We investigate the mechanism of tactile transduction during active exploration of finely textured surfaces using a tactile sensor mimicking the human fingertip. We focus in particular on the role of exploratory conditions in shaping the subcutaneous mechanical signals. The sensor has been designed by integrating a linear array of MEMS micro-force sensors in an elastomer layer. We measure the response of the sensors to the passage of elementary topographical features at constant velocity and normal load, such as a small hole on a flat substrate. Each sensor’s response is found to strongly depend on its relative location with respect to the substrate/skin contact zone, a result which can be quantitatively understood within the scope of a linear model of tactile transduction. The modification of the response induced by varying other parameters, such as the thickness of the elastic layer and the confining load, are also correctly captured by this model. We further demonstrate that the knowledge of these characteristic responses allows one to dynamically evaluate the position of a small hole within the contact zone, based on the micro-force sensors signals, with a spatial resolution an order of magnitude better than the intrinsic resolution of individual sensors. Consequences of these observations on robotic tactile sensing are briefly discussed.
Johansson, R; Flanagan, J. Coding and use of tactile signals from the fingertips in object manipulation tasks. Nat. Rev. Neurosci 2009, 10, 345–59. 19352402
[3]
Westling, G; Johannson, RS. Factors influencing the force control during precision grip. Exp. Brain Res 1984, 53, 277–284. 6705863
[4]
Dahiya, RS; Metta, G; Valle, M; Sandini, G. Tactile sensing—From humans to humanoids. IEEE Trans. Rob 2010, 26, 1–20, doi:10.1109/TRO.2009.2033627.
[5]
Maheshwari, V; Saraf, RF. High-resolution thin-film device to sense texture by touch. Science 2006, 312, 1501–1504, doi:10.1126/science.1126216. 16763143
[6]
Someya, T; Sekitani, T; Iba, S; Kato, Y; Kawaguchi, H; Sakurai, T. A large-area, flexible pressure sensor matrix with organic field-effect transistors for artificial skin applications. Proc. Natl. Acad. Sci. USA 2004, 101, 9966–9970, doi:10.1073/pnas.0401918101. 15226508
[7]
Mannsfeld, SCB; Tee, BCK; Stoltenberg, RM; Chen, CVHH; Barman, S; Muir, BVO; Sokolov, AN; Reese, C; Bao, Z. Highly sensitive flexible pressure sensors with microstructured rubber dielectric layers. Nat. Mater 2010, 9, 859–864, doi:10.1038/nmat2834. 20835231
Cutkosky, R; Howe, M. Dynamic tactile sensing: perception of fine surface features with stress rate sensing. IEEE Trans. Rob. Autom 1993, 9, 140–151, doi:10.1109/70.238278.
[10]
Tanaka, M; Leveque, J; Tagami, H; Kikuchi, K; Chonan, S. The “haptic finger”—A new device for monitoring skin condition. Skin Res. Technol 2003, 9, 131–136, doi:10.1034/j.1600-0846.2003.00031.x. 12709131
[11]
Mukaibo, Y; Shirado, H; Konyo, M; Maeno, T. Development of a Texture Sensor Emulating the Tissue Structure and Perceptual Mechanism of Human Fingers. Proceedings of the 2005 IEEE International Conference on Robotics and Automation, Barcelona, Spain, 18–22 April 2005; pp. 2565–2570.
[12]
Hosoda, K; Tada, Y; Asada, M. Anthropomorphic robotic soft fingertip with randomly distributed receptors. Robot. Auton. Syst 2006, 54, 104–109, doi:10.1016/j.robot.2005.09.019.
[13]
Wettels, N; Santos, V; Johansson, R; Loeb, G. Biomimetic tactile sensor array. Adv. Rob 2008, 22, 829–849, doi:10.1163/156855308X314533.
[14]
Beccai, L; Roccella, S; Arena, A; Valvo, F; Valdastri, P; Menciassi, A; Carrozza, MC; Dario, P. Design and fabrication of a hybrid silicon three-axial force sensor for biomechanical applications. Sens. Actuat. A 2005, 120, 370–382, doi:10.1016/j.sna.2005.01.007.
[15]
Edin, B; Beccai, L; Ascari, L; Roccella, S; Cabibihan, J; Carrozza, M. Bio-Inspired Approach for the Design and Characterization of a Tactile Sensory System for a Cybernetic Prosthetic Hand. Proceedings of the 2006 IEEE International Conference on Robotics and Automation, ICRA 2006, Orlando, FL, USA, 15–19 May 2006; pp. 1354–1358.
[16]
Beccai, L; Roccella, S; Ascari, L; Valdastri, P; Sieber, A; Carrozza, M; Dario, P. Development and experimental analysis of a soft compliant tactile microsensor for anthropomorphic artificial hand. IEEE/ASME Trans. Mechatron 2008, 13, 158–168, doi:10.1109/TMECH.2008.918483.
[17]
Vásárhelyi, G; Adam, M; Vazsonyi, E; Vizvary, Z; Kis, A; Barsony, I; Ducso, C. Characterization of an integrable single-crystalline 3-D tactile sensor. IEEE Sens. J 2006, 6, 928–934, doi:10.1109/JSEN.2006.877990.
[18]
Oddo, CM; Beccai, L; Felder, M; Giovacchini, F; Carrozza, MC. Artificial roughness encoding with a bio-inspired mems-based tactile sensor array. Sensors 2009, 9, 3161–3183, doi:10.3390/s90503161. 22412304
[19]
Klatzky, R; Lederman, S. Hand movements: A window into haptic object recognition. Cognit. Psychol 1987, 19, 342–368, doi:10.1016/0010-0285(87)90008-9. 3608405
[20]
Klatzky, R; Lederman, S; Pellegrino, J; Doherty, S; McClosky, B. Procedures for haptic object exploration vs manipulation. In Vision and Action: The Control of Grasping; Goodale, M, Ed.; Ablex: New York, NY, USA, 1990; pp. 110–127.
[21]
Lederman, S; Klatzky, R. Action for perception: Manual exploratory movements for haptically processing objects and their features. In Hand and Brain: The Neurophysiology and Psychology of Hand Movements; Academic Press: London, UK, 1996; pp. 431–446.
[22]
Yamada, D; Maeno, T; Yamada, Y. Artificial finger skin having ridges and distributed tactile sensors used for grasp force control. J. Rob. Mechatronics 2002, 14, 140–146.
[23]
Scheibert, J; Leurent, S; Prevost, A; Debregeas, G. The role of fingerprints in the coding of tactile information probed with a biomimetic sensor. Science 2009, 323, 1503–1506, doi:10.1126/science.1166467. 19179493
[24]
Oddo, CM; Beccai, L; Wessberg, J; Wasling, HB; Mattioli, F; Carrozza, MC. Roughness encoding in human and biomimetic artificial touch: Spatiotemporal frequency modulation and structural anisotropy of fingerprints. Sensors 2011, 11, 5596–5615, doi:10.3390/s110605596. 22163915
[25]
Wandersman, E; Candelier, R; Debregeas, G; Prevost, A. Texture-induced modulations of friction force: The fingerprint effect. Soft Condens Matter 2011. arXiv:1107.2578v1.
[26]
Johansson, R. Tactile sensibility in human hand-receptive-field characteristics of mechanoreceptive units in glabrous skin area. J. Physiol 1978, 281, 101–123. 702358
[27]
Scheibert, J; Prevost, A; Debrégeas, G; Katzav, E; Adda-Bedia, M. Stress field at a sliding frictional contact: Experiments and calculations. J. Mech. Phys. Solids 2009, 57, 1921–1933, doi:10.1016/j.jmps.2009.08.008.
[28]
Johnson, KL. Contact Mechanics; Cambridge University Press: Cambridge, UK, 1985.
[29]
Fretigny, C; Chateauminois, A. Solution for the elastic field in a layered medium under axisymmetric contact loading. J. Phys. D 2007, 40, 5418–5426, doi:10.1088/0022-3727/40/18/S02.
[30]
Levesque, V; Hayward, V. Experimental evidence of lateral skin strain during tactile exploration. Proceedings of Eurohaptics, Dublin, Ireland, July 2003; pp. 261–275.
[31]
DiCarlo, JJ; Johnson, KO; Hsiao, SS. Structure of receptive fields in area 3b of primary somatosensory cortex in the alert monkey. J. Neurosci 1998, 18, 2626–2645. 9502821
[32]
DiCarlo, JJ; Johnson, KO. Velocity invariance of receptive field structure in somatosensory cortical area 3b of the alert monkey. J. Neurosci 1999, 19, 401–419. 9870969
[33]
DiCarlo, JJ; Johnson, KO. Spatial and temporal structure of receptive fields in primate somatosensory area 3b: Effects of stimulus scanning direction and orientation. J. Neurosci 2000, 20, 495–510. 10627625
