Active touch with voluntary movement on the surface of an object is important for human to obtain the local and detailed features on it. In addition, the active touch is considered to enhance the human spatial resolution. In order to improve dexterity performance of multifinger robotic hands, it is necessary to study an active touch method for robotic hands. In this paper, first, we define four requirements of a tactile sensor for active touch and design a distributed tactile sensor model, which can measure a distribution of compressive deformation. Second, we suggest a measurement process with the sensor model, a synthesis method of distributed deformations. In the experiments, a five-finger robotic hand with tactile sensors traces on the surface of cylindrical objects and evaluates the diameters. We confirm that the hand can obtain more information of the diameters by tracing the finger. 1. Introduction Human voluntarily touches an object and perceives its characteristic features. The procedure is called as active touch. Gibson has indicated that the active touch is important for shape perception [1]. In addition, it has been reported that two-position recognition threshold on human finger tip is 2 to 3?mm. The threshold gives us an impression of large value. Then, Loomis and collins have reported that the sensitivity for stimulus in active touch becomes high [2]. In order to perceive shape of objects, the results indicate an importance of moving hands. Therefore, not only a development of tactile sensor but also a measurement method based on exploratory moving is necessary for developing dexterous robotic hand. Various studies of robotic hands with tactile sensor have been discussed [3–7]. The tactile sensors are used for recognition. Okamura and Cutkosky have proposed a method which detects small textural features by tracing with robotic fingers [4]. In the case, the hand recognized a local area on an unknown object, and it is called the local exploratory operation. Pribadi et al. have proposed a method to estimate the contour of unknown objects [5]. Allen and Michelman have focused on sensing of global object shapes and fitting shapes to object models [6]. Wang and Li have applied a tactile sensor for surface tracking of a manipulator [7]. Nakamoto et al. have proposed a method of classifying the shape of an object that a five-finger robot is grasping [8]. The purposes of them are recognitions of unknown area by robotic hands with tactile sensor. Using tactile information, Wang and Li have proposed a feedback to control a robotic arm interacting
References
[1]
J. J. Gibson, “Observations on active touch,” Psychological Review, vol. 69, no. 6, pp. 477–491, 1962.
[2]
J. M. Loomis and C. C. Collins, “Sensitivity to shifts of a point stimulus: an instance of tactile hyperacuity,” Perception and Psychophysics, vol. 24, no. 6, pp. 487–492, 1978.
[3]
T. Mouri, H. Kawasaki, and K. Umebayashi, “Developments of new anthropomorphic robot hand and its master slave system,” in Proceedings of the IEEE IRS/RSJ International Conference on Intelligent Robots and Systems (IROS '05), pp. 3474–3479, August 2005.
[4]
A. M. Okamura and M. R. Cutkosky, “Feature detection for haptic exploration with robotic fingers,” International Journal of Robotics Research, vol. 20, no. 12, pp. 925–938, 2001.
[5]
K. Pribadi, J. S. Bay, and H. Hemami, “Exploration and dynamic shape estimation by a robotic probe,” IEEE Transactions on Systems, Man and Cybernetics, vol. 19, no. 4, pp. 840–846, 1989.
[6]
P. K. Allen and P. Michelman, “Acquisition and interpretation of 3-D sensor data from touch,” IEEE Transactions on Robotics and Automation, vol. 6, no. 4, pp. 397–404, 1990.
[7]
J. Wang and Y. Li, “Surface-tracking of a 5-DOF manipulator equipped with tactile sensors,” in Proceedings of the 11th International Conference on Control, Automation, Robotics and Vision (ICARCV '10), pp. 2448–2453, Singapore, December 2010.
[8]
H. Nakamoto, F. Kobayashi, N. Imamura, H. Shirasawa, and F. Kojima, “Shape classification in rotation manipulation by universal robot hand,” in Proceedings of the IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS '08), pp. 53–58, Nice, France, September 2008.
[9]
J. Wang and Y. Li, “A study on a robotic arm contacting with human skin using tactile sensing feedback strategies,” in Proceedings of the IEEE International Conference on Robotics and Biomimetics (ROBIO '10), pp. 1559–1564, Tianjin, China, December 2010.
[10]
J. Wang and Y. Li, “Massaging human feet by a redundant manipulator equipped with a tactile sensor,” in Proceedings of the IEEE/ASME International Conference on Advanced Intelligent Mechatronics (AIM '10), pp. 7–12, Montreal, Canada, July 2010.
[11]
M. Shimojo, “Mechanical filtering effect of elastic cover for tactile sensor,” IEEE Transactions on Robotics and Automation, vol. 13, no. 1, pp. 128–132, 1997.
[12]
W. Fukui, F. Kobayashi, F. Kojima et al., “Fingertip force and position control using force sensor and tactile sensor for universal robot hand II,” in Proceedings of the Workshop on Robotic Intelligence in Informationally Structured Space (RIISS '11), pp. 43–48, Paris, France, April 2011.
[13]
R. L. Klatzky and S. J. Lederman, “Stages of manual exploration in haptic object identification,” Perception and Psychophysics, vol. 52, no. 6, pp. 661–670, 1992.