Convergence characteristics of PD-type iterative learning control in discrete frequency domain |
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Affiliation: | 1. Institute of Cyber-Systems and Control, National Key Laboratory of Industrial Control Technology, Zhejiang University, Hangzhou, 310027 Zhejiang, China;2. Department of Chemical Engineering, Chung-Yuan Christian University, Chung-Li 320, Taiwan, ROC;1. School of Automation & Electronics Engineering, Qingdao University of Science & Technology, Qingdao 266042, PR China;2. Advanced Control Systems Lab, School of Electronics & Information Engineering, Beijing Jiaotong University, Beijing 100044, PR China;3. EXQUISITUS, Centre for E-City, School of Electrical & Electronic Engineering, Nanyang Technological University, Singapore 639798, Singapore |
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Abstract: | On the basis that a Dirichlet-type signal over a finite time period can be expanded in a Fourier series consisting of fundamental-frequency sinusoidal and cosine waves plus a sequence of higher-frequency harmonic waves, this paper investigates the convergence characteristics of the first- and second-order proportional-derivative-type iterative learning control schemes for repetitive linear time-invariant systems in discrete spectrum. By deriving the properties of the Fourier coefficients in a complex form with respect to the linear time-invariant dynamics and adopting Parseval's Energy Equality, the average energy of the tracking error signal over the finite operation time interval is converted into a quarter of a summation of the fundamental spectrum plus the harmonic spectrums. By means of analyzing the feature of discrete frequency-wise spectrum of the tracking error, sufficient and necessary conditions for monotone convergence with respect to the first-order iterative learning control scheme is deduced together with convergence of the second-order learning scheme is discussed. Numerical simulations manifest the validity and the effectiveness. |
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Keywords: | Iterative learning control Monotone convergence Discrete frequency-domain spectrum Fourier series Parseval's Energy Equality |
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