Lena Sperling

A cube model for the classification of work with hand tools and the formulation of functional requirements

In an interdisciplinary research project, a model, visualized as a cube, was developed for the classification and analysis of work with hand tools and for communication of different ways of solving problems related to manual handling. The dimensions of the cube are demands of force, precision and time. Each dimension is divided into three levels of low, moderate and high demands respectively. Preliminary limits are proposed for acceptable and non-acceptable use situations and for situations that have to be investigated further. Using a case study of plate shears as a starting point, various measures of improving the position in the cube are discussed. The hand tool, the workplace, the work organization as well as the user of the hand tool are included in the analysis.

An approach to ergonomics evaluation of hand tools

Based on current knowledge of cumulative trauma disorders in the hand and forearm, related to the use of hand tools, an analysis was undertaken of variables to be considered in ergonomics evaluation of hand tools. Measurement methods were developed and an evaluation station was implemented. Measurement methods are physical, physiological or psychophysical. They focus on the tool, and on the effect of typical use of the tool on the operator. The evaluation station serves as a resource in the development, selection, and testing of tools for a given purpose.

Swedish anthropometrics for product and workplace design

The present study describes the anthropometrics of the Swedish workforce, aged 18-65, and compares the measurements with data collected four decades earlier. This anthropometric information is based on measurements of a total of 367 subjects, 105 males and 262 females. Of the 367 subjects, 268 responded to advertisements (Study A) and 99 were randomly selected from a community register (Study B). Subjects were scanned in four positions. Manual measuring equipment was used for hands, feet, head and stature. As differences between significant measurements in Studies A and B were negligible, the data were merged. Anthropometric descriptive statistics of women and men are presented for 43 body dimensions. Participants represent the Swedish population fairly well when compared with national statistics of stature and weight. Comparing new anthropometric data with old shows that the breadth, depth, height, and length measurements of Swedes as well as weight have increased and that Swedish anthropometric homogeneity has decreased. The results indicate that there is a need to update ergonomic recommendations and adjust products and workplaces to the new information.

Tool design, user characteristics and performance: a case study on plate-shears

Performance, grip forces and fatigue were studied in six male and six female subjects while cutting with plate-shears. Three types of plate-shears were used, one standard and two modified, either with a spring grip, or with a spring grip in combination with a reduced grip span. In addition, three types of plate - easy, moderately difficult and difficult to cut - were used. Male subjects used around 40% of their maximal grip force and female subjects around 60% with the moderately difficult plate; the male subjects produced more than twice as long a cutting distance as the females. Neither EMG analysis (frequency shifts) nor subjective exertion or reduction of handgrip MVC indicated a more pronounced fatigue in women than in men, probably because the female subjects used about a 50% lower cutting rate than the men. Productivity (in cm cut per min) was strongly related to measures of hand size and to the relative grip force used. Thus in a multiple regression analysis using metacarpal hand circumference and relative grip force as independent variables, R2 was 0.77. The two types of modified plate-shears were preferred by all and gave a roughly 30% higher productivity in the male subjects but did not improve productivity in the females. However, with a spring grip and reduced grip span, the female subjects reduced the relative grip forced used from around 65 to 50%. The total work (force-time integral) per cm cut was not influenced by type of plate-shear.

A control handling comfort model based on fuzzy logics

Abstract The car interior is a complex man–machine interface. Poor interior design contributes to traffic accidents as well as discomfort and disorders in professional and long distance drivers. When buying a car comfort is for many customers an important factor. Consequently, car interior comfort besides safety is of great importance when designing cars. Comfort is a subjective feeling and hard to model mathematically. The aim of this paper is to show the feasibility with fuzzy logics to model relations between human perception, human characteristics and workplace structure. A model where drivers’ perceived comfort when handling interior controls is in relation to anthropometrics and control positions are used as illustration. A series of control reach studies in simulated car driving was used for the development of a comfort model. Combined with a human simulation program the comfort model may be used by car designers at an early stage of the design process for evaluation of design concepts aiming at reachable and manageable controls in a safe and comfortable interior. The comfort model illustrates that fuzzy logics provides a constructive way of turning qualities into mathematics. Relevance to industry Fuzzy logics provide the opportunity to model physical parameters from the human and the technical system together with human perceptions. Such model can be combined for instance with human simulation tool and reduce ergonomic tests in real physical environments.

ANNIE, a tool for integrating ergonomics in the design of car interiors

In this ANNIE project – Applications of Neural Networks to Integrated Ergonomics – BE96-3433, a tool for integrating ergonomics into the design process is developed. This paper presents some features in the current ANNIE as applied to the design of car interiors. A variant of the ERGOMan mannequin with vision is controlled by a hybrid system for neuro-fuzzy simulation. It is trained by using an Elite system for registration of movements. An example of a trajectory generated by the system is shown. A fuzzy model is used for comfort evaluation. An experiment was performed to test its feasibility and it showed very promising results.

Remote assessment of intangible product experiences-challenges and implications

This paper presents two pilot studies done as part of the development of a future tool for remote customer assessment of intangible product experiences. There is a need from industry to better understand how customers perceive products in relation to other products. The aim is to provide industry and researchers with a new approach that is easier to work with and that is more reliable than existing traditional web surveys. In the first study a mock-up tool was emailed to international respondents. The second study was a situated usability study of a prototype version of the tool concerned with how the respondent interface might be developed further from experiences made in the first study. The findings of this paper present suggestions to how future remote product assessments could be made more efficient. The contribution of this paper is the characteristics and quality of a new assessment method. Results from qualitative respondent assessments of the tool indicated that this objective was achieved.