Adaptive Signal Selection Control Based on Adaptive FF Control Scheme and Its Applications to Sound Selection Systems

Abstract

Noise pollution is one of the social problems, and many researches on active noise control (ANC) or active vibration control (AVC) have been done (Tokhi & Veres, 2002). Almost all previous studies were interested in suppression of unwanted noise signals. However, actually some necessary signals should not be suppressed but transmitted and only unnecessary noise should be blocked. Therefore, a control method which can selectively attenuate only unnecessary signals is needed. In this chapter, we will propose a novel control scheme which can transmit necessary signals (Necs) and attenuate only unnecessary signals (Unecs) selectively. The control scheme is named as Signal Selection Control (SSC) scheme. The purpose of this chapter is to develop two types of the SSC; one is Necs-Extraction Controller which transmits only signals set as Necs, and the other is Unecs-Canceling Controller which attenuates only signals set as Unecs. The Necs-Extraction Controller was proposed by us before (Okumura & Sano, 2009), and the Unecs-Canceling Controller is newly proposed in this chapter. Results of both controllers are the same; both controllers transmit Necs and attenuate Unecs selectively, however, the design concept of each controller is different. When some Necs are known, the Necs-Extraction Controller is suitable and the Necs is set to be transmitted. On the other hand, when some Unecs are known, the Unecs-Canceling Controller is suitable and the Unecs is set to be attenuated. We can choose these two controllers according to the application systems. The SSC is based on adaptive feedforward (FF) control schemes which were adopted in the fields of ANC and AVC due to its excellent performance of noise attenuation. In this chapter, four adaptive controllers will be introduced and characterized; (i) the filtered-X LMS controller which is a conventional approach in the adaptive FF control field (Burgess, 1981; Widrow et al, 1982), (ii) the 2-degree-of-freedom filtered-X LMS controller (Kuo, 1996, 1999), (iii) the Virtual Error controller which is proposed by one of the authors before (Kohno & Sano, 2005; Ohta & Sano, 2004), and (iv) the 2-degree-of-freedom Virtual Error controller which is also proposed by us before(Okumura & Sano, 2009). To validate effectiveness of the proposed SSC, two applications to Sound Selection Systems (SSS) are considered as numerical simulations.