Dynamic simulation of baby carriage under running condition: analyzing vibration when passing over a level difference

Baby carriage vibrations cause unpleasant sensations for both the babies and carriage operators. This study analyzed the baby carriage vibration generated by passing over a level difference on a road surface because this situation introduces a large physical burden and significant stress. The purpose of this study is to develop simulation models in order to improve the performances of baby carriages under operating conditions efficiently. Furthermore, experiments were conducted using a real baby carriage to verify the accuracy of the simulation models. We focused on vibrations in the front leg because characteristic vibrations were generated in this part. Baby carriage models, such as the rigid body model (modeled as a rigid body other than the elastic deformation of suspension) and the elastic connection model (modeled the movement of joints around the legs), have been developed. However, the accuracy of these models are insufficient because these are not able to model high-frequency vibrations and the trend in the vibration peaks when the baby carriage passes over the level difference. Additionally, we developed the front leg elastic body model considered the elastic deformation of front legs based on the finite segment method. In the front leg elastic body model, front legs were divided into fifths, which were connected by translational and rotational springs because the time is required for analysis using the general finite element method. This model was able to provide the trend similar to the experimental result. Finally, the vibration reduction design for a baby carriage was considered by using the developed simulation model.