Active Cornering Enhancement

Active Cornering Enhancement, abbreviated to ACE, is an active anti-roll system developed by Land Rover for its larger off-road vehicles. Its aim is to resolve a long-standing conflict in the engineering of capable four-wheel-drive cars: the wish to keep the body upright and stable through corners on the road, set against the need to let the wheels move freely and independently over rough ground off it. ACE addresses this by varying how strongly the anti-roll bars resist body lean according to circumstances.

A conventional anti-roll bar, or sway bar, is a torsion spring linking the wheels across an axle; it stiffens the suspension in roll to reduce lean in corners, but in doing so it also ties the two wheels together, which limits how far one wheel can droop or rise relative to the other. Off-road, that limitation reduces articulation and can lift a wheel clear of the ground, costing traction. ACE replaces the fixed bars with hydraulically actuated ones, fitted with hydraulic actuators in place of, or acting on, the conventional drop links.

The system works under the control of an electronic unit fed by sensors monitoring lateral acceleration, steering and speed. On the road, when the car corners, the control unit drives a hydraulic pump and valves to pressurise the actuators, which apply a twisting force to the anti-roll bars proportional to the cornering force. This actively counteracts body roll, so the vehicle leans far less than its tall, soft, off-road-biased suspension would otherwise allow, giving more car-like composure and reassurance at speed.

The clever part is what happens off the road. At low speeds and when articulation is needed, the system relaxes the hydraulic pressure so that the anti-roll bars exert little or no restraint, effectively decoupling the wheels across each axle. This allows the suspension to flex to its full travel, letting wheels rise and fall independently to follow the contours of the terrain and keep tyres pressed into the ground for maximum grip on rocks, ruts and steep cambers.

In this way ACE delivers the best of both regimes that fixed anti-roll bars force a designer to choose between. The driver gets reduced lean and confident, stable handling on tarmac without sacrificing the deep wheel articulation that defines a genuine off-road vehicle. As with any hydraulically actuated suspension feature, it adds a pump, lines, valves and actuators that introduce complexity and maintenance considerations, and it relies on its sensors and electronics functioning correctly to apply the right amount of restraint at the right moment.

ACE belongs to the broader family of active anti-roll and roll-mitigation systems and is closely related to the humble anti-roll bar it refines. It shares its underlying goal of controlling body roll on demand with active roll mitigation systems and with adaptive suspension generally, and it parallels in concept, though not in detail, other manufacturers' active suspension efforts such as Mercedes-Benz's Active Body Control, each tackling the trade-off between comfort, on-road control and, in Land Rover's case, off-road capability.