Sensor-in-the-loop tractor stability control: Look-ahead attitude prediction and field tests

Rollover protective structures (ROPS) have been recognized as the most effective device to prevent tractor-related fatalities due to tractor rollover. However, ROPS provide only passive protection from rollover-caused fatalities. The most effective way to eliminate rollover-caused fatalities is to prevent the rollover from occurring. This research proposes the use of “sensor-in-the-loop (SIL)” online tractor attitude and motion simulation to provide rollover warnings based on estimated look-ahead tractor attitude and motion status. A stereovision camera was used as the visual sensor for the SIL system to create a three-dimensional virtual terrain map on which a virtual vehicle travels. This progressively estimates the tractor attitude and motion on the terrain to provide warning of potential rollovers. A series of field tests on various terrains were conducted to evaluate the dynamic performance of the SIL tractor motion simulator in an actual field environment. The validation test results indicated that the SIL vehicle attitude simulator could predict the attitude and motion status of the vehicle approximately 8.0 m ahead of its actual position with favorable and consistent accuracy at all test sites. Such information can be used as baseline data for a warning signal to prevent rollovers from occurring.