Banded on-off control method for semi-active dampers

A controllable suspension system, comprising:

• (a) at least two semi-active dampers attached between a first moving member and a second moving member and controlled by a primary control algorithm, each said semi-active damper including a semi-active valve for semi-actively varying a damping state of said semi-active dampers between a high-damping On state and a low-damping Off state in real time;
• (b) at least two acceleration sensors from which an electrical signal indicative of the absolute velocity differential and a directional sign indicative of direction of movement between two spaced apart portions of said first moving member can be derived;
• and
• (c) means defining a null band setting interacting with said primary control algorithm which is responsive a preselected threshold value of said absolute velocity differential derived from said sensors such that when said absolute velocity differential is below said reselected threshold value said means defining a null band setting is adjusted to set said null band wider and said low-damping Off state is provided and when said absolute velocity differential is exceeded and said directional sign is indicative of movement of said spaced apart portions in opposed directions, said means defining a null band setting set said null band setting narrower and a control of said dampers is initiated to command a higher damning setting.

A method of controlling a semi-active suspension system, comprising the steps of:

• (a) setting an On state and Off state damping level of at least two semi-active dampers dependent upon a driver selected setting;
• (b) determining the absolute velocity differential and a directional sign indicative of movements of at least two spaced apart portions of a first moving member;
• (c) setting a preselected threshold width of a null band of a primary control algorithm responsive to said absolute velocity differential and said directional sign indicative of movements of said at least two spaced apart portions;
• and
• (d) overriding said damping level dependent on said driver selected setting when said absolute velocity differential exceeds said preselected threshold width of said null band and when said directional signs are opposite, thus commanding said null band to a narrower width and as a result, initiating control of said On state and said Off state of said semi-active dampers.