Search Results

The purpose of this study is to develop an evaluation method for the postural stability using a digital human model. Experiments were carried out to measure two kinds of stability limits defined in this study. Based on the results new software was developed to visualize the postural stability of the digital human model Jack (EDS). Using the model a methodology was proposed to judge easily whether the human body in any working postures could be maintained with effort or not. It was also demonstrated that the postures unsafe to work could easily be found.

The objective of this pilot study was to investigate how far dimensional constraints (vision requirements, head clearance) influence postures of car drivers. For that purpose the preferred sitting postures of 9 subjects were recorded twice. Furthermore the drivers were interviewed regarding their perceived comfort. The data show that limited vision conditions, head clearance and maximum adjustment travels influence the subjective rating, joint angles, eye and head position. It can be concluded that these factors should be considered in posture studies and included in posture models intended for posture prediction what has not been done yet. In further investigations, results so far found in this study have to be verified with larger samples and in other packages or cars under dynamic test conditions.

Simulation of human motions in virtual environments is an essential component of human CAD (Computer-aided Design) systems. In our earlier SAE papers, we introduced a novel motion simulation approach termed Memory-based Motion Simulation (MBMS). MBMS utilizes existing motion databases and predicts novel motions by modifying existing ‘root’ motions through the use of the motion modification algorithm. MBMS overcomes some limitations of existing motion simulation models, as 1) it simulates different types of motions on a single, unified framework, 2) it simulates motions based on alternative movement techniques, and 3) like real humans, it can learn new movement skills continually over time. The current study evaluates the prediction accuracy of MBMS to prove its utility as a predictive tool for computer-aided ergonomics. A total of 627 whole-body one-handed load transfer motions predicted by the algorithm are compared with actual human motions obtained in a motion capture experiment.

Improvement in the accessibility assessment of the seatbelts using a Digital Human Model requires a precise description of driver belt donning movement and of the associated discomfort. In order for automotive designers to be able to simulate seatbelt reaching movement, a general approach of motion simulation for complex and specific tasks has been proposed in this paper. It consists of three steps: constitution of a structured database, selection of an appropriate movement and its adaptation to meet new constraints. From an experiment, a database of 644 movements of automotive seatbelt reaching movements has been built-up. In order to structure the database, the temporal and spatial characteristics of the trajectories of main markers (e.g. markers attached to the hand and the torso) as well as joint movements were analysed, allowing us to identify motion control strategies.

This paper describes postural behaviour in static reaching sidewards, and the role of the trunk in particular. It turned out that the trunk (chest, pelvis) is not involved when reaching sidewards up to roughly 40-50° (depending on the reach distance). At greater angles the arm, the chest, and the pelvis each contribute at a particular rate to get the index finger onto target. These rates are reasonably similar to the average contributions of the arm, chest, and pelvis to the total of the range of motions of the arm, chest, and pelvis, suggesting that these segments share the musculoskeletal load equally.

This paper details the application of three-dimensional image warping techniques to full body scan data. Borrowed from the toolbox of geometric morphometries—methods commonly used to quantify the size and shape of anatomical objects in biological research— image unwarping transforms a given image such that relevant landmark positions of the starting image coincide with their positions in the consensus or target configuration. This study demonstrates the process of transforming static scan data to any posture, position, or homology for which landmark data is available, enabling detailed human models to be re-postured and examined in design environments widely varied from the one in which they were scanned.

An ergonomics study was conducted in a mock-up with a fixed steering wheel position. Drivers adjusted the seat and pedals to a comfortable position. A three-dimensional coordinate measurement machine (CMM) was used to measure the comfortable position of 21 participants. Proven test methods were used to collect the posture data. A model is described to assist in seat and pedal placement for cockpit design.

According to NASA, any person with physical characteristics that are between those of a 5th percentile Japanese female and a 95th percentile American male shall be eligible to become an astronaut. Because of this guideline, pathways and workspaces within a space vehicle must accommodate a wide range of population. Unfortunately, there is often a shortage of space inside the space vehicle. Hence, designers try to maximize the use of space. One way to accomplish this is by finding the minimum volumetric requirement that would ensure safety and comfort for the crewmembers. Until now, static, uni-variate anthropometric data were used to derive these guidelines. Our concern is that they may misrepresent the dynamic postural variations of the crew onboard the space vehicle. We used a posture based whole-body anthropometric approach to determine the variation in the three different clearances and updated the design guidelines accordingly.

The layout of special-purpose vehicles for global distribution has to ensure that all products can “fit” worldwide operators. Since spring 2001, BOMAG has implemented RAMSIS software, a CAD-based 3D man model, into the conception and design phases for their construction machines. First applications comprised the ergonomic optimization of the configuration and layout for driver's cabs and control elements, specifically related to a small single drum roller, a tandem roller, a big refuse compactor and in addition maintenance issues. First results of the enhanced design process highlighted the benefits of applying such ergonomic tools, providing anthropometrical and additional human data for consideration in the layout of workplaces.

This study attempts to discover how ergonomic guidelines should be visualized in order to make it easier and more interesting to find and interpret the guidelines throughout the construction process. A prototype visualizing ergonomic guidelines at the intranet has been developed and evaluated at a company that produces cars for the global market. The results shows that the visualization of ergonomic guidelines should preferably be based on a picture of the physical car with hyperlinked segments easy to relate to a group of guidelines or a specific guideline. A specific ergonomic guideline should preferably have measurements related to pictures of car objects and human body parts.

Workstation design is one of the most essential components of proactive ergonomics, and digital human models have gained increasing popularity in the analysis and design of current and future workstations (Chaffin 2001). Using digital human technology, it is possible to simulate interactions between humans and current or planned workstations, and conduct quantitative ergonomic analyses based on realistic human postures and motions. Motion capture has served as the primary means by which to acquire and visualize human motions in a digital environment. However, motion capture only provides motions for a specific person performing specific tasks. Albeit useful, at best this allows for the analysis of current or mocked-up workstations only. The ability to subsequently modify these motions is required to efficiently evaluate alternative design possibilities and thus improve design layouts.

This paper presents the results of a study using computer human modeling to examine machine appendage speed. The objective was to determine the impact of roof bolter machine appendage speed on the likelihood of the operator coming in contact with. A contact means two or more objects intersecting or touching each other, e.g., appendage makes contact with the operator’s hand, arm, head or leg. Incident investigation reports do not usually contain enough information to aid in studying this problem and laboratory experiments with human subjects are also not feasible because of safety and ethical issues. As an alternative, researchers developed a computer model approach as the primary means to gather data. By simulating an operator’s random behavior and machine’s appendage velocity, researchers can study potential hazards of tasks where it is not possible to perform experiments with human subjects.

Data from man-in-the-loop simulation, where the separation assurance is either ensured by air traffic control or delegated to the pilots, is used to derive and validate models correlating instantaneous self assessment and objective factors. Factors are selected, parameters are computed and models are assessed in terms of correlation and ability to classify. Models for air traffic controllers are based on functions of density, number of aircraft in an airspace and take into account the presence or absence of a conflict detection and resolution tool. Workload models for pilots are centered primarily around a number of functions - those associated with the number of conflicts during present and previous time periods, those contributing to convergence and, finally, those related to conflict detection and resolution horizon. This paper discusses the technical approaches taken to develop these models.

The aim of this study was to examine the influence of computer manikin users' background and knowledge for the results of a computer manikin simulation. Subjects taking part in the study were either production engineers or ergonomists. A manual task that presented production and ergonomics problems was used. The task was simulated prior to the subjects' sessions, using the computer manikin software Jack. During the sessions, the animated simulation was shown to the test subject. Results show that there are differences in how production engineers and ergonomists interpret results from a manikin simulation. Depending on the user's background, certain aspects that are difficult to visualise with the computer manikin were interpreted differently, regarding e.g. detected problems and holistic perspectives.

The objective of this ongoing research project is to link IPME (Integrated Performance Modeling Environment) and SAFEWORK to provide a holistic environment in which to view simulated humans operating in their proposed, or existing, workplace. The two Application Processes are able to communicate in real time using a bi-directional architecture that utilizes callbacks and shared interfaces. A Communication Interface Protocol based on a Client-Server socket strategy permits effective communication at each lower level task. The preliminary results indicate the architecture successfully solves communication between the two simulation applications by applying IPME variables to drive SAFEWORK manikin movements. It is anticipated that the integration of SAFEWORK and IPME will combine anthropometrics, geometrical, scheduling and mental workload data to provide a scalable solution for designing individual workstation environments to complex operational scenarios

This paper gives an overview of the current design process of BMW and the application of human models within this process. A distinction is made concerning 2½D and 3D methodologies and their applicability in the overall process. Advantages and disadvantages of these methodologies are discussed and the best practices for the different phases of the product development process are described. A proposal is made for a unified methodology of human models integrating 2½D and 3D approaches as well as hardware mock-ups and the measurement process for validation and target definition.

Human models are viable methods of introducing human factors and ergonomic objectives into the design process at an early stage. Used correctly, they allow users to simulate and analyze potential human-machine interactions saving time and money. As with any model, mistakes can be made. The primary sources of error stem from incorrect use and misinterpretation of the results by the analyst. The development of three-dimensional human modeling software has only compounded these issues by adding a digital subject, itself a human model. This complicates the interpretation and use of these tools by layering one human model on top of another. The purpose of this paper is to highlight common categories of misuse and misinterpretation of digital human models as well as to propose a method for improving user understanding of human models through formal documentation of critical components.

A systematic approach to the design, the development and the evaluation of new generations of advanced driver assistance systems is outlined. In contrast to the predominant technology-driven developments we propose a task-oriented method as a basic procedure for future developments that is rooted to two common societal aims: safety and efficiency. These aims are the framework that defines an aspired target-strategy, which will be derived by a systematic process: the target-strategy-identification. To keep the driver-vehicle system within the limits of appropriate and safe traffic participation the target-strategy has to be implemented into the technical system to provide a database for necessary and adequate assistance. For the system's decisions about the required assistance the actual driver-strategy has to be compared with the target-strategy. The driver-strategy will be estimated from data collected by special methods of driver-monitoring based on psychological behavior models.

This paper describes the study performed to build an accurate and reliable digital model of a human hand. A mould was manufactured using alginate contact-safe rubber and a plaster model made. The model was digitized using a contact probe system with 0.02-mm chordal tolerance, 0.2-mm stepover and 0.2 mm nominal pitch and the CAD model created. This model was used to manufacture CNC, SLA, SLS and LOM prototypes. Overall, CNC prototyping revealed, for this purpose, the adequate choice, since a lower cost and a less delivery time was obtained with this technology. The procedure developed allowed very accurate digital and prototype models of the human hand and can be applied to manufacture other type of anatomical models of the human body.

A unique measurement device, called StickMan, and a customized vehicle climate control system, were developed to measure thermal comfort under transient and non-uniform conditions inside vehicle. The systems were fully calibrated and then used to characterize the vehicle thermal environments (air temperature, radiant temperature, air velocity, relative humidity) at 20 locations. Coupled with a seventeen segment version of the human thermal model TRANMOD (Jones and Ogawa, 1992), one can predict both whole body and local thermal sensation accurately based on the StickMan measurements. Therefore, using a device such as StickMan may reduce the design cycle and costs by eliminating the need of large number of human subjects to evaluate thermal comfort satisfaction in vehicle prototypes.