Christopher M. Schlick

Task modelling for cooperative work

Modern work systems are characterized by a high amount of cooperation among working persons. Thus, task modelling for cooperative work is of great significance for an appropriate design of work systems. Due to the special characteristics of cooperative work, several requirements for the modelling technique have to be met. In this paper, first the requirements for a task modelling technique are derived and compared with existing approaches. Then, as no existing technique completely fulfils the important requirement for abstraction in order to model weakly structured activities , a new technique is presented, which is on the one hand essentially based on an existing modelling language for deterministic software intensive systems and on the other hand has been enlarged by additional concepts for being able to model tasks carried out cooperatively by human beings. The results of a case study in which the new technique has been applied are presented and discussed. Finally, an outlook towards future research co...

Evaluating swabbing: a touchscreen input method for elderly users with tremor

Elderly users suffering from hand tremor have difficulties interacting with touchscreens because of finger oscillation. It has been previously observed that sliding ones finger across the screen may help reduce this oscillation. In this work, we empirically confirm this advantage by (1) measuring finger oscillation during different actions and (2) comparing error rate and user satisfaction between traditional tapping and swabbing in which the user slides his finger towards a target on a screen edge to select it. We found that oscillation is generally reduced during sliding. Also, compared to tapping, swabbing resulted in improved error rates and user satisfaction. We believe that swabbing will make touchscreens more accessible to senior users with tremor.

Age-Differentiated Work Systems

Demographic change is an important social phenomenon in many developed countries. It is characterised by a rapidly increasing average age in the population as a result of longer life expectancies and lower birth rates. In the United States, for instance, there were approximately 37 million citizens aged 65 and over in 2006, or 12.5 percent of the total population. This number is expected to grow to about 72 million by the year 2030, or 19.3 percent of the total population. Demographic change is also having a big impact in the European Union (EU). The proportion of the working population between the ages of 55 and 64 is expected to increase from 56 million in 2006 (11.4 percent of the total population) to 70 million in 2030 (13.5 percent). Furthermore, the number of people in the EU aged 65 and older is expected to increase from 82 million in 2006 (16.8 percent) to 122 million in 2030 (23.5 percent). One way in which the government has responded to the shrinking working-age population is by raising the age at which people can start to receive their full social security retirement benefits. The German government has recently adopted this approach and changed the minimum age from 65 to 67. The literature tells us that as people age, changes occur in their perceptual, cognitive and motor systems that can have significant effects on their performance and well-being in work systems. The German Research Foundation (Deutsche Forschungsgemeinschaft) responded to this insight by establishing Priority Programme 1184 on Age-differentiated Work Systems in 2005. This interdisciplinary basic research programme brings together a total of 13 research groups from engineering, psychology and economics with the goal of studying the implications and effects of demographic change on human work and developing live-span models to create adequate working and learning conditions for employees of different ages. For this special issue on age-differentiated work systems, we have collected a series of five papers to give readers a brief but concise overview of macroand micro-ergonomics research in Priority Programme 1184. The first paper, written by Julia Weichel, Sanjin Stanic, José Alonso Enriquez Diaz and Ekkehart Frieling, considers job rotation, a classic organizational intervention measure, and analyzes its effect on ageing and impaired employees in the German automotive industry. The results show that older and impaired employees rotate less and that employees who rotate between larger numbers of workstations assess their job performance and health more positively than employees who do not. The second paper, contributed by Melanie Hahn, Michael Falkenstein and Nele Wild-Wall, addresses the growing number of older drivers. In their study, young and old participants performed a simulated driving task in a dual task condition: a visuo-motor tracking task and a visual attention task. An age-related slowing of response speed was observed in the visual attention task. Independent of age, both groups showed similar error proportions and were able to improve their performance with time-on-task. In the tracking task, older participants generally showed poorer performance than the young group and they could not significantly improve their tracking performance with longer task experience. The third paper, by Michael Sengpiel and Hartmut Wandke, investigates the effect of computer literacy on interaction with a computer-based ticket vending machine. To compensate for any potential lack of computer literacy, an experimental

Self-optimising Production Systems

One of the central success factors for production in high-wage countries is the solution of the conflict that can be described with the term “planning efficiency”. Planning efficiency describes the relationship between the expenditure of planning and the profit generated by these expenditures. From the viewpoint of a successful business management, the challenge is to dynamically find the optimum between detailed planning and the immediate arrangement of the value stream. Planning-oriented approaches try to model the production system with as many of its characteristics and parameters as possible in order to avoid uncertainties and to allow rational decisions based on these models. The success of a planning-oriented approach depends on the transparency of business and production processes and on the quality of the applied models. Even though planning-oriented approaches are supported by a multitude of systems in industrial practice, an effective realisation is very intricate, so these models with their inherent structures tend to be matched to a current stationary condition of an enterprise. Every change within this enterprise, whether inherently structural or driven by altered input parameters, thus requires continuous updating and adjustment. This process is very cost-intensive and time-consuming; a direct transfer onto other enterprises or even other processes within the same enterprise is often impossible. This is also a result of the fact that planning usually occurs a priori and not in real-time. Therefore it is hard for completely planning-oriented systems to react to spontaneous deviations because the knowledge about those naturally only comes a posteriori.

Comparison of a map- vs. camera-based user interface in a multi-robot navigation task

Many missions with semi-autonomous multi-robot systems rely on the basic function to autonomously navigate within an unknown operational area. For missions in hazardous environments the efficiency of a robots autonomous navigation system in an unknown terrain is difficult to estimate. In the case of performance degradations the human operator as a supervisory controller has to intervene and interactively improve the systems quality of service. A study of a novel multi-robot user interface for effective operator intervention is presented. Therefore, a simulated semi-autonomous multi-robot system with three different user interface configurations as well as 1,2, or 4 robots was compared. Central to the studys task is that operators can improve system performance by careful monitoring and intelligent intervention. According to the results this is possible for single robot scenarios but not for the multi-robot settings.

Automation of robotic assembly processes on the basis of an architecture of human cognition

A novel concept to cognitive automation of robotic assembly processes is introduced. An experimental assembly cell with two robots was designed to verify and validate the concept. The cell’s numerical control—termed a cognitive control unit (CCU)—is able to simulate human information processing at a rule-based level of cognitive control. To enable the CCU to work on a large range of assembly tasks expected of a human operator, the cognitive architecture SOAR is used. On the basis of a self-developed set of production rules within the knowledge base, the CCU can plan assembly processes autonomously and react to ad-hoc changes in assembly sequences effectively. Extensive simulation studies have shown that cognitive automation based on SOAR is especially suitable for random parts supply, which reduces planning effort in logistics. Conversely, a disproportional increase in processing time was observed for deterministic parts supply, especially for assemblies containing large numbers of identical parts.

Design pattern TRABING: touchscreen-based input technique for people affected by intention tremor

Tremor patients are frequently facing problems when interacting with IT systems and services. They do not reach the same levels of input efficiency and easily become unhappy with a technology they do not perceive as a general asset. Cases of Intention tremor show a significant comparative rise in inaccurate movement towards a real button or virtual buttons on touch screens, as this particular tremor increases its symptoms when approaching a desired physical target. People suffering from this specific tremor have been identified as the target group. This group has been closely investigated and thus, a new input procedure has been developed which may be used on standard touch screens. The new technique enables users, accordingly tremor patients, to fully operate IT-based systems and therefore possess full control over input. Deviations caused by the tremor are compensated with a continuous movement instead of a single targeted move which remains the most difficult task to the user. Also, the screen surface will present a frictional resistance, which significantly hinders tremor symptoms. Input can be identified by the computer system with high accuracy, by means of special heuristics, which support barrier free access beyond the target group.

A simulation approach for evaluation and improvement of organisational planning in collaborative product development projects

Human behaviour and organisational structure impact collaborative product development outcome on a large scale. Therefore, companies are continuously seeking new opportunities to increase the efficiency, effectiveness and predictability of their collaborative product development projects, and to develop innovative principles for organisational design and management such as multi-functional teams. However, there are many factors which have to be considered and assessed to systematically optimise organisational planning in respect of team configuration, structure organisation, and human behaviour. This paper proposes an agent-based simulation methodology to evaluate and improve the organisational planning in complex product development projects. An agent-based integrated simulation model is formulated which can explicitly represent human behaviour, organisational interactions, and tasks networks. Based on the model, the design agent structure and behaviour protocols are studied in detail, and a simulation platform is developed. Finally, the methodology is evaluated in a collaborative roadway design project, and several management insights are established, which are proven to be effective for the organisational optimisation. The results of the case study also show that the methodology can effectively support the evaluation and improvement of organisational planning.

Investigation of Input Devices for the Age-differentiated Design of Human-Computer Interaction:

Demographic change demands new concepts for the support of computer work by aging employees. In particular, computer interaction presents a barrier due to a lack of experience and age-specific changes in performance. This article presents a study in which different input devices (mouse, touch screen and eye-gaze input) were analyzed regarding their usability and according to age diversity. Furthermore, different Hybrid Interfaces that combine eye-gaze input with additional input devices were investigated.

Modelling and simulation of the task scheduling behavior in collaborative product development process

Collaborative Product Development CPD process is characterized by autonomous task control, dynamic task sequence, and frequent team collaboration, which endow the process with high flexibility and uncertainty. To make the process predictable and improve process efficiency, it is essential to model, simulate, and analyze the process by considering all these characteristics. As most CPD models are developed to simulate task structures and task-flow process, our work focuses on studying the human working behaviors in CPD process by agent-based simulation, which we think is the main source of process uncertainty and flexibility. In this paper, the local task scheduling behavior of designer agents and the resource conflict resolution behavior of the manager agent are studied under the framework of agent-based simulation. In the simulation, the designer agent schedules his local tasks according to his personal priority, and the manager agent resolves resource conflicts according to collective utility function. To make the process more efficient, a collective utility function is developed for the manager agent, in which task priority, spare resource, and waiting time are considered simultaneously. To validate the effectiveness of the collective utility, simulation experiments are designed and carried out among entire-waiting utility, entire-replacement utility, and collective utility strategy. The simulation results indicate that the proposed utility strategy can effectively shorten the project total time and cost of the case. There are two engineering applications of this approach. First, by simulating and evaluating different task scheduling and resource conflict resolution behaviors of the agents, designers and managers can adopt suitable scheduling strategies at the planning stage of the CPD project. Second, in the executing process of the CPD project, the proposed scheduling priority and utility functions can be used in the dynamic scheduling by developing software agents in the CPD management systems.