Braking efficiency the big hurdle for autonomous vehicles

One of the biggest things that may be holding back autonomous vehicles from becoming more ubiquitous around the world is the way in which they brake. There have been many headlines about accidents in which a car did not brake at the right time despite ample time to do so and all the "proper" inputs indicating that it should – and these failures can have catastrophic results.

Take, for instance, the recent autonomous vehicle crash in Taiwan, in which a car in "autopilot" mode ran into an overturned box truck, according to Slash Gear. The vehicle was traveling at north of 68 miles per hour, and despite the driver's efforts to brake manually, it was too late to avoid a collision. The autonomous driving system, of course, was supposed to swerve to avoid the obstacle, but simply did not, and more to the point, the driver's efforts to hit the brakes were ineffective at best.

While this fortunately did not end up being anything more than an embarrassing and slightly injurious accident, it does highlight one of the biggest issues many may have with getting behind autonomous vehicles as a concept, let alone driving one themselves.

Safe brakes may be vital to improved perception of AVs.Safe brakes may be vital to improved perception of AVs.

The heart of the issue
When it comes to getting the braking systems of driverless vehicles right, there's more to consider than whether they can be used to stop a vehicle on their own, according to Engineer Live. After all, most of these vehicles will be be partially or entirely electric-powered, meaning that when the brakes are applied, they should divert some of the energy created by that action to the battery.

However, some experts are concerned as to what happens when batteries are full, the report said. In some cases, it may be the case that vehicles do not go as quickly when in autonomous mode, which isn't ideal. But neither is non-dynamic braking that does not apply the brakes as strongly as might be needed. Fortunately, parts developers are now pushing out auxiliary braking systems that work in tandem with standard options to make better use of the energy created in braking – even when the battery is full.

For instance, one such option pumps a cooled liquid onto the brakes that is heated by the braking action itself, then pumps it to the radiator so it can be used to heat the vehicle's interior, the report said. Without that system, heat or energy escapes uncaptured, and there's no guarantee that the standard braking system will work as effectively as it should in all situations.

Coming into focus
With a number of recent high-profile crashes around the world, the autonomous vehicle development industry is certainly working hard to ensure these problems don't persist. One such company recently received an exemption from the National Highway Traffic Safety Administration for complying with some low-speed autonomous vehicle standards for a driverless delivery vehicle service, which is specifically designed to operate without a human occupant.

Notably, the standards for which the company received its exemption are those that would really only be necessary if a human occupant had backup control of the vehicle, such as using mirrors, a windshield and so on, the NHTSA said. In announcing the decision, U.S. Secretary of Transportation Elaine Chao said that requiring these features for Nuro's R2 vehicle would "no longer make sense" because it is completely without occupants.

The exemption lasts for two years and will allow the developer to put 5,000 or fewer of its R2 vehicles onto U.S. streets, the report said. The NHTSA will also have the company under a microscope during that period to ensure everything goes as hoped for its local delivery service, meaning greater oversight despite the waiver.

Public perception still a problem?
It's worth noting that in part because of the issues with development and rollout, as well as the notable crashes involving such vehicles, almost three-quarters of Americans say autonomous vehicle technology may not be ready for a broad rollout, according to a poll from the industry group Partners for Autonomous Vehicle Education. Indeed, almost half of respondents said they would not get into a taxi or ride-share vehicle without a driver, and only slightly more than 1 in 3 even believe the advantages of such vehicles outweigh the problems they could cause.

Interestingly, almost 3 in 5 said they think AVs they consider safe might be ready for public use a decade from now, but another 1 in 5 told pollsters that no such day will ever come.

With all this in mind, companies may need to do more to make sure their driverless vehicles are safe before pushing them out to the public, including upgrading their artificial intelligence and braking systems to be more responsive and safer than they are now.

Greening Testing Laboratories is a fully certified brake testing lab that provides a variety of brake testing services worldwide. Contact Greening Associates for a complimentary consultation.