A measurement setup for the 3D validation of fingertip deformation models

Deformable models of the human fingertip are commonly validated by evaluating a finger's silhouette when charged with a line load. To validate models, it would be desirable to measure 3D data of the fingertip at a high frequency. This paper proposes the use of a stereo camera setup to measure the 3D surface of the fingertip's side. The setup offers a theoretical depth resolution of 0.17 mm at a frame rate above 100 Hz. A feature point matching algorithm incorporating scene knowledge is implemented to obtain 3D points to which a paraboloid surface is fitted. Precision is compared with reference to a LIDAR sensor and experiments applying normal and tangential force to the fingertip recorded with a 6-DOF force sensor setup. The results imply that state-of-the-art feature-based algorithms are insufficient or unsuited to match the fingertip surface reliably. Further approaches are proposed to improve robustness.