  The importance of force perception in interacting with the environment was
proven years ago. However, it is still a challenge to measure the contact force
distribution accurately in real-time. In order to break through this
predicament, we propose a new vision-based tactile sensor, the Tac3D sensor,
for measuring the three-dimensional contact surface shape and contact force
distribution. In this work, virtual binocular vision is first applied to the
tactile sensor, which allows the Tac3D sensor to measure the three-dimensional
tactile information in a simple and efficient way and has the advantages of
simple structure, low computational costs, and inexpensive. Then, we used
contact surface shape and force distribution to estimate the friction
coefficient distribution in contact region. Further, combined with the global
position of the tactile sensor, the 3D model of the object with friction
coefficient distribution is reconstructed. These reconstruction experiments not
only demonstrate the excellent performance of the Tac3D sensor but also imply
the possibility to optimize the action planning in grasping based on the
friction coefficient distribution of the object.
