Tactile Based Active Sensing for Detecting Stiffness and Contact Point Using Robotic Finger

This paper discusses an approach for detecting not only a contact point between an environment and a robotic finger, but also the local stiffness of the environment where the finger makes contact. We assume that the environment's stiffness is three dimensional with coupling terms, whereas most the conventional studies have assumed a one-dimensional spring as an environment model for simplification. When a finger confirms that there exists considerable compliance, the finger tip is pressed against the environment and starts several active pushing motions in various directions to eventually obtaining the stiffness matrix. After the stiffness matrix is obtained, the initial contact point can be evaluated by using the measured stiffness matrix. The overall concept is also verified by experiments utilizing a wire-driven robotic finger.