  In this paper, we present a new version of tactile sensor GelSlim 2.0 with
the capability to estimate the contact force distribution in real time. The
sensor is vision-based and uses an array of markers to track deformations on a
gel pad due to contact. A new hardware design makes the sensor more rugged,
parametrically adjustable and improves illumination. Leveraging the sensor's
increased functionality, we propose to use inverse Finite Element Method
(iFEM), a numerical method to reconstruct the contact force distribution based
on marker displacements. The sensor is able to provide force distribution of
contact with high spatial density. Experiments and comparison with ground truth
show that the reconstructed force distribution is physically reasonable with
good accuracy.
