Contact Force Recognition in Robotic Fingertips’ Interface

Contact force recognition is a tribological topic of great significance in many industrial applications and especially in robotic grasping and manipulation. In fact, grasping is a very delicate operation which implies dexterity and precision to ensure proper support and no damage to the grasped object. Furthermore, in many industrial and medical applications a controlled grasping with force recognition and tuning is crucial to help humans performing specific harmful or delicate tasks. For these reasons, contact force detection methods should be implemented in robotic grippers to allow the grasping of specific objects or to perform specific tasks preventing object falls and avoiding deformations or breakages. This paper is focused on the application of Force Sensing Resistors to different fingertips of robotic fingers to get information to calibrate the grasping for specific objects and tasks. In particular, the characterization of the force sensors is performed and then the calibration of the sensor on two fingertips in order to obtain accurate values of contact forces detected in the normal direction to the sensor's sensing area. In addition, the contact model of the studied fingertips is deduced and stiffnesses are calculated. All these information will be useful to design grippers with controlled grasping forces for different industrial applications.