In this paper, a two-degree-of-freedom (DOF) dynamic model of an on-highway truck seat is created using the Simulink simulation program from MATLAB. Engineering properties of the seat used in the model are measured in the laboratory, obtained from seat component manufacturers, or estimated using engineering judgment. Modeled parameters include: air spring force, damper force, end-stop force, cushion force, seat belt force, driver mass, and cab vertical oscillations due to road disturbances. The model is developed to facilitate seat design as a means of increasing the comfort level that on-highway truck drivers face while carrying out their everyday tasks.
Field testing of the seat is performed in order to validate the model. National Instruments hardware and Labview software are used for the data acquisition. Cab floor acceleration and seat height relative to the cab floor are measured and collected while the truck in which the seat is mounted is traveling over several different types of roads. Cab floor displacements are formulated from cab floor acceleration signals using Fourier methods and integration. These filtered cab floor displacements serve as inputs to the two-DOF model.
Model outputs are compared with measured seat outputs using the power spectra of the seat height relative to the cab floor. Initially, overall agreement of model outputs to measured seat outputs is encouraging. There is better agreement observed at frequencies of about 2.5 Hz and higher. Seat model parameters are adjusted from the original model as an attempt to improve the agreement between model and actual measured outputs. It is seen that, at least for inputs from certain roads, the model can be improved by changing some of its parameters.