An alternative speed control for industrial sewing machines

Occupations which normally involve a fixed workstation and can be effectively operated from a sitting position would appear to be highly compatible with the lack of mobility of paraplegics. However, owing to the traditional operational-control configuration of many machines which require use of the lower limbs, employment for paraplegics is limited in these occupations. A speed-control mechanism suitable for use by paraplegics was designed and compared with the traditional treadle speed control used on industrial sewing machines. This control was operated by chest movement displacing a lever in contact with the subject in the region of the sternum. Subjects for this study were twenty non-handicapped individuals primarily without any previous sewing experience. Data were collected by questionnaires, anthropometric measurements, and performance on sewing tasks. There was no significant difference between the two control devices in accuracy and task-completion time. The chest-control device required significantly fewer machine stops during task performance. The chest-control device produced less overall postural stress than the traditional treadle control. Overall preference for the two control devices was divided equally among the subjects. The chest-control device will enable many of those unable to use their lower limbs to operate any one of a series of stitching-related machines by providing access to, and control of, the machine. The control device appears to provide the potential for both the handicapped and non-handicapped to achieve performance equal to that achieved by the latter group with conventional treadle controls. It is suggested that the alternative control could be used not only with industrial sewing machines, but also with other machines that require a fixed workstation and can be operated from a sitting position.