Electrified vehicle wheel speed control using heave when traversing deformable terrain

Abstract

An electrified vehicle, system, and method include an electric machine, a traction battery coupled to the electric machine, and a controller programmed to control wheel slip to provide high wheel slip to traverse deformable terrain, such as sand or loose soil, and lower wheel slip to avoid excessive soil removal beneath the wheels after detecting a vertical acceleration or heave event, such as after landing when driving over a jump or bump. When vehicle vertical acceleration exceeds a first threshold, and a ratio of a wheel angular acceleration to vehicle longitudinal acceleration exceeds a second threshold, the electric machine is controlled to limit wheel slip to a lower value that provides sufficient tractive force to maintain some forward motion. Otherwise, the electric machine is controlled to limit wheel slip to a higher value to accommodate higher vehicle speeds over the deformable terrain.