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Application of predictive control scheduling method to real-time periodic control tasks overrun 被引量:1
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作者 沈青 桂卫华 +1 位作者 阳春华 杨铁军 《Journal of Central South University of Technology》 EI 2007年第2期266-270,共5页
Based on the abort strategy of fixed periods, a novel predictive control scheduling methodology was proposed to efficiently solve overrun problems. By applying the latest control value in the prediction sequences to t... Based on the abort strategy of fixed periods, a novel predictive control scheduling methodology was proposed to efficiently solve overrun problems. By applying the latest control value in the prediction sequences to the control objective, the new strategy was expected to optimize the control system for better performance and yet guarantee the schedulability of all tasks under overrun. The schedulability of the real-time systems with p-period overruns was analyzed, and the corresponding stability criteria was given as well. The simulation results show that the new approach can improve the performance of control system compared to that of conventional abort strategy, it can reduce the overshoot and adjust time as well as ensure the schedulability and stability. 展开更多
关键词 real-time system OVERRUN predictive control scheduling stability
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Velocity plus displacement equivalent force control for real-time substructure testing 被引量:1
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作者 Zhou Huimeng D.Wagg Wang Tao 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2018年第1期87-102,共16页
This paper employs a velocity plus displacement(V+D)-based equivalent force control(EFC) method to solve the velocity/displacement difference equation in a real-time substructure test. This method uses type 2 fee... This paper employs a velocity plus displacement(V+D)-based equivalent force control(EFC) method to solve the velocity/displacement difference equation in a real-time substructure test. This method uses type 2 feedback control loops to replace mathematical iteration to solve the nonlinear dynamic equation. A spectral radius analysis of the amplification matrix shows that the type 2 EFC-explicit, Newmark-β method has beneficial numerical characteristics for this method. Its stability limit of Ω = 2 remains unchanged regardless of the system damping because the velocity is achieved with very high accuracy during simulation. In contrast, the stability limits of the central difference method using direct velocity prediction and the EFC-average acceleration method with linear interpolation are shown to decrease with an increase in system damping. In fact, the EFC-average acceleration method is shown to change from unconditionally stable to conditionally stable. We also show that if an over-damped system with a damping ratio of 1.05 is considered, the stability limit is reduced to Ω =1.45. Finally, the results from an experiment with a single-degree-of-freedom structure installed with a magneto-rheological(MR) damper are presented. The results demonstrate that the proposed method is able to follow both displacement and velocity commands with moderate accuracy, resulting in improved test performance and accuracy for structures that are sensitive to both velocity and displacement inputs. Although the findings of the study are promising, additional test data and several further improvements will be required to draw general conclusions. 展开更多
关键词 real-time substructure test EFC velocity/displacement control newmark-β method stability
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Real-Time Detection of Unstable Control Loop Behavior in a Feedback Active Noise Cancellation System for In-Ear Headphones
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作者 Sven Hö ber +1 位作者 Christian Pape Eduard Reithmeier 《Engineering(科研)》 2015年第12期796-802,共7页
Active noise controls are used in a wide field of applications to cancel out unwanted surrounding noise. Control systems based on the feedback structure however have the disadvantage that they may become unstable duri... Active noise controls are used in a wide field of applications to cancel out unwanted surrounding noise. Control systems based on the feedback structure however have the disadvantage that they may become unstable during run-time due to changes in the control path—in this context including the listener’s ear. Especially when applied to active noise cancellation (ANC) headphones, the risk of instability is associated with the risk of harmful influence on the listener’s ear, which is exposed to the speaker in striking distance. This paper discusses several methods to enable the analysis of a feedback ANC system during run-time to immediately detect instability. Finally, a solution is proposed, which identifies the open loop behavior parametrically by means of an adaptive filter to subsequently evaluate the coefficients regarding stability. 展开更多
关键词 ACTIVE Noise control FEEDBACK stability real-time Analysis
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