Ford is working on a crazier version of the Hummer EV’s Crab Walk

One of the most eye-catching features of the new GMC Hummer EV and the upcoming Chevy Silverado EV is the four-wheel steering, specifically the Hummer’s “Crab Walk” mode. The system allows the vehicle to drive diagonally, which GMC says can help the truck negotiate a variety of terrain obstacles. It’s basically a very neat party trick, and apparently one that Ford engineers are quite interested in recreating. In fact, patent documents indicate the Dearborn automaker is looking to expand the system’s capabilities within its own inventory of off-road vehicles.

Documents filed with the United States Patent and Trademark Office show that Ford sees value not only in crab walking, but also in taking concepts like Rivian’s Tank Turn or its own Trail Turn Assist to a whole new level. We talk pretty crazy stuff.

Ford

The patent document itself was filed at the end of September 2020, but it was only published on March 31 this year. Titled “CRAWL OPERATIONS FOR FOUR-WHEEL STEERING VEHICLES,” it features illustrations of a previous-generation F-150 Raptor pickup equipped with four-corner steering. That said, it appears that this system will only be for electric trucks like the F-150 Lightning. As you can see below, some of the things Ford wants this off-road truck to do require electric driving.

The first thing Ford describes is somewhat bizarre. In a nutshell, it wants to turn the front wheels to the right or left while turning the rear wheels in the opposite direction and then drive the two axles towards each other. In this way, the car can move left or right on a loose surface without moving forward or backward, much like an all-round forklift. If this is a little confusing, the automaker provides illustrations to better explain what it’s trying to do.

This type of system could be achieved with any number of powertrains, but it seems a dual-motor layout is what Ford has in mind. As the flowchart above indicates, this system would work pretty seamlessly from the driver’s perspective. The truck would stop, the differentials would lock, the wheels would turn, and the car would start moving left/right based on undefined driver inputs. Would you turn the steering wheel to move left or right, or press the gas pedal? Unclear. However, a yaw sensor would ensure the vehicle remains straight, but modulate the power to the front/rear axle to ensure this is the case.

Ford doesn’t stop there either. In addition to having a mode for the system that appears to work very similar to the Hummer EV’s Crab Walk, the truck appears to be equipped with steering that is completely decoupled from the steering wheel itself. This allows each of the truck’s wheels to turn independently, which means that while e.g. the left front tire is turned to the left, the front right tire can be turned to the right – same for the rear axle. Thankfully there are pictures for this too.

Why would a driver want this? Well, basically the patent says that this mode is intended as a kind of last ditch effort to crawl out of trouble. If you’re completely stuck, Ford says a little, “Yeah, sure, why not turn all the wheels against each other to try to get out?” In theory, this might give the truck just the right amount of traction it needs to free itself. And like the previous mode, it locks all differentials and uses a yaw sensor to make that happen.

The patent further indicates that all these operations can be performed manually or automatically. However, there is no mention of using them on the pavement, to be clear. “Snow, sand, mud, ruts, etc,” are the places where this kind of thing will be used, ie a truck potentially equipped with this system will not be able to slide sideways into a parking space. Not without making an awful lot of noise and probably doing a number on the truck’s suspension. The document mentions that the wheels will have their own torque sensors to determine the level of traction at each corner, so it will very likely be able to figure out the driver’s intentions. Or, Ford can also just say that using the pavement mode voids your warranty, etc.

In any case, I think it’s only fair to pop a champagne bottle and announce that the four-wheel steering wars have officially begun. Assuming this system makes it onto an off-road version of the F-150 Lightning, it’s only a matter of time before that truck and the Hummer are taken off-road to test their radical capabilities. If you thought Rivian’s tank turn was extreme, think again, Dearborn might just be taking things to a whole new level.

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