Rivian’s R1T and R1S: the technology behind their management

Long before Tesla entered the market, automakers tinkered with electrified vehicles and worked to create an alternative to gasoline-powered cars. Aimed at urban commuters looking to save a few bucks at the gas pump, cars like Toyota’s Prius and Chevrolet’s Volt have emerged as promising frontrunners, followed by today’s Hyundai Ionic 5 and Volkswagen ID.4 among others.

Today the race to the next frontier has begun: battery-powered off-road vehicles. GMC accelerated its production schedule for the Hummer EV, which features a crab trick made for tight turns on rough terrain, and Ford’s new all-electric F-150 Lightning was no exception. Chevrolet is hot on its heels with an electric Silverado truck coming to market soon.

Meanwhile, Rivian in small batches sells its R1T pickup from 2021 and R1S SUV from 2022, and has invented new ways to make electric trucks capable both off the curb and on it. Part of that formula can be attributed to the kinetic system, a proprietary electro-hydraulic roll control configuration that replaces a mechanical anti-roll bar and makes the ride smoother. On traditional vehicles, a sway bar is a simple U-shaped piece of metal that acts as a torsion spring, connecting the axles to prevent excessive roll that is both uncomfortable and difficult to control the vehicle.

The company sent teams in both of its vehicles to this year’s all-female Rebelle Rally, the longest rally raid (long-distance off-road race that takes place over several days) in the United States, over 1,600 miles between Nevada and California. At the rally, Rivian put his trucks to the test on dirt, rock and sand, finishing triumphantly. Team rookie Lillian Macaruso and Alex Anderson, both of the automaker’s engineers, finished fourth overall out of 53 teams with an R1T and Rosanna Nuch and Nicole Johnson also performed admirably in the upper half of the field with an R1S. Macaruso explained more about the Rivian technology at Pop Sci during a lap after the competition to explain how it works.

Rivian’s hydraulic roll control provides cornering stiffness in the same way (and with similar equipment) as a McLaren 720S supercar. It’s no coincidence: Rivian recruited Chief Engineer Charles Sanderson from the automaker in 2018, and Sanderson integrated the Tenneco-supplied hydraulic connected damper system that he knew quite well. This means that the R1T has a sports car feel, especially when accelerating, but the system leaves room for a wider adaptation in situations where there is articulation, vertical travel of the wheels or the distance the axle can move up and down.

On a typical gas-powered off-road vehicle, the anti-roll bar (another name for anti-roll bar) reduces the roll and sway of the vehicle’s bodywork to stabilize weight distribution. One thing you don’t want when you are entering a curve on a track, or on top of a dune, is that a shift in weight causes the car to overturn; in heavy electric vehicles, even more so. A significant “toss of the head”, or the way the vehicle shakes your body as it crosses uneven ground, is clearly undesirable and Rivian strives to improve driving for what Macaruso calls “living room comfort.”

“Essentially, you feel the vehicle roll over or lean when you turn a corner, and that’s what happens [the hydraulic system] check with different pressures on each corner of the vehicle “, says Macaruso.” Imagine if you had to try to climb a flight of stairs with your arms and legs on all fours and one leg starts to tire more, the other three compensate for it. “

Rivian’s R1T has 800 horsepower and over 900 foot-pounds of torque on tap, and drivers can hit the accelerator and hit 60 mph in just three seconds. It’s great when speed is the goal, but driving four by four requires more finesse to avoid breaking the truck. The R1T boasts balanced geometry for its approach, breakover (the angle between the vehicle’s tires and the center of its belly) and starting angles paired with a fairly generous 15-inch ground clearance, giving the truck lots of balance and constant movement over obstacles on the track.

The company is watching how the truck handles the toughest tests and is adjusting accordingly. After longtime Rebelle team Emme Hall and Rebecca Donaghe felt the settings of their R1T model were not conducive to sand dune driving during the 2021 rally, Rivian added a soft sand mode to both the R1T and the ‘R1S and the over-the-air software update earlier this year. On hard sand, you don’t need to switch to soft sand mode, but floating on top of dunes or on a beach requires more rotation and the mode allows for better control.

“When you turn on the soft sand mode, it changes the amount of wheel spin you can have,” says Macaruso. “And he’s essentially saying to the truck, ‘Hey, you can dig harder’ because every single wheel is independently controlled. And that means that each motor can control a wheel and move it differently. “

While Rivian’s recent recall due to an insufficiently tightened steering knuckle fastener scared investors this week, the company is moving forward with its impressive truck and SUV. If they can handle the Rebelle Rally, they are well positioned to succeed.

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