In daily life, a lot of information is transferred though the various sensory channels. In particular, the sense of touch can play a versatile role, introducing the field of haptics. There is still much to explore and research to be done regarding haptic feedback. This project specifically looked into the actuation method for haptic wearables, comparing the influence of shape memory alloy (SMA) and electromechanical actuation.
Through a literature review, the field of affective haptics became the focus of the project, applying cutaneous haptic wearables on the forearm to influence the emotions of the user. Additionally, evaluation metrics relevant to haptic wearables were determined. Two sensations were selected to explore the influence of the actuation method on the design process of the designer as well as the user experience of the user: a short, intense squeezing sensation opposing a long, soft stroking sensation. Using either actuation method a haptic wearable was designed for each sensation, resulting in four devices. Using these devices, user tests have been conducted.
The insights gathered during the project showed that electromechanical actuation is more suitable in several situations, and SMA actuation in other. Mechanical actuation needs to be used if a sensation using high frequency repetition needs to be created, whilst SMA actuation is more suitable when several sensations in close proximity are desired. When creating a big displacement along lengths, mechanical actuation is needed, however, when following the curves of the human body, SMA actuation should be used. Mechanical actuation can provide precise control over the movement, while SMA actuation provides simpler, more intuitive control over the final movement. When looking at key metrics, mechanical actuation can provide noticeable differences in speed, and SMA actuation noticeable differences in force. The user experience of SMA actuation is pleasant and humanlike, providing a sense of comfort; whilst mechanical actuation is experienced as intense and creates a sense of urgency in the user. As a conclusion to this project, these results were gathered and summarized into a decision flowchart.