Suspension system

A suspension system comprising:

• (a) a vibration obtaining device configured to obtain vertical vibration of each of at least one of a sprung portion and an unsprung portion of a vehicle;
• (b) a processing device configured to subject the obtained vibration to a phase advance processing, and having a plurality of characteristics different from each other with respect to a degree by which a phase of the obtained vibration is advanced;
• (c) a characteristic selector configured to select one of the plurality of characteristics, based on frequency of the obtained vibration of each of at least one of the sprung and unsprung portions, whereby the obtained vibration is subjected to the phase advance processing that is performed in accordance with the selected one of the plurality of characteristics of said processing device;
• (d) a suspension controller configured to control a suspension disposed between the sprung and unsprung portions, based on the vibration subjected to the phase advance processing;
• wherein said vibration obtaining device includes an unsprung-portion vibration obtaining portion configured to obtain the vibration of the unsprung portion,
• wherein said processing device has first and second characteristics as the plurality of characteristics, such that the phase of the obtained vibration is advanced by a larger degree when the phase advance processing is performed in accordance with the second characteristic, than when the phase advance processing is performed in accordance with the first characteristic,
• and where said characteristic selector includes a frequency-basis selecting portion configured to select the first characteristic when the frequency of the obtained vibration of the unsprung portion is lower than a predetermined threshold value, and to select the second characteristic when the frequency of the obtained vibration of the unsprung portion is not lower than the predetermined threshold value, such that the obtained vibration of the unsprung portion is subjected to the phase advance processing that is performed in accordance with the first characteristic when the frequency of the obtained vibration of the unsprung portion is lower than the predetermined threshold value, and such that the obtained vibration of the sprung portion is subjected to the phase advance processing that is performed in accordance with the second characteristic when the frequency of the obtained vibration of the unsprung portion is not lower than the predetermined threshold value.