Dan Lämkull

Industrial customisation of digital human modelling tools

Computer aided visualisation and simulation enables earlyevaluation of important design parameters of future products and productionsystems. Typically, humans affect the system performance, and in order toachieve the expected system efficiency ergonomics needs to be considered inthe design process in addition to the more technical or logistical matters.Hence, there is a call for ergonomics to be a natural part of the product andproduction development process, also at virtual stages. Three examples of thedevelopment of Digital Human Modelling-(DHM)-based company-specific

Digital Human Modeling Requirements and Standardization

This paper will initiate a discussion on automotive industry requirements and associated standardization of digital human modeling software (DHMS) as applied to manufacturing operations. Industry benefits of standardization are vast, making it difficult to identify and provide an exhaustive list. High value benefits will be listed for the purpose of this discussion. Industry users of DHMS will benefit by the standardization of an application programming interface, classification of anthropometry and simulation data translation. A list of high value standardization goals will be provided for the purpose of this discussion. Two examples of standardization goals include 1) a reduction in the time and cost required to integrate research results into commercial software and 2) improved simulation data transfer and linkages between DHMS to simplify the use of multiple tools when analyzing a single problem. This paper will provide an introduction to and proposal for standardization of DHMS. It will introduce the concept of a digital human modeling (DHM) architecture. It will also include a proposal on areas of standardization for future discussion.

Uniformity in manikin posturing: A comparison between posture prediction and manual joint manipulation

This paper presents the results of a comparison of manikin posturing within and between simulation engineers. Five simulation engineers were asked to simulate four manual assembly cases. They repeated each task six times, three times with a posture prediction tool and three times with manual adjustment of the body angles. The results show that the posture-prediction-tool was not used in an optimal manner. Although the prediction-tool was quick at suggesting a likely posture, the simulation engineers were reluctant to consider a simulation task completed until the manikins posture was realistic in all aspects. The comparison indicates that if a posture-prediction-tool is to be beneficial, results with postures containing some non-cosmetic elements must be accepted. It is not until such an acceptance is achieved that the successful use of a posture-prediction-tool will become a reality.

Digital Human Modeling Simulation Results and Their Outcomes in Reality: A Comparative Study within Manual Assembly of Automobiles

The objective of this study was to examine to what extent ergonomics simulations of manual assembly asks correctly predict the real outcomes in the plants and if recommended measures originating from ergonomics simulations are taken into consideration. 155 ergonomics simulation cases were used in the study and all cases were performed by nine simulation engineers at Volvo Car Corporation in Gothenburg. The evaluations of the ergonomics conditions of the simulated tasks were done by six professional ergonomists working at Volvo Car Corporation in Gothenburg. The results show that digital human modelling tools (DHM-tools) are useful for the purpose of providing designs for standing and unconstrained working postures. Furthermore, the design of various auxiliary devices and their needed space for movements is a prevalent use of DHM-tools. However, the study also identifies areas that require additional development in order to further improve the digital human modelling tools’ possibility to correctly predict a work task’s real outcome, i.e. hand access, push pressure and pull forces, leaning and balance behaviour and field of vision. Moreover, a better feedback of product and process changes and a more careful order description of simulation cases to the simulation engineers would lead to improved simulation results in current and future projects.

Using methods-time measurement to connect digital humans and motion databases

To simulate human motions in DHM tools, using techniques which are based on real human data is one promising solution. We have presented a solution in this study to connect motion databases with DHM tools. We have showed that using a motion database with MTM-based annotations is a promising way in order to synthesize natural looking motions. A platform consists of a Motion Database, a Motion Generator, and a DHM tool was introduced and tested. The results showed successful application of the presented platform in the designed test case.

Schema for motion capture data management

A unified database platform capable of storing both motion captured data and information about these motions (metadata) is described. The platform stores large motion captured data in order to be used by different applications for searching, comparing, analyzing and updating existing motions. The platform is intended to be used to choose a realistic motion in simulation of production lines. It is capable of supporting and handling different motion formats, various skeleton types and distinctive body regions in a uniform data model. Extended annotating system is also introduced to mark the captured data not only in the time domain (temporal) but also on different body regions (spatial). To utilize the platform, sample tests are performed to prove the functionality. Several motion captured data is uploaded to the database while MATLAB is used to access the data, ergonomically analyze the motions based on OWAS standard, and add the results to the database by automatic tagging of the postures.

Consistency in Figure Posturing Results within and between Simulation Engineers

This paper presents the results of an effort to compare figure posturing results within and between simulation engineers. The simulation engineers simulated four manual tasks. Alternately they used a posture prediction tool, and alternately they were only allowed to apply manual adjustments of the body angles. The simulation engineers repeated each task six times and always with at least six days between each occasion, to minimize the subjects rememberance of how she/he carried out the cases. Results show that the use of a posture prediction tool, in such complex tasks as the study includes, neither reduces needed time to fulfill a simulation, nor differences within or between simulation engineers. Differences in simulation results often originate from the different assumptions the simulation engineers have of the task when positioning the manikins. The differences could be minimized by a more careful orderer description and by such activities as simulation engineering days at assembly plants and by bringing the people working with human simulation tools together in the organization. Copyright

An algorithm for data-driven shifting bottleneck detection

Abstract Manufacturing companies continuously capture shop floor information using sensors technologies, Manufacturing Execution Systems (MES), Enterprise Resource Planning systems. The volumes of data collected by these technologies are growing and the pace of that growth is accelerating. Manufacturing data is constantly changing but immediately relevant. Collecting and analysing them on a real-time basis can lead to increased productivity. Particularly, prioritising improvement activities such as cycle time improvement, setup time reduction and maintenance activities on bottleneck machines is an important part of the operations management process on the shop floor to improve productivity. The first step in that process is the identification of bottlenecks. This paper introduces a purely data-driven shifting bottleneck detection algorithm to identify the bottlenecks from the real-time data of the machines as captured by MES. The developed algorithm detects the current bottleneck at any given time, the average and the non-bottlenecks over a time interval. The algorithm has been tested over real-world MES data sets of two manufacturing companies, identifying the potentials and the prerequisites of the data-driven method. The main prerequisite of the proposed data-driven method is that all the states of the machine should be monitored by MES during the production run.

Identifying Time-Consuming Human Modelling Tool Activities

The aim of this study was to identify and measure timeconsuming human modelling tool activities. Five human modelling tool users at Volvo were observed for five days each. The results showed a wide distribution of both indirect and direct working tasks, as well as nonvalue added tasks such as waiting time. Most of the activities identified appear to be necessary to perform human modelling simulations of high quality. However, the time distribution could be questioned to some extent. There are many activities associated with communication, including a variety of contacts and meetings, where there appears to be potential to increase efficiency.

Digital Human Models' Appearance Impact on Observers' Ergonomic Assessment

The objective of this paper is to investigate whether different appearance modes of the digital human models (DHM or manikins) affect the observers when judging a working posture. A case where the manikin is manually assembling a battery in the boot with help of a lifting device is used in the experiment. 16 different pictures were created and presented for the subjects. All pictures have the same background, but include a unique posture and manikin appearance combination. Four postures and four manikin appearances were used. The subjects were asked to rank the pictures after ergonomic assessment based on posture of the manikin. Subjects taking part in the study were either manufacturing engineering managers, simulation engineers or ergonomists. Results show that the different appearance modes affect the ergonomic judgment. A more realistic looking manikin is rated higher than the very same posture visualized with a less natural appearance. Therefore, it is important to educate human simulation tool users to always combine visualizations (pictures) with an objective ergonomic evaluation method.