There have been numerous works dealing with precise and automated steering of off-road vehicles and agricultural machineries, but due to drawbacks such as cost and technological limitations, they mostly have not been welcomed or popularized. In this study, an interchangeable system, with fairly low cost, and moderate technological requirements was developed, constructed and tested which can be installed on most agricultural tractors, and other off-road, self-propelled machineries. The system comprised of a cable-spreading unit with a slim steel cable, a fifth-wheel (or ground-wheel) with some cable-positioning sensors, a control unit and processor along with an electro-mechanical steering wheel driver. To steer on a predefined path, the vehicle should be initially steered manually on the first path. On subsequent pass, automatic steering is obtained by putting the fifth-wheel on the previously put down-cable. A prototype of this system was fabricated and installed on a MF285 tractor with intentional accuracy of ±2.5 centimeters. The overall offset deviation (error) from the desired path was ±2.6 cm/m and ±2.4 cm/m of longitudinal path, on soil and asphalt surfaces, respectively. However, this can be diminished through design characteristics modification such as using a narrower position sensors. In large fields and long paths, an accurate steering with the least tiredness, as well as more attention on implement adjustments and performance instead of vehicle driving would be achieved.

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