Development of an Electric Tugger for Patient Bed Transportation

Abstract

Transporting a patient in a bed within Songklanagarind Hospital, Faculty of Medicine, Prince of Songkla University, typically requires at least two workers. During peak hours, insufficient personnel often overburdens the patient transportation team. To address this challenge, this research aims to develop an electric tugger, or e-tugger, to facilitate patient bed transport. The e-tugger is designed to enable a single staff member to haul a patient bed on flat surfaces and up to a 5% incline to the destination. The e-tugger's design includes an electric tugger and a forklift. The tugger’s structure provides space to install the necessary components. A 3-kW brushless DC motor, powered by 72V, 15Ah Li-ion batteries, drives the system, allowing it to move a patient bed weighing up to 400 kg on a 5% incline. The staff can control the e-tugger's motion using either a control box or a joystick. The forklift, when viewed from the side, has an L-shape and is equipped with an integrated electric scissor jack that lifts the forklift up and down, operated via the control box. The e-tugger’s performance study focuses on two main aspects: (1) the user experience of coupling the e-tugger to the patient bed, and (2) the e-tugger’s operation on a 30-meter flat surface and in a passageway. Onsite testing demonstrates that one staff member can effectively transport a patient in a bed using the e-tugger. Coupling the e-tugger to a patient’s bed takes only 10 seconds. The e-tugger can propel a 255-kg patient bed at approximately 1.66 m/s. The electric motor consumes 2.46 A on a flat surface and 4.46 A on a 5% incline. Additionally, after transporting a 380-kg patient bed for 2.36 km, the battery's state of charge decreases by 2 %, with the e-tugger's average energy consumption rate being approximately 91.5 Wh/ 10 km.