Open-field navigation with GPS and RTK
For large open-field operations like grain farming, row crops planted in wide, exposed fields give a robot or autonomous tractor a relatively clean line of sight to the sky, making satellite-based positioning viable. Standard GPS alone typically isn't precise enough for tasks like following a planted row without straying onto it, so these systems commonly use RTK, real-time kinematic correction, which uses a fixed reference station with a known precise location to correct the satellite signal in real time, tightening positioning accuracy down to the centimeter level. This lets large equipment autonomously follow straight or curved rows across a field with very little drift over long distances, which is exactly what's needed when a single pass might cover hundreds of meters.
This approach works well specifically because open fields offer good sky visibility and relatively predictable, repeatable row geometry, since the rows were planted by a machine following a plan in the first place. It's a strong match for equipment like large planters, sprayers, and harvesters that need to cover ground efficiently along mostly straight paths, where the main navigation challenge is holding a precise line rather than reacting to complex, cluttered surroundings.