Re: 4C - How it Works (napster)
A brief description dated back to S60R, which should be pretty accurate today as well. Basically, it adjusts the stiffness of each shock absorber individually and continuosly, based on pre-set, driving conditions and driver's input (steering wheel, throtlle position and brakes). (from my archive)
"Four-C Technology
The Most Advanced Active Chassis on the Market
Four-C Technology (Continuously Controlled Chassis Concept) is the command center of the new Volvo S60 R sedan. Considered the world's most advanced active performance chassis, the Four-C helps bring the promise of the Volvo Performance Concept Car (introduced in Paris, 2000) to production reality.
Volvo S60 R delivers the uncompromising road contact of an extreme sports sedan, but it's also capable of providing the comfort essential for a drive with the family. With the versatility to combine both, the S60 R presents performance unmatched on the road today.
The Continuously Controlled Chassis Concept (Four-C)
What differentiates the Volvo Four-C from other chassis concepts is its ability to process enormous amounts of information. Strategically placed sensors on the chassis measure the longitudinal, lateral, and vertical acceleration of the car relative to driving conditions.
There are sensors to measure:
the rotational speed and vertical movement of each wheel
steering wheel deflection and velocity
cornering (yaw rate)
engine torque (calculated)
braking interventions by ABS and DSTC
In much the same manner as the human brain, the sensory information is received and immediately acted upon. The Four-C's sophisticated microprocessor computes the motions of the car to adapt the hardness of the shock absorbers. The result is that the car is always fluid with the surface of the road.
While the S60 R negotiates varying terrain, the shock absorbers are updated with new information 500 times a second. In essence, the system makes adjustments continuously, and instantaneously.
The Four-C is a first in the world of cars. To develop this totally new technology Volvo collaborated with high-tech system developer Öhlins Racing AB and shock absorber manufacturer Monroe (both leaders in their fields).
The computerized electrical system of the Volvo S60 R, known as Multiplex, also sends information to the Four-C system. Under severe braking for instance, the Four-C system receive the braking information a few milliseconds before the brake pads touch the brake disc. By then the Four-C microprocessor has computed how much the braking will cause the front end of the car to dive, and uses this information to set the shock absorbers to maximize control and tire grip.
When the car is accelerating, Four-C receives the corresponding information from the longitudinal acceleration sensor. Similarly, the system passes on information about a sharp deflection of the steering wheel a few milliseconds before the car actually changes direction.
So Four-C can predict what is going to happen, making the pun in its name (foresee) highly appropriate."