Three passive arm-support exoskeletons have inconsistent effects on muscle activity, posture, and perceived exertion during diverse simulated pseudo-static overhead nutrunning tasks.

Arm-support exoskeletons (ASEs) are an emerging technology with the potential to reduce physical demands during diverse tasks, especially overhead work. However, limited information is available about the effects of different ASE designs during overhead work with diverse task demands. Eighteen participants (gender-balanced) performed lab-based simulations of a pseudo-static overhead task. This task was performed in six different conditions (3 work heights × 2 hand force directions), with each of three ASEs and in a control condition (i.e., no ASE). Using ASEs generally reduced the median activity of several shoulder muscles (by ∼12-60%), changed working postures, and decreased perceived exertion in several body regions. Such effects, though, were often task-dependent and differed between the ASEs. Our results support earlier evidence of the beneficial effects of ASEs for overhead work but emphasize that: 1) these effects depend on the task demands and ASE design and 2) none of the ASE designs tested was clearly superior across the tasks simulated.

Physical capability limits for right-angle power tool operation.

Automotive assembly operations require power tools to secure fasteners and these operations have been linked to increased risk of musculoskeletal disorders. This work was designed to develop physical capability limits for direct current right-angle power tool (RAPT) operations using psychophysics. Forty females fastened joints of different hardness's using three fastening strategies, at three fastening frequencies. Participants chose to fasten, independent of orientation, joints up to 89 (10.6) Nm using Atlas Copco's TurboTight®, compared to 51.8 (8.1) Nm using Atlas Copco's Quickstep and 48.6 (10.2) Nm using Stanley's Automatic Tightening Control. The differences between fastening strategies were not as large when fastening soft joints; 59.2 (16.2), 52.3 (14.6), and 53.5 (11.3) Nm, respectively. As fastening frequency increased, participants chose lower target torque magnitudes to fasten. Based on this work, RAPT manufactures can adjust fastening strategies to improve their tool's ergonomics performance. Practitioner summary: Fastening tasks was identified as posing an injury risk to workers performing automotive assembly, yet presently there are no published physical capability limits for direct current right-angle power tool operation. Using a psychophysical methodology, physical capability limits for RAPT fastenings were established for different joint hardness, fastening frequencies and RAPT position/orientation.

Usability, User Acceptance, and Health Outcomes of Arm-Support Exoskeleton Use in Automotive Assembly: An 18-month Field Study.

OBJECTIVE: Examine arm-support exoskeleton (ASE) user experience over time, identify factors contributing to ASE intention-to-use, and explore whether ASE use may influence the number of medical visits. METHODS: An 18-month, longitudinal study with ASE (n = 65) and control groups (n = 133) completed at nine automotive manufacturing facilities. RESULTS: Responses to six usability questions were rather consistent over time. ASE use perceived effective in reducing physical demands on the shoulders, neck, and back. Perceived job performance, and overall fit and comfort, appeared to be key determinants for ASE intention-to-use. Based on medical visits among both groups, ASE use may decrease the likelihood of such visits. CONCLUSIONS: These field results support the potential of ASEs as a beneficial ergonomic intervention, but also highlight needs for further research on ASE designs, factors driving intention-to-use, and health outcomes.

Effects of an arm-support exoskeleton on perceived work intensity and musculoskeletal discomfort: An 18-month field study in automotive assembly.

BACKGROUND: Exoskeleton (EXO) technologies are a promising ergonomic intervention to reduce the risk of work-related musculoskeletal disorders, with efficacy supported by laboratory- and field-based studies. However, there is a lack of field-based evidence on long-term effects of EXO use on physical demands. METHODS: A longitudinal, controlled research design was used to examine the effects of arm-support exoskeleton (ASE) use on perceived physical demands during overhead work at nine automotive manufacturing facilities. Data were collected at five milestones (baseline and at 1, 6, 12, and 18 months) using questionnaires. Linear mixed models were used to understand the effects of ASE use on perceived work intensity and musculoskeletal discomfort (MSD). Analyses were based on a total of 41 participants in the EXO group and 83 in a control group. RESULTS: Across facilities, perceived work intensity and MSD scores did not differ significantly between the EXO and control groups. In some facilities, however, neck and shoulder MSD scores in the EXO group decreased over time. Wrist MSD scores in the EXO group in some facilities remained unchanged, while those scores increased in the control group over time. Upper arm and low back MSD scores were comparable between the experimental groups. CONCLUSION: Longitudinal effects of ASE use on perceived physical demands were not found, though some suggestive results were evident. This lack of consistent findings is discussed, particularly supporting the need for systematic and evidence-based ASE implementation approaches in the field that can guide the optimal selection of a job for ASE use.

A survey of right-angle power tool use in Canadian automotive assembly plants.

Right-angle power-tools (RAPT) employed in automotive manufacturing promote greater productivity and quality fastenings, as well as, improve process efficiency. Due to RAPT technological advances automotive manufactures desire to understand their ergonomics consequences within a laboratory environment, however, laboratory-based representation must accurately represent the real world. A survey within automotive assembly plants was conducted to capture RAPT operation data. After examining 80 total RAPT operations, we logged the 3D locations of the fastener location (with respect to the operator), direction and the hand placement location used by operators. Four common locations with respect to the midpoint between the ankle (in cm; X = sagittal plane, Y = transverse plane, Z = coronal plane): 1) 2, 113, 62; 2) 42, 104, 45; 3) -26, 151, 36; 4) -37, 92, 52. These locations can be used to simulate RAPT operations within a laboratory. The survey provided insight into current workstation layout when operating RAPTs and, knowledge for laboratory-based RAPT examinations so that simulated tasks best represent their operation in automotive manufacturing.

RGB-D ergonomic assessment system of adopted working postures.

Ensuring a healthier working environment is of utmost importance for companies and global health organizations. In manufacturing plants, the ergonomic assessment of adopted working postures is indispensable to avoid risk factors of work-related musculoskeletal disorders. This process receives high research interest and requires extracting plausible postural information as a preliminary step. This paper presents a semi-automated end-to-end ergonomic assessment system of adopted working postures. The proposed system analyzes the human posture holistically, does not rely on any attached markers, uses low cost depth technologies and leverages the state-of-the-art deep learning techniques. In particular, we train a deep convolutional neural network to analyze the articulated posture and predict body joint angles from a single depth image. The proposed method relies on learning from synthetic training images to allow simulating several physical tasks, different body shapes and rendering parameters and obtaining a highly generalizable model. The corresponding ground truth joint angles have been generated using a novel inverse kinematics modeling stage. We validated the proposed system in real environments and achieved a joint angle mean absolute error (MAE) of 3.19±1.57∘ and a rapid upper limb assessment (RULA) grand score prediction accuracy of 89% with Kappa index of 0.71 which means substantial agreement with reference scores. This work facilities evaluating several ergonomic assessment metrics as it provides direct access to necessary postural information overcoming the need for computationally expensive post-processing operations.