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The development of automated guidance for agricultural tractors has addressed several basic and applied issues of agricultural equipment automation. Basic analyses have included the dynamics of steering systems and posture sensors for guidance. Applied issues have evaluated the potential of several commercial sensing systems and a commercial mechanical guidance system. A research platform has been developed based on a Case 7220 Magnum1 2-wheel drive agricultural tractor. An electrohydraulic steering system was used and characterized in support of automated guidance control. Posture sensing methods were developed using GPS, geomagnetic direction sensors (GDS), inertial, and machine vision sensing systems. Sensor fusion of GPS-inertial-machine vision and GPS-GDS-machine vision provided the most flexible and accurate guidance and capable for operation under dynamically changing field conditions.

The present ABS is controlled by the slip ratio and the wheel acceleration. On rough roads, the slip ratio is weighted to eliminate the wheel velocity fluctuation. That results in poor performance of the ABS, Therefore a new algorithm is investigated without the slip ratio. The algorithm consists of major two concepts. One of which is to shift the wheel acceleration threshold which determines the initiation of the brake-pressure reduction by the road friction coefficient and the disturbance. The other is to determine the proper duration for the pressure reduction by the road friction coefficient at same time. The new algorithm was estimated by computer simulations. Therefore, the reduction of velocity-fluctuation, more effective steerability and a shorter stopping-distance can be expected.