Orientation discrimination of patterned surfaces through an actuated and non-actuated tactile display

This paper investigates the tactile orientation discrimination of virtual, small-scale, patterned surfaces through a tactile display. The tactile display is an array of 4×4 vertically moving pins which can simulate the shape of small scale features. Its small size and low mass allow users to explore virtual surfaces freely and intuitively. The evaluation method consisted of measuring the orientation discrimination threshold for virtual surfaces with sinusoidal profiles. The threshold was compared with the threshold obtained using a non-actuated tactile display of equal spatial resolution and with the threshold obtained using the bare finger to explore real surfaces. This comparison was done to evaluate the quality of the rendered virtual surfaces, the performance of the device as a control system and the efficiency of the tactile rendering algorithm. This study also measured the speed and normal force during the tactile exploration that allowed investigation of the exploration strategies used when touching through normal indentation displays and through the bare finger. Furthermore they are the necessary interaction parameters for assessing the bandwidth and force output of the device.