Study on Simultaneous Classification of Object Properties by Using Soft Tactile Sensor Array System Utilizing Local Spatial-temporal Information of Contact

• Published in: Nihon Kikai Gakkai rombunshuu. C hen Vol. 72; no. 721; pp. 2964 - 2971
• Main Authors: ICHIKAWA, Sumiaki, WATANABE, Kenshi, HARA, Fumio, OHKUBO, Kenichi
• Format: Journal Article
• Language: Japanese
• Published: The Japan Society of Mechanical Engineers 2006
• Subjects: 8-Cells Spatial-Temporal Pattern; Information Processing and Signal Analysis; Object Properties of Shape; Robot; Sensor; Simultaneous Classification; Size and Softness; Soft Tactile Sensor Array System
• ISSN: 0387-5024; 1884-8354; 1884-8354
• DOI: 10.1299/kikaic.72.2964

This paper deals with simultaneous classification of shape, size, and softness of cylindrical objects by using soft tactile sensor array system of a five-links single robotic finger. The front surface of each link is covered with semicircular silicone rubber equipped with 235 small on-off switches. The on-off data from these switches obtained during grasping an object is transformed into a spatial-temporal matrix form. As 8 cells around the contact switch is considered useful to extract the local spatial-temporal character of contact physics, the frequency of the 8 cells patterns composed of 0-1 data around the switch contacted is obtained for each object and then used to form a contact-feature vector. This vector is obtained 10 times of experimental trial, corresponding to each object. The vectors are classified by Mahalanobis distance for 27 objects (3 shapes, 3 sizes and 3 kinds of softness) resulting in 48 grasping postures. By using the most effective 7 kinds of 8-cells patterns, over 95% classification accuracy is obtained.