For immediate release
Continuously Controlled Chassis Concept: How It Works
FOUR-C - A Unique Chassis
The most interesting feature on the Volvo Performance Concept Car cannot really be seen from the outside or even under the hood: it is the unique continuously controlled chassis that creates unsurpassed potential for optimizing the dampers to suit the driver's bias towards comfortable progress or enthusiastic driving.
FOUR-C (Continuously Controlled Chassis Concept), as Volvo Cars has dubbed the system, is the outcome of close long-term cooperation with ohins Racing AB, one of the world's foremost manufacturers and developers of advanced high-technology damper systems, and Monroe.
What is unique about FOUR-C is its ability to collect huge amounts of information about the way in which the car moves and to respond instantly by the adjusting the damper characteristics to suit.
Every alternate millisecond, that is to say 500 times per second, the system's microprocessor monitors the precise position of each wheel, assessing its degree of grip and so on, and alters the damping characteristics of each individual wheel accordingly.
A Large Amount Of Information
The main body of information supplied to the dampers comes from the height sensors and body-mounted "accelerometers" that measure the position and movements of each wheel and the car 's body. The car 's on-board computer system, Volvo's Multiplex processor system, also supplies vital information to the dampers, helping the system to foresee events before they actually occur. For example, if the driver brakes firmly, this information reaches the dampers a few milliseconds before the brake pads actually grab the discs.
In this tiny time gap, the FOUR-C microprocessor will have calculated just how much the car will want to pitch once the brake pads are actually activated, and using this information, will instantly reset and prepare the dampers to maximize control and road-holding before the body actually has time to alter its pitch.
If braking is so harsh that the ABS system is activated, the dampers are set to maximize tire grip on the road surface. A corresponding effect resulting from harsh acceleration and quick steering wheel movements is also taken care of invisibly by the FOUR-C system.
Three Chassis Modes
FOUR-C offers three chassis modes that can be selected by the driver via a button set into the instrument panel:
1. Comfort
2. Sport
3. Advanced Sport
However, these chassis modes are not fixed settings. They are more a way for the driver to indicate to the system which driving style he or she prefers for the moment. Is it time to pack the car with family and luggage for the annual summer holiday - or for some active driving on curvy roads?
The normal mode, Sport, is optimized for normal driving, with a well-balanced mix of comfort and driving pleasure. On top of this, the driver can select the two other modes.
"The Comfort mode optimizes the FOUR-C body's isolation from irregularities in the road," explains Marcus Rothoff, development engineer at Volvo Cars and the person responsible for the development of FOUR-C. He says that it is as though the car has simulated or virtual dampers suspended in the sky. "Sky Hook " is in fact the term that is used in the industry.
The Advanced Sport mode totally alters the character of the car:
"The system gives top priority to maximum driving pleasure and road-holding, permitting a firmer ride so that the driver has more direct contact with the road surface," continues Marcus Rothoff.
The Volvo Performance Concept Car is equipped with DSTC (Dynamic Stability and Traction Control). It serves as a "helping hand," stepping in to help the driver avoid a skid. In the Volvo Performance Concept Car, the choice of chassis mode influences just how early or late in a skid the DSTC system steps in to recover the car 's poise. The Stability Traction System (STC) is disengaged in the Advanced Sport chassis mode.
FOUR-C significantly enhances the sum total of active driving pleasure, stability and comfort. The three manually controlled modes make it possible to discover and appreciate the thrilling properties of a high-performance car. The system offers enthusiastic sporty driving on demand - in a car that is equally at home driving to the supermarket to do the weekly shopping.
Electronically managed All-wheel drive
The Volvo Performance Concept Car is also fitted with electronically managed all-wheel drive, AWD. It has been developed together with one of the foremost experts in this field - Haldex of Sweden.
The AWD system is linked to the car's Multiplex system. This means that it communicates continuously with the car's other functions to optimize all-wheel-drive operation to suit current conditions. The unique interaction between AWD, DSTC and FOUR-C gives the car exactly the intended ride and road-holding characteristics - anywhere between comfort and advanced sportiness.
The electronically controlled AWD system is characterized by extremely rapid engagement and disengagement. Since the AWD system responds so swiftly, it is possible to balance and control over-steering and under-steering tendencies with immense precision and stability.
"In this application, we're not using all-wheel drive for enhanced off-road ability, but optimizing it for superb road-holding and dependable stability," says Hans Nilsson, overall project manager of the Volvo Performance Concept Car.
"The work we have done with the Performance Concept Car helps us to choose the right path for a feasible high-performance model in the future," concludes Hans Nilsson.
