Objective tuning of semi-active dampers: Method development for ride metric optimisation utilizing a four poster rig

Abstract

Active systems in premium passenger cars are gaining popularity which in turn leads to higher demands on these systems to perform. One such system are semi-active dampers which can replace passive dampers and is a big part in how the suspension performs. Traditionally, semi-active dampers are tuned by experienced engineers with focus on subjective assessment and understanding of vehicle dynamics. Test driving and analysing data lets the engineers tune the specific system to a desired functionality. To achieve an overall better result for semi-active damper systems it would be effective to extend the objective capabilities of the tuning process. This is exactly where this project finds its purpose. This project aims to create a method that makes it possible to objectively tune semi-active dampers utilizing a four poster rig. Focus was on primary ride comfort, looking at the level of damper control and ride abruptness. To do so a metric for primary ride control was found and validated on the four poster rig. Optimisation of semi-active damper parameters was investigated in CAE and transferred to the four poster rig. A complete vehicle was setup on the rig and the semi-active damper ECU was connected to a laptop. The laptop measured and updated the vehicle according to patternsearch optimisation while the vehicle got excited by a recorded. Different target functions and initial guesses were investigated, which resulted in three interesting outcomes. The optimisation worked well on the rig and it ran continuously without human input. To conclude the project, a metric was found and validated and an objective tuning method was found. With that conclusion the aim of the project was satisfied.