Biman Das

Industrial workstation design: A systematic ergonomics approach

For the design of an industrial workstation, ergonomics guidelines are presented in a systematic manner. The guidelines provide a conceptual basis for a good workstation design. In a real world design situation, the implementation of the recommendations or guidelines needs the matching of the population anthropometry with the various components of the workstation. Adequate posture, work height, normal and maximum working areas, lateral clearance and visual requirement are determined for the intended user population. The procedure for determining the workstation dimensions and layout has been explained. The importance of building a mock-up of the designed workstation and its evaluation with representative subjects is emphasized. A case problem (supermarket checkstand workstation) is discussed to illustrate the workstation design procedure.

Maximum reach envelope for the seated and standing male and female for industrial workstation design.

Maximum reach envelopes for the 5th, 50th and 95th percentile reach lengths of males and females in seated and standing work positions were determined. The use of a computerized potentiometric measurement system permitted functional reach measurement in 15 min for each subject. The measurement system captured reach endpoints in a dynamic mode while the subjects were describing their maximum reach envelopes. An unbiased estimate of the true reach distances was made through a systematic computerized data averaging process. The maximum reach envelope for the standing position was significantly (p < 0.05) larger than the corresponding measure in the seated position for both the males and females. The average reach length of the female was 13.5% smaller than that for the corresponding male. Potential applications of this research include designs of industrial workstations, equipment, tools and products.

Computer-aided human modelling programs for workstation design.

In designing a workstation, computer-aided human modelling programs can be used advantageously to analyse human-fit to the workstation components. The analysis is performed within a three-dimensional computer graphics environment. To illustrate the current state of development, six representative programs were selected: CYBERMAN, COMBIMAN, CREW CHIEF, JACK, SAMMIE, and MANNEQUIN. The programs differ considerably in terms of system requirement, operating characteristics, applicability and the various ergonomic evaluation functions available in the human modelling programs. The comparative analysis of the programs will aid the user to select the appropriate program for a particular workstation design.

Ergonomics evaluation and redesign of a hospital meal cart

The ergonomic, design and other problems of a conventional hospital meal cart were evaluated with a view to redesign a hospital meal cart by incorporating ergonomic principles and data. The operators encountered difficulty in setting the cart in motion, seeing over the cart, turning the cart and stopping the cart while in motion. The operators expressed postural discomfort in the shoulder, neck, back, lower back, knee and leg, and ankle and foot. The cart with meal trays and food was found to exceed the acceptable initial turning push force requirement of 5th percentile females. Recommendations were made for proper placement of cart handles and handle diameter, provision of large-diameter cart wheel made of hard rubber tire, reduction of cart height, use of plastic material for cart construction, provision of emergency brake, provision of individually (electrically) heated plates for soup and main meal, provision of thick air-tight transparent plastic doors, and reduction of the meal tray size. Several recommendations were adopted by the manufacturer in the new model.

Structural anthropometric measurements for wheelchair mobile adults

Structural anthropometric measurements for males and females were determined for the wheelchair mobile adults. A photogrammetry methodology was used to obtain the measurements. The various subject demographics including age, level or type of dysfunction as well as the specified anthropometric dimensions of the wheelchair mobile subjects were identified. The data would be useful for the design of industrial workstations for wheelchair mobile adults. Present workstation design principles based on seated able-bodied anthropometric measurements would not be suitable for this population.

Three-Dimensional Workspace for Industrial Workstations

Direct anthropometric measurements of maximum functional reach points were made for male and female populations to determine a three-dimensional (3D) workspace for industrial workstation design. The reach distances in the workspace spectrum were not constantly proportional to the arm length of a man or woman. It was shown that the conventionally determined workspace envelope could not be reached by 95% of the population but, rather, by only 73% of men and 75% of women. A new method was developed to determine the 3D workspace for any percentile for which the corresponding percentage population could actually reach and work efficiently. The percentile workspaces determined by the conventional and new methods were compared and found to be significantly different. Actual or potential applications of this research include designs of industrial workstations, equipment, tools, and products.

The relationship between worker satisfaction and productivity in a repetitive industrial task

The objective of this investigation was to determine the manner by which production standards or goals, performance or production feedback and monetary or wage incentive affected or moderated the relationship between worker satisfaction and productivity in a repetitive production task in a fishing industry. The industrial study was conducted to measure worker satisfaction and productivity under various experimental conditions involving production standards, performance feedback and monetary incentive. Only the participative standard and performance feedback condition affected the worker satisfaction-productivity relationship significantly for the fish-trimming task. The positive correlation coefficient (0.87) for this condition was found to be highly significant. This has an important implication for setting a strategy for achieving higher worker satisfaction and productivity in such an industry. Production standards with feedback generally improved worker satisfaction and productivity. Monetary incentive further improved worker performance but added no incremental satisfaction gain. The incorporation of production standards, performance feedback and monetary incentive affected worker satisfaction and productivity differently and this had an effect on the worker satisfaction-productivity relationship. In an earlier laboratory study, no significant worker satisfaction-productivity relationship was found when subjects (college students) were provided with similar experimental conditions.

Isometric Pull-Push Strengths in Workspace: 1. Strength Profiles

The isometric pull and push strength profiles of males and females were determined in seated and standing positions in the workspace. The strongest pull strength location was at extreme reach vertically above the shoulder for both males and females. The greatest pull strength of400 Newtons (N) for males was recorded in the seated and standing positions. Females’ pull strengths in the seated and standing positions were 222 and 244 N, respectively. The strongest push strength was always at the maximum reach at the overhead location. Males’ maximum push strength was 227 N in the seated position and 251N in the standing position. Females’ maximum push strength was 96Nin the seated position and 140 N in the standing position. On the average the strength in the standing position was 79% of the seated position. The push strength was 71% of the pull strength and females were 56% as strong as males.

A strategy for improving worker satisfaction and job attitudes in a repetitive industrial task: application of production standards and performance feedback

Worker satisfaction improved significantly as a consequence of the provision of the assigned and participative standards with performance feedback in a repetitive industrial production task. The maximum improvement in worker satisfaction was found for the participative standard and feedback condition. Only this condition had a significant positive effect on worker job attitudes. Monetary incentive, when provided with an assigned or participative standard with feedback, added no incremental worker satisfaction or job attitudes gain. The participative standard with feedback condition emerges as the optimum strategy for improving worker satisfaction and job attitudes in a repetitive industrial production task.

Human: An autocad based three dimensional anthropometric human model for workstation design

A three dimensional (3D) human modeling program has been developed to work in conjunction with computer aided design software, Autocad. The program allows the creation and manipulation of variable size, 3D human models and provides the flexibility of a professional CAD system. The special features of the program and its application in workstation design are described and illustrated with examples. This program operates on a personal computer and provides a low cost but effective alternative to main-frame based similar systems.