Most important is the convergence of several important algorithmic developments: map making, meaning the vehicle can use its sensors to create a map; localization, meaning the vehicle can use its sensors to figure out where it is on the map; perception, meaning the vehicle can perceive the moving objects on the road; planning and decision-making, meaning the vehicle can figure out what to do next based on what it sees now; and reliable hardware, as well as driving datasets that enable cars to learn how to drive from humans.
Level 4 autonomy has been enabled by a decade of advances in the hardware and algorithms available to the robots. Most important is the convergence of several important algorithmic developments: map making, meaning the vehicle can use its sensors to create a map; localization, meaning the vehicle can use its sensors to figure out where it is on the map; perception, meaning the vehicle can perceive the moving objects on the road; planning and decision-making, meaning the vehicle can figure out what to do next based on what it sees now; and reliable hardware, as well as driving datasets that enable cars to learn how to drive from humans. Today, we can do so many simultaneous computations, crunch so much more data, and run algorithms in real time. These technologies have taken us to a point in time where we can realistically discuss the idea of autonomy on the roads.