Intelligent Combination of Software Calibration and High Responsive Hydraulics Control for a Low-Noise and Cost-Efficient Semi-Active Chassis System

Abstract

A semi-active suspension system is often used to allow a broad spread between ride comfort and handling ability. The performance of the chassis system is directly related to the high responsive hydraulics control as well as the control strategy. This control software is using information from the vehicle applying through the CAN connection and other functions developed by the suspension supplier to assure driving safety, handling control and riding comfort independent on the road solicitation by controlling electro-magnetic valves at each shock absorber.

Upon the physics there are existing borders for those systems in regards of possible noise impacts in case of high frequency or high amplitude road inputs which can be solved by passive systems using mechanical rubber stops at the rebound or compression side. Such a system requires additional package and increases the cost of the shock absorber.

The proper use of a software solution can avoid the implementation of hydraulic rebound or compression stoppers and thus reduce the dimensions of mechanical rubber stoppers keeping the overall shock absorber length on an equal level and furthermore avoid additional cost for additionally required components.

New software functions can be implemented into the same ECU as for the semi-active suspension system providing a higher damping robustness for extreme road input. Furthermore, it is possible to adapt the damping force progressivity by modifying the gradient and activation point for rebound and compression conditions.

The paradigm change from the classical development of mechanical components towards the finding of numerical solutions of solving a big variety of vehicle drivability issues is the key item for the future enablement of moving towards the virtual development of shock absorbers and chassis systems.

Improving the behavior of the suspension purely by the adjusting of the related application software, allows the adaption of different control strategies according to the requirements of the applied vehicle reducing the variants of shock absorbers and thus the overall development effort just by software map definition.

Finally, the focus on software solutions will reduce cost and shorten the lead time both at OEM and supplier side by reducing loops of bench and vehicle validation during the setting definition.