Robots are already capable of cutting grass and taking on other agricultural tasks. The Graze is a fully autonomous electric lawn mower that can cut mid to large sized commercial lawns efficiently. It has GPS based mapping & computer vision, sensors for safety, and machine learning.
This model comes with a long battery life. As the company explains:
Machine learning, coupled with computer vision and a robust system of sensors allows the new Graze commercial lawn mower to map job sites, plan and execute mowing paths, avoid obstacles and dangerous inclines (i.e. trees, terrain, people etc.), while continuously collecting and apply data to further improve aesthetic quality and efficiency
These mowers can be powered by solar power too. More info is available here.