Drift-Free Joint Angle Calculation Using Inertial Measurement Units without Magnetometers: An Exploration of Sensor Fusion Methods for the Elbow and Wrist.

Joint angles of the lower extremities have been calculated using gyroscope and accelerometer measurements from inertial measurement units (IMUs) without sensor drift by leveraging kinematic constraints. However, it is unknown whether these methods are generalizable to the upper extremity due to differences in motion dynamics. Furthermore, the extent that post-processed sensor fusion algorithms can improve measurement accuracy relative to more commonly used Kalman filter-based methods remains unknown.

Applying the Worker Well-Being Framework to Identify Factors that Impact Turnover Among Long-Haul Truck Drivers.

Background: Drivers in the long-haul trucking industry have chronic health conditions, engage in unhealthy behaviors, and leave the industry at high rates. Previous work has not considered the health and safety outcomes resulting from the conditions of work in the trucking industry and their role in turnover. The goal of this study was to understand the expectations of an incoming workforce, explore how work conditions impact their well-being, and identify strategies for retention.

Gyroscope vector magnitude: A proposed method for measuring angular velocities.

High movement velocities are among the primary risk factors for work-related musculoskeletal disorders (MSDs). Ergonomists have commonly used two methods to calculate angular movement velocities of the upper arms using inertial measurement units (accelerometers and gyroscopes). Generalized velocity is the speed of movement traveled on the unit sphere per unit time.

Assessing the relationship between domestic work experience and musculoskeletal health among rural Nigerian women.

Background: Women performing strenuous domestic tasks (especially those in developing countries) are at risk of experiencing musculoskeletal pain (MSP). Physical, psychosocial, and social conditions of work in rural environments contribute to women's domestic work experiences (DWEs) and the risk of MSP. The impact of DWEs on women's health is especially severe in water-insecure countries like Nigeria.

Novel methods to detect impacts within whole-body vibration time series data.

We present three candidate mathematical models for detecting impacts within time series accelerometer data in the context of whole-body vibration (WBV). In addition to WBV, data included recordings of erector spinae muscle activity and trunk posture collected during use of agricultural machines in a previous study. For each model, we evaluated associations between several mechanical and biomechanical variables at the time of predicted impact onset and the odds of subsequently observing a bilateral response of the erector spinae muscles.

Understanding Rural Women's Domestic Work Experiences (DWE) in Ibadan, Nigeria: Development of a Measurement Tool Using Confirmatory Factor Analysis.

Gender norms prescribe domestic labor as primarily a female's responsibility in developing countries. Many domestic tasks depend on access to water, so the physical, emotional, and time demands of domestic labor may be exacerbated for women living in water-insecure environments. We developed a set of domestic work experience (DWE) measures tailored to work in rural areas in developing countries, assessed rural Nigerian women's DWE, and examined relationships among the measures.

The association between drought conditions and increased occupational psychosocial stress among U.S. farmers: An occupational cohort study.

Background: Drought represents a globally relevant natural disaster linked to adverse health. Evidence has shown agricultural communities to be particularly susceptible to drought, but there is a limited understanding of how drought may impact occupational stress in farmers.

Methods: We used repeated measures data collected in the Musculoskeletal Symptoms among Agricultural Workers Cohort study, including 498 Midwestern U.

Assessment of occupational personal sound exposures for music instructors.

Daily activities performed by music instructors generate high sound levels that could potentially lead to overexposure. Adverse outcomes associated with high-exposure to sound, such as hearing loss and tinnitus, can be especially devastating to music instructors as hearing is essential to both job performance and career reward. The primary objective of this study was to compare sound exposures of music instructors to recommended exposure limits.

Comparing upper arm and trunk kinematics between manufacturing workers performing predominantly cyclic and non-cyclic work tasks.

Musculoskeletal disorders (MSDs) are common among manufacturing workers. Exposure to non-neutral postures and high movement speeds associated with MSDs among manufacturing workers may depend on the extent of the variability in the work tasks performed (i.e.

Measuring upper arm elevation using an inertial measurement unit: An exploration of sensor fusion algorithms and gyroscope models.

Many sensor fusion algorithms for analyzing human motion information collected with inertial measurement units have been reported in the scientific literature. Selecting which algorithm to use can be a challenge for ergonomists that may be unfamiliar with the strengths and limitations of the various options. In this paper, we describe fundamental differences among several algorithms, including differences in sensor fusion approach (e.

Biomechanical factors during common agricultural activities: Results of on-farm exposure assessments using direct measurement methods.

Agricultural work is associated with increased risk of adverse musculoskeletal health outcomes. The purpose of this study was to quantify exposure to biomechanical factors among a sample (n = 55) of farmers in the Midwest region of the U.S.

Reliability of observational- and machine-based teat hygiene scoring methodologies.

Removal of teat-end debris is one of the most critical steps in the premilking process. We aimed to estimate inter- and intra-rater reliability of an observation-based rating scale of dairy parlor worker teat-cleaning performance. A nonrandom sample of 8 experienced raters provided teat swab debris ratings scored on a 4-point ordinal visual scale for 175 teat swab images taken immediately after teat cleaning and before milking unit attachment.

Association between Occupational Injury and Subsequent Employment Termination among Newly Hired Manufacturing Workers.

Few longitudinal studies have examined occupational injury as a predictor of employment termination, particularly during the earliest stages of employment when the risk of occupational injury may be greatest. Human resources (HR) records were used to establish a cohort of 3752 hourly employees newly hired by a large manufacturing facility from 2 January 2012, through 25 November 2016. The HR records were linked with records of employee visits to an on-site occupational health center (OHC) for reasons consistent with occupational injury.

Radio frequency identification to measure the duration of machine-paced assembly tasks: Agreement with self-reported task duration and application in variance components analyses of upper arm postures and movements recorded over multiple days.

Technical advances in inertial measurement units (IMUs) with data logging functionality have enabled multi-day collection of fullshift upper arm postures and movements. Such data are useful for characterizing job-level exposures and, when coupled with task-level information, can inform interventions to mitigate high-exposure tasks. Previously reported methods for capturing task-level information, however, were limited primarily to self-report diaries or direct observation.

Whole-Body Vibration and Trunk Posture During Operation of Agricultural Machinery.

Exposure to whole-body vibration (WBV) is common among agricultural workers and is associated with musculoskeletal health outcomes such as low back pain. Little is known, however, about the characteristics of exposure experienced during actual production practices. We measured WBV levels during agricultural machinery use among a sample of farmers (n = 55) performing routine agricultural activities and explored machinery attributes that may explain WBV summary measures.

Digital Human Modeling in the Occupational Safety and Health Process: An Application in Manufacturing.

Digital human modeling (DHM) and simulation software has been identified as an effective tool for evaluating work tasks and design alternatives without requiring the expense of physical mock-ups and production trials. Despite recent commercial advancements and a broader availability of DHM platforms, the peer-reviewed scientific literature lacks sufficient demonstration of the application of DHM software within an occupational safety and health process for mitigating exposures to physical risk factors in a real work environment. We describe the implementation of a commercially-available DHM platform as a component of an occupational safety and health process in a manufacturing environment over the course of one year.

Accuracy of angular displacements and velocities from inertial-based inclinometers.

The objective of this study was to evaluate the accuracy of various sensor fusion algorithms for measuring upper arm elevation relative to gravity (i.e., angular displacement and velocity summary measures) across different motion speeds.

Characterizing exposure to physical risk factors among reforestation hand planters in the Southeastern United States.

Low back and neck/shoulder pain are commonly reported among reforestation hand planters. While some studies have documented the intensive cardiovascular demands of hand planting, limited information is available regarding exposures to physical risk factors associated with the development of musculoskeletal disorders (MSDs) among hand planters. This study used surface electromyography (EMG) and inertial measurement units (IMUs) to characterize the muscle activation patterns, upper arm and trunk postures, movement velocities, and physical activity (PA) of fourteen Southeastern reforestation hand planters over one work shift.

Effects of Movement Speed and Magnetic Disturbance on the Accuracy of Inertial Measurement Units.

This study evaluated the effects of motion speed and magnetic disturbance on the spatial orientation accuracy of an inertial measurement unit (IMU) on the hand. Thirteen participants performed six trials of a repetitive material transfer task. Movement speed (15, 30, 45 transfers/minute) and magnetic disturbance (absent, present) were the independent variables.

Full-shift and task-specific upper extremity muscle activity among US large-herd dairy parlour workers.

US large-herd dairy parlour workers experience a high prevalence of musculoskeletal symptoms in the upper extremity. The purpose of this study was to estimate and compare full-shift and task-specific muscle activity of the upper extremity among parlour workers. Surface electromyography data were recorded continuously throughout a full work shift for each participant (n = 60).

Effect of a novel teat preparation system on upper extremity muscle activity among U.S. large-herd dairy parlor workers.

Background: Dairy production in the U.S. is moving towards large-herd milking operations resulting in an increase in task specialization and work demands.

Effects of milking unit design on upper extremity muscle activity during attachment among U.S. large-herd parlor workers.

Background: Large-herd dairy parlor workers experience a high prevalence of musculoskeletal symptoms in the upper extremity. The purpose of this study was to evaluate the effect of milking unit design on upper extremity muscle activity during milking unit attachment.

Methods: Upper extremity muscle activity was recorded among U.

Upper trapezius muscle activity in healthy office workers: reliability and sensitivity of occupational exposure measures to differences in sex and hand dominance.

Patterns of cervical muscle activity may contribute to overuse injuries in office workers. The purpose of this investigation was to characterise patterns of upper trapezius muscle activity in pain-free office workers using traditional occupational exposure measures and a modified Active Amplitude Probability Distribution Function (APDF), which considers only periods of active muscle contraction. Bilateral trapezius muscle activity was recorded in 77 pain-free office workers for 1-2 full days in their natural work environment.