F2008-12-151
A Simple Method to Study Combined Effects of Vehicle Suspension Kinematic and Compliance Response on Steady State Cornering
A Simple Method to Study Combined Effects of Vehicle Suspension Kinematic and Compliance Response on Steady State Cornering
Julian, Ben*, Siegler, Blake, Regan, Chris Oxford Brookes University, UK Honda Research and Development Europe (UK), UK
KEYWORDS - Vehicle Dynamics, Ride and Handling, Chassis, Suspension, Steering.
ABSTRACT - Vehicle suspension test rigs (1) have been around for some time and are commonly used to understand the response of suspension system designs. Currently these responses are analysed separately for geometry (kinematics) and forces (compliance).
In real world situations these two factors combine to give an overall response of the vehicle´s suspension system (2) as the vehicle´s body not only moves relative to the wheels causing geometry changes but forces generated by the tyres create a compliant response of the suspension system.
In the past the overall response has been studied using full vehicle model simulation packages that predict the overall response of the suspension system. These can be multi-body based (3) and use the individual component designs to predict the vehicle´s response. Or parameter based (4) and use the overall system responses to predict the vehicle´s response. It can take some time to generate enough data to fully build a full model of a vehicle.
This paper outlines a simple technique for quickly combining the rig based measurements of the kinematic and compliance responses for a vehicle undergoing a steady state cornering test. The technique involves making a basic estimation of the vehicle´s lateral load transfer during cornering and using this to estimate the suspension system movement and forces generated by the tyres. These two estimations are then combined to give a total response of the suspension system.
The results from this basic technique are then compared with actual response data measured on a vehicle during an actual test. The simple approximation is shown to give a valid estimation of the actual vehicle´s total suspension system response. This total response would be difficult to predict by looking at the kinematic and compliant responses in isolation. And similarly looking at the total response it is difficult to understand the separate kinematic and compliant contributions.
The paper then goes on to apply this technique to several vehicles measured on a suspension testing rig. An estimation is made of how various suspension system designs achieve their predicted overall response. It can be seen from the results that by clever use of design, deficiencies in cheaper semi-linked axle suspension systems can be overcome. This is shown to make their responses more desirable and more similar to more expensive independent multi-link suspension systems.
REFERENCES
(1) MTS Website: http://www.mts.com/en/vehicles/performance/Suspension/index.asp. (2) Catala, Alexandre, Dynamic Wheel Position Measurement System for the Road Testing, F2004F401 - FISITA Conference, Barcelona Spain, 2004. (3) MSC Website: http://www.mscsoftware.com/products/adams.cfm?Q=396&Z=397. (4) CarSim Website: http://www.carsim.com/products/carsim/.
Session: Chassis