INAIL - Istituto Nazionale per l'Assicurazione contro gli Infortuni sul Lavoro

INAIL - Istituto Nazionale per l'Assicurazione contro gli Infortuni sul Lavoro

The integration of ethnography and movement analysis in disabled workspace development

Ambito: Analisi del Movimento
Rivista: AHFE 2012 - 2nd International Conference on Applied Digital Human Modeling
Anno di pubblicazione: 2012
 

The aim of this paper is to report the process conducted by an interdisciplinary team to analyze human-product physical interaction and develop a PC workplace to be used by physically impaired people to ease their professional reintegration.

In previous experiences simple biomechanical measurements and electromyographic analysis were used to evaluate the physical stress connected to different workplace situations. In the present context we have chosen to apply to occupational ergonomics both a biomechanical and ethnographic approach and then correlate them in an integrated approach. The idea of merging qualitative and quantitative methods has become increasingly appealing in areas of applied research. As Human Machine Interfaces (HMI) and ergonomics are multifaceted issues it is important to approach them from different perspectives and to combine data coming from different methods.

We began with 10 ethnographic investigations on subjects affected by spinal cord lesion at different neurological levels to detect their user habits and solution strategies. Observations together with contextual interview were carried out in the real user environment (6 homes and 4 offices) and involved 7 paraplegic subjects and 3 quadriplegic. On this basis we defined a test setting and a series of motor tasks to be investigated from the biomechanical point of view. Then a virtual analysis based on a biomechanical model which includes six degrees of freedom (dof) for the upper trunk, three dof for each shoulder, two dof for the elbows, two dof for the wrist was implemented in order to compute the joint moments required to perform the different tasks. The outputs regarding user behaviour and movement simulation were used to define the first design proposals and a functional mock-up of the workstation has been built to perform movement acquisition and evaluation on healthy subjects in a first stage to define the strength associated to reaching objects in different positions in the extracorporeal space. A stereophotogrammetric system with eight infrared TVcameras was used to detect the movement of the upper limbs in relation to the trunk, and the movement of the trunk in relation to an absolute reference system fixed within the laboratory. Retro-reflective markers were attached to the head, shoulders (acromions), elbows, wrists, and metacarpal area and dorsal surface of the trunk.

The outputs of the biomechanical tests permitted to fine tune the concept and realize a prototype workstation to be tested regarding usability and acceptability by the end user. From methodological point of view, we found a positive conciliation to integrate ethnographic qualitative data and physical modelling movement quantitative data in product development defining an proactive approach to ergonomics based on data related to physical interaction between the human and new or existing products. The method was applied to disabled worker PC station development while its extension to other aspects and other concepts is under development. Further developments should also take into account the integration of functional supports needed by persons with spinal cord lesions who sometimes make use of assistive devices and functional electrical stimulation to perform basic functions.

Ultimo aggiornamento: 01/01/2012


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