# Design and Calibration of a Sensory System of an Adaptive Gripper
## 1 Introduction  
Adaptive grippers are gripping systems used in industrial robots to grip parts of various shapes and sizes. Also, in many cases, it is more efficient to design a gripper adapted to a series of real robotic applications, for gripping parts of varied shapes and with relatively large variations in size. In addition, adaptive gripper systems are able to take into account the particularities of the gripped part (shape and weight) and make decisions to obtain a safe grip, thanks to the provision of appropriate sensory systems. As examples of such grippers, three cases are first presented: Robotiq 2 Finger Adaptive [1], with a single contact area with the gripped object on each holder element; the SamPIIng gripper [2], which has two contact areas with the gripped object on the holder elements, and the evaluation of dynamic adaptation for a sinusoidal test signal is presented without details about the calibration of the sensors used; the Cassino 1 gripper [3], which uses piezoelectric force sensors, without detailing the calibration stage; and the Cassino2-LARM Hand gripper [4], which has a higher degree of adaptation to the type of gripped part. An adaptive gripper with three jaws that can be replaced by three fingers is described in [5], with the possibility of two fingers adapting to the orientation of the surface of the piece to be gripped by self-orientation. A gripper similar to the Barrett gripper is described in [6], which can grip small parts especially by grasping, without referring to the calibration of the sensors used. In the paper [7], a gripper with local adaptivity, with two fingers, specialized for gripping and manipulating, including the mounting of electronic cables,is described without referring to the sensors used. Another somewhat adaptive gripper capable of gripping parts at predetermined points is described in [8], which shows the use of depth sensors, without detailed references to them. These grippers tend to be used more and more to replace grippers with jaws [9], which are limited to gripping a single type of shape or size. In the papers [10; 11], which focus on the calibration of sensors used in robotic gripping systems, specifically a force sensor and a slip sensor, different situations are analyzed than the one in this work and at a much more general level. The information in this regard is limited, and the complexity of the calibration process is not adequately highlighted, which is what the present paper aims to address. This paper briefly presents the design, highlighting the innovative aspects, and in more detail the calibration of the force sensor and the slip sensor for each gripper module. This paper first presents the logical architecture for the design of the electro-electronic part of each gripping module. It then describes the main elements of the design of the slip sensor and the force sensor on each gripping module, after which the calibration of the force sensor and the slip sensor and the results of the validation tests of their proper functioning are presented. At the end of this paper, the gripping of two real parts with the designed adaptive gripping system is described, which validates the correct functioning of the designed and calibrated sensors used.