Method for controlling active suspension system on the basis of rotational motion model

An active suspension control method for controlling a vehicle active suspension system which includes a main tank for storing fluid, and suspension cylinders provided at wheels of the vehicle and connected to said main tank for being supplied with said fluid to control the attitude of the vehicle body, said method comprising the steps of:

• sensing an acceleration acting on the body of the vehicle which is in a running state;
• predicting a rotational angle of said vehicle body using a controller by solving a dynamic model equation of rotational motion of the vehicle mathematically according to a value of sensed acceleration and predetermined parameter coefficients of said model equation, said predicted rotational angle being provided as a control signal, wherein the dynamic model equation includes an equation for roll motion of:
• In.phi..sub.2 +Cn.phi..sub.1 +(Kr-Ms.multidot.Hr.multidot.g).phi..sub.0 =Ms.multidot.Ay.multidot.Hr . . .
• where
• Ir is the roll moment of inertia;
• .phi..sub.0 is the roll angle;
• .phi..sub.1 is the roll angular velocity;
• .phi..sub.2 is the roll angular acceleration;
• Cr is the roll-equivalent damping coefficient;
• Kr is the roll stiffness;
• Ms is the on-sprung weight;
• Hr is the distance between roll axis centroids;
• g is the gravitational acceleration;
• and
• Ay is the lateral acceleration signal;
• and further includes the equation for pitch motion of:
• Ip.lambda..sub.2 +Cp.lambda..sub.1 +(Kp-Ms.multidot.Hp.multidot.g).lambda..sub.0 =Ms.multidot.Ax.multidot.Hp . . .
• where
• Ip is the pitch moment of inertia;
• .lambda..sub.0 is the pitch angle;
• .lambda..sub.1 is the pitch angular velocity;
• .lambda..sub.2 is the pitch angular acceleration;
• Cp is the pitch-equivalent damping coefficient;
• Kp is the pitch stiffness;
• Hp is the distance between pitch axis centroids;
• and
• Ms is the sprung weight;
• and
• controlling the supply of fluid from said main tank to said suspension cylinders according to said control signal representing the predicted rotational angle of the vehicle body, wherein said predicting step includes the steps of detecting at least one roll angle and pitch angle of the vehicle body, and correcting a predicted rotational angle with a signal indicative of the detected angle, and correcting said parameter coefficients I.sub.R of the roll motion equation with the actual roll angle and the predicted roll angle, and/or correcting said parameter coefficient I.sub.p of the pitch motion equation with the actual pitch angle and the predicted pitch angle.