Evaluation of JACK for Investigating Postural Behaviour at Sewing Machine Workstations 2003-01-2218

The study was undertaken to investigate ways in which the JACK computer-aided ergonomics system can be used to evaluate workstations for tasks in which there are complex and precise visual and manual demands, taking sewing machine operation as an example. The posture data produced was used to validate the simulation by comparison with real postural behaviour in sewing machine operation recorded in an earlier study by Li et al [1], as well as to assess the ease and limitations of the JACK analysis process itself. The results showed that the initial posture used as a starting point had an effect on the final posture determined automatically by JACK in terms of the eye's view of the workstation and of the potential for collisions between the arm and parts of the workstation. Further manual adjustment to the postures could overcome most of these problems, although some discrepancies were still found in upper arm postures when these were compared with the postures adopted by the human subjects in Li et al's experiment [1]. With this manual adjustment, it was concluded that JACK was capable of producing valuable data for detailed posture analysis but that greater understanding of postural behaviour is needed to improve simulation in relation to visual demands and to arm postures for precision tasks.