Abstract
This abstract is a further release of the one which introduced SCOOP project to the ATA Conference held last 17-19 November 1999 in Florence; since that presentation this Brite-Euram project has been completed. Vehicle comfort is a growing concern of the driving public, with marketing studies consistently pointing to comfort as a decisive factor determining vehicle sales. It has long been recognised that the seat system plays a fundamental role towards determining the comfort of the whole vehicle. Comfort is also a very important health and safety concern.
The main objective of this project is to develop a Seat Vibrational Comfort Testing procedure (SVCTP). The reason is that few test procedures currently exist in industry, and no international standards define a complete procedure. Fundamental issues such as how to choose mission signals, how to treat the complex (non-linear) behaviour of the person/seat system and how to choose human test subjects are completely lacking from all existing national and international standards. Vehicle and seat system manufacturers currently cannot compare test results obtained by different laboratories or exchange data. This situation is economically damaging because it adds large additional costs to vehicle and seat development programs by eliminating chances for concurrent engineering.
The seat comfort optimisation procedure can and has not be treated as an isolated problem. The comfort is not only dependent of the seat but also of the car and the passenger. To deal with the coupling between the seat and the passenger, SCOOP has involved real passengers in the seat design. Tests on real passengers has been used to study the effects of the anthropometric parameters on seat testing results and to develop new comfort criteria based on human perception. To deal with the coupling between the seat and the car, seats have not only been tested on a seat test rig where the seat is completely isolated from its environment but also on a four poster test rig where the seat is embedded inside the car environment.
SCOOP can be broken down into the following objectives:
1) Define the bounds of the vibrational environment in vehicles and define a technically adequate, industrially feasible method for synthesising seat vibrational missions from large amounts of road data.
2) Develop a next generation real-time vibration controller, and tailor its characteristics to the seat testing application.
3) Develop new and better ways of quantifying and analysing the non-linear behaviour of the person/seat system.
4) Develop new methods of test jury selection so as to achieve small jury sizes and test times.
5) Develop more accurate methods of quantifying human vibrational comfort.
6) Model the dynamics of person/seat interaction and identify the key vibrational parameters for the purposes of synthesis and data exchange.
7) Perform a numerical study to identify optimal seat parameters to maximise perceived vibrational comfort while respecting postural and material property constraints.
8) Implement and validate the SVCTP on seat test rigs, vehicle 4 poster rigs and vehicle 7 poster rigs.
9) Obtain industrial acceptance of the SVCTP and possible standardisation.