Ever since the latticed snowshoe was developed some 6,000 years ago, humanity has been trying to improve its footing on poor and slippery surfaces. Yet, we still trip, we still fall, and we still break our legs from time to time.
Perhaps cars have done even better than we have. Snow- and all-season tires, anti-lock brakes, traction control, and stability control provide sure-footed driving in poor-weather and slippery surface conditions for every car on the American market. All-wheel drive permeates throughout, too, but is not a requirement.
Yet, despite having all these systems at our disposal, automakers haven’t stopped developing new ideas in the quest for better handling. Turns out there is some extra bandwidth in the wet-traction stakes and Porsche has found it. The new 2020 911 sports car features what Porsche calls Wet Mode, a driving program designed to reduce the risk of hydroplaning on wet roads.
Beyond improving the new 911’s handling in rain, Wet Mode technology has greater implications for the future of self-driving cars. When that day comes, and the car encounters a sudden downpour, a system like Wet Mode could ensure passenger safety and security as the vehicle navigates the weather.
How Does Wet Mode Work?
Wet Mode uses the new 911’s existing stability sensors and related components, working with other systems that maximize stability, traction, and braking to make driving the car in prevailing wet conditions more manageable and easier.
The system locates acoustic (yes, acoustic) sensors, similar to those used in parking distance applications, behind the front tires in order to read the level of water spray coming off the tires’ treads. If that spray reaches a prescribed level, the car’s stability control system engages earlier and the car suggests to the driver that full Wet Mode ought to be manually turned on.
Let’s say the car reads a level of spray that indicates water of about one-millimeter depth on the road (and this correlation is programmed into the system). It then alerts the driver through a dashboard light and automatically changes the stability control to intervene at a lower level or a lower relative speed in turns. Secondarily, if the driver then manually selects the car’s Wet Mode, stability control becomes even more sensitive.
Wet Mode also relaxes accelerator pedal response to driver input, effectively softening the throttle. And since snow is also wet, Wet Mode can be used in the slushy white stuff, too.
Porsche engineers are cautionary, though, with regard to what Wet Mode cannot do. For example, the 911 can still reach its top speed of 190-plus mph in Wet Mode, as the system does not restrict engine power. It also cannot prevent drivers from driving too fast for conditions. In other words, Wet Mode assists the driver and does not restrict, scold, or prevent the driver from being, well, stupid.
All stability systems in all cars use essentially the same data coming from a bevy of sensors all over the car. These sensors transmit data on wheel speed, steering angle, throttle position, engine speed, selected gear, and brake pedal pressure. Plus, an accelerometer records cornering, braking, and acceleration force and several other measures that are even more esoteric.
Porsche’s Wet Mode is effectively even more cautionary programming of the car’s already sophisticated stability control system. Wet Mode adds one more input stream from the front wheel wells to inform the car directly about damp roads, making the system – and the driver – even more informed than before.
One day, something like Wet Mode might also make your self-driving car more informed, too.