How to control weeds is a very in-depth topic, especially in agriculture. Being able to use targeted herbicide is not only cheaper, but is better for the environment, and the crops. Being able to use no chemicals at all is idea.
This is my attempt at weed control. It uses a tracked mobile robot called a Bunker to move around my yard. A Gen3 arm from Kinova is mounted on top, and it has a propane-powered flamethrower. The built-in camera on the arm sends a video feed to an Nvidia Jetson, where a neural-network finds weeds. The arm then moves the flamethrower to murder the weeds.