostic indicators to guide individualized treatment.
基金National Natural Science Foundation of China! ( No.6 9772 0 3 1)Natural Science Foundation of Henan Province
文摘Sensor management plays an important role in data fusion system, and this paper presents an algorithm of sensor management that can be used in target detection, identification and tracking. First, the basic concept, rule, range and function of sensor management are introduced. Then, the quantifying problems of target priority and sensor (or combination)-target pairing in multisensor management are discussed and the efficiency and waste functions are established based on the functions of target priority and sensor-target pairing. On this basis, a distribution algorithm of multi-sensor resources is given, which is optimized by the principle of maximum synthesis efficiency in the multisensor system and constrained by sensor maximum tracking power and what target must be scanned. In addition, the waste measure of sensor resources is introduced to improve the algorithm. Finally, a tactical task that includes three sensors and ten targets is set, and the simulation results show that the algorithm is feasible and effective.
文摘Based on nominal model, a novel global sliding mode controller （GSMC） with a new control scheme is proposed for a practical uncertain servo system. This control scheme consists of two combined controllers, One is the global sliding mode controller for practical plant, the other is the integral backstepping controller for nominal model. Modeling error between practical plant and nominal model is used to design GSMC. The steady-state control accuracy can be guaranteed by the integral backstepping control law, and the global robustness can be obtained by GSMC. The stability of the proposed controller is proved according to the Lyapunov approach. The simulation results both of sine signal and step signal tracking for 3-axis flight table are investigated to show good position tracking performance and high robustness with respect to large and parameter changes over all the response time.
基金Supported by the National Natural Science Foundation of China (No.60574038).
文摘To reduce the variations of the production process in penicillin cultivations, a rolling multivariate statis-tical approach based on multiway principle component analysis (MPCA) is developed and used for fault diagnosis of penicillin cultivations. Using the moving data windows technique, the static MPCA is extended for use in dy-namic process performance monitoring. The control chart is set up using the historical data collected from the past successful batches, thereby resulting in simplification of monitoring charts, easy tracking of the progress in each batch run, and monitoring the occurrence of the observable upsets. Data from the commercial-scale penicillin fer-mentation process are used to develop the rolling model. Using this method, faults are detected in real time and the corresponding measurements of these faults are directly made through inspection of a few simple plots (t-chart, SPE-chart, and T2-chart). Thus, the present methodology allows the process operator to actively monitor the data from several cultivations simultaneously.
基金Project supported by the National Natural Science Foundation of China(No.11772205)the Scientific Research Fund of Liaoning Provincial Education Department(No.L201703)+1 种基金the Liaoning Revitalization Talent Program(No.XLYC1807172)the Training Project of Liaoning Higher Education Institutions in Domestic and Overseas(No.2018LNGXGJWPY-YB008)
文摘A novel vibration isolation device called the nonlinear energy sink(NES)with NiTiNOL-steel wire ropes(NiTi-ST)is applied to a whole-spacecraft system.The NiTi-ST is used to describe the damping of the NES,which is coupled with the modified Bouc-Wen model of hysteresis.The NES with NiTi-ST vibration reduction principle uses the irreversibility of targeted energy transfer(TET)to concentrate the energy locally on the nonlinear oscillator,and then dissipates it through damping in the NES with NiTi-ST.The generalized vibration transmissibility,obtained by the root mean square treatment of the harmonic response of the nonlinear output frequency response functions(NOFRFs),is first used as the evaluation index to analyze the whole-spacecraft system in the future.An optimization analysis of the impact of system responses is performed using different parameters of NES with NiTi-ST based on the transmissibility of NOFRFs.Finally,the effects of vibration suppression by varying the parameters of NiTi-ST are analyzed from the perspective of energy absorption.The results indicate that NES with NiTi-ST can reduce excessive vibration of the whole-spacecraft system,without changing its natural frequency.Moreover,the NES with NiTi-ST can be directly used in practical engineering applications.
基金Project(60604011) supported by the National Natural Science Foundation of China
文摘To improve the accuracy of strapdown inertial navigation system(SINS) for long term applications,the rotation technique is employed to modulate the errors of the inertial sensors into periodically varied signals,and,as a result,to suppress the divergence of SINS errors.However,the errors of rotation platform will be introduced into SINS and might affect the final navigation accuracy.Considering the disadvantages of the conventional navigation computation scheme,an improved computation scheme of the SINS using rotation technique is proposed which can reduce the effects of the rotation platform errors.And,the error characteristics of the SINS with this navigation computation scheme are analyzed.Theoretical analysis,simulations and real test results show that the proposed navigation computation scheme outperforms the conventional navigation computation scheme,meanwhile reduces the requirement to the measurement accuracy of rotation angles.
基金by National Natural Science Foundation of China(No.61972443)National Key Research and Development Plan Program of China(No.2019YFE0105300)+1 种基金Hunan Provincial Hu-Xiang Young Talents Project of China(No.2018RS3095)Hunan Provincial Natural Science Foundation of China(No.2020JJ5199).
文摘Rotating machinery is important to industrial production. Any failure of rotating machinery, especially the failure of rolling bearings, can lead to equipment shutdown and even more serious incidents. Therefore, accurate residual life prediction plays a crucial role in guaranteeing machine operation safety and reliability and reducing maintenance cost. In order to increase the forecasting precision of the remaining useful life(RUL) of the rolling bearing, an advanced approach combining elastic net with long short-time memory network(LSTM) is proposed, and the new approach is referred to as E-LSTM. The E-LSTM algorithm consists of an elastic mesh and LSTM, taking temporal-spatial correlation into consideration to forecast the RUL through the LSTM. To solve the over-fitting problem of the LSTM neural network during the training process, the elastic net based regularization term is introduced to the LSTM structure.In this way, the change of the output can be well characterized to express the bearing degradation mode. Experimental results from the real-world data demonstrate that the proposed E-LSTM method can obtain higher stability and relevant values that are useful for the RUL forecasting of bearing. Furthermore, these results also indicate that E-LSTM can achieve better performance.
文摘In this paper, a new adaptive hierarchical sliding mode control scheme for a 3D overhead crane system is proposed. A controller is first designed by the use of a hierarchical structure of two first-order sliding surfaces represented by two actuated and un-actuated subsystems in the bridge crane. Parameters of the controller are then intelligently estimated, where uncertain parameters due to disturbances in the 3D overhead crane dynamic model are proposed to be represented by radial basis function networks whose weights are derived from a Lyapunov function. The proposed approach allows the crane system to be robust under uncertainty conditions in which some uncertain and unknown parameters are highly difficult to determine. Moreover, stability of the sliding surfaces is proved to be guaranteed. Effectiveness of the proposed approach is then demonstrated by implementing the algorithm in both synthetic and reallife systems, where the results obtained by our method are highly promising.
