How Do Self Driving Cars Work?

Fully autonomous vehicles aren’t really here yet, at least not in the way we’ve imagined them in the past. They’re coming, but in the meantime, autonomous features enable some pretty powerful and convenient functions.

For people just learning about new mobility technology, the term “autonomous vehicle” can be a bit confusing. What is an autonomous vehicle? Is a self-driving car autonomous all the time, or can humans take control of driving functions where and when they want? How exactly do autonomous vehicles work? This article offers insights into the world of autonomous vehicles.

What is an autonomous vehicle?
First and foremost, an autonomous vehicle has an internal computing platform that can take over some or all of the driving tasks and free up the vehicle’s driver to do other things, such as work-related activities, entertainment, or nothing at all. Of course, the phrase “take over the duties of driving” does not imply simplified functionality; even if those duties are applied only to parking, there are myriad inputs, variables and decision-making processes to consider.

How does a self-driving vehicle work?
First, sensors-including radar, sonar, and/or LiDAR (which stands for light detection and ranging)-are used in conjunction with cameras for self-driving cars to build a picture of their surroundings and upcoming events. One of the main functions of autonomous vehicle platforms is to detect obstacles and/or moving objects-whether pedestrians, other vehicles, motorcycles, or bicycles-and avoid them so that collisions do not occur. A radar transceiver emits a radio wave that reflects objects and obstacles and bounces back to the transceiver’s sensor for processing. The length of time it takes for the wave to bounce back determines the distance to a particular object or obstacle. Sonar and LiDAR work in the same way, except that sonar uses sound instead of radio waves and LiDAR uses lasers.

In addition to these sensors, driverless cars use cameras as well as global navigation satellite systems (GNSS)-of which the U.S. government-funded Global Positioning System (GPS) is one type. Self-driving vehicles take all of these inputs-sensors, cameras, and GNSS data-and synthesize them to obtain a very accurate three-dimensional model of what surrounds them. By constantly updating this data dozens or even hundreds of times per second, autonomous vehicle platforms can see what objects are moving (e.g., cars that make up oncoming traffic) and predict their trajectories seconds (or even minutes) into the future.

The other main function of autonomous vehicle platforms is to apply braking, acceleration, and steering so that vehicles can drive themselves (displacing human drivers) when and where necessary. To accomplish this, autonomous vehicle platforms must be physically wired to the electronic control units (ECUs) that control these functions of the cars in which they are installed.

SAE autonomy levels of self-driving vehicles.
The circumstances under which a car takes control of driving functions and what a driver must do when this occurs are described by autonomy levels defined by the Society of Automotive Engineers (SAE). These levels are as follows:

Level 0: At this level (“No automation”), there is no autonomous function of a vehicle at all; cars that are not autonomous vehicles operate at SAE autonomy level 0.
Level 1: This level (“Driver Assistance”) allows a vehicle to assist a driver with certain functions, such as Adaptive Cruise Control (ACC); The vehicle can either accelerate/brake or steer, but not both at the same time.
Level 2: At this level (“Partial Automation”), advanced driver assistance systems (ADAS) allow a vehicle to handle both acceleration/braking and steering simultaneously. Drivers still need to keep their hands on the vehicle’s steering wheel and their feet on the brake and gas pedal pedals.
Level 3: This level (“Conditional Automation”) allows a vehicle to take over driving completely under certain circumstances. Drivers can take their hands off the wheel, but must still keep their attention on the road and their immediate surroundings. Drivers must be ready to resume control of their vehicle in a few seconds (in cases where drivers are unwilling or unable to take back this control, their vehicle gradually slows to a complete stop).
Level 4: At this level (“High Automation”), drivers can completely divert their attention from the road and the driving task so that they can engage in other activities, including socializing with other passengers and entertainment. It is envisioned that driver seats in a number of SAE Level 4-capable vehicles of the future will be able to rotate 180 degrees, allowing the driver to face the rear of the vehicles and interact directly with rear-seat passengers.
Level 5: This level (“full automation”) of autonomy is what most people envision when they think of driverless cars; The car does absolutely everything itself; There is no longer a “human” driver “. In fact, purpose-built SAE Level 5 vehicles typically lack all driving controls, such as a steering wheel, manual brakes, and an accelerator pedal; The person who was previously the driver of the vehicle is now considered simply another passenger.
In general, the higher you go on the SAE autonomy scale, the more expensive the technology required to achieve such a level.

Self-driving car benefits
Why do we need self-driving cars? It’s a great question-because just because we can make this technology work, the question remains-why is it beneficial to us?

The immediate answer should be obvious: safety. Every year, at least 1.35 million people die in traffic accidents worldwide. A common goal of self-driving car developers is to one day achieve “Vision Zero”-an idealized goal of reducing traffic-related fatalities to zero through the use of a variety of strategies, including (in many cases) the universal adoption of autonomous vehicles (and in a large number of cases, the banning of non-autonomous vehicles) on public roads.

Beyond safety, there are the factors of comfort and convenience to consider. Imagine if drivers no longer had to operate their vehicles themselves. What could they do with this newfound freedom and time? Rapid advances in car cockpit technology have allowed people to relax, connect with colleagues, family and friends, and communicate and share messages, data and even streaming video with them. With infotainment systems, passengers and drivers can now watch movies, listen to music, and enjoy the latest video games and interactive entertainment in their driverless cars.

As technology increases, this infotainment becomes more immersive, and augmented reality (AR) and virtual reality (VR) experiences allow vehicle occupants to leverage their real-world location and surroundings to increase productivity and leisure. Vehicles are becoming intelligent, and technologies such as driver monitoring are enabling autonomous vehicle platforms to know when (and if) vehicle occupants can and should take over driving or perform other tasks.

As more cars become self-driving, intelligent transportation systems (ITS) can use artificial intelligence (AI) and Big Data to optimize traffic flow on roads and make travel more efficient for millions of travelers.

The current state of self-driving car technology
Currently, many new vehicles have adequate SAE-defined autonomy, which typically includes at least some features that would be considered SAE Level 1 and 2 features such as adaptive cruise control (ACC), lane departure warning (LKA), and active park assist (APA). Some cars have gone further and incorporated advanced features such as traffic sign recognition (TSR) and remote park assist.

But a true SAE Level 3 operation-where drivers can take their hands off the wheel (while keeping their eyes on the road) and let the car drive itself-has been included on only a handful of cars, including vehicles from Audi, Nissan, and NIO. A major drawback to this SAE Level 3 functionality is that, depending on the car manufacturer, it only works on highways and possibly only at low speeds or in single lanes.

For SAE Level 4 functionality, one must turn to “robotaxi” services operated by companies such as Waymo, Aptiv, and DeNA. In limited, well-defined areas (where weather and traffic are generally mild), these companies’ robotaxi vehicles can perform most driving functions. In many cases, however, a backup driver is still present in the vehicle for safety reasons. For truly driverless SAE Level 5 operations, one must turn to low-capacity, minivan-style autonomous vehicles currently in use at a select number of locations around the world, including some airports and office parks. These vehicles literally lack any kind of manual driving controls, as well as anything that can be called a “driver’s seat. “At the same time, many of these vehicles do not drive in mixed traffic-instead, they drive in dedicated lanes or on dedicated roads and only at low speeds (below 40 km/h).

To see more advanced progress in terms of SAE-defined autonomous functionality, one may have to look at other autonomous vehicle types—self-driving trucks, buses, and industrial/commercial vehicles. In some of these cases, clear task-based functions make autonomous driving easier and a better fit based on particular operating constraints and/or environments.

Driverless cars in the future
Going forward, more automakers will start to add highway-only SAE Level 3 capability to their cars. Slowly over time, the caveats that are present with this functionality in today’s cars will disappear. At some point in time, this Level 3 operation will transition to SAE Level 4—but only on highways.

It may be a decade or more before we see SAE Level 3 or 4 operation on normal streets due to liability reasons. Until the robotaxi-style SAE Level 4 operation that’s been successfully demonstrated by Waymo and others can be replicated universally on all roads, in all towns and cities, under any weather or traffic conditions, the risks are too great for carmakers to incorporate this functionality in their vehicles. (In 2018, an Uber self-driving car accidentally killed a pedestrian in Arizona—an incident that sent shock waves through the self-driving vehicle industry and led to a re-examination of many testing practices.)

However, it’s possible that in the medium-term future, some automakers may allow SAE Level 4 or 5 functionality to be “switched on” in certain geographic areas at certain hours of the day or in specific weather conditions (clear, sunny skies, for instance). While the “Vision Zero” goal of zero fatalities from traffic accidents may never be achieved in reality, it’s possible—even likely—that we will one day get very close to it.

In summary, it’s been a long journey research- and development-wise to get to the level we’re at currently regarding self-driving vehicle technology. Many millions of kilometers have been driven in test vehicles, and billions of kilometers have been run in simulations to get autonomous vehicle platforms to the state they’re in today. While some industry observers were predicting we’d all be driving SAE Level 5-capable autonomous cars by now, progress has been slower on several fronts than many researchers expected. Component costs, technology constraints, and simply the sheer number of potential scenarios that a vehicle can encounter when traveling on public roads have all been limiting factors that have impeded the rapid achievement of universal SAE Level 5 functionality. But if the recent past is anything to go by, it’s quite possible that by 2025, we’ll be well on our way to the long-envisioned dream of fully self-driving cars where the word “drive” will only apply to machinery, and the occupants in a vehicle will all be passengers.

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