Poka-yoke process controller: designed for individuals with cognitive impairments

Poka-yoke is a Japanese term meaning "error proofing." Poka-yoke techniques were developed to achieve zero defects in manufacturing and assembly processes. The application of these techniques tends to reduce both the physical and cognitive demands of tasks and thereby make them more accessible. Poka-yoke interventions create a dialogue between the worker and the process, and this dialogue provides the feedback necessary for workers to prevent errors. For individuals with cognitive impairments, weighing and counting tasks can be difficult or impossible. Interventions that provide sufficient feedback to workers without disabilities tend to be too subtle for workers with cognitive impairments; hence, the feedback must be enhanced. The Poka-Yoke Controller (PYC) was designed to assist individuals with counting and weighing tasks. The PYC interfaces to an Ohaus CT6000 digital scale for weighing parts and for counting parts by weight. It also interfaces to sensors and switches for object counting tasks. The PYC interfaces to a variety of programmable voice output devices so that voice feedback or prompting can be provided at specific points in the weighing or counting process. The PYC can also be interfaced to conveyor systems, indexed turntables, and other material handling systems for coordinated counting and material handling operations. In all of our applications to date, we have observed improved worker performance, improved process quality, and greater worker independence. These observed benefits have also significantly reduced the need for staff intervention. The process controller is described and three applications are presented: a weighing task and two counting applications.