A lot of countermeasures have been developed in order to reduce interior noise. For example, improvements of rubber mount characteristics and other measures have been implemented. Recently electromagnetic active engine mounts based on a hydraulic engine mount have been developed. They are significantly effective for the reduction of the booming noise which is unpleasant for passengers. Although the LMS algorithm has been generally used for the active control, it has been used only for reducing booming noise.
The authors developed a new control method in order to reduce not only the booming noise but also the noise and the vibration over wide frequency band for comfortable vehicle interior space. The authors studied the method which determines the feedback gain according to various conditions by modifying LMS algorithm. In this modified LMS algorithm, only an error signal was used as an input signal.
At first, the new control method was compared with the conventional LMS algorithm by computer simulation. The result was that the new control method is effective for wide frequency band compared to the LMS algorithm.
In addition the new control method and the conventional LMS algorithm were tested on a recreational vehicle equipped with hydraulic active mounts. The authors demonstrated that the new control method reduces the transmitted force, the seat rail vibration and the interior noise over wide frequency band and the conventional LMS algorithm can only reduce the first firing order at idle speed. It is shown that this new control method is effective from the viewpoint of comfort.