Abstract
Keywords: long distance, ride comfort, subjective evaluation, driving tests, objectifying subjective aspects
,,Driving longer and arriving more relaxed"- What are the costumers needs? This is the main question to be answered by results of investigations which were done by Volkswagen Group Research. Characterisation of vehicle comfort considering especially long distance rides by objective parameters was investigated. Former results indicated that seating comfort, interior acoustics, interior climate and driving behaviour play a main role for subjective impression of test candidates. Drivers' evaluation depends on his personal experience, the characteristics of the vehicle and the surrounding conditions (road characteristics, traffic, weather etc.). To investigate this more deeply and to achieve validated objective parameters one single vehicle with different properties concerning driving behaviour (suspension, gear shift points of transmission), seating and interior acoustics was evaluated by a number of certain test persons. Test persons were all men with similar age and experience in long distance driving. Tests were conducted on motorways and country roads.
The suspension and steering wheel behaviour of the test vehicle could be modified in two conditions, one comfort oriented and the other sporty. Also in the comfort mode the interior acoustics were modified in that way that two dominating engine orders were reduced by means of an active noise cancellation system. In the sporty mode other engine orders were amplified to achieve a powerful "V8-sound". To differentiate between sporty and comfort drive two different seats were mounted on drivers' side.
During the driving tests the drivers were asked to rate their comfort perception by an automatic record system. In parallel the data stream of the vehicle CAN-Bus was recorded and also interior noise and accelerations at relevant positions (e.g. seat rail, floor) were measured. At the end the subjects filled out an extensive questionnaire about the cars properties, traffic, weather etc. Main objective of these tests was to find correlations between the subjective ratings of the test persons and vehicle characteristics/conditions. Concerning acoustics for instance sound pressure level (SPL) and Articulation Index (AI) were investigated.
This paper presents a model of the interaction between surrounding (traffic conditions, weather etc), driver and vehicle. It can be stated that a vehicle is the "mediator" between surrounding and driver. The drivers' evaluation of the vehicle characteristics depend on surrounding (e.g. sunny weather, rough road) and traffic conditions.
Results show that considering the overall judgement of the vehicle characteristics its differences were noticed significantly, whereas differences in ratings of test persons were not significant. Traffic conditions seem to be significant, too. However, it is difficult to investigate the influence of traffic conditions because it is depending strongly on test persons' Geschwindigkeit, m/s Kraft, N Komfort Sport Velocity m/s Force , N Comfort Sport subjective impression. To explore this more deeply one approach could be the investigation of vehicle data such as velocity, distance to vehicle in front (from adaptive cruise control).