A Study on Development and Applications of Feedforward Adaptive Control

点击翻译按钮获取中文摘要

The feedforward control can much improve control performance by effectively using accessible signals. Since it depends on accuracy of the model of controlled systems, adaptive approaches with assured stability and convergence should be developed. The research results are summarized as follows :(1)A new direct adaptive approach is proposed for general multichannel active noise control(ANC) and multichannel sound reproduction (SRP) when all of the path channels are uncertain and changeable. To reduce the canceling or reconstruction errors, two kinds of virtual errors are introduced and are forced into zero by adjusting three adaptive FIR filter matrices in an on-line manner, by which the convergence of the actual canceling errors to zero can be attained at the objective points. Unlike other conventional approaches, the proposed algorithm can give an inverse controller directly without need of explicit identification of the secondary path channels, and requires neither any dither signals … More nor the PE property of the source signals, which is a great advantage of the proposed approach.(2)A new time-domain adaptive predistortion scheme has been developed for compensating nonlinearity of high power amplifiers (HPA) in OFDM systems. A power series model with memory(PSMWM) is proposed to approximately describe the nonlinear input-output relation of HPA with dynamics. By using the PSMWM, the compensation input to HPA is calculated in a real-time manner so that the linearization from the predistortor input to the HPA output can be attained even if the nonlinear input-output relation of HPA is uncertain and changeable. The effectiveness of the proposed adaptive compensation scheme is validated by numerical simulation for 64QAM--OFDM systems.(3)Magnetorheological(MR) damper is a promising semi-active device for vibration control of structures. A simple mathematical model of MR damper with a small number of model parameters has been given to express its hysteresis behavior of nonlinear dynamic friction mechanism of the MR fluid. The adaptive identification algorithm is also proposed in which the uncertain model parameters and internal state variable can be estimated. The proposed model has an advantage that by using its inverse model we can analytically determine the necessary input voltage to the MR damper so that the desirable damper force can be added to the structure in an adaptive manner. Experimental results validate the proposed adaptive modeling and control schemes in vibration isolation of three story structure. Less