First validation of the Haptic Sandwich: A shape changing handheld haptic navigation aid

This paper presents the Haptic Sandwich, a handheld robotic device that designed to provide navigation instructions to pedestrians through a novel shape changing modality. The device resembles a cube with an articulated upper half that is able to rotate and translate (extend) relative to the bottom half, which is grounded in the user´s hand. The poses assumed by the device simultaneously correspond to heading and proximity to a navigational target. The Haptic Sandwich provides an alternative to screen and/or audio based navigation technologies for both visually impaired and sighted pedestrians. Unlike many robotic or haptic navigational solutions, the haptic sandwich is discrete and unobtrusive in terms of form and sensory stimulus. Due to the novel nature of the interface, two user studies were undertaken to validate the concept and device. In the first experiment, stationary participants attempted to identify poses assumed by the device, which was hidden from view. 80% of poses were correctly identified and 17.5% had the minimal possible error. Multi-DOF errors accounted for only 1.1% of all responses. Perception accuracy of the rotation and extension DOF was significantly different. In the second study, participants attempted to locate a sequence of invisible navigational targets while walking with the device. Good navigational ability was demonstrated after minimal training. All participants were able to locate all targets, utilizing both DOF. Walking path efficiency was between 32%–56%. In summary, the paper presents the design of a novel shape changing haptic user interface intended to be intuitive and unobtrusive. The interface is then validated by stationary perceptual experiments and an embodied (walking) target finding pilot study.