This paper presented an evaluation approach of time delays for networked control systems (NCS). An improved scheme based on optimal LQG control was designed to achieve desired performance despite the uncertain delays ...This paper presented an evaluation approach of time delays for networked control systems (NCS). An improved scheme based on optimal LQG control was designed to achieve desired performance despite the uncertain delays in the system. The experimental results illustrate the effectiveness of the proposed control design and satisfactory performance of the closed loop system.展开更多
The paper presents results from a study of a series-connected single-phase APF （active power filter） with a control system based on hysteresis control, both with and without limitation of the maximum switching frequ...The paper presents results from a study of a series-connected single-phase APF （active power filter） with a control system based on hysteresis control, both with and without limitation of the maximum switching frequency. The general purpose of the series APF is to eliminate the low order harmonics of the source （grid） voltage. The filter operation at limited and unlimited maximum switching frequency is explained and it is described using building blocks and time diagrams illustrating the tracking down of the reference curve. Waveforms from the computer simulation and waveforms from the experimental tests of the filter are presented also for the two situations. Operations at limited and unlimited maximum switching frequency are compared regarding the quality of the voltage across the load, the complexity of the implementation of the control system, and the electromagnetic compatibility. The investigation proved capability of the series APF to achieve its general purpose using the hysteresis control methods studied （limited and unlimited switching frequency）.展开更多
Headphones with an integrated active noise cancellation system have been increasingly introduced to the consumer market in recent years. When exposing the human ear to active noise sources in this striking distance, t...Headphones with an integrated active noise cancellation system have been increasingly introduced to the consumer market in recent years. When exposing the human ear to active noise sources in this striking distance, the ensuring of a safe sound pressure level is vital. In feedback systems, this is coupled with the stability of the closed control loop; stable controller design is thus essential. However, changes in the control path during run-time can cause the stable control system to become unstable, resulting in an overdrive of the speakers in the headphones. This paper proposes a method, which enables the real-time analysis of the current system state and if necessary stabilizes the closed loop while maintaining the active noise reduction. This is achieved by estimating and evaluating the open loop behavior with an adaptive filter and subsequently limiting the controller gain in respect to the stability margin.展开更多
In this paper, the platoon control problem of autonomous vehicles in highway is studied. Since the autonomous vehicles have the characteristics of nonlinearities, external disturbances and strong coupling, a novel ada...In this paper, the platoon control problem of autonomous vehicles in highway is studied. Since the autonomous vehicles have the characteristics of nonlinearities, external disturbances and strong coupling, a novel adaptive fuzzy sliding coordinated control system is constructed to supervise the longitudinal and lateral motions of autonomous vehicles, in which the fuzzy system is employed to approximate the unknown nonlinear functions. Due to the low sensitivity to disturbances and plant parameter variations, the proposed control approach is an efficient way to handle with the complex dynamic plants operating under un-certainty conditions. The asymptotic stability of adaptive coordinated platoon close-loop control system is verified based on the Lyapunov stability theory. The results indicate that the presented adaptive coordinated platoon control approach can accurately achieve the tracking performance and ensures the stability and riding comfort of autonomous vehicles in a platoon. Finally,simulation test is exploited to demonstrate the effectiveness of the proposed control approach.展开更多
An open-loop control system for hovering at any selected position on spacecraft orbit is first presented given that the satellite＇s engine provides continuous finite thrust. Actually, the hovering states are unstable...An open-loop control system for hovering at any selected position on spacecraft orbit is first presented given that the satellite＇s engine provides continuous finite thrust. Actually, the hovering states are unstable considering perturbations and thrust errors, so a feedback sliding mode variable structure control, which is adaptive and chattering-free, is designed. Under this feedback control scheme, the high-frequency chattering phenomenon is avoided, while the system stays highly robust at the same time. Simulation results show that the feedback control thrusts are continuous and the steady-states error can be confmed to 10-4 m at the presence of uncertain perturbations. Finally, the feasibility of realizing hovering orbits is analyzed taking the ＂Moliya＂ and geosynchronous Earth orbit （GEO） satellites as examples.展开更多
This paper extends the unknown control coefficients with lower and upper constant bounds to the ones which may take arbitrarily large and /or small values.Since the existing methods are no longer applicable and the te...This paper extends the unknown control coefficients with lower and upper constant bounds to the ones which may take arbitrarily large and /or small values.Since the existing methods are no longer applicable and the technical obstacles caused by the extensions are essential,new control design scheme should be exploited to the global practical tracking.By the approaches of Nussbaum-gain and adding a power integrator,the authors successfully propose the design scheme of the adaptive practical tracking controller for the systems.It is shown that the designed controller guarantees that all the closed-loop system states are bounded and the tracking error becomes prescribed arbitrarily small after a finite time.展开更多
文摘This paper presented an evaluation approach of time delays for networked control systems (NCS). An improved scheme based on optimal LQG control was designed to achieve desired performance despite the uncertain delays in the system. The experimental results illustrate the effectiveness of the proposed control design and satisfactory performance of the closed loop system.
文摘The paper presents results from a study of a series-connected single-phase APF （active power filter） with a control system based on hysteresis control, both with and without limitation of the maximum switching frequency. The general purpose of the series APF is to eliminate the low order harmonics of the source （grid） voltage. The filter operation at limited and unlimited maximum switching frequency is explained and it is described using building blocks and time diagrams illustrating the tracking down of the reference curve. Waveforms from the computer simulation and waveforms from the experimental tests of the filter are presented also for the two situations. Operations at limited and unlimited maximum switching frequency are compared regarding the quality of the voltage across the load, the complexity of the implementation of the control system, and the electromagnetic compatibility. The investigation proved capability of the series APF to achieve its general purpose using the hysteresis control methods studied （limited and unlimited switching frequency）.
文摘Headphones with an integrated active noise cancellation system have been increasingly introduced to the consumer market in recent years. When exposing the human ear to active noise sources in this striking distance, the ensuring of a safe sound pressure level is vital. In feedback systems, this is coupled with the stability of the closed control loop; stable controller design is thus essential. However, changes in the control path during run-time can cause the stable control system to become unstable, resulting in an overdrive of the speakers in the headphones. This paper proposes a method, which enables the real-time analysis of the current system state and if necessary stabilizes the closed loop while maintaining the active noise reduction. This is achieved by estimating and evaluating the open loop behavior with an adaptive filter and subsequently limiting the controller gain in respect to the stability margin.
基金supported by the National Natural Science Foundation of China(Grant Nos.61304193&U1564208)National Key R&D Program of China(Grant No.2016YFB0100900)
文摘In this paper, the platoon control problem of autonomous vehicles in highway is studied. Since the autonomous vehicles have the characteristics of nonlinearities, external disturbances and strong coupling, a novel adaptive fuzzy sliding coordinated control system is constructed to supervise the longitudinal and lateral motions of autonomous vehicles, in which the fuzzy system is employed to approximate the unknown nonlinear functions. Due to the low sensitivity to disturbances and plant parameter variations, the proposed control approach is an efficient way to handle with the complex dynamic plants operating under un-certainty conditions. The asymptotic stability of adaptive coordinated platoon close-loop control system is verified based on the Lyapunov stability theory. The results indicate that the presented adaptive coordinated platoon control approach can accurately achieve the tracking performance and ensures the stability and riding comfort of autonomous vehicles in a platoon. Finally,simulation test is exploited to demonstrate the effectiveness of the proposed control approach.
基金supported by the National Natural Science Foundation of China (Grant No. 10702078)the National Basic Research Program of China ("973" Program) (Grant No. JC08-01-05)
文摘An open-loop control system for hovering at any selected position on spacecraft orbit is first presented given that the satellite＇s engine provides continuous finite thrust. Actually, the hovering states are unstable considering perturbations and thrust errors, so a feedback sliding mode variable structure control, which is adaptive and chattering-free, is designed. Under this feedback control scheme, the high-frequency chattering phenomenon is avoided, while the system stays highly robust at the same time. Simulation results show that the feedback control thrusts are continuous and the steady-states error can be confmed to 10-4 m at the presence of uncertain perturbations. Finally, the feasibility of realizing hovering orbits is analyzed taking the ＂Moliya＂ and geosynchronous Earth orbit （GEO） satellites as examples.
基金supported by the National Natural Science Foundations of China under Grant No.60974003 and 61143011the Natural Science Foundation for Distinguished Young Scholar of Shandong Province of China under Grant No.JQ200919+5 种基金the Program for New Century Excellent Talents in University of China under Grant No.NCET-07-0513the Key Science and Technique Foundation of Ministry of Education of China under Grant No.108079the Excellent Young and Middle-Aged Scientist Award Grant of Shandong Province of China under Grant No.2007BS01010the Independent Innovation Foundation of Shandong University under Grant No.2009JQ008the Scholarship Award for Excellent Doctoral Student granted by Ministry of Educationthe Graduate Independent Innovation Foundation of Shandong University
文摘This paper extends the unknown control coefficients with lower and upper constant bounds to the ones which may take arbitrarily large and /or small values.Since the existing methods are no longer applicable and the technical obstacles caused by the extensions are essential,new control design scheme should be exploited to the global practical tracking.By the approaches of Nussbaum-gain and adding a power integrator,the authors successfully propose the design scheme of the adaptive practical tracking controller for the systems.It is shown that the designed controller guarantees that all the closed-loop system states are bounded and the tracking error becomes prescribed arbitrarily small after a finite time.
