Environmental Engineering Reference
In-Depth Information
does. For simplicity, in this chapter, the haptic devices will denote the force feedback
interfaces. Haptic devices are mechatronic input-output systems capable of tracking a
physical movement of the users (input) and providing them force feedback (output).
Therefore, haptic devices allow users to interact with a virtual scenario through the sense
of touch. In other words, with these devices the users can touch and manipulate virtual
objects inside of a 3D environment as if they were working in the real environment. These
devices enable to simulate both unimanual tasks, which are performed with just one hand
(for example grasping an object and insert it into another one), and bimanual tasks in
which two hands are needed to manipulate an object or when two objects need to be
dexterously manipulated at the same time (Garcia-Robledo et al. (2011)). Figure 2 shows
some commercial haptic devices. Some relevant features of a haptic device are: its work-
space, the number of degrees of freedom, the maximum level of force feedback and the
number of contact points. The selection of a haptic device to be used in a MTS depends on
several factors mainly, on the type of task to be learnt, the preferences/needs of trainees
and cost constraints.
Fig. 2. Commercial haptic devices. On the left, PHANToM haptic devices with 6-DOF by
SensAble. On the middle, the FALCON device with 3-DOF by NOVINT. On the right, the
Quanser 5-DOF Haptic Wand, by Quanser
The sensorial richness of multimodal systems translates into a more complete and coherent
experience of the virtual scenario and therefore the sense of being present inside of this VE is
stronger (Held & Durlach (1992); Sheridan (1992); Witmer & Singer (1998)). The experience of
being present is specially strong if the VE includes haptic (tactile and kinesthetic) sensations
(Basdogan et al. (2000); Reiner (2004)).
In this chapter, a multimodal system combined with a set of suitable training strategies can be
considered as a Multimodal Training System.
2.3 Multimodal feedback in Virtual Training Systems
The use of multimodal feedback can improve perception and enhance performance in a
training process, for example, tasks trained over multiple feedbacks can be performed better
than tasks completed within the same feedback (Wickens (2002)). Various studies have
supported the multiple resource theory of attention.Wickens et al. (Wickens et al. (1983))
found that performance in a dual-task was better when feedback was manual and verbal
than when feedback was manual only. Similarly, Oviatt et al. (Oviatt et al. (2004)) found that
a flexible multimodal interface supported users in managing cognitive load.
Ernst and Bülthoff (Ernst & Bülthoff (2004)) suggested that no single sensory signal can
provide reliable information about the structure of the environment in all circumstances.
