Ergonomic evaluation of a product requires building up a physical mock-up or a prototype, having a group of experts or a representative sample of users to test it and to give their discomfort feeling. This is an expensive and time-consuming process. Digital Mock-Ups together with Digital Human Models, are used more and more often in the early phase of product design for reducing product development time and cost.
In order to help the designer to evaluate the future product, the digital human should ideally behave like human beings, not only in terms of anthropometry but also in terms of motion, discomfort perception and work related tissue injury. So the main objective of the project is to develop more advanced digital humans for ergonomic design of products (DHErgo), which are capable of:
- Evaluating the discomfort based on advanced musculoskeletal models of the human body.
- Simulating a population behaviour especially including age effects.
- Simulating the interaction of the human body with the task-related environment.
- Proposing design variants even for applications subjected to restricted resources, and
- Demonstration of productive usage.
To achieve this objective, the project mainly developed a generic biomechanical human model for modelling motion induced discomfort. As motion is generated by the contraction of muscles, kinematic parameters alone cannot explain perceived discomfort. Dynamic and muscular parameters must also be investigated. The development of such a generic dynamic human musculoskeletal model will rely on existing data and computerised human models. A European consortium composed of complementary expertises was the only way to collect data and to validate models for industrial applications. Automotive industry is one of most active end-users of digital human simulation tool, because of high pressure for reducing time-to-market and cost. The final results of the project were demonstrated through case studies related to car design.
The project mainly focussed on the following scientific issues:
- Development of multi-body dynamic motion reconstruction methods in order to estimate joint motion and joint forces.
- Integration of existing human anatomic data and development of detailed human musculoskeletal digital models.
- Collecting all necessary data for model developing and validation. Collecting of the basic human functional data such as joint strength and joint limit will be continued.
- Development of a hybrid optimisation/data based complex motion simulation approach. Optimisation criteria based on joint force and muscle performance will be explored
- Development of a generic motion-based biomechanical discomfort criterion. Thanks to the musculoskeletal models to be developed, different biomechanical parameters including muscle forces and other soft tissues loads will be investigated
- Elderly people. Basic biomechanical data of the elderly people will be collected. The effects of ageing on movement and perceived discomfort will be studied.
- A large amount of human data was collected in this project for developing realistic human models. For instance, data of joint strength and joint range of motion with consideration of adjacent joints are collected at the Technical University of Munich (TUM) and the French institute of science and technology for transport, spatial planning, development and networks(IFSTTAR).
- In addition to detailed musculoskeletal data, l'Université libre de Bruxelles (ULB) also investigated shoulder complex motion both in vitro and vivo so as to find the mechanical relationships between the humorous position and orientation and the related attitude of the scapula and clavicle.
- Central European Institute of Technology (CEIT) has developed a dynamic motion simulation method which takes into account the constraints due to motion dynamics. The reconstructed motions using a multi-body human model can now be exported into ESI's musculoskeletal model including deformable soft tissues so as to estimate muscle forces as well as contact pressure.
- A generic motion-related discomfort assessment approach has also been developed using the concept of 'less-constrained motion'. The less constrained motions are those preferred by users and can be experimentally obtained, making it possible to evaluate a design solution by comparing it with the less constraint motions.
- Three automotive applications oriented case studies have been carried out at IFSTTAR in close collaboration with three car manufacturers as end-users in project. The data sets are used for testing the motion and discomfort simulation methods.
- In addition to the implementation of the new functionalities from the project research, design orientated interfaces have also been developed in the DHERGO demonstrator.
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