A Unified Chassis Control Strategy

Today’s vehicles do much more than transport passengers from location to location. Cars, trucks and SUVs are becoming extensions of consumers’ personalities and often help characterize and define their owners.

Consumers search for a certain brand, character, look and feel of their automobiles while concentrating on safety and performance. So this is where automakers create the distinctions and although many mechanical aspects may appear similar, there are variations in feel.

Traditionally, vehicles contain steering, braking and suspension systems that act independently. Each of these systems is tuned to match the desired performance and brand character of the vehicle. In order to achieve overall balance, performance trade-offs are required in steering, braking and damping. Delphi Corporation’s Unified Chassis Control (UCC) strategy can ultimately make this approach obsolete.

UCC integrates two or more electronically-controlled chassis systems for enhanced vehicle safety, performance and control. UCC is the next leap ahead due to the ability to intelligently integrate chassis systems to eliminate trade-offs, simplify chassis system tuning and greatly enhance overall chassis performance versus traditionally tuned, independently controlled systems. The result is enhanced safety, improved vehicle performance and improved ride comfort and control.

Delphi’s UCC strategy builds upon the current and anticipated future innovations in the areas of controlled braking (antilock braking, traction control, vehicle stability control and brake-by-wire); controlled steering (electric power steering, electric rear-wheel (four-wheel) steering and steer-by-wire); and controlled suspension (controlled variable damping and dynamic body control).

New system performance and tuning flexibility is achieved through the UCC control strategy. The strategy is comprised of electronics and sophisticated algorithms that functionally integrate these once-independent subsystems to increase stability and control.

This approach utilizes shared sensor data and a flexible architecture to provide seamless connection between the steering, braking and suspension subsystems. This control and architecture strategy ensures optimized coordination, communication management and diagnostics of the subsystems.

Delphi’s first production application of UCC can be found on the 2002 Cadillac Seville and DeVille. These vehicles contain Delphi’s TraXXar vehicle stability control (controlled braking) and continuously-variable real-time damping (CVRTD), or controlled suspension.

Future Delphi UCC applications that combine controlled rear steering and controlled braking can intervene at a much lower threshold to correct vehicle instability. For example, as the system begins to detect slight amounts of vehicle instability, it will activate an appropriate rear-wheel steering motion to correct the situation. Unlike brake-only systems, the correction can take place before most drivers even become aware of instability.

In addition, if the situation requires, the system can also apply the appropriate corner brakes in a coordinated effort (using brakes and steering) to maintain control. During ABS braking, coordinating the brakes to slow down the vehicle and steering to maintain directional control can reduce stopping distance by up to 14% in certain conditions.