Method for controlling variable damping suspensions

A method for controlling a suspension system for a vehicle, wherein the suspension system comprises:

• a plurality of semi-active dampers which are interposed each between a body and a respective wheel of the vehicle and are configured to change their damping coefficient in response to a control signal, wherein a damping force of each damper is a function of the respective damping coefficient and of the difference between a velocity of the body and a velocity of the respective wheel along a damping direction of the damper;
• sensors for acquiring a current measurement of an acceleration h(t=0) of the vehicle along a heave axis, of an angular acceleration r(t=0) of the vehicle around a roll axis and of an angular acceleration p(t=0) of the vehicle around a pitch axis;
• a memory module configured to store at least M+1 acceleration measurement values h(t=0, t=−1, . . . , t=−M), r(t=0, t=−1, . . . , t=−M), p(t=0, t=−1, . . . , t=−M) of the vehicle;
• a controller functionally connected with said dampers and with said memory module, the controller being configured to send a respective control signal to each damper to adjust the respective damping coefficient of the latter,
• the method comprising cyclically carrying out the steps of:
• i) at each cycle of the method, acquiring current acceleration values h(t=0), r(t=0), p(t=0) of the vehicle (V) from said sensors (2);
• ii) filtering said current acceleration values h(t=0), r(t=0), p(t=0) of the vehicle taking into account a number N of past acceleration measurements h(t=−1, . . . , t=−N), r(t=−1, . . . , t=−N), p(t=−1, . . . , t=−N) of the vehicle, taken at previous cycles and stored in the memory module, to obtain current filtered acceleration values, so-called indexes, Ih(t=0), Ir(t=0), Ip(t=0), wherein N≤M;
• iii) comparing each of the current filtered acceleration values Ih(t=0), Ir(t=0), Ip(t=0) with the respective previous filtered acceleration values Ih(t=−1), Ir(t=−1), Ip(t=−1);
• iv) based on the result of the comparison in step iii), determining the sign of a variation step to be applied to a state of the heave damping coefficient Ch*, to a state of the roll damping coefficient Cr* and to a state of the pitch damping coefficient Cp*, respectively, each state being obtained on previous output values of the heave damping coefficient Ch(t=−1), of the roll damping coefficient Cr(t=−1) and of the pitch damping coefficient Cp(t=−1), respectively, wherein said step of determining the sign of said variation step comprises the operation of checking, for each of the states Ch*, Cr* and Cp*, if the current filtered acceleration values Ih(t=0), Ir(t=0), Ip(t=0) are greater than the respective filtered acceleration values Ih(t=−1), Ir(t=−1), Ip(t=−1) taken at the previous cycle and, if so, reversing the sign of said variation step with respect to the sign of the variation step at the previous cycle, otherwise keeping unchanged the sign of the previous variation step;
• v) obtaining current values of the heave damping coefficient Ch(t=0), of the roll damping coefficient Cr(t=0) and of the pitch damping coefficient Cp(t=0) by summing each variation step with the respective values of the state of the heave damping coefficient Ch*, of the state of the roll damping coefficient Cr* and of the state of the pitch damping coefficient Cp*;
• and
• vi) transmitting to each damper said respective control signal which corresponds to a desired value of the damping coefficient, said desired value of the damping coefficient being based on the current values of the heave damping coefficient Ch(t=0), of the roll damping coefficient Cr(t=0) and of the pitch damping coefficient Cp(t=0) of the vehicle.