Developing vibrotactile haptic stimuli based on measured human capabilities

Abstract

This paper describes an approach to design tactile haptic signals that help humans “visualize” an environment through the use of a vibrotactile haptic wristband that has four vibration motors. A human response map to tactile input while sitting was determined experimentally. It shows the zones where humans can classify signals with a high success rate based on minimum Duration of Stimulus (DOS) (“on” periods) and “off” periods of the haptic signals. It was also shown experimentally that a human’s ability to recognize tactile patterns depends on the level of engagement required by the activity. This paper provides an approach to predict a human response map for various activities. The map during sitting is used to design the signals to send information to a human. Two types of signals are developed: sequence stimuli and digital codes. Sequence stimuli create an on/off rhythm for the vibration motors that humans can sense directly without a decoding process. Experiments show that humans can recognize 10 levels of sequence stimuli with a success rate greater than 80%. This class of signals is useful for applications where information must be repeated frequently, e.g., range information sent to a human parking a car. The second class of signals is digital codes, similar to Morse code, where a sequence of long and short motor DOS represents each code. The meaning of the signal is associated with a specific code. From 27 digital codes, experiments showed a successful recognition rate of 78.7%. An application for the digital code method is to pick specific menu items, based on the codes, for fast food restaurants.