Normal Work Area Research Articles

An approach with genetic algorithms to improve the workstation space planning

Industry 4.0 is characterized by the use of digital solutions and computational technologies. The proposed paper presents a workstation space plan solution using an intelligent computational approach: Genetic Algorithms. On the one hand, we have the operator’s effort represented by the motion trajectories in the normal work area. On the other hand, the production flow requires some constraints on the sequence of the assembled components or their location. Considering both the constraints and the reduction of the operator’s effort, the planning solution proposed in this paper ensures the improvement of the working process by applying the principles of motion economy under the conditions of the constraints required by the production process. The resulting sequence and type of the components and operator effort for the production process is indicated to the operator on the modular workstation. Furthermore, the component placement can be adapted to the characteristics of the production process or of the operator’s needs (left handed, has some disabilities, etc.). The solution proposed in this paper was applied in an experimental laboratory where components from the automotive industry are assembled.

Movement times for a seated operator moving within and outside the Zone of Convenient Reach

An experiment was aimed at determining the effect of the location of the movement on the movement time taken. The movements were made within the normal working area (NWA), zone of convenient reach (ZCR) and outside the zone of convenient reach. The latter movements required trunk movement to reach the movement zone. It was found that movement time (MT) was dependent only on Fitts' Index of Difficulty (ID) for movements within NWA and ZCR, but was also dependent on the amplitude of the movement when outside the ZCR, where trunk motion was required. Significant differences in MT occurred between each movement zone. Movements between NWA and ZCR zones were not significantly different in time to those within these zones. Times for movement between the NWA and outside the ZCR were not different to those made outside the ZCR. Relevance to industryTimes for making movements are dependent on the region forward of the person in which the movements are made. When making movements outside the zone of convenient reach, where the arm is fully extended, trunk movement is required and movement times are increased.

Subjective estimates of times for assembly work

Research by Chan and Hoffmann (2013, 2016) showed that people can estimate task times with reasonable accuracy. That work included experiments on Fitts’ task, a double component movement task, pin-to-hole assembly and ballistic movement tasks. In each case, a linear relationship was found relating subjective estimates of task time and actual task times. In this research, the work has been extended to two industrial assembly tasks: assembly of a U-bolt from components and the more complex task of assembling a hacksaw. These tasks were done in an ergonomically designed work space, with components placed within the Normal Work Area and using jigs for convenience of using two-handed assembly. Actual and estimated component times were obtained from video and voice recordings. Results showed that estimated times were lower than actual assembly times, but higher than times predicted using the MODAPTS predetermined motion time system. Participants appeared to have most difficulty estimating times for task components involving fine manipulation, such as inserting and tightening screws.

The Implementation of a Drilling-and-Completions Advanced Collaborative Environment—Taking Advantage of Change

Summary Advanced collaborative environments (ACEs) were planned as an integral part of the operator's new Aberdeen office. The move in early 2008 coincided with a major business reorganization that prompted a critical reassessment of their scope and functionality. The selected approach is well suited to operations in a mature area. During the pilot project, three ACE implementation types were tested. One of these provided dedicated data feeds and visualization tools within the normal work area, operating only during normal working hours. The other two were (1) an asset-based, on-site, round-the-clock type and (2) an outsourced model, each representing a business-model extreme. The selected configuration was closest to the first of these models, with careful provision for future growth. The results of the pilot studies supported the business case but suggested that the realization of many of the benefits would hinge on attitudes, behaviors, and working practices. It was concluded that steady growth, based on demand and keeping pace with the changing habits, would give the best return. Detailed plans were created for each of the people, process, technology, environment, and organization components of the operator's ACE model. The new building design and layout has greatly enhanced the overall working environment. Other activities included the upgrading of fiber links, the introduction of an operability laboratory to test the compatibility of data feeds and systems, extensive human-factor studies, contract reassessment, and the introduction of a dedicated ACE support team. By June 2008, seven rigs were being supported simultaneously, including monitoring the progress of a wired-pipe trial in Trinidad. All this has been achieved during a period of outstanding drilling-and-completions (D&Cs) performance. This measured approach has delivered results, helping to win hearts and minds while avoiding overstretching resources. The paper includes details of the pilot project, implementation, and the progress and challenges to date.

Normative, descriptive and formative approaches to describing normal work area

This paper examines normative and formative approaches toward describing normal work area. Squires’ model of normal work area is an example of a normative approach, which prescribes the shape of normal work area. Squires’ model has been taken as the starting point for more recent attempts to delineate reach boundaries in the workplace. However, his original paper does not present the derivation for his model or his claim that the distal boundary of his normal work area can be described by a prolate epicycloid. This paper presents the derivation for Squires’ model and shows that the resulting curve is not a prolate epicycloid, but a related form, a hypotrochoid. It then identifies shortcomings of normative models, like Squires’, notably the viability of the reach assumptions on which such normative models are based and their inability to deal with context-conditioned variability in the workplace. Finally, it examines the application of formative models, which attempt to identify constraints on the types of reach actions that people use. Data on how people actually reach may constitute a more appropriate foundation for constructing work area models needed to develop workplace standards.

Developing Formative Models of Craniofacial Growth and Workplace Design: Personal Reflections on the Work and Influenceof Robert E. Shaw

In each domain in which Bob Shaw has conducted programmatic research, he has gone to considerable effort to identify and describe the constraints on the event or activity that is the focus of the research. This entails describing the event or activity at a scale appropriate to human perceivers. The first part of this article offers a personal reflection on Bob Shaw's research on the information for craniofacial growth. At the heart of this program, Bob Shaw worked toward a model that captured physical constraints on craniofacial form. In doing so, Shaw extended the method of coordinate transformations developed by D'Arcy Thompson (1917/1992) by using the language of geometric transformations to formalize the changes in craniofacial form that occur over growth. The second part of this article examines how my research with Marvin Dainoff on seated posture at computer workstations and the description of so-called normal work area is indebted to Shaw's constraint-based approach. The challenge of identifying the constraints on events and activities is an important part of the foundation of Gibson's (1979/1986, Part 1) ecological approach to perception. This task is not to be taken lightly.

Normal horizontal working area: the concept of inner boundary

A model was developed to determine the inner boundary of the normal horizontal working area based on the concept that the elbow and forearm-hand should move on the table surface while describing the area. The proposed model was applied to determine the normal horizontal working areas for the 5th percentile female and 95th percentile male. It was shown that the conventional models that had disregarded the concept of the inner boundary overestimated the area on the average by 26%. The proposed model is more realistic and accurate than the conventional models.

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.

Comfortable Working Area of Seated Operators.

Comfortable working area for knob and lever controls was developed to modify the concept of conventional working area. A proposed working area based on the actual working comfort of an operator avoids dichotomy which is the reachability of control devices, and shows a distinct shape compared with existing normal working area following the Farley's concept. It is shown that the distance from the body to control devices and the slope of a work table have the quadratic effect to working comfort, and that the most comfortable area for the controls is located at the distance of about 2-4cm in the sagittal direction and about 42-43cm in the frontal direction from the shoulder respectively, which is located outside the existing normal working areas. The result of the response surface analysis indicates that a little slope of the control panel, about 15°, improves the working comfort. From the study, it was found that the working comfort varies within the working area even if each position is equally far from the body. It is suggested that the conventional normal working area needs to be refined based on the actual working comfort. Moreover, the comfortable working area could differ from control to control, and the primary working area souhld be determined by the type of a control. It is expected that the isocomfort working area generated in this study is used as a useful guideline for control panel layout.

Determination of the normal horizontal working area: a new model and method

A new model was developed for the determination of the normal horizontal working area by extending Squires' concept. The elbow not only moves freely straight ahead, but also to the right and left of the operator in describing the working area. The parametric equations developed in this research enabled us to determine working area curves which lie on both sides of the body median. Experimental results showed that the relevant anthropometric parameters were poorly correlated. A new method was developed to determine correctly the normal horizontal working area curves for the 5th, 50th, and 95th percentiles of male and female populations. When compared to the corresponding curve generated by the new method, Squires' curve for the 10th percentile male considerably overestimated the normal horizontal working area to the right of the body median and underestimated it to the left.

Workplace Design for Manual Assembly Tasks: Effect of Spatial Arrangement on Work-Cycle Time.

This article reports the results of an experimental study undertaken to investigate the effect of spatial arrangement of assembly board and parts bin in the normal work area on work-cycle time in manual assembly tasks. Operator performance was measured in terms of average work-cycle time taken to complete a laboratory-simulated manual assembly task. Results showed that both location and distance factors had significant effects on work-cycle time. Effect of the size of parts was also investigated in the study. Average observed work-cycle times were compared with the methods-time measurement (MTM) values. Repetitive manual assembly tasks are common in industry and are thought to lead to musculoskeletal disorders. The results of this research are important for ergonomic design of the workplace for assembly tasks, which would help to enhance operators' efficiency.

Narrow-band indoor measurement of the sound power of a complex mechanical noise source

There is a need to develop practical standard sound-power tests for manufactured products independent of the test location. That it is possible to develop such standards, for use in a normal work area, has been demonstrated in tests with six light vehicles. The sound power of each vehicle was measured for different engine speeds and loads using a semicircular array of sound-intensity probes rotated over a hypothetical, hemispherical surface enclosing the vehicle running on a dynamometer roll. The presence of the walls and ceiling of the work area appears to have a negligible effect on A-weighted sound-power measurement. Good agreement was obtained with the overall sound power of a standard reference source. Results for the six vehicles indicate that the peaks in the narrow-band sound-power spectra occur at frequencies corresponding to the orders of excitation of components of the vehicle power train. This has diagnostic value because it identifies noisy components and provides a quantitive measure of their contribution to the total sound power of the vehicle. It could also be used to detect malfunctioning and wear of components.

Comparative Analysis of the Normal Working Area in the Horizontal Plane

The normal working areas in the horizontal plane as developed by Farley and Squires were compared, in terms of one-handed, two-handed and total normal working areas and front and side ranges of the normal working areas, for the general male, female and combination of male and female operators and the individual male and female operators for the 5th, 50th and 95th percentiles. Squires’ method provided a considerable gain in the one-handed, two-handed and total normal working areas and the front range of the normal working area for all types of operator population and resulted in a relatively small loss in the side range of the normal working area in all but one instance. In consideration to the dynamic nature of the arm, while the hand sweeps an arc in the normal working area in the horizontal plane and the stated overall gain in the normal working area, Squires’ method should be used in preference to the most frequently employed Farley's method.

The Shape of the Normal Work Area in the Horizontal Plane

Abstract The dimensions of the normal work area originally proposed by Barnes and modified by Squires were determined for a sample representative of the current United States population. One standard work area is not satisfactory for everyone. More emphasis should be given to movements straight ahead of the worker and less emphasis should be given to movements to the side. Work areas are given for the 5th, 50th, and 95th percentiles of the male and female United States population.