Autonomous Robotic System Conducting Nasopharyngeal Swabbing

Abstract

The nasopharyngeal swab test is a procedure where a healthcare worker inserts a swab through the nose until it reaches the nasopharynx located at the back of the nasal cavity in order to collect secretions that can later be examined for illnesses. This procedure saw heightened use to detect cases during the COVID-19 pandemic. Its ubiquity also highlighted fragilities in the healthcare system by way of the hazards to healthcare workers from infectious patients and the pressures a pandemic can inflict upon an unready healthcare system. In this thesis we consider and propose an autonomous robotic system for performing nasopharyngeal swab tests by use of a collaborative robotic manipulator arm, under the ideology that the hardware and techniques could eventually be applied to other types of close-contact tasks to support the healthcare system. We also assume that prospective patients would be standing unrestrained in front of the arm, which adds the challenges of adjusting to arbitrary poses of the head and compensating for natural head motion. We first designed an instrumented end-effector to attach to a robotic arm to enable suitable vision and force sensing capabilities for the task. Next, we developed a finite element modeling simulation environment to describe the deformation of the swab as it moves through the nasal cavity, and solve an optimization problem to find ideal paths through the nasal cavity. A visual servo system was designed to properly align the swab next to the nose using visual information using advances in deep learning and state-estimation, which we validated with a number of human trials. A torque controlled force compliant system was designed and evaluated to determine the feasibility of using force measurements to correct for misalignment when the swab is inserted into a nasal cavity phantom. Finally, we integrated all the system components into a cohesive system for performing nasopharyngeal swab tests. We created a simulator using a nasal cavity phantom and a second robot arm to mimic natural motions of the head. This simulator was leveraged to perform extensive experimentation that found promising controller configurations that were able to compensate for head motion.