Comparative Experimental Research on Haptic Display Methods of Virtual Surface Shape Based on Touch Screen.

With the wide application of touch screen technology in daily life, more and more studies have tried to use touch screen as a carrier to convey the surface shape features of virtual objects to people. Current studies have proposed methods such as direct height mapping and haptic illusion based on lateral force to display the geometric shape of virtual surfaces on the touch screen. However, whether there are differences in the performance of these methods in displaying the shape features, and whether the lateral force-based haptic illusion can be used to display the shape features of complex surfaces, has not been fully explored. Aiming at this situation, in this article, we carry out user experiments on two regular shapes and eight natural images under displacement field and two types of lateral force fields with the help of three haptic devices previously designed. We also evaluate the effect of image smoothing on users' perception of natural image shape features. Experimental results show that the current shape display devices and methods that can simulate the lateral force field proposed by (Minsky et al., 1990) cannot achieve the display effect of the displacement field on complex shapes, and the shape display effect is the worst when only resistive lateral force feedback is employed. Nevertheless, since methods based on lateral force field, such as electrovibration, allow people to directly perceive the shape features of the virtual surface on the touch screen with their bare fingers, continuous research on this shape expression method still has a very attractive prospect.