Realistic Computer aided design : model of an exoskeleton

Abstract: The musculoskeletal disorders have significant health care, social and economic consequences in the factories nowadays. One of the most promising possible solutions is the use of exoskeletons in the workstations. Exoskeletons are assistive wearable robotics connected to the body of a person, which aims to give mechanical power or mobility to the user (Wang, Ikuma, Hondzinski, & de Queiroz, 2017). The objective of this project is to create a realistic CAD model of a passive exoskeleton which will be used in future research to analyse the behaviour of the workers in a virtual environment with and without the exoskeleton. This model will be a virtual representation of the exoskeleton EKSOVest which has been designed to support these workers who have to realize overhead tasks. This virtual representation will be carried out in PTC CREO and exported to IPS IMMA in order to check the viability of this model. To achieve a realistic model, the exoskeleton should have the same characteristics than the real exoskeleton. The objectives of this project will be defined for these characteristics, which are part creation, mechanisms, forces simulation, and parametrization. The parts and the mechanisms will be created and defined in PTC CREO with the same dimensions and behaviour as the real exoskeleton. Furthermore, this report will be focussed mainly in force simulation and the parametrization. The forces of the EKSOVest are generated by two different spring and by a high-pressure spring. To simulate these forces, the equation of these springs will be obtained and introduced in PTC CREO. These equations will be obtained through the regression of a set of points, which will be obtained from the real exoskeleton using a dynamometer. The parametrization will be carried out with the objective to make the virtual model adaptable for every type of mannequins. This parametrization will modify the length of the exoskeleton’s spine bar and the distance between the mechanical arms. These distances will be adapted according to the mannequin’s measures which will be introduced by the user. The measures that have to be introduced by the user are shoulder height, liac spine height, and chest width. In conclusion, it can be said that the regression of the springs obtained are an accurate result which can imitate quite well the forces of this exoskeleton. Furthermore, the results of the parametrization allow the exoskeleton adaptable to any type of dimensions that the mannequin could have. The final model obtained has been exported to IPS IMMA and implemented in a mannequin.