Tactile Displays for Virtual Reality Applications

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Object of this proposal is the development, construction and the trial of a tactile display intended to stimulate the mechanoreceptors within the human skin. The display is able to exert forces and vibrations to the fingertip in normal as well as lateral direction. For this purpose a piezoelectrical bending actuator is combined with an electromagnetically driven normal force actuator into a single pin. Besides dimensioning of the pins, the interaction between individual actuators has to be investigated. If necessary, an electronically controlling scheme has to be developed in order to adjust the performance of the individual actuators of the whole system. The electronics for driving this combined actuators aims for expandability and therefore consists of several modules including a main processing board and a variable amount of signal generators and operational amplifiers. The resulting system is particularly compact and can be operated autonomously without the need for an external computer. The data for controlling the individual pins is generated by a neurophysiological motivated model based on Finite Element simulations. It aims to create adequate stimuli for the mechanoreceptors using the display to approximate the original tactile impression as close as possible. The model is able to transfer real surface topography to complex vibration patterns in order to recreate the originally occurring vibration patterns at the receptors position closely. An intermediate representation called "tactile map" is used to store an abstract representation of the surface and allows to take coarse as well as fine surface features into account. Based on our newly developed 4-pin tactile display, an extension of the driving electronics and our new innovative model for creating the stimuli, the concept needs to be extended to a 4x4 actuator array. Besides creating the conductor paths for addressing each of the 32 degrees of freedom of the final display, the bearing of the coupled actuator may need optimizations. Additionally, the driving electronics need to be extended. The driving electronics should also track the tactile display's orientation besides its position. This way, natural movement of the user's finger can be mapped to the model more accuratly. The performance of the combined system then needs to be evaluated extensively by a series of trials. These studies will be conducted in cooperation with a perceptual psychologist.