A low friction tractor seat with nonlinear stiffness and dead-band damping was investigated both by simulation and experimentation. The objective was to determine if a practical, “soft” suspension system could be developed that offered improved vibration performance compared to a typical mechanical commercial tractor seat suspension. A “hard” damper was used to prevent end stop impacts that were more likely with the soft suspension. In addition the damper had a dead-band centered at the seat’s static equilibrium position. The dead-band damping was achieved with a switchable damper using relative seat displacement as the control signal. The objective of the dead-band was to allow a soft undamped operating region that gave good vibration attenuation. If the relative seat displacement passed the dead-band limits due to sudden harsh inputs, the hard damping would take over and prevent end stop impacts. An experimental rig with nonlinear seat and switchable damping was built and tested with the same parameters and inputs as those used in the simulations. The simulation and experimental results compared well. Both the simulation and experimental results showed that a combination of nonlinear stiffness and dead-band damping used on a tractor seat gives reduced rms acceleration compared to a linear, conventionally damped seat.

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