In the first of a two-part article, our mechanical engineer explains the technology of active suspension.
In 1993’s Formula One season, the Williams FW15C racecar demonstrated the winning performance of active suspension.
THE human body is like a moving machine, with an incredible degree of control to maintain balance, level, shock absorption, skid alleviation and stability at speed. Furthermore, human beings do not need to think or analyse aspects of their mobility to maintain smooth progress. It is all done automatically. It’s absolutely state-of-the-art active (human) body control. Compared to that, the average car’s body control system is primitive – a set of springs, dampers and some linkages, all of which basically “react” to road conditions. Said system is a purely passive one. Hit a bump on the road and the suspension arms move, taking along the springs and dampers that are preset to cater for a specific range of dynamic conditions, and never all of them.
It was Colin Chapman, founder of Lotus Cars and original team principal of Team Lotus F1, who first mooted the idea of continuously re-calibrating suspension elements so that the car would ride and handle consistently regardless of road or speed. Chapman was way ahead of his time, though, because the necessary high-speed hardware and electronic control weren’t suffi ciently developed in 1982 to enable his F1 cars to win races. It was only a decade later that Frank Williams’ F1 machines showed the worth of “active suspension” to the world. Indeed, in the 1990s, the game of highspeed electronic processor control and super-responsive actuators had moved to a far higher level than in the 1980s.
The first task of active suspension is to maintain the car’s level and ride height.
With 21st century technology, active suspension is now appearing in passenger cars, albeit mostly high-end models for now. It is not quite humanoid yet, but real-time variance of springing, damping and ride level has considerably enhanced vehicle dynamics and eased the dreaded ride/ handling compromise. Like all modern systems found in today’s automobiles, active suspension relies on accurate solid-state sensors, an electronic control unit and fastacting actuators. The first task of active suspension is to maintain the car’s level and ride height. This story (and the “active action”) will be continued in our next issue.