See all ›
7 CitationsSee all ›
26 ReferencesPsychophysically determined forces of dynamic pushing for female industrial workers: Comparison of two apparatuses
Abstract
Using psychophysics, the maximum acceptable forces for pushing have been previously developed using a magnetic particle brake (MPB) treadmill at the Liberty Mutual Research Institute for Safety. The objective of this study was to investigate the reproducibility of maximum acceptable initial and sustained forces while performing a pushing task at a frequency of 1 min−1 both on a MPB treadmill and on a high-inertia pushcart. This is important because our pushing guidelines are used extensively as a ergonomic redesign strategy and we would like the information to be as applicable as possible to cart pushing. On two separate days, nineteen female industrial workers performed a 40-min MPB treadmill pushing task and a 2-hr pushcart task, in the context of a larger experiment. During pushing, the subjects were asked to select a workload they could sustain for 8 h without “straining themselves or without becoming unusually tired, weakened, overheated or out of breath.” The results demonstrated that maximum acceptable initial and sustained forces of pushing determined on the high inertia pushcart were 0.8% and 2.5% lower than the MPB treadmill. The results also show that the maximum acceptable sustained force of the MPB treadmill task was 0.5% higher than the maximum acceptable sustained force of Snook and Ciriello (1991). Overall, the findings confirm that the existing pushing data developed by the Liberty Mutual Research Institute for Safety still provides an accurate estimate of maximal acceptable forces for the selected combination of distance and frequency of push for female industrial workers.
- CitationsCitations7
- ReferencesReferences26
- There are many tools and devices that allow inward and outward rotational manipulations manipulation (Ciriello et al., 2010). One of such devices includes the manual screwdriver, where inward torque direction is applied in order to fasten screws and outward torque direction is applied in order to unfasten screws.
[Show abstract] [Hide abstract] ABSTRACT: TRIZ refers to a methodology for systematic problem solving based on logic and data rather than intuition. It also promotes the ability to solve problems creatively. Using TRIZ tools for problem-solving such as the cause and effect chain analysis, engineering contradiction and 40 inventive principles, a design solution for a manual screwdriver was developed such that rotations in the outward directions were eliminated. This allowed users to avoid using awkward wrist postures whenever attempting to unfasten screws with manual screwdrivers. The ergonomic solution involves the use of the epicyclic gear train system, which allows the exchange between the input and output among the gears in order to invert the outward torque direction to an inward torque direction. The inward directional screwdriver potentially improves the twisting force and axial push force produced on the screwdriver handle such that inward torque can be used efficiently to both fasten and unfasten screws while avoiding outward torque, which can lead to unnatural hand postures and force generation beyond the user's maximum torque capacity. Eventually, this new product can reduce domestic household or industrial injuries and enhance human performance.- Knobs are also used on treadmills for controlling the resistance of the treadmill belt (Ciriello et al. 2010). The resistance, which is controlled by turning the knob, increases with a clockwise rotation and decreases with a counterclockwise rotation (Ciriello et al. 2010; Mathiowetz et al. 1985). Gearshift knobs are knobs available in cars and manipulated by drivers (Schutte and Schuder 1997).
[Show abstract] [Hide abstract] ABSTRACT: Hand-related apparatus designs that fail to accommodate appropriate hand postures can cause hand-related musculoskeletal disorders. While there have been studies on the handling and design of various hand-related apparatus, little has been written on the ergonomics aspects of knob designs. The aim of this paper is to review various knob designs and their ergonomics aspects. The literature review suggests that gearshift knobs, door knobs, gas valve knobs, butterfly nuts and screw knobs are common knobs used for daily living activities. Other knobs like the convex, knurled, spherical, cone-shaped and ridged knob are often used for industrial-related applications. The ergonomics considerations identified in knobs include aesthetic attraction, position, torque requirement and shape-coding. This literature review can be used as groundwork for the development of ergonomics theory and hand-related studies. Engineers can use this literature review to identify certain ergonomics aspects in knobs to improve equipment designs, operating efficiency and working comfort.- The psychophysical approach usually consists on tests where individuals determine forces or maximum weight that can be moved during an 8-hour shift per day, without feeling unusually tired, weakened or fatigued (Ciriello et al, 2010). Between these three approaches, the psychophysical is highlighted by the active participation of individuals in determining the psychophysical criteria, for simplicity and ease of application (Ciriello et al., 2010 ), and also because it is a common approach to study the MMH tasks (see e.g. Wu & Chang, 2010, Li et al., 2007, Choi & Fredericks, 2007, Wu & Cheng, 2001, Yoon & Smith,1998, Mital et al. 1997 Ciriello, 1990).
[Show abstract] [Hide abstract] ABSTRACT: The psychophysical criteria are important to develop manual material handling guidelines. It is essential that the studies that use a psychophysical approach be carried out as accurately as possible. However, the sample used in these studies can influence the results, if not appropriate. This work intends to analyze the influence of the sample in determining the maximum acceptable weight (MAW) in tasks of manual transport of loads transportation. The study involved 10 students and 10 workers. The participants' task was to carry a box for 13 minutes and travel six meters. The box had the dimensions of 60 cm length × 40 cm width x 40 cm deep and the handles had 2.7 cm width and 9.0 cm in length. Moreover, subjects were required to carry out the movement of the box with the trunk erect and the forearms perpendicular to the body. In the end, the MAW and the rate of perceived exertion (RPE) were determined. A strength test was applied to each individual. The MAW was higher for students (11.6kg) than for workers (10.8kg), however, it was not verified significant differences between groups. For students, the MAW depended on the selected IW. Students also assigned RPE values higher than workers. These results suggest that the workers' experience may be a determining factor in the MAW. Although the study has not provided conclusive results, it can be argued that samples comprised by students may affect the results, being that these groups of samples should be used with caution. So, whenever possible it should be used experienced workers in real work context for psychophysical studies.- [Show abstract] [Hide abstract] ABSTRACT: Best achievable SISO simultaneous performance is formulated as a minimum distance problem from a point to a nonconvex set defined by interpolation and simultaneous stabilization constraints. It is shown that constraint truncation and underestimation and subsequent use of duality theory lead to a bilevel program whose solution can be found through iteration between a convex and a linear program. The proposed procedure is shown to identify best achievable simultaneous performance as the limit of a nondecreasing sequence of rigorous lower bounds
- [Show abstract] [Hide abstract] ABSTRACT: The purpose was to compare psychophysiological responses between healthy male and female workers during dynamic pushing. Using a psychophysical approach, 27 participants chose an acceptable force that they could push over a 7.6m distance at a frequency of 1 push per min on a treadmill. On a separate day, cardiopulmonary (e.g., whole-body oxygen uptake, heart rate, ventilation volume) and muscle metabolic measurements (change in muscle blood volume [ΔtHb] and Tissue Oxygenation Index [TOI]) from the right and left gastrocnemius muscles were collected simultaneously while participants pushed the previously chosen acceptable force on the treadmill at a similar frequency and distance for 2h. Results showed no significant difference between men and women for integrated force exerted on the instrumented treadmill handle and cardiopulmonary responses. In contrast, women demonstrated 45.7% lower ΔtHb but 3.6% higher TOI in the gastrocnemius region as compared to men, suggesting a lower hemoglobin concentration in women and high venous oxygen saturation during pushing. When ΔtHb and TOI were corrected for both body mass and pushing force, the disparity in gender was retained, implying an increased muscle oxygen saturation per force development in women than men during pushing. In the left gastrocnemius region, ΔtHb was 60% lower and TOI was 5.7% higher in women than men, suggesting an uneven muscle loading during pushing. Overall, the gender similarity in cardiopulmonary responses versus disparity in muscle metabolic responses suggest the importance of evaluating human performance during physical work at both whole-body and localized muscle levels.
- [Show abstract] [Hide abstract] ABSTRACT: The objective of this paper was to perform a comprehensive review of psychophysically determined maximum acceptable pushing and pulling forces. Factors affecting pushing and pulling forces are identified and discussed. Recent studies show a significant decrease (compared to previous studies) in maximum acceptable forces for males but not for females when pushing and pulling on a treadmill. A comparison of pushing and pulling forces measured using a high inertia cart with those measured on a treadmill shows that the pushing and pulling forces using high inertia cart are higher for males but are about the same for females. It is concluded that the recommendations of Snook and Ciriello (1991) for pushing and pulling forces are still valid and provide reasonable recommendations for ergonomics practitioners. Regression equations as a function of handle height, frequency of exertion and pushing/pulling distance are provided to estimate maximum initial and sustained forces for pushing and pulling acceptable to 75% male and female workers. At present it is not clear whether pushing or pulling should be favored. Similarly, it is not clear what handle heights would be optimal for pushing and pulling. Epidemiological studies are needed to determine relationships between psychophysically determined maximum acceptable pushing and pulling forces and risk of musculoskeletal injuries, in particular to low back and shoulders. Relevance to industry: This article provides a concise discussion of important factors relevant to designing and analyzing pushing/pulling tasks. Regression equations to estimate initial and sustained pushing and pulling forces acceptable to 75% male and female workers are provided and can be used to design and analyze pushing and pulling tasks common in industry.
People who read this publication also read
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.
This publication is from a journal that may support self archiving.
Learn more