A New Test Bench System for Hammer Drills: Validation for Handle Vibration

Trends in Robotics Research in Occupational Safety and Health: A Scientometric Analysis and Review

Robots have been deployed in workplaces to assist, work alongside, or collaborate with human workers on various tasks, which introduces new occupational safety and health hazards and requires research efforts to address these issues. This study investigated the research trends for robotic applications in occupational safety and health. The scientometric method was applied to quantitatively analyze the relationships between robotics applications in the literature. The keywords "robot", "occupational safety and health", and their variants were used to find relevant articles. A total of 137 relevant articles published during 2012-2022 were collected from the Scopus database for this analysis. Keyword co-occurrence, cluster, bibliographic coupling, and co-citation analyses were conducted using VOSviewer to determine the major research topics, keywords, co-authorship, and key publications. Robot safety, exoskeletons and work-related musculoskeletal disorders, human-robot collaboration, and monitoring were four popular research topics in the field. Finally, research gaps and future research directions were identified based on the analysis results, including additional efforts regarding warehousing, agriculture, mining, and construction robots research; personal protective equipment; and multi-robot collaboration. The major contributions of the study include identifying the current trends in the application of robotics in the occupational safety and health discipline and providing pathways for future research in this discipline.

The contact length parameter as a geometric factor for user-centered design of pistol grip geometries of power tools

In this study the geometric parameter of the contact length is introduced, which intends to combine force exertion and perceived handle comfort in an anthropometric length in order to determine an optimal handle circumference. To prove suitability of the approach, 31 subjects were determined and correlations to handle circumferences with the highest finger forces and highest rated comfort were investigated. For all fingers, medium correlations were found among the contact lengths and the circumferences determined with maximum force (p < 0.001, r_index = 0.348, r_middle = 0.419, r_ring = 0.374 and r_little = 0.337) with high accordance of median values. Weak to moderate correlations were found between circumferences with maximum comfort and the contact lengths (p < 0.001, r_index = 0.150, r_middle = 0.265, r_ring = 0.174). Using finger-specific proportionality factors, the contact lengths can be determined directly from the hand lengths, which enables great benefits for user-centered design.

The influence of human interaction on the vibration of hand-held human-machine systems - The effect of body posture, feed force, and gripping forces on the vibration of hammer drills

In hand-held human machine systems the biodynamic response of the human hand arm system influences the overall dynamic behavior. The biodynamic response of the hand arm system is affected by several influencing factors. These influencing factors include the feed force, body posture, gripping force, and anthropometric properties. In present studies the importance of the gripping force on the biodynamic response is highlighted. In the state of the art; however, the magnitude of gripping forces as well as the influence of the human factors body posture and feed force on hammer drills for a larger group of professional users is unclear. To analyze the influence that these human factors have on hammer drill vibrations, a study with 15 professional power tool test personnel has been conducted. Characteristic gripping force values have been measured (Median: 84 N-156 N at the main handle, 10 N-30 N on the auxiliary handle) for different feed forces (100 N, 150 N, 200 N) and body postures. Then the influence of body posture, feed force, and gripping force on the hammer drill vibration is determined. A significant influence of the body posture (ANOVA: p = .003, r = .367) on the RMS acceleration of the main handle was observed. Furthermore, the feed force has a significant influence on the vibration of the hammer-drill for some groups. The data also demonstrates that for increasing gripping forces, the RMS of the acceleration and frequency weighted acceleration a_hv on the main and auxiliary handle decrease. The findings of this study represent a starting point for the development of adjustable hand-arm models for the reproducible vibration assessment of power tools.

Using the Blood Coagulation Factors as a Predictor Component of the Occupational Vibration Exposure

Background:

Exposure to hand–arm vibrations higher than permissible standard rates can have destructing effects on workers’ health. Pneumatic hammers are among the tools that are used in civil and industrial projects, transferring high vibration acceleration to the workers. This study has considered the probable effects of hand–arm vibrations on the performance of blood coagulation factors in the workers using this tool and exposed to high vibration acceleration.

Methods:

Five new workers without any experience in exposure with hand–arm vibrations were selected for this interventional study. Blood sample was taken from each worker before they started working for the required analysis. Sampling was repeated in two other stages in 2-month intervals from the first sampling, whereas the workers were then experienced in working with pneumatic hammers. Measuring the vibration of the pneumatic hammer was done according to ISO 28927-10 standard.

Results:

The point of measuring the vibration acceleration was selected close to the hand, in accordance with the standard. Regarding the exposure time of the workers, the amount of vibration acceleration was obtained 15.54 m/s². Activated partial thromboplastin times of four samples in the second and third stages have shown increases in comparison to the first stage in that respect. On the other hand, a number of red blood cells, white blood cells, and platelets did not show a consistent trend in the three stages.

Conclusions:

The considered samples showed longer time for blood coagulation as compared to the reference time. Thus, it can be concluded that the main reason is the acceleration in three different coordinate axes of x, y, and z. Hence, the values beyond permissible standard rate of hand–arm vibration in 8 h shifts affect the blood parameters, among which the considered coagulation parameters in this study showed more tangible changes in that respect.

Pneumatic rock drill vs. electric rotary hammer drill: Productivity, vibration, dust, and noise when drilling into concrete

OBJECTIVES

Both pneumatic rock drills and electric rotary hammer drills are used for drilling large holes (e.g., 10-20 mm diameter) into concrete for structural upgrades to buildings, highways, bridges, and airport tarmacs. However, little is known about the differences in productivity, and exposures to noise, handle vibration, and dust between the two types of drills. The aim of this study was to compare these outcomes with similar mass electric rotary and pneumatic rock drills drilling into concrete block on a test bench system.

METHOD

Three experiments were conducted on a test bench system to compare an electric (8.3 kg) and pneumatic drill (8.6 kg) on (1) noise and handle vibration, (2) respirable silica dust, and (3) drilling productivity. The test bench system repeatedly drilled 19 mm diameter x 100 mm depth holes into cured concrete block while the respective exposure levels were measured following ISO standards.

RESULTS

Productivity levels were similar between the electric and the pneumatic drill (9.09 mm/s vs. 8.69 mm/s ROP; p = 0.15). However, peak noise (L_Peak: 117.7 vs. 139.4 dBC; p = 0.001), weighted total handle vibration (a_hw: 7.15 vs. 39.14 m/s²; p = 0.002), and respirable silica dust levels (0.55 vs. 22.23 mg/m³; p = 0.003) were significantly lower for the electric than the pneumatic drill.

DISCUSSION

While there were no differences in drilling productivity between an electric and pneumatic drill of similar mass, there were substantial differences in exposure levels of noise, handle vibration, and respirable silica dust. Structural contractors should switch from pneumatic rock drills to electric rotary hammer drills for structural drilling into concrete in order to reduce worker exposures to the hazards of noise, hand vibration, and silica dust.