Tire blowouts lead to dozens of highway deaths every year. For autonomous trucks, they pose a prickly problem: how to regain control without a human driver at the wheel.
“We can talk about redundancy in our sensors, machine-learning algorithms and all this fancy stuff until we’re blue in the face,” said Don Burnette, co-founder and CEO of Kodiak Robotics. “But at the end of the day, if you press the brake pedal and your tires don’t respond, it’s not useful.”
Kodiak is working with Bridgestone Americas to share information that could lead to more robust tire safety.
“We knew from the very beginning that we needed to figure out ways to improve upon, or at least understand as deeply as possible, how to maintain the integrity and quality of the tires during autonomous operations,” Burnette said.
Of the 4,965 fatal truck crashes recorded in federal Fatal Accident Recording System data for 2020, 28 listed a flat tire or a blowout as the cause, according to Harry Adler, principal at the Institute for Trucking Safety, a Washington-based advocacy group for truck crash victims. From 2010 to 2020, flat tires and blowouts accounted for 307 deaths, the data showed.
That doesn’t count the near misses. During the Commercial Vehicle Safety Alliance’s 2019 international road check blitz, 19% of the 11,910 vehicles were taken out of service for tire and wheel violations, second only to braking issues.
The number of tire-related fatalities pales in comparison with those linked to speeding and distracted driving, major causes of truck crash deaths. But letting off the throttle is easier to address than an unexpected tire failure that can send an 80,000-pound truck careening out of control.
Most tire blowouts are caused by under inflation, which causes the side of a tire to flex more and generate heat. And it’s the heat that leads to the blowout. Experienced drivers who know their trucks and loads often can bring a semi under control. But can robot drivers?
“The ability to infer load on the tires in real time is helpful to autonomy,” Burnette said. “With more advanced, newer sensors coming out, they’ll be able to measure individual loads on individual tires, which can give us the total value of the load rather than just looking and trusting the piece of paper that says, ‘Yeah, this is how much mass you have.’”
A work in progress
Tire safety is a top-of-mind issue at TuSimple, the first autonomous trucking startup to test driverless trucks late last year.
“Human drivers can kind of manage [a blowout],” said Cheng Lu, TuSimple adviser and former CEO. “But with autonomy, we have to understand the health of the tire much better.”
TuSimple has a partnership with Goodyear Tire & Rubber Co. to add tires to the list of issues that early research shows makes driverless trucks safer in long-haul operation than those driven by humans.
“The driver is usually the one who notices something wrong with the tires. They can feel it while they’re driving,” Dustin Lacey, Goodyear’s commercial product marketing manager, told FreightWaves. “When you remove the driver, you have nothing to sense anything that is going on with your tires if you get a flat or you have a blowout.”
When a blowout happens, a driver tries to safely get the truck to the side of the road and alert other motorists by placing safety triangles or flares behind the trailer. A skilled driver can fix a flat in as little as 10 minutes if the rim does not need to be removed. Often a mobile repair unit is dispatched, which is what will happen with autonomous trucks.
‘Tons of sensors’
Goodyear is working to incorporate different types of sensors that can work with the vehicle to identify air pressure loss or loss of pounds of pressure per square inch. Goodyear can build sensors into valve stems and extend lessons from tire pressure monitoring systems, which have been required in passenger vehicles since 2007.
“Those vehicles are going to have tons of sensors on them, reading things from all around. The tires are going to be something that fits into that formula of all that information that is being collected by the [autonomous] vehicle,” Lacey said.
A tire wear study that Goodyear planned for tires it provides for the dozens of TuSimple autonomous trucks hauling freight under human driver supervision was put on a temporary hold during the pandemic.
“I think we’re at the early stages of what autonomous vehicles are going to mean for tires in the future, and Goodyear is trying to strategize and figure that out,” Lacey said.
A tire blowout is one of five remaining critical issues that San Francisco-based Embark Trucks lists for solving from a list of 16.
“We have developed an understanding of how the Embark Driver must instantly identify tire degradation and then react, just as we’d expect an experienced human driver to do,” said Sam Abidi, Embark chief commercial officer. “For example, skilled drivers know to apply the throttle when a steer tire is blown before bringing the vehicle to a controlled stop.”
That kind of intuition and logic is what Embark wants to master for its autonomous system.
“The ability to handle blown tire scenarios has been outlined as a capability on Embark’s technical road map since 2021,” Abidi said. “We are actively working on this capability, which is scheduled for completion in 2023 ahead of commercial deployment of the Embark Driver in 2024.
Burnette said Kodiak can provide high-fidelity, granular data like forces on the tire and reports of how the truck is being driven to Bridgestone. The tiremaker can use that with sensor data it gathers on cornering, torque, acceleration, temperature and braking pressure to create a picture of tire health.
“Advancements in tire-centric technologies are critical to unlocking greater innovation in mobility, while also delivering significant sustainability benefits,” said Paolo Ferrari, Bridgestone Corp. global chief solutions officer and president and CEO, Bridgestone Americas.
Kodiak builds foreign object and debris detection into its perception system, which decides whether the truck should swerve, stop or hit an object.
Aurora Innovation, which applies its Aurora Driver to both cars and trucks, upgraded the high-resolution cameras in its latest-generation system to take in four times as much data and detect obstacles, including road debris, at twice the distance of the first release.
Goodyear uses predictive algorithms to anticipate when a tire is likely to have a problem.
“We’re trying to catch those issues before they happen, before that vehicle even gets on the road,” Lacey said. “That breakdown in the future without a driver could be more catastrophic.”
Regardless of sophisticated sensor development that could prevent a tire issue, human inspection before and after a trip is more important.
“In the short term, you’re going to have humans at either end of the trip who are going to do full inspections and make sure everything is all good, but you never can be certain what’s going to happen out there on the road,” Burnette said.
That’s why the Institute for Trucking Safety endorses technologies like automatic emergency braking, speed limiters and lane departure warning.
“These are the building blocks to autonomous trucking,” Adler said. “Speed limiters are a great way to reduce the instances of blowouts. We don’t think trucks should be going 75 or 80 miles an hour.”
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