Hybrid analog digital control method and apparatus for estimation of absolute velocity in active suspension systems

A method for producing a signal indicative of the absolute velocity of a mass including the steps of:

• providing an input signal idicative of the motion condition of said mass;
• integrating said input signal over time using an analog integrator means to produce a time integrated signal;
• stabilizing said time integrated signal by feedback of a digital offset signal produced from said time integrated signal to said analog integrator means to produce a stabilized signal within a selected oscillatory voltage range;
• removing relatively low frequency components of said stabilized signal by a digital filter means to locate the short term mean of the relatively high frequency components of said stabilized signal about a selected voltage and to produce a signal indicative of the absolute velocity of said mass;
• providing an analog to digital signal conversion means for conditioning output signals from said analog integrator means;
• and,
• providing a digital to analog signal conversion means for conditioning input signals fed back to said analog integrator means.

An analog and digital controller for producing an output signal indicative of the absolute velocity of a mass comprising:

• input signal element for providing an input signal;
• analog integrator means receiving said input signal and producing a time-integrated signal;
• digital stabilizer means for receiving said time-integrated signal from an analog to digital converter and producing a feedback signal through a digital to analog converter to said analog integrator means to offset the constant and relatively low frequency components of said integrated signal and provide a stabilized, integrated signal;
• and
• digital filter means for receiving said stabilized, integrated signal through said analog to digital converter and locating the short-term frequency mean of said stabilized, integrated signal about a selected voltage and to produce a signal indicative of the absolute velocity of said mass.

An analog/digital controller for producing an output signal indicative of the absolute velocity of a mass comprising:

• input signal means for providing an input signal indicative of a motion condition of said mass;
• analog integrator means receiving said input signal and producing a time-integrated signal;
• digital stabilizer means providing a feedback signal through a digital to analog converter to said analog integrator means to constrain the constant and relatively low frequency components of said integrated signal and provide a stabilized, integrated signal;
• and
• digital filter means receiving through an analog to digital converter said stabilized, integrated signal and eliminating constant low frequency components thereof to produce said output signal proportional in magnitude and sign to the absolute velocity of said mass.