Soft pneumatic devices for blood circulation improvement

摘要

The research activity I am presenting in this thesis lies within the framework of a cooperation between the University of Cagliari (Applied Mechanics and Robotics lab, headed by professor Andrea Manuello Bertetto, and the research group of physicians referencing to professor Alberto Concu at the Laboratory of Sports Physiology, Department of Medical Sciences), and the Polytechnic of Turin (professor Carlo Ferraresi and his equipe at the Group of Automation and Robotics, Department of Mechanical and Aerospace Engineering) This research was also funded by the Italian Ministry of Research (MIUR – PRIN 2009). My activity has been mainly carried on at the Department of Mechanics, Robotics lab under the supervision of prof. Manuello; I have also spent one year at the Control Lab of the School of Electrical Engineering at Aalto University (Helsinki, Finland). The tests on the patients were taken at the Laboratory of Sports Physiology, Cagliari. I will be describing the design, development and testing of some soft pneumatic flexible devices meant to apply an intermittent massage and to restore blood circulation in lower limbs in order to improve cardiac output and wellness in general. The choice of the actuators, as well as the pneumatic circuits and air distribution system and PLC control patterns will be outlined. The trial run of the devices have been field--‐tested as soon a prototype was ready, so as to tune its features step--‐by--‐ step. I am also giving a characterization of a commercial thin force sensor after briefly reviewing some other type of thin pressure transducer. It has been used to gauge the contact pressure between the actuator and the subject’s skin in order to correlate the level of discomfort to the supply pressure, and to feed this value back to regulate the supply air flow. In order for the massage to be still effective without causing pain or distress or any cutoff to the blood flow, some control objective have been set, consisting in the regulation of the contact force so that it comes to the constant set point smoothly and its value holds constant until unloading occurs. The targets of such mechatronic devices range from paraplegic patients lacking of muscle tone because of their spinal cord damage, to elite endurance athletes needing a circulation booster when resting from practicing after serious injuries leading to bed rest. Encouraging results have been attained for both these two categories, based on the monitored hemodynamic variables.