How Safe Are Self-driving Cars?

Introduction

Self-driving cars are a part of the broad spectrum of autonomous vehicles. These are vehicles in which very little to no human control is required to operate the vehicle. These vehicles have the capability to gather information about their surroundings using a combination of sensors such as sonar, computer vision, GPS, Lidar etc and software that enable them to control and navigate [1] the vehicle. In other words, these vehicles can exercise total autonomous behaviour; the power to make driving decisions like obstacle avoidance, lane departure, back up parking, collision warning [2] among others.

It is worth noting that cars are manufactured to 6 different levels of autonomy as specified by the SAE international (Society of Automotive Engineers):

• Level 0(No automation): A person controls driving completely.
• Level 1(Driver assistance): In some driving modes the steering and braking are controlled but never all at once and the human driver needs to ready to take full control at any instant.
• Level 2(Partial assistance): Similarly, the car can handle steering, throttle and braking in some driving modes, but the driver must always stay alert. The driver still must be aware of the surrounding traffic and road conditions.
• Level 3(Conditional assistance): The car can do as mentioned above as well as change lanes and monitor surroundings. The driver is alerted if their intervention is required.
• Level 4(High automation): The car can drive itself with the driver on board. The car can monitor the surroundings perform functions (steering, throttling, braking and parking). There are moments when the driver can be inattentive. If the car is faced with a situation it cannot read the driver is requested. If the driver does not respond the car will handle the situation autonomously.
• Level 5(Full automation): The car requires no human intervention completely. The car needs not to be designed to the ‘conventional operational format’. These cars have no pedals, seats facing forwards or even a person within [3]. Level 5 cars are still at the conceptual stage at this moment in time.

 Level 4 and 5 cars are genuinely considered self-driving cars for instance Google’s self-driving vehicle Waymo. This report will take a focus on this end of the broader spectrum of autonomous vehicles with a deeper look on the safety aspects involved. Then truly consider whether these cars can truly pose no threat to human lives and even take a step forward in the other direction in reducing present road accidents.

How safe are self-driving cars?

According to the National Highway Traffic Safety Administration “94 percent of serious crashes are brought about by human error” [4] and fatal crashes occur about “once for every 3.3million hours of driving” [5]. Self-driving vehicles have the capacity to bring an end to this statistic or at least limit it, reducing the numbers of those injured or killed.

Main Safety Features

Therefore, there are several safeties features as shown in fig 1.1 that self-driving cars by virtue of their design have that aim to curb this statistic:

Lane Keep assist: This ensures that the car stays at the centre of the road. It often involves a system of cameras that are designed to read the lane markings to ensure that the car stays on the desired path. If the driver starts drifting out of the lane warning systems are triggered [6]. To ensure satisfactory lane keeping performance the active disturbance rejection control (ADRC) is implemented. The ADRC can process real data on vehicle uncertainties and disturbances. Successfully managing to keep the car in lane with a “maximum lateral offset of 0.1m” [7].

Cruise control: This ensures that the car is at a safe constant distance to the car ahead. It involves the use radar technology whereby reflected microwaves allow for the speed and location of nearby vehicles to be computed [8].

Active park assist: This makes use of ultrasound waves as illustrated in fig 1.0 below. The sound waves reflected of the nearby surfaces allows for the cars distance to them to be registered [8]. This feature means that the car can be able to park itself whilst the driver remains free handed. Simply put, the car has incredibly accurate sensors fitted on both sides. That can detect a parking spot that can even be as small as “1.2 times the car length”. The onboard computer system can precisely determine the steering turn angle required allowing the car to manoeuvre into the spot at first attempt. This lessens the period for which the car obstructs oncoming traffic [9].

Emergency braking: Involves a system of cameras that can judge distances to surrounding obstacles pedestrians, vehicles, physical structures etc. The car automatically activates the brakes if a collision danger is intercepted [6].

Adaptive Front Lighting: They illuminate the road in front and on the side in a desired illumination pattern depending on the cars speed to maximize night-time visibility. For example, at high speeds the beam pattern longer and narrower to see further [10].

Software Failure

Despite all these technical features put in place automated systems still have the potential for failure and even a delayed software response by a fraction of a second on a highway can be life threatening [5]. For example, when a self-driving uber struck and killed a pedestrian. Even though the car had been fitted with cameras, LIDAR, navigation sensors and a computing unit. The pedestrian couldn’t be detected until a second after collision. On the other hand, there have also been cases of plastic bags flying by and triggering the car to break [13].  Furthermore, there are a host other problem raised by self-driving cars: multiple sensors with conflicting information, weather that can impair the visibility of the sensors by reducing their range and accuracy, vulnerability to hacking of even the most rudimentary levels [14].

Conclusion

Consequently, the state of technology regarding self-driving cars indicates that decades of long research is still needed before launching a level 5 car. This involves research in different fields, for example, computer science, cognitive science, psychology etc. As “It involves not looking-in but also looking-out of a vehicle.” [15] Breakthroughs are needed in software engineering to ensure that the cars can handle the complex everchanging road conditions by making decisions within fractions of a second. Ultimately to safeguard human lives. Seemingly this is a great task that foretells huge expenses.

Reference List

[1] Union of Concerned Scientists, Self-Driving cars explained, 03/18. [Online] Available from: https://www.ucsusa.org/clean-vehicles/how-self-driving-cars-work#.W87ajtJua00 [Accessed 22/10/18]

[2] K. A. Redmill, T. Acarman, and Ü. Özgüner, Autonomous Ground Vehicles, London: Artech House, 2011

[3] M.May, “The 6 levels of self-driving  car- and what they mean for motorists”, the journal.ie, Sept. 18,2018.[Online], Available from: http://www.thejournal.ie/self-driving-cars-autonomy-levels-3603253-Sep2017/

[4] Anonymous, “Self-driving cars raise safety, ethical concerns,” University Wire, May. 10, 2018. [Online], Available from: https://search.proquest.com/docview/2036889169?accountid=12152

[5] S. Shaldover, “The truth about “Self-Driving cars,” vol.314, pp. 52-57, Jun 2016.

[6] S. Huntington, “What are the safety features in autonomous cars”, Automative iq, Jan.23, 2018.[Online], Available from: https://www.automotive-iq.com/autonomous-drive/articles/what-are-safety-features-autonomous-cars

[7] Z. Chu, Y. Sun, C. Wu, N. Sepheri, “Active disturbance rejection control applied to automated steering for lane keeping in autonomous vehicles,” Control of Engineering Practice, vol.74, pp.13-21, May 2018.

[8] H. Fountain, “Yes, driverless cars know the way to san jose,” New York Times Oct.28,2012.[Online], Available from: https://www.sciencedirect.com/science/article/pii/S0967066118300121

[9] Expert Reviews staff, Active park assist, Expert reviews, 04/2011. [Online] Available from: http://www.expertreviews.co.uk/cars/6201/active-park-assist

[10] R. Bishop, Intelligent Vehicle Technology and Trends, London: Artech House, 2005.

[11] The Economist, How does a Self-driving car work [Online image], 2015. Available from: https://www.economist.com/the-economist-explains/2015/05/12/how-does-a-self-driving-car-work [Accessed 23/10/2018]

[12] Confused.com, Car parking technology [Online image], 2016. Available from: https://www.confused.com/on-the-road/gadgets-tech/parking-technology-brief-history [Accessed 23/10/2018]

[13] S. Parker, “Self-driving Uber vehicle that struck woman in Tempe was not programmed to brake,” University Wire, Jun.1, 2018. [Online], Available from: https://search.proquest.com/docview/2048248995/fulltext/FD759AE7DD284118PQ/1?accountid=12152

[14] O. Salon, “Why self-driving cars aren’t safe yet: rains, roadworks and other obstacles,” The Guardian, Jul.5, 2016. [Online], Available from: https://www.theguardian.com/technology/2016/jul/05/tesla-crash-self-driving-car-software-flaws

[15] C. Hong, Autonomous intelligent vehicles: theory, algorithms and implementation,  London: Springer, 2011.