Entwicklung einer kooperativen Patiententransporthilfe für den Rettungsdienst

• Development of a cooperative patient transportation aid for emergency medical services

Verjans, Mark; Radermacher, Klaus (Thesis advisor); Flemisch, Frank O. (Thesis advisor)

Düren : Shaker (2021)
Book, Dissertation / PhD Thesis

In: Aachener Beiträge zur Medizintechnik 65
Page(s)/Article-Nr.: 194 Seiten : Illustrationen, Diagramme

Dissertation, RWTH Aachen University, 2021

Abstract

The transport of patients is associated with great physical challenges for the employees of emergency medical services and the recommended load limits are exceeded regularly. Consequently, work-related injury and illness rates are far above the national average for this occupational group. One main reason for these high loads are obstacles in the transport route, such as stairs, which occur frequently and prevent the ergonomic use of current transportation aids. For these reasons, there is a need for transportation aids which can be universally used and reduce the loads of the user. In the context of this work, a new cooperative transportation aid is developed and evaluated. The general concept is based on the fusion of stair climbing kinematics, based on a triangular-shaped wheel carrier, with a self-stabilizing control. Within the scope of an initial risk analysis, instabilities and inaccuracies of the self-stabilizing control loop have proven to be particularly critical. A targeted control development and evaluation is necessary due to the special conditions and requirements of this application. Accordingly, both a model-predictive and sliding mode controller have been developed based on an analytical and adaptive model of the system. These controllers were assessed in an experimental evaluation regarding the resulting cooperative user interaction and their robustness against uncooperative patient behavior. It was found that the sliding mode controller has a more comfortable performance for the user and a high robustness despite slightly slower dynamics. Therefore, this sliding mode controller was transferred to a stair climbing prototype and the resulting usability was assessed in a first test. Within the scope of this study, a typical transport scenario was simulated and the working postures, user forces and perceived usability were evaluated in relation to ergonomic guidelines. It was shown that the new transport aid enables an upright and healthy posture for the lower back and that the user forces do not exceed an acceptable level. A comparison with transportation aids used currently shows that the new system has a similar ergonomic design to the caterpillar stair chair, which is considered in the literature to be the most ergonomic transportation aid available. In contrast to the caterpillar stair chair, however, the system developed here allows a more universal application, such as on curved stairs. Considering further possible optimizations, this system can, therefore, make a relevant contribution to relieving the workload of emergency rescue service personnel in the future.