Validation of Lumbar Compressive Force Simulation in Forward Flexion Condition

Safety standard requirements must be implemented for lumbar support robots, which are mainly used for preventing low back pain (LBP) in caregivers. Usually, simulations are used to mimic actions that are not allowed for a real person. However, a comprehensive validation of a simulator in dynamic conditions has not been conducted. In this study, an ergonomic simulator is validated through forward flexion invasive experiments. The correspondence between the simulated and experimental compressive force (CF), as well as the CF obtained using two existing models about the unified angle, is investigated. The results show that the CF error between the measurements and the simulator at a flexion angle of 30∘ is 11.8% and is lower than those obtained for the other two models (16.8% and 20.6%). Linear regression shows that the invasive data and estimated CF are close (slope = 1) in Merryweather’s model and CF simulator but not for Potvin’s model. We evaluate the precision of the simulator by using intraclass correlation coefficient method. Merryweather’s model is moderately consistent with invasive measurements, with R–0.685 and 0.627 at 0 and 30∘, while the CF simulator shows good consistency with Merryweather’s model with R–0.879 and 0836 at 0 and 30∘.