Modelling patient dynamics and controller impact analysis for a novel self-stabilizing patient transport aid

Abstract

Abstract Patient transport results in high physical stresses for paramedics, because transport aids which provide sufficient support with satisfactory dynamics and mobility are currently not available. A novel concept of an active transport aid is based on a self-balancing drive system which is steered externally by a paramedic while providing an ergonomic patient chair for transport. For the development of a robust self-balancing controller a model of the system is necessary. Current models neglect the dynamic influence of the user and use a rigid body instead, but for this application this simplified approach is questionable. In contrast to classical self-balancing transporters, in our case the patient should not have a severe impact on the stability of the driving system, even in case of uncooperative behavior. To analyze the influence of passive and active movements of the patient on the performance of the controller, a parametric multi-body patient model was designed and evaluated. Our findings show a relevance of passive movements especially during decelerations of the transport aid, when the upper body tilts forward and is restrained by seatbelts. Active movements like restless sitting, external forces or cramping seizures showed a clear deterioration of the controller performance. Therefore characteristics of active and passive patient movements during controller development should be considered and a tight and secure fixation of the patient is necessary to achieve sufficient safety for both patient and paramedic.