Auto-calibrated Wearable System for Load Vertical Location Estimation During Manual Lifting

TL;DR

This paper introduces an unobtrusive wearable system with a novel barometer-based method and calibration technique to accurately measure load vertical location during manual lifting, aiming to reduce low-back pain risk.

Contribution

It presents a new wearable system combining smart insoles and wristbands with a barometer-based measurement and calibration method for LVL estimation.

Findings

Achieved a mean absolute error of 5.71 cm in LVL measurement.

Demonstrated potential for reliable LVL assessment in real workplace environments.

Proposed method outperforms traditional IMU-based approaches.

Abstract

Lifting during manual material handling is a major cause of low-back pain (LBP). As an important risk factor that directly influences the risk of LBP, the Load vertical location (LVL) during lifting needs to be measured and controlled. However, existing solutions for LVL measurement are inefficient, inaccurate, and impractical for real-world workplace environments. To address these problems, an unobtrusive wearable system, including smart insoles and smart wristbands, was proposed to measure LVL accurately in workplace environments. Different from traditional methods which rely on Inertial Measurement Unit (IMU) and suffer from integral drifting errors over time, a novel barometer-based LVL measurement method was proposed in this study. To correct the environment-induced LVL measurement errors in the barometer-based method, a novel Known Vertical Location Update (KVLU) method was proposed. This method calibrates the measured LVL using a known wrist vertical location at known postures during frequently used daily activities such as standing and walking. The proposed wearable system achieved a mean absolute error (MAE) of 5.71 cm in LVL measurement. This result indicates that the proposed system has the potential to reliably measure LVL and assess the risk of LBP in manual lifting tasks.