Electric-vehicle skateboard: Car of future?
New self-contained-platform chassis design might be with us fairly soon
Several automakers plan to add numerous electric vehicles to their offerings — Audi, for example, is promising 20 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 integrated electronic motors, battery and driving components that can be scaled to various sizes and topped with a variety of bodies.
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 startup 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.
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 to increase range or performance.
The skateboard also includes the electric motor — or motors, depending on the driveline. 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 ones to drive each rear wheel.
Electric vehicles with allwheel 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.
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.
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.
The skateboard might seem new, but it dates to the Autonomy, a GM concept car from 2002. It was designed to be hydrogen-powered and completely autonomous; 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.
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.