Postural Comfort Inside a Car: Development of an Innovative Model to Evaluate the Discomfort Level 2009-01-1163
How can car designers evaluate device’s position inside a car today? Today only subjective tests or “reachability” tests are made to assess if a generic user is able to reach devices, but it’s no longer enough.
The aim of this study is to identify an instrument (index) that is able to provide a numerical information about the discomfort level connected with a posture that is kept inside a car to reach a device, by this instrument it should be possible not only judge a posture, but also compare different solutions and get rapid and accurate evaluations.
In the state of the art there are many indexes developed to evaluate postural comfort (like RULA, REBA and LUBA [3, 4, 5]) but none of them has been realized to evaluate postures’ conditions that can be detected inside a car, so their evaluations cannot be acceptable. There are also many other studies (like Porter and Gyi, Krist, Grandjean, Rebiffe, Dreyfuss 2D and 3D) which deal with postural comfort inside car, but they have only assess neutral angles and ranges of comfort, so their evaluations are qualitative and discontinuous.
For these reasons it has been realized a new instrument (implemented by our research group using Matlab™ to give the wanted numerical evaluation; it is based on an human scale manikin that can reproduce each user and each posture which can be introduced directly or imported from a digital human modeling (DHM) software (like JACK™ developed by U.G.S.), on discomfort functions (one for each degree of freedom of the manikin) and on a method (based on the distribution of the weights of the human body on the different joints) to aggregate them and return total discomfort values.