Haptic information for reliable displays

Abstract

Humans have several senses, all of which are usually used to navigate through life. Technical systems are much simpler, often engaging only one sense. Literature suggests that this might be the reason for some of the problems encountered with human–system interaction. In modern railways, operators almost exclusively interact with technical systems. Information is provided on displays; operators act on what they see. In some safety-critical situations, it is crucial that the displayed information is indeed showing the state of the outside situation and that the operator can rely on it. Failures of the system must be exposed. In two methods, the authors have researched how acoustic (i.e. transmitted via hearing) and haptic (i.e. transmitted via touch) signals can be used in combination with visual information to help people to identify errors of displayed items. After an overview of today’s research into the use of haptic displays and the basic ideas of transmission of multisensory information, the concept for using a multisensory approach in railway operator workstations has been explained. Then the two methods are described. The first one is a computer game style application in which erroneous symbols need to be identified. In the second method, a simple workstation layout is given in which participants need to identify signals which show an erroneous red aspect. In both cases, the participants are aided in their task by receiving information about the symbols and signals via haptic, acoustic or combined haptic and acoustic feedback. Regarding the error detection rates, a significant difference between the three versions of feedback modes was not determined in any method. However, in the second method (workstation), participants were faster when provided with haptic feedback. Also, the participants rated haptic and haptic–acoustic feedback subjectively better than acoustic feedback alone. The methods have shown that the idea of using a variation of feedback modes to reveal mistakes on a display does work. The results are a first step to develop systems which make it possible for the operator to detect inaccuracies in the information displayed without complex electronic systems but with a modern, multisensory approach.