Abstract This paper investigates the use of vibrotactile feedback to add a further dimension of reality to virtual environments. We describe a system which incorporates low frequency force feedback and an inexpensive vibrotactile display system composed of modified audio speakers, a PC sound card and a 2 channel current amplifier. We examine the initial problem of stiffness perception based on this vibrotactile feedback. To determine the appropriate waveforms to use in virtual environments we examine the waveforms that are produced when subjects tap on surfaces of varying stiffness with an aluminum stylus. A simple exponentially damped sinusoidal model is presented for these vibrations. This model is then used to produce waveforms for an experiment that assessed the validity of this characterization and the effectiveness of vibrotactile stimulation in conveying stiffness information in a virtual environment. The results are compared with a similar experiment in which subjects tapped directly on different real surfaces using a stylus. Using these simple waveforms for vibrotactile display in our test system gives a relatively accurate description of the phenomenon and allows subjects to accurately distinguish surface stiffness.
Wellman et al. (Sun,) studied this question.