Control software with supporting features to enhance the quality of tactile feedback

Tactile displays are devices for cutaneous stimulation to be integrated in haptic feedback systems e.g. in robot-assisted minimally invasive surgery. In general, there are severely limited in performance due to the necessary small size. In this work, we have developed a control software with the goal to allow simple hardware to present sensible tactile information to the user. For the development and evaluation of the software including various features to improve tactile feedback, a tactile display with twelve servo-driven pins was used. With the pins moving upwards and downwards, height maps can be presented to the user’s finger. The feedback system runs at a frequency of 50 Hz which generates the sensation of a fluid movement. The supporting features include a simulation of shear forces which give the user information on the movement direction of the sensor. A smoothing algorithm was implemented to prevent jerky pin movements. High effort was put in the generation of well distinguishable vibration patterns. These serve to enhance the presentation of the height maps or even allow a second layer of information.In an evaluation series, the control software and the support functions were extensively tested. The users were capable of distinguishing differences in height as low as 0.05 mm or differences in width smaller than the pin spacing. The task to find an invisible object only with the help of different vibration patterns was solved with great success. In a practical test, the users had to pursuit invisible paths standing out from the surroundings for 1 mm and less using the mouse relying only on tactile feedback. The users showed very good performance here with each user finishing every part of the test. This leads to the conclusion that our control software is an appropriate mean to create sensible tactile feedback even with limited hardware.