On Optimal Control of a Multichamber Air Spring and Experimental Validation over Speed Bumps

This paper deals with a preview- based optimal control of a multichamber suspension over speed bumps. A multichamber suspension is an innovative type of road vehicle suspension whose spring is composed of multiple auxiliary air reservoirs connected to a main pneumatic chamber. A set of controllable valves regulate the airflow among the different chambers, allowing the modulation of the spring equivalent stiffness. Multichamber suspensions are the only existing architecture in the market capable of vertical stiffness regulation. The first goal of this paper is to find an optimal valve position sequence which minimizes the vertical acceleration over some known speed bump profiles, under the hypothesis of perfect road preview. This optimization is carried out in simulation considering a control- oriented model of the multichamber suspension. A sensitivity study is then performed considering different bump shapes and vehicle speeds. The second goal of this work is to apply and validate the control sequence on a real vehicle equipped with commercial multichamber suspensions. Experimental results successfully reported improvements in corner vertical acceleration up to 16% and chassis pitch rate up to 12% compared to the passive benchmark.