@article{oai:nagoya.repo.nii.ac.jp:00008528,
 author = {Ohka, Masahiro and Mitsuya, Yasunaga and Matsunaga, Yasuaki and Takeuchi, Shuichi},
 issue = {2},
 journal = {Robotica},
 month = {Mar},
 note = {This paper describes precision enhancement of an optical three-axis tactile sensor capable of detecting both normal force and tangential force. The sensor's single cell consists of a columnar feeler and 2-by-2 conical feelers. We have derived equations to precisely estimate the three-axis force from the area-sum and area-difference of the conical feelers’contact areas by taking into account wrench-length shrinkage caused by a vertical force. To evaluate the equations and determine constants included in the equations, we performed a series of calibration experiments using a manipulator-mounted tactile sensor and a combined load-testing machine. Subsequently. to evaluate the tactile sensor's practicality. it was mounted on the end of a robotic manipulator which rubbed flat specimens such as brass plates with step-heights of δ=0.05, 0.1, 0.2 mm and a brass plate with no step-height. We showed from the experimental data that the optical three-axis tactile sensor can detect not only the step-heights but also the distribution of the coefficient of friction, and that the sensor can detect fine plate inclination with accuracy to about ±0.4°.},
 pages = {213--221},
 title = {Sensing characteristics of an optical three-axis tactile sensor　under combined loading},
 volume = {22},
 year = {2004}
}