Smart suspension latest high-tech frontier
Back in the dark ages, 4WDs had a commercial origin and, while good for off-road work, road cars were the norm for comfortable daily transport.
But modern engineering principles and design mean high levels of creature comfort, performance and economy are no longer unattainable for 4WDs. The latest driver-assist technologies that were once appropriate on the pages of a good science-fiction novel are increasingly common across manufacturers.
Think adaptive radar cruise control, collision detection, corrective lane wander, wade sensing and even vehicles capable of self-parking.
But while these are nifty technologies, what makes a 4x4 good off-road creates equally proportional weaknesses in dynamic on-road handling.
A supple suspension system provides long wheel travel and flex over undulating terrain and maintains wheel contact with the surface for traction. It improves stability by allowing the driver to keep the vehicle as level as possible when negotiating challenging conditions.
The exact opposite applies during high-speed on-road cornering. That supple flex creates excessive body roll and a slow turn-in, which makes for a clumsy ride, and is detrimental to vehicle stability in an emergency.
Enter the next three avant-garde technology musketeers working to remove the inefficiencies of a fixed mechanical suspension system: infinitely variable shock absorbers, sway bars and torque vectoring.
Drive modes such as comfort, normal or sport can be achieved by varying shock-absorber response. But they require the driver to manually switch between modes.
Modern systems use magnetic fluid; an electric charge alters fluid viscosity to change the damping rate. Unlike preset modes, it is infinitely variable and automatically adjusts in milliseconds to respond to any type of terrain or road speed, immediately providing the driver with the best available control.
Sway bars improve on-road handling by reducing body roll but off-road are restrictive as they limit suspension flex. Manually disconnecting the sway bars in off-road conditions provides a good compromise.
However, dynamic systems use variable sway bars controlled via an actuator to respond to differing conditions. They offer excellent off-road flex but tighten up to minimise body roll during on-road cornering in a transition imperceptible to the driver.
Finally there’s torque vectoring — needing to maintain throttle application in soft sand, while making a turn, usually results in understeer.
During acceleration torque vectoring acts like the skid steer of a bobcat by braking the inside wheels and sending more of the available spread of torque to the outside wheels.
It results in a more responsive turn in assisting the driver to keep a tighter radius. It also has the same effect on the blacktop, minimising understeer providing greater stability and safety.
So what’s next, artificial intelligence?
Let’s hope not, or you might be in for a shock. Imagine jumping into your pride and joy to pop down to the shops for the paper.
But the vehicle won’t start, instead there’s a condescending tone from the voice-activation system: “Sir, the seat pressure sensors indicate you’ve gained a little weight over the past few journeys, the forecast is for fine weather. I recommend you walk. Would you like directions sent to your mobile phone — please confirm yes or no!”
© The West Australian
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