StepSense

Overview

As part of the course, Haptics, Tactile and Tangible Interaction, during my master's education, I designed and researched on foot-based haptic feedback (FBHF) device that uses vibrotactile and thermal stimulation. The findings of this project contribute to the advancement of FBHF devices and their potential to enhance immersion and presence in virtual reality (VR) systems.

Approach

Pre-study: Literature Review

As a pre-study to learn and analyze the research around foot haptics, we conducted a literature review on the area. The process helped us to see the overall trend of research and to find the gap in the research that we wanted to work on.

Concept Exploration #1 - Brainstorming

To deep dive into exploring the concept of our design and research, the team gathered for a focused one-day design sprint. During this collaborative session, we engaged in multiple brainstorming sessions and produced a multitude of sketches to crystallize our ideas. The decision to adopt a form similar to a foot sole emerged as the consensus, driven by the aim of facilitating seamless device implementation and ensuring user-friendly intuitiveness.

Concept Exploration #2 - Tactile Workshop

To deepen our understanding of how the foot perceives various materials and haptic stimuli, we conducted a tactile workshop as a part of our design sprint. This hands-on session involved the exploration of tactile stimulation using different objects, the discernment of vibrations through varied motors, and the experience of thermal sensations using diverse heat pads. The workshop yielded valuable insights, leading us to identify the most effective sensory modalities for the foot within the VR environment—specifically, vibrotactile and thermal stimulations.

Prototyping & Pilot Study

Guided by our chosen concept, we started building our first prototype by incorporating force sensors as inputs, along with a heat pad and six distinct vibration motors, used as outputs. Concurrently, we crafted a virtual reality (VR) environment featuring hot asphalt, gravel, and sand to assess the device's impact on user experience and immersion.

Prototype of a FBHF device with Arduino and haptic motors.

VR environment and close-up of virtual sand material.

In pursuit of concept validation and experimental refinement, we executed a pilot study, wherein external participants engaged with the device to evaluate its informative capabilities. The findings revealed that the deployment of six vibration motors proved excessive, hindering the distinction of effects.

Subsequently, we refined the design, opting for four motors strategically arranged based on the relative locations of the active vibrotactile senses in our feet. Simultaneously, adjustments were made to the VR materials to align with the sensations felt through our thermal stimulation and vibrotactile design, enhancing the overall coherence of the immersive experience.

Evaluation & Result Analysis

The evaluation process was carefully designed, employing a mixed-method approach. Quantitative analysis was conducted through a 7-point Likert scale survey, designed by Witmer & Singer's Presence Questionnaire. Simultaneously, the qualitative aspect of the evaluation was addressed through semi-structured interviews, providing a comprehensive understanding of user experiences beyond numerical ratings.

The quantitative analysis involved statistical methods such as the Mann-Whitney U-test and Spearman’s rank correlation coefficient. Through these statistical measures, we successfully validated the device's capacity to significantly enhance the immersive experience in virtual reality (VR).

The qualitative analysis of the interviews employed thematic analysis, revealing crucial themes pivotal for further development. Notably, issues regarding the synchronization of haptic output without latency in response to users' behavior emerged as significant areas to address. Simultaneously, the qualitative findings validated the positive impact of thermo haptics and underscored the immense potential of vibrotactile haptics in elevating the overall VR experience.

If you want more details on this project, please access full report.