Ergonomic studies in computer-aided design

Abstract

This paper describes the results of an ergonomic survey on interactive graphics workstations for computer-aided design (CAD). A work-sampling study was carried out to characterize the use of keyboard, digitizer tablet and video display. Subjective impressions of CAD software, CAD hardware and health aspects were collected by means of a questionnaire. Working methods and working postures were recorded on videotape. The two most important differences in comparison with other office terminals are: (i) dynamic working methods result in an absence of constrained postures in CAD operators and allow full-body exercise; (ii) CAD operators spend more time (46–68 per cent of working hours) viewing the video display than the average office terminal operator. Some ergonomic recommendations have been deduced for the construction of CAD terminals, as well as for the ergonomic improvement of existing workstations.     

Ergonomic keyboard design

Abstract

The design of keyboards is still characterized by that of mechanical typewriters. This paper presents a summary of a research project dealing with the ergonomic improvement of keyboards, carried out at the IAO in Stuttgart during the past five years. Extensive laboratory evaluation of experimental keyboards, where different design parameters were tested under real life conditions, have produced a relative optimum regarding ergonomic keyboard design. An accompanying investigation of user acceptance evaluated all realized parameters. In co-operation with a keyboard manufacturer, the results were used to design a marketable product, which may be seen as an important contribution to ergonomic keyboard design.     

Ergonomic keyboard design

The design of keyboards is still characterized by that of mechanical typewriters. This paper presents a summary of a research project dealing with the ergonomic improvement of keyboards, carried out at the IAO in Stuttgart during the past five years. Extensive laboratory evaluation of experimental keyboards, where different design parameters were tested under real life conditions, have produced a relative optimum regarding ergonomic keyboard design. An accompanying investigation of user acceptance evaluated all realized parameters. In co-operation with a keyboard manufacturer, the results were used to design a marketable product, which may be seen as an important contribution to ergonomic keyboard design.     

Ergonomic design in ancient Greece.

Although the science of ergonomics did not actually emerge until the 20th century, there is evidence to suggest that ergonomic principles were in fact known and adhered to 25 centuries ago. The study reported here is a first attempt to research the ergonomics concerns of ancient Greeks, on both a conceptual and a practical level. On the former we present a collection of literature references to the concepts of usability and human-centred design. On the latter, examples of ergonomic design from a variety of fields are analysed. The fields explored here include the design of everyday utensils, the sculpture and manipulation of marble as a building material and the design of theatres. Though hardly exhaustive, these examples serve to demonstrate that the ergonomics principles, in content if not in name, actually emerged a lot earlier than is traditionally thought.     

Ergonomic principles and map design

Ergonomic principles have seldom been applied to the design of maps for use in aviation. Maps are not usually evaluated as displays of information, and the contents of maps often do not match the needs of the user. Most maps are visually so complex that it is not immediately apparent whether standard recommendations for the coding and display of information apply to them. Methods for evaluating maps have to be devised, and comparisons made between subjective and objective measures. A series of experiments has considered the content of maps in relation to the needs of the users, and has examined new methods for presenting information on maps, with a view to increasing the efficiency of map communication.     

Ten challenges in computer-aided design

This short paper presents 10 challenging research areas in the general field of computer-aided design. The research problems come from the author's personal experience, and as such are highly subjective. All findings and opinions are those of the author and do not represent any of the institutions the author is affiliated with.     

Tolerances in computer-aided geometric design

In the design of discrete part shapes, the specification of tolerance constraints can have major consequences for product quality and cost. Traditional methods for tolerance analysis and synthesis are timeconsuming, and have limited applicability. This paper presents the results of research into the use of solid modeling technology for the automated solution of tolerancing problems. A linear programming method is presented for the solution of tolerance analysis problems on a worst-case basis. A Monte Carlo method is presented for both worst-case and statistical tolerance analysis. Both methods automatically derive all necessary geometric relationships from a solid model of the assembly. Example problems are solved using the experimental GEOTOL geometric design system.     

Interactive computer-aided formwork design

While disciplines such as structural analysis are reaping the benefits of computer implementation, temporary works design lags well behind. Some of the reasons given by temporary works designers are that their designs are very practical and depend largely on the designer's experience and engineering judgement. By designing a highly interactive user friendly interface, a comprehensive program that runs on IBM compatibles has been developed. The program can be used to design formwork for walls and soffits using traditional timber and/or proprietary formwork components. The program incorporates many features commonly associated with business oriented software interfaces, placing special emphasis on the ease of use and at the same time allowing users to incorporate their own engineering judgement. The user interface features include the use of bar menus, windows and data entry screens. Formwork design may involve the use of material components from different sources, therefore, it is highly data dependent. Consequently, a database management system (DBMS) is used to manage a database of material properties, costs and other attribute data. Formwork members are designed using a rational approach to BS5975: 1982 and the recommendations of the Concrete Society's book Formwork: A Guide to Good Practice. The program produces design details, a schedule of quantities, a cost comparison between purchased and hired proprietary formwork and a cost estimate.     

Ergonomic design of large forestry machines

Since 1967, the ergonomic design of large forestry machines has been the subject of continuous study. Ergonomic guidelines have been developed and successfully introduced to the manufacturers of the machines and to the forest industries.

Manufacturers have implemented comprehensive ergonomic improvements. Operator workspace, visibility, lighting, operator's seats, mounting and alighting, cab climate, and service of machines have been improved. Noise and vibration levels have been reduced. The risk of accidents is slight. In many respects, the ergonomic standard is now good.

Increasing mechanization is posing new problems, however. Operators of forestry machinery are being afflicted by overload injuries to the neck, arms, and cervical spine. The main causes of these injuries are probably excessive periods of sitting, excessive work intensity during work in fixed, ergonomically inappropriate positions, and repetitive, short-cycle movement patterns. Ergonomic improvements in equipment design (particularly controls) and work organization are proposed in this report.     

A course in computer-aided aerospace design

This paper describes a new sophomore course being offered at Purdue University in the area of aerospace design. While the course and the examples used in this presentation deal with aerospace engineering, the overall structure is presented as being applicable in other engineering areas as well. The basic idea is that, with time, more of the design processes will involve the use of a computer and this necessarily will force the design process towards a higher degree of organization. The course is a simple illustrative example within this viewpoint. The basic modules of aerospace engineering of flight mechanics, aerodynamics, structures, propulsion, weights, air transportation, stability and control, and performance are used to formulate a set of constraints, which, in the particular example, are positive static stability, trim, structural integrity, and range. A (paper) aircraft is defined as an element of the set of feasible values of design parameters (geometry, altitude, speed). Then, given the subset of aircraft which satisfies all the constraints, the aircraft, with the optimum index of performance, is defined to be the best aircraft.     

Anatomical modeling with computer-aided design

Many industrial computer aided design (CAD) programs contain highly developed facilities that can be used to create and analyze three dimensional models of biological structures. In this paper we describe the use of one such program package for modeling the rat brain and a component thereof. Special features of the models of interest to morphologists are illustrated.