The Ground X Vehicle Technologies program explores the advantages of powering vehicles with multiple electric motors

In late June 2018, shortly after IEEE Spectrum’s recent feature on in-wheel motors for electric vehicles went to press, the Defense Advanced Research Projects Agency (DARPA) issued a press release describing various novel concepts for military vehicles, some of which make use of distributed electric motors. These prototypes were developed as part of DARPA’s Ground X Vehicle Technologies (GXV-T) program, which is intended to find ways to make military vehicles less vulnerable to attack. The usual technique for doing that is, of course, to add heavy armor. The GXV-T program explored another approach—to make vehicles nimbler and thus “improve survivability without up-armoring the vehicle,” according to program manager Amber Walker.

One of the technologies developed under the GXV-T program is an in-wheel motor developed by U.K.-based QinetiQ. Like the commercial in-wheel motors described in Spectrum’s recent feature article, QinetiQ’s motor can improve the handling of a vehicle by allowing each wheel to be powered separately. It differs from the commercial offering described in Spectrum‘s July issue, though, in that it has a built-in transmission. (The commercial unit makes do with no gearing at all.)

For a military vehicle, a key advantage of using in-wheel motors rather than a centrally mounted electric motor and transmission is that it eliminates the drive shafts or axles that you’d otherwise need under a vehicle—components that can become deadly projectiles in a military vehicle should it run over an explosive more