Recently,
several factors have contributed to an increase in interest in the
evaluation of comfort
experienced by passengers in vehicles. Due to rising
mobility, the time that people spend in vehicles has grown
substantially. The criteria applied by consumers have
changed on account of generally heightened expectations,
resulting in a growing demand for enhanced ride comfort. Also,
there are marketing factors, from the car manufacturers' point of
view, because differentiation between models in the same
market segment is becoming more difficult to establish on grounds
of performance or aesthetics.
The comfort experienced by humans in a given environment can be
classified as a subjective assessment, because it is possible to find a
considerable variation in responses of different people to the
same situation. Nevertheless, the factors on
which the opinions of people on comfort level are based are physical
variables that characterize the surroundings, e.g. temperature,
air velocity,
acceleration, and light intensity.
So, the first step
in any assessment is to list the different kinds of stimulus that can be
detected by human senses and judged a cause of annoyance, leading thus
to a sensation of discomfort.
In the case of passengers riding in vehicles, the
following are the main aspects
that should be considered: temperature, air quality,
noise, vibration, light, and ergonomics.
Many different measuring and evaluation methods
have been developed to study the
comfort of occupied spaces, involving one or more of the
aforementioned stressors. Besides discrete measured values of relevant
physical parameters, comfort indices related to human sensitivity and
weighting the influences of different variables
have also been built in for each kind
of stimulus. Subjective assessments from evaluation panels are also
extensively used. Because researchers
are conscious of the importance of the
interaction between the passengers and the environment,
various measuring mannequins with the capability of simulating
some human functions, e.g. thermal regulation or
breathing, have been developed.