Hisashi Sano

Vibration/noise active control system for vehicles

A vibration/noise active control system for automotive vehicles which generates a canceling signal for canceling vibrations and noises generated within the compartment of the vehicle, based on a reference signal related to the vibrations and noises by means of an adaptive filter. The canceling signal is converted into a canceling sound. The adaptive filter has a filter coefficient thereof changed based on the cancellation error between the canceling sound and the vibrations and noises within the compartment, detected by an error sensor, and the reference signal. A memory stores a plurality of filter coefficient values of the adaptive filter corresponding to a plurality of predetermined traveling conditions of the vehicle. A discriminator reads out a filter coefficient value of the adaptive filter corresponding to the detected predetermined traveling condition of the vehicle, supplies the read-out filter coefficient value to the adaptive filter to generate the canceling signal, and stores a filter coefficient value of the adaptive filter which has been changed based on the generated canceling signal.

Active control system for low-frequency road noise combined with an audio system

An active control system for low-frequency road noise in automobiles combined with an audio system is developed as a commercial application for the first time in the world, and installed in a station wagon. The purpose of this paper is to provide an outline of the system and describe the newly developed cost-reduction technology used for it, since the reduction of system costs is a major reason that active noise control technology could successfully be applied in a commercial product. The methods used to reduce costs include utilization of feedback control, implementation by analogue circuits, and common use of audio system speakers. This system reduces low-frequency road noise in the front seat by about 10 dB and improves audio system listening experience while driving.

Application of a least squares lattice algorithm to active noise control for an automobile

The purpose of this paper is to propose an alternative approach to active noise control (ANC) using the least squares lattice (LSL) algorithm. Typically, in ANC applications, the leastmean-square (LMS) algorithm has been used because of its simplicity. However, the LMS algorithm has the disadvantage of slow convergence speed in the case of broadband noise, such as the road noise present in the passenger compartment of automobiles traveling on rough road surfaces. In order to solve this problem, the LSL algorithm for ANC is considered. By computer simulation using actual car data, the LSL algorithm proves to be more effective than the LMS one.