The thermal sensation corresponding to the touching of an object is one of the most important factors in material recognition. In virtual reality or tele-operation systems, thermal display functions should be embedded in order to obtain satisfactory realism. Since our skin sensors are sensitive to rapid changes in temperature, thermal sensations are thought to arise mainly from the rapid temperature decrease that occurs at the moment of contact between our fingers and an object. Based on this consideration, the present paper proposes a new control method for thermal tactile display to simulate the temperature decrease at the moment of contact. The proposed method controls a thermal tactile display based on the prediction of contact temperature, so that the correct temperature decrease can be produced at the fingertip surface. In addition, we herein report an additional method by which to optimize the thermal rendering for individual subjects. In the optimization, the thermal property of each subject is estimated immediately prior to thermal presentation. The experimental results reveal that the tendency of material discrimination for the thermal tactile display is similar to that for real objects, indicating the validity of the proposed method.

1. [1] D. G. Caldwell, and C. Gosney, “Enhanced tactile feedback (teletaction) using a multi-functional sensory system,” Proc. ICRA 1993, pp. 955-960, 1993.
2. [2] S. Ino, S. Shimizu, T. Odagawa, M. Sato, M. Takahashi, T. Izumi, and T. Ifukube, “A tactile display for presenting quality of materials by changing the temperature of skin surface,” Proc. Second IEEE International Workshop on Robot and Human Communication, pp. 220-224, 1993.
3. [3] K. Matsumoto, and S. Yamamoto, “Enhancement of an Object Display – Thermal Tactile Display (Original title in Japanese: Buttai Display no Koudoka – Ondo-Shokkaku Display),” Proc. 2002 Autumn meeting of Japan Society for Precision Engineering, pp. 682-683, 2002 (in Japanese).
4. [4] M. B. Kohdja, M. Hafez, J. M. Alexandre, and A. Kheddar, “Thermal feedback interface requirements for virtual reality,” Proc. Euro-Haptics 2003, pp. 438-443, 2003.
5. [5] B. Cros, A. Yamamoto, and T. Higuchi, “Simulation and analysis of the perception of the temperature factor for virtual reality applications,” SICE System Integration Division Annual Conference, Vol.2, pp. 409-410, 2002.
6. [6] A. Yamamoto, B. Cros, H. Hashimoto, and T. Higuchi, “Control of thermal tactile display based on prediction of contact temperature,” Proc. 2004 IEEE International Conference on Robotics & Automation (ICRA 2004), pp. 1536-1541, 2004.
7. [7] D. R. Kenshalo, C. E. Holmes, and P. B. Wood, “Warm and cold thresholds as a function of rate of stimulus change,” Perception and psychophysics, Vol.3, pp. 81-84, 1968.