Abstract
Keywords - Multiple Stressors, Thermal Comfort, Air Quality, Noise and Vibration
Abstract - This article deals with a research project that has the objective of evaluating the combined effect of different discomfort stimulus acting on a passenger in a vehicle cabin. The idea is to develop a general comfort index, capable of forecasting the average human evaluation of the environmental conditions in a car cabin, where the passengers are subjected to the combined influence of multiple stressors (thermal comfort, noise, vibration, air quality, light and ergonomics). This project is sponsored by the Portuguese Science and Technology Foundation and has the participation of a university, a polytechnic institute and a bus manufacturer company.
Data about the physical parameters used to characterize the most relevant causes of discomfort for riding passengers in a bus are collected in parallel with the subjective evaluation of people, for different road, climate and driving conditions. Measuring equipments for air temperature, air velocity, radiant temperature, relative humidity, concentration of bio-effluent gases, sound pressure and vibration are used during tests. Also mannequins, both thermal and acoustic, collect the integral influence of different physical variables and surrogate the human presence inside the vehicle compartment. The subjective response data is correlated with the physical data collected during the experiments, using mathematical models or computing algorithms (e.g. multivariable regression analysis or neural networks software).
The most suitable indices used for each discomfort stressor are selected and adapted to a uniform scale to facilitate the determination of its weighting factors in different conditions that will be tested during road travels or laboratory simulations. The final model should be able to predict the evaluation of a human panel to a given condition, using as input the measured or introduced values of the relevant physical parameters. An index of this type will be an important tool to car and other land vehicles manufacturers and users, allowing the characterization and differentiation of the comfort conditions provided to the passengers by each vehicle and acting as a measure of the vehicle-passenger friendliness.