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Exploratory Design for Haptic Symbol:

On-Body Vibrotactile Patterns

to Convey Specific Information

Final Master Project 2020 | 5 months

Industrial Design, University of Technology Eindhoven, NL

Skills: haptic interaction design, design research, design tools, prototyping

Project Coach: Mathias Funk

Expert: Manus VR

Exhibition: DDW2020 - UpClose&Personal

In this project, I took a detour from the traditional scientific studies of haptics and propose an exploratory design process to create the haptic symbols. Here, 'haptic symbol' was defined as a set of designed spatial-temporal vibrotactile patterns that could link to specific abstract information in HCI. The results show the potential of using haptic symbols as a new interaction modality and provides a stepping stone for further research in haptic interaction design. I focus on the vibrotactile stimuli on the lower back area, generated by a three-by-three matrix of vibration motors. The matrix is attached to a garment prototype, which is used for usability evaluation. After the analysis and evaluation, I recommend a set of haptic symbols that are readily being employed. The final step is to implement the recommended haptic symbols in various scenarios.

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“We have the ability to discriminate tactile patterns and process and learn them just as we do for recognizing letters or words in speech and vision.”

 

—— Sherrick, 1975, The art of tactile communication

Research Through Design Process

In this project, the constructive design research method (Wensveen, 2011) was applied. The process of the five-month project is instructed by the IDEO Human-centered design model (IDEO, 2020). 

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Co-Design Haptic Symbol

Vocabulary Items                          Tools                                        Co-Design    

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Chuang et al. (2018) proposed a list of design vocabulary items in this scenario (Chuang, Chen, & Liu, 2018). Based on this list, I deliberately selected the items that represent the information flow from the system to the users. I further narrowed down the selection by judging the suitability of the items being encoded into vibrotactile patterns.

Confirm: informing the users that the
expected results were accepted and allowed

Reject: refusing the users’ command or input

Emergency: showing emergency

Low Battery Power: showing low power

Reminder: reminding the users about something in the schedule 

Show Progress: giving information to the user about the  progress of certain tasks

Booting: indicating the machine is booting

Request: asking assist from the users
 

> Grouping the descriptive words of the vibrotactile sensations based on the five facets by Seifi et al. (2017). 

> Visualization tools helping to demonstate the vibrotactile patterns from two perspectives: 1) the frequency/intensity /time of single vibration motor; 2) temporal and spatial parameters of 3×3 matrix (Novich et al., 2015).

As the haptic sensation is highly personal (Janidarmian et al., 2019), I proposed a co-design session to generate vibrotactile patterns that could consider the subject-to-subject difference to some extent. The co-design session allowed the designers and users to work together to create the vibrotactile patterns linking to the specific information. The session was held online using web-based workspace Mural.

 

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Haptic Symbols

This formative co-design session finally yielded eight vibrotactile patterns mapped to eight information items, by summarizing the common ground and characteristics of each design concept from the participants.

Show Progress

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Low Power

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Booting​

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Request

Reject

Confirm

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Emergency

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Reminder

Prototype

A fully functional and experiential prototype was designed and created. The vibrotactile patterns were created through vibration motors attached in a garment and closely pressed to the back area of the users. 

The prototyping process: a) learning and testing the usage of the Adafruit 16-Channel PWM Driver Shield, in order to individually control multiple motors by Pulse Width Modulation signals, b) hand-made cube to enclose the Eccentric Rotating Mac (ERM) vibration motor to make sure it works when attached to fabric; c) The first iteration of the prototype; d) prototype experiment and pilot test; e) soldering and neaten the circuit; f) arrange and glue the vibration motor to the garment; g) making and finishing the garment.

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Evaluation

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In this section, I briefly summarize the evaluation, including usability test, expert evaluation and data analysis. More detailed information can be found in the report.

 

Usability Test

Distinguishability of the patterns: accessed by the recognition rate

Affordance: measured by the mapping rate with the information items

Subjective workload and user experience: rated through a Likert Scale questionnaire modified from the UEQ questionnaire (Team UEQ, 2018).

 

The participants were encouraged to think aloud and speak. A semi-structured interview conducted at the end of the session. The notes were informally analyzed based on the content analysis method (Lazar, Feng, & Hochheiser; Harry, 2017).

Expert Evaluation

The aim of the expert evaluation is not limited to the design concept itself, but also gathering feedback about the application and further development. Five experts were recruited from Manus VR, three wearable designers (one lead director, one for generating concepts, one for bringing concept to prototype), one industrial designer and one lead director focusing on wearable hardware engineer. The expert evaluation was conducted in the office of Manus VR in Eindhoven.

The interview notes were analysed by content analysis tools.

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Conclusion

The design and evaluation process could provide knowledge of designing vibrotactile patterns carrying certain meanings.

 

The project shows the potential of using haptic symbols as a new interaction modality.

 

I proposed a set of recommended haptic symbols that could be readily employed in different contexts and gave example to explain how to implement it in three scenarios.

 

This research can be used as a starting point for further research in bringing vibrotactile patterns to HCI.

In the future, the research could be a pilot for creating a common basis to better encode and decode the information to vibrotactile patterns.

Reference

Chuang, Y., Chen, L. L., & Liu, Y. (2018). Design vocabulary for humanIoT systems communication. Conference on Human Factors in Computing Systems - Proceedings, 2018-April(2018). https://doi. org/10.1145/3173574.3173848

IDEO. (2020). Human-centered Design. Retrieved from https://www.ideo. org/tools

 

Janidarmian, M., Roshan Fekr, A., Radecka, K., & Zilic, Z. (2019). Wearable Vibrotactile System as an Assistive Technology Solution. Mobile Networks and Applications. https://doi.org/10.1007/s11036-019-01304- 9

Novich, S. D., & Eagleman, D. M. (2015). Using space and time to encode vibrotactile information: toward an estimate of the skin’s achievable throughput. Experimental Brain Research, 233(10), 2777–2788. https:// doi.org/10.1007/s00221-015-4346-1

Seifi, H., & MacLean, K. E. (2017). Exploiting haptic facets: Users’ sensemaking schemas as a path to design and personalization of experience. International Journal of Human Computer Studies, 107(August 2016), 38–61. https://doi.org/10.1016/j.ijhcs.2017.04.003

Sherrick, C. E. (1975). The art of tactile communication. American Psychologist. US: American Psychological Association. https://doi. org/10.1037/0003-066X.30.3.353

Team UEQ. (2018). User Experience Questionnaire (UEQ).

Wensveen, S. A. . (2018). Constructive Design Research. Eindhoven.