Active Toe Control

Prodrive is currently developing an innovative system called Active Toe Control that may eliminate the need for complicated multi-link rear suspension setups.

Active Toe Control works on the rear axle of a front wheel drive car to adjust the toe angle depending on the speed of the vehicle. Toe angle is typically set between a compromise of giving a vehicle agile handling at lower speeds (toe-out on the rear axle) or making it more stable and predictable at high speed (toe-in). Active Toe Control eliminates this compromise, ensuring optimum toe angle at all times.

“Typically most drivers stay well within 60-70 per cent of their car’s capabilities. This means vehicle manufacturers are increasingly focusing on making their cars feel more sporty in this region, without necessarily increasing their outright performance,” says Matt Taylor, Prodrive chief dynamics specialist.

According to Taylor, handling characteristics are increasingly becoming attributes of vehicle brands. A German car is expected to have its yaw rate and lateral acceleration build at the same time, so you feel as if the rear wheels are following the front wheels, with the car turning around the rear axle.

A typical French front wheel drive car however, is expected to have its lateral acceleration lag behind the yaw rate gain where the suspension flexibility allows the rear wheels to move sideways before ‘pushing’ the rear of the car.

“This gives the driver the sensation that the car is momentarily turning on the spot around its centre of gravity, as the nose tucks in and the back kicks out, giving an agile feeling. Neither approach is right or wrong, it’s a matter of preference. Vehicle manufacturers really want ways to reduce the production cost of their cars. Replacing simple twist beam axles with more expensive multi-link systems goes against the grain, but as they all strive for class leading handling, it is direction they are being forced to take. With Active Toe Control you have the added benefit of refining the handling simply by changing the control algorithms on the production line or at the dealer, to give the characteristics favoured by whichever market the car is to be sold,” adds Taylor.

Active Toe Control is still conceptual at this time, and Prodrive is looking for a hardware partner to take the project to a working prototype.

Related Links:
What is Toe Angle? (Wikipedia)