Low-Cost and Light-Weight Assistive Suit for Caregivers' Transfer Work and an Evaluation of Compensation of the Load to the Spine's L5/S1 Segment

Life-supporting technology helps elderly and disabled individuals maintain their ability to perform daily activities, such as transferring between a bed and a wheelchair. Caregivers assist care recipients in utilizing their remaining functional abilities more actively. Additionally, caregivers can undergo training to minimize their risk of lower back pain, particularly when performing transfer tasks. However, many institutions face challenges such as workforce shortages, an aging staff, and heavy care workloads. Previous studies have identified excessive pressure on the L5/S1 segment of the spine as a primary cause of lower back pain. The load on this segment is determined by the force exerted by the erector spinae muscles, as well as spinal posture, which is influenced by upper-body posture, the angle between the upper body and thighs, and knee joint angles. The proposed assistive suit features a passive elastic back blade made of carbon fiber-reinforced plastic (CFRP) that supports the caregiver's posture and reduces spinal load. Simulations show that the suit effectively mitigates compressive forces, depending on the load transmission rate. A precise mechanical model was employed to estimate the load on the L5/S1 spinal segment, which was then compared with the load generated by other types of assistive suits.