Vibrotactile stimulation is an efficient way to provide feedback when a user is interacting with a mobile device. Because the device is held in hand, the user's input, such as touch and gesturing, can be easily measured with force- and motion sensors. In addition, the feedback can be provided into the same device with a vibrotactile actuator. This thesis introduces a set of methods to provide the vibrotactile feedback dynamically i.e. proportionally to the applied input in real-time during the interaction. The effects of dynamic tactile feedback in gesture and touch interaction are investigated in five studies reported in the thesis. The first two studies introduce the method for providing the dynamic feedback based on wavetable synthesis and assess the perceptual dimensions of the feedback when coupled with gesture movements. The studies indicated that the method is a powerful tool for creating an illusion of real textures with a simple vibrotactile actuator and motion sensor. Modifications in texture ridge length and spatial density lead into large variation in subjective evaluations of texture roughness, bumpiness, stickiness and pleasantness. In study III, mobile device was used to search for targets in the environment. Tactile feedback turned out to be an efficient way to indicate target directions. The finding hints that vibration could be efficiently used as a private and transparent signal to indicate directions and target locations in augmented reality interaction. In study IV, dynamic tactile feedback was provided when playing a gesture controlled virtual musical instrument. The feedback reflecting the distance to a virtual control surface assisted the temporal accuracy of the playing. In study V, vibrotactile feedback was provided proportionally to the applied force on a rigid surface. In a force repetition task, all the dynamic feedback models assisted the accuracy of the force control. On contrast, in a force hold task, the feedback did not assist the performance. Dynamic tactile feedback appeared to be a powerful tool to create illusions of real textures and it improved the motor accuracy in repetitive gesture- and force based interaction. The findings make a contribution to research focusing on touch and gesture based user interfaces as well as psychophysics research dealing with augmented feedback. In order to apply the findings in future user interfaces of mobile devices, more studies are needed. In further work, system latency should be minimized and tactile feedback should be design in parallel with visual and auditory feedback.
|Translated title of the contribution||Dynaaminen tuntopalaute ihmisen ja koneen välisessä vuorovaikutuksessa|
|Publication status||Published - 2012|
|MoE publication type||G5 Doctoral dissertation (article)|
- tactile feedback
- human computer interaction