Title :
Characterization and Psychophysical Studies of an Air-Jet Lump Display
Author :
Gwilliam, J.C. ; Bianchi, Matteo ; Su, L.K. ; Okamura, Allison M.
Author_Institution :
Dept. of Biomed. Eng., Johns Hopkins Univ., Baltimore, MD, USA
Abstract :
Development of tactile displays to enhance palpation of lumps during robot-assisted minimally invasive surgery is challenging due to size and weight constraints, motivating a pneumatic actuation strategy. This work describes the quantitative and psychophysical assessment of an air-jet tactile display that creates a lump percept by directing pressurized air through an aperture onto the finger. The air pressure and aperture size are meant to control the hardness and size, respectively, of the perceived lump. Jet impingement pressure and flow rate were measured by capacitive tactile sensors and mass flow meters at varying aperture sizes and pressures. The air-jet pressure profile width evolves as jet theory predicts and is largely independent of supply pressure (and therefore jet exit velocity). The method of constant stimuli was used to determine the just noticeable differences (JNDs) for the air pressure and aperture size. Qualitative results indicate that subjects perceive the stimulus as a “lump-like” shape. Pressure JNDs ranged from 19.6-24.4 kPag and aperture size JNDs ranged from 0.50-0.66 mm. No significant correlation exists between the supply pressure and changes in perceived lump size. However, pressure JNDs show significant (p<; 0.001) inverse correlation with aperture size, with improved discrimination at larger apertures, where a greater finger pad area is stimulated.
Keywords :
capacitive sensors; display devices; flow measurement; jets; medical robotics; pneumatic actuators; pressure measurement; surgery; tactile sensors; touch sensitive screens; air-jet lump tactile display; air-jet pressure profile width; air-jet tactile display; aperture size control; capacitive tactile sensors; finger pad area; flow rate measurement; hardness control; inverse correlation; jet exit velocity; jet impingement pressure measurement; just noticeable differences; lump palpation enhancement; mass flow meters; perceived lump size; pneumatic actuation strategy; pressure JND; pressurized air; psychophysical assessment; quantitative assessment; robot-assisted minimally invasive surgery; size constraints; size displays; supply pressure; weight constraints; Apertures; Pressure measurement; Sensor arrays; Size measurement; Surgery; Tactile sensors; Haptics; RMIS; lump display; tactile display;
Journal_Title :
Haptics, IEEE Transactions on
DOI :
10.1109/TOH.2012.71