HighlightsThis study created a simulation model to predict the ride vibration of a tractor and to optimize its suspension.The parameters of the tractor were obtained from various tests to create a fully validated model.The acceleration measured in a tractor cabin was compared with the simulation model in the time and frequency domains.The ride vibration of a tractor was evaluated under various road conditions with a fully validated model. Abstract. A typical problem with tractors and other agricultural machinery is the excessive ride vibration, which results in an inconvenient working environment and poses a risk to the health of operators. In this study, a simulation model for predicting the ride vibration of a tractor and optimizing the cabin suspension was developed to address this limitation. First, the required parameters used computation tests to create the simulation model. Mode and frequency-response function analyses were then performed to validate the model for ride vibration, from which the natural frequency and mode shape were analyzed. Subsequently, the riding characteristics of an actual tractor on a stepped road surface were simulated using a four-post road simulator, and the acceleration measured in the cab was compared with that of the simulation model in the time and frequency domains. Finally, the parameters of the cabin suspension were optimized using the validated simulation model, and the correlation between the cabin suspension parameters and ride vibration was examined. Following optimization, the vibration value of the tractor cab was found to decrease as the damping coefficient of the cabin suspension decreased for all surface conditions selected in the simulation. Thus, the developed tractor simulation model can be used as a ride vibration simulation when developing the control logic of a tractor’s cabin suspension, as well as a plant model of hardware-in-the-loop simulation to verify the control logic. Keywords: Hydro-pneumatic suspension, Optimization, Ride vibration, Simulation model, Tractor cab, Validation.

The driving performance of an off-road vehicle is closely related to soil strength. A bevameter is used to measure the soil strength, and it usually consists of two independent devices: a pressure–sinkage test device and a shear test device. However, its development and measurement processes have not been standardized; thus, researchers apply it in various fields according to their own discretion. In this study, a new bevameter was developed, and experiments were conducted to clarify the factors that affect the measurement performance of the bevameter. The pressure–sinkage test device was tested with circular plates of different sizes, and the results confirmed that the pressure–sinkage parameters decreased with the plate size. For the shear-test device, normal pressure was applied using a dead load to prevent normal-pressure variation due to displacement and speed. In addition, a spline was installed on top of the shaft connected to the shear ring to measure slip sinkage during the shear test. The results showed that the slip sinkage increased in proportion to the normal pressure and slip displacement, but the increase gradually decreased and converged to a certain point.

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In this study, the design and driving performance evaluation of a driving system for driving on deformable terrain was performed using terramechanics theory and multi-body dynamics simulation. For the design of the driving system, the mechanical interaction of track-terrain was analyzed using a Bekker-based model. Based on the analyzed results, the design of a track suitable for the deformable terrain to be driven and selection of a power source (engine, transmission, etc.) were carried out. A multi-body simulation model of the tracked vehicle reflecting the designed track and the selected power source was developed, and a ground model reflecting the mechanical property of terrain was also developed to analyze the mechanical interaction of the track-terrain through simulation. In addition, each link constituting the track was modeled as a 6 DOF spring/damper system to consider the track's tension force and load distribution under the track, and through this, different ground pressure and soil thrust were applied according to the motion state of each link. Finally, driving performance analyses were performed using the developed tracked vehicle, and as a result, it was confirmed that the driving requirements of the tracked vehicle were satisfied.