Hi everyone, I'm Shuchang Xu from Tsinghua University.
I will present our recent research on accessbility entitled
"Virtual Paving: Rendering a Smooth Path for People with Visual Impairment
through Vibrotactile and Audio Feedback".
Our work is inspired by physical tactile pavings,
which are public works for visually impaired people.
Compared to canes and dogs,
tactile pavings could help users directly find a collision-free path through haptic cues underfoot.
However, their usability is greatly affected by bad maintenance,
installation errors, and obstructions.
In this paper, we propose Virtual Paving,
which aims to support independent navigation by "rendering" a safe and smooth path
to visually impaired people through non-visual feedback.
Conceptually, Virtual Paving not only inherits the benefit of tactile pavings,
but also saves the cost of physical deployment and maintenance.
Virtual Paving relies on three techniques: sensing, planning, and rendering.
This work focuses on designing a user-friendly feedback solution to render Virtual Paving.
To render Virtual Paving,
the key task is to guide users along a continuous path smoothly and efficiently,
which is, in essence, a path-following task.
To support this task, prior works mainly explored how to provide turn-by-turn navigation,
or how to guide users towards a sequence of waypoints.
However, few existing systems were validated to support users
to follow a continuous path smoothly and efficiently.
To address the above research question,
we conducted three user studies.
Firstly, we conducted semi-structured interviews with visually impaired people.
Our goal was to understand their current practices and difficulties
with tactile pavings and path-following tasks.
Through the interview, we identified
the main concerns and issues affecting the usability of tactile pavings,
and the information needs for path-following tasks.
Based on these findings, we summarized a set of design guidelines of Virtual Paving.
We also distilled three path characteristics that will affect the walking experience.
Next, to find a user-friendly feedback modality to render Virtual Paving,
we conducted co-design with visually impaired people,
and identified four promising feedback modalities.
We tested the four modalities in navigational tasks with four basic path types:
straight paths, gentle turns, sharp turns, and continuous turns.
Both performance data and subjective feedback were adopted as evaluation metrics.
Results of study 2 showed that vibrotactile feedback on the shoulders and waist
outperformed the other three modalities, having lower cognitive loads,
higher convenience in daily use, and higher overall satisfaction.
As a result, in our final feedback solution,
we selected vibrations on the shoulders and waist to indicate directional cues.
Moreover, all participants indicated that verbal audio could be additionally employed
to describe road conditions ahead of the user,
such as, "Low obstacles two meters ahead on your left.".
They stated that such environmental descriptions would make them feel safe.
Therefore, we also included the audio descriptions of road conditions
in our final feedback solution.
The multi-modal feedback solution was integrated into a wearable backpack
for the convenience of daily use.
To enable users to walk smoothly and efficiently,
we also designed the strategy to indicate directional cues,
with the goal to minimize both the likelihood of users walking into the danger zone
and the frequency to trigger orientation-adjusting cues.
The thresholds of the cue generation strategy were selected
based on user behavior observed in Study 2.
Finally, to evaluate whether the multi-modal feedback solution could support
better navigation experience than a single-modal feedback,
we conducted a lab test with a computer vision module to recognize labelled paths.
Guided by the designed feedback,
16 visually impaired participants completed 127 trials out of 128 trials
on 2.1m-wide basic paths.
Results showed that Vibration+Audio feedback outperformed Vibration-Only feedback
in keeping users within the 1.2m-wide zone
and gained higher ratings on walking smoothness and overall satisfaction.
The contributions of this work are three-fold:
First, we revealed the current practices and issues of visually impaired people
with tactile pavings and path-following tasks.
Second, we proposed a set of design guidelines of Virtual Paving
and a method to optimize the feedback solution.
Third, we designed and implemented a multi-modal feedback solution to render Virtual Paving,
based on the co-design and evaluation with visually impaired people.
Our feedback solution enabled visually impaired users
to navigate along 2.1m-wide paths smoothly.
Thanks for your attention. Please refer to our paper for more details.