Some observations regarding the vibrational environment in child safety seats.

A growing issue in the area of vehicular ride comfort is that of child safety seats. Postural, thermal and vibrational comfort considerations are finding their way into child seat design. This paper makes some observations regarding the current state of child safety seat design, then goes on to present the results of vibration tests performed over two road surfaces using two child seats and two children. The vibration levels measured at the interfaces between the children and their seats were found to be higher than the vibration levels between the driver and the driver's seat. Calculated power spectral densities and acceleration transmissibility functions showed that the vibration transmission characteristics of the coupled system consisting of the automobile seat, child seat and child were different from those of the driver/seat system. Whereas, automobile seats normally reduce vibrational disturbances at most frequencies, the child seats tested amplified vibration at most frequencies up to 60 Hz.