How It Works: Electric Vehicle Skateboard Chassis

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Several automakers plan to add numerous electric vehicles to their offerings — Audi, for example, is promising twenty of them over the next five years. And their success may ultimately rest on a skateboard.

A skateboard chassis, actually, which helps bring down the cost and complexity. It’s a self-contained platform with the electronic motors, battery, and driving components integrated into it, and which can be scaled to various sizes and topped with a variety of bodies.

Electric vehicles are still low-volume, and that makes them pricey to build. The skateboard allows an automaker to create EVs in several vehicle segments, without engineering each one individually from the ground up. With any vehicle, research and development costs make up a major portion of the car’s overhead. Keeping this under control on lower-volume vehicles is especially important because there are fewer of them built to amortize the costs.

Tesla already uses a skateboard chassis, while Audi and GM are planning a series of vehicles with such platforms. Other companies include Rivian, where they will underpin an electric truck and SUV, while Hyundai and Kia have partnered with Los Angeles-based start-up Canoo to produce a skateboard platform for their vehicles.

Using one basic chassis design for several vehicles —– known as platform sharing — isn’t new, and virtually every automaker does it. But on most vehicles, the “platform” referred to isn’t the actual chassis, but the engineering design that will be used to produce it. By tweaking and resizing the basic design, it becomes the blueprint to build a variety of body structures. The most efficient platforms are modular, with components shared across several vehicles for more cost savings.

  • The skateboard chassis for GM’s Hy-Wire concept carGeneral Motors
  • GM’s Autonomy chassis was designed to incorporate its hydrogen power sourceGeneral Motors
  • The chassis for the GM Autonomy concept carGeneral Motors
  • GM’s Autonomy concept, showing the body over the chassisGeneral Motors
  • GM’s Autonomy concept car, unveiled for 2002, is considered the first skateboard chassisGeneral Motors

On a unibody vehicle, this platform design becomes part of the body structure. It’s slightly different with trucks and some SUVs, which use a separate frame with the body attached to it. On both of these, once the vehicle structure is built, the engine, driveline components, and suspension are then bolted in.

But on a skateboard, the components required to drive the vehicle are integral components of the chassis itself. The battery is long and wide, and it’s part of the floor structure. Positioned so far down, the battery gives the vehicle a low centre of gravity, which in turn improves handling. The battery itself can be modular, with more cells added as needed. This gives the automaker the ability to tailor the battery to the vehicle’s requirements, such as adding more cells to increase range or performance.

The skateboard also includes the electric motor — or motors, depending on the driveline — as part of it. An all-wheel-drive EV usually uses one front and one rear motor, but Audi’s e-tron S uses three, with one motor driving the front wheels, and two smaller engines to drive each rear wheel.RELATEDLooking Ahead: New Electric Vehicles arriving in 2020Motor Mouth: Can electric vehicles sell without incentives?

Electric vehicles with all-wheel drive don’t require a central driveshaft running from front to rear as with a gasoline-powered AWD system, and torque vectoring — powering one wheel more than another on curves to improve handling — is achieved with software, rather than a mechanical connection.

As with a conventional car, the wheels are connected to the motor with driveshafts. While they’re still at the concept-car stage, some automakers are experimenting with in-wheel motors that fit within the hubs – and once they come to market, they’ll be a natural fit to a skateboard chassis. Using software to determine conditions and power each wheel as needed, an in-wheel system could improve vehicle stability, and even make it easier to park.

The skateboard chassis also includes drive-by-wire modules, which transfer the driver’s input – such as accelerator pressure or gear selection – without a mechanical connection. Drive-by-wire is also used on most conventional vehicles, but on the skateboard, everything’s integrated into the chassis.

The skateboard might seem brand-new, but it dates back to the Autonomy, a GM concept car from 2002. It was designed to be hydrogen-powered and completely autonomous, and without an engine or driver controls, everything could be integrated into the chassis. The name came from to the flat chassis’ resemblance to a skateboard.

  • Audi’s e-tron skateboard chassisAudi
  • The skateboard chassis’ low design provides more interior spaceAudi
  • Audi’s skateboard chassis with a different body on topAudi

The Autonomy wasn’t operational, but it inspired another concept, the Hy-Wire, which was. The body mounted to the Hy-Wire’s skateboard chassis with ten attachment points. GM said this could allow owners to swap one body style for another as their needs changed, such as replacing a coupe with a sedan for a growing family. While it’s unlikely customers would actually do this, it highlighted the skateboard’s construction and its efficiency for manufacturing, even if it took a while before anyone actually built a production vehicle with one.

A skateboard chassis can also be tuned for specific ride and handling characteristics. This gives an automaker even more flexibility when using the same base under several vehicles. Honda and GM are planning to share GM’s new platform and battery, tweaked for each company’s specifications, which will help distribute the overhead and reduce the cost for each company.

Designed as a concept but now used in production, skateboard platforms offer modular design, lower costs, and with their components mounted low and tucked in, more space for passengers and cargo. They may be relatively small players in the auto industry right now, but they have the potential to be something very big.

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