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Abstract
In this project, a simulation was developed to take known chassis input in order to evaluate the suspension, damper system design, and control system design for a semi-active seat suspension system for various applications including off-highway and utility vehicles. The software MATLAB/Simulink was employed to create a system model based on the elements of the semi-active seat suspension system, including environmental inputs, as well as the chassis vibration profile and the operator profile. The system model analyzes motion in three axes to predict the resulting movement the driver/operator experiences. Components of the system are three individual dampers employing variable flow hydraulic valves, a proportional–integral–derivative [PID] control system, and the mechanical suspension system of the seat. This software model will aid in the development of the semi-active seat suspension system by allowing several iterations to be run to evaluate different valve designs and control system strategies.
From the results of the model it is seen that more work is needed to increase the fidelity of the model. This could be done by including the piston and shim stack design in the model. Other opportunities for further model development are to improve the control system methodology and to account for the interrelationships between the three axes to determine the effect that vibration in one axis may have on vibration in the other axes.