טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentEldar Ranit
SubjectTowards an Ergonomic Design Assessment Tool:
Visualizing Postural Comfort
DepartmentDepartment of Architecture and Town Planning
Supervisor Dr. Dafna Fisher Gewirtzm
Full Thesis textFull thesis text - English Version


Abstract

In human-product interaction, employing ergonomic assessments methods, associated with postural comfort, is essential in preventing work-related musculoskeletal disorders, and for designing safe and comfortable artifacts.  Employing these methods from the early stages of the design process has been widely accepted.

It is recognized, however, that there are ‘gaps’ in ergonomic discipline data available to designers. Whereas considerable assessment methods on human comfort level have been carried out, a need for additional unique method was identified, one that is more applicable to the design process and within the designers’ requirements, determined as ‘visual thinkers’.

The objective of this research was to develop an ergonomic design assessment model for visualizing dynamic postural comfort level, based on real-time and on motion history volumes mapping (‘RT-MHV’). 

The challenge was how to integrate the various concepts of the ergonomic discipline, the design discipline and computer technology in order to develop an assistive model for design applications.

Our aim was to combine the three human-centered design assessment methods: scenario-based, empirical, experimental methods, and the designers’ requirements, in order to assess the comfort factors of the interaction between the user, the product and space.

Hence, this research was based on a four-stage model development undertaken to address some of these challenges and related methods ‘gaps’.  The potential needs for a design-relevant assessment model were identified in stage 1.

The interrelation between the three ergonomic design-assessing methods were critically reviewed in stage 1, with the aim of establishing the research structure and the database processing of the novel model development found in stage 2.

Originating from a valid motion-capture laboratory system, the scenario-based model focused on the mobile-worker’s tablet tasks occurring at a public location. Body motions were analyzed to determine the work-related musculoskeletal disorder risk levels of the joints’ limbs, head, neck and trunk. The risk level scores were centered on empirical literature recommendations.

The RT-MHV assessment model development in stage 3 was generated from the database output in stage 2. In order to gain an understanding of the large data sets, via visualization, efficient algorithms and intuitive three-dimensional graphic-user-interfaces were developed. The visual display based on color-coding techniques, representing local risk levels of each joint in real-time and MHV at the joint center of rotation of the avatar’s segments, represented actual users.

In order to validate the research objective and hypothesis and with the intention to improve the visualization application and usability problems, step 4 included an analytical heuristics expert reviews (n=5). The procedure included three steps of human-computer interaction methods. A heuristic usability questionnaire guided the assessment of a problem driven scenario of the ‘mobile worker’s tablet tasks’ test and two visualization option tests aimed at defining the ‘optimal tablet place’.

All experts have demonstrated that the RT-MHV model visualization values are effective in assessing postural comfort levels, and might save time and money in all design stages. With future development of the RT-MHV model, designers will be able to visualize, in real-time, work-related musculoskeletal disorders risk-levels and some motion dependencies factors as they occur.