| 摘要 |
An automatic tractor guidance system for controlling the steering of a tractor to follow a previously plowed furrow is disclosed. A furrow follower is provided with a sensor for sensing the direction of the path relative to the direction of travel of the tractor. The steering direction of the tractor is likewise sensed. The two sensor signals are combined and compared to a convergence frequency signal to produce a digital control signal. Each logic state of the control signal effects a turn in the steering of the tractor, right then left. If the duty cycle of the control signal is 50%, no net turn either right or left is effected. However, when the duty cycle deviates from 50%, a net rotation in one direction or the other will occur depending on which logic state of the digital signal occurs for a longer portion of each cycle of the control signal. Also provided is an offset adjustment to adjust the steering direction of the tractor to compensate for forces acting on the tractor which tend to change the direction of travel of the tractor without an accompanying steering control change.
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