Evaluation of seat discomfort using real-time measurements of whole body vibration and seat pressure distribution while driving trucks

This Master thesis project is based on the fact that Volvo Truck Corporation received complaints from drivers concerning the comfort of their seats in the FH12 truck. The complaints concerned especially the ventilated comfort seat. The seat is evaluated in this project to find the source of the complaints. It is also compared to the updated version of the seat to determine if improvements have been done. The focus in this project has been to implement real-time measurements of whole body vibration and seat pressure distribution during a long-term drive in trucks. The measurements have been analysed with calculated parameters and ratings of discomfort according to standards and recommendations. The two seats were tested by six drivers during an each time 120 km long test road. Three distances were chosen from this drive representing different types of road conditions. A method measuring whole body vibration and pressure simultaneously was used during the test drives. The post processing of the measurements began with an identification of existing methods used to analyse the objective test results. Decisions were made regarding how and when the identified methods are appropriate to use in terms of evaluating how whole body vibration and seat pressure affect the drivers’ comfort. The analysis showed that no significant differences exist between the two seats concerning whole body vibrations. This is not at all surprise since the seats are based on the same frame. The vibration accelerations for both seats do not exceed the limitation stated by the European Union. Some values do, however, exceed the recommendation made by the Swedish work environment authority. This leads to the conclusion that measures should be taken to decrease the vibration acceleration i.e. improve the driver’s working environment. No significant differences could either be shown in the pressure measurements but all calculated pressure parameters indicates that the old ventilated seat is better than the updated version. Numerous of parameters have been calculated and evaluated to obtain a complete picture of the pressure. None of the parameters should, however, be analysed alone but as a part of a complete analysis. Even though no significant differences could be pointed out between the seats a lot of information about the weaknesses and strengths for both seats were obtained during this project. A relationship between vibration and pressure has also been examined.Validerat; 20101217 (root