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Publication

Design guidelines for vibrotactile motion steering

Book - Dissertation

Vibrotactile motion steering is defined as providing instant feedback on the human posture and movement using vibrations. It is an extra sensory function when visual and auditory communication channels are already used. Furthermore, it can provide real-time automated communication using wearable actuators in situations where it is complicated to accurately and consistently assess the quality of maintaining a predefined position or movement as in a busy environment or during a complex task. A systematic review shows that vibrotactile motion steering already has interesting potential applications, although usability during physical effort in sports is uncertain. Therefore, this thesis investigated the effects of vibrotactile motion steering for the specific case of assessing and correcting the aerodynamic cycling position. The perception of vibrating signals, and the opportunities to provide real-time feedback during cycling, as well as the outdoor applicability of vibrotactile motion steering were analysed. The results indicate that vibrations are perceived equally precisely during cycling at 50, 70, and 90% of the maximal power output compared to stationary position (p > 0.1) for both the spine and the thighs, where vibrotactile motion steering on the spine is preferred for cycling aerodynamics. Secondly, this study describes an indoor training setup where the projected frontal area of a cyclist is continuously calculated as an indicator of aerodynamic efficiency. Experiments demonstrated that vibrotactile feedback improves the accuracy to recapture the optimal aerodynamic cycling pose compared to no feedback (p < 0.001). Lastly, the relevance of vibrotactile motion steering in situations outside a lab was considered. The results show that the projected frontal area can be estimated using body measurements and joint angles measured using motion capturing with inertial measurement units. The consecutive studies showed that vibrotactile motion steering can have potential during physical effort, where the effectiveness can be optimized by 1) ensuring that the vibrating actuators make direct contact with the skin to ensure the accurate perception of vibrations for the user, 2) using only one threshold simultaneously as a parameter to provide feedback to avoid confusing the user, and 3) optimizing the accuracy of the measurement of that threshold to avoid false positive or false negative vibrotactile feedback. Considering these requirements, various potential applications of vibrotactile motion steering are achievable. The first application is cycling aerodynamics as described in the experimental studies. The promising results of vibrotactile motion steering in cycling also open up new perspectives for alternative sports as badminton.
Number of pages: 128
Publication year:2021
Keywords:Doctoral thesis
Accessibility:Open