A Robotic System for Medical Hoses Manipulation and Quality Check

This paper proposes a robotic based system, equipped with suitably developed mechatronic tools, able to fine manipulate medical hoses directly from the production line and during the execution of quality check tasks. The system combines suitably developed technologies (i.e., tactile sensors and cutting machine) with methodological approaches (i.e., tactile indicator, blind search methods, image processing) in order to automatize the manipulation of very thin and soft linear deformable objects, where the main challenge is the very small forces involved during manipulation. The work presents the system testing during the execution of two real quality check scenarios: verification of the hose internal diameter and checking of the hose section shape and dimensions. For the internal diameter check, a suitably defined contact indicator based on tactile signals is proposed, and it is combined with a blind search method, based on the use of a spiral path, in order to generalize the task execution, by overcoming limitations due to the possible misalignment among grasped area and hose end. For the inspection of the hose section, a specific cutting tool has been developed and image processing methods have been implemented, by means of microscope feedback, for the centering and focus of the hose sample to be analyzed. Note to Practitioners - This paper is motivated by the problem of robotic manipulation for quality check of medical hoses, which are deformable and very thin (typical diameters are equal to 0.5-2, mm). On the basis of customer application, the producer is requested to check up to 100% of the lot. Currently, quality control operations are carried out manually by human operators, executing very alienating tasks, which lead to an increasing percentage of hoses check errors over long working shifts. In this paper, both hardware and software details needed to reproduce the system are reported: tactile sensors compatible with commercial parallel gripper, used to manipulate hoses during the interaction with the other mechanical tools; a cutting machine with a microscope used for the inspection of the hose section; an approach for the execution of standard Go/No-Go tests, exploited for hose internal diameter evaluation; an approach for the centering and focus of microscope images, implemented for the inspection of the hose section. The proposed approaches are also presented in algorithmic fashion in order to simplify the implementation for interested reader. The system has been demonstrated in a real production scenario. Further refinements are planned in order to speed up the system, to manage the failures and to extend the proposed solution to longer hoses and hoses with additional type of sections.