VSC is the latest in brake-slip-control offering from TRW, combining the capabilities of ABS and traction control (TC) with a new lateral stability-control feature. Building upon ABS and TC functions, the system uses more powerful computers to process and react to additional information provided by brake pressure, steering angle, lateral acceleration, and yaw-rate sensors. TRW will make use of its Center of Automotive Technology (CAT) in Redondo Beach, CA, so braking systems can benefit from the same technology used in TRW's aerospace and defense programs, such as advanced algorithm designs and lightweight silicon materials.

TRW predicts significant volume increases in the production of Vehicle Stability Control (VSC) systems will drive down costs in the coming years.

TRW says it will be the first to market with VSC systems for North American-designed SUVs and minivans. In addition, the company signed nine VSC contracts within the last 18 months with automakers around the world.

"As vehicle manufacturers become increasingly focused on safety," said Jeff Shaya, TRW's Director, Slip Control, "we are responding by offering a product that will provide this enhanced safety at an affordable cost."

By reducing both engine drive torque and applying brake pressure to one or more of the wheel ends, TRW's VSC alters the turning capabilities of the vehicle for the given road conditions and ensures that the vehicle remains stable and tracks the driver's intended path. To accomplish this, the system relies on information from ABS and TC sensors as well as data input from other sensors. A steering angle sensor, along with a pressure transducer on the master cylinder, is used to determine the driver's intent. A yaw-rate sensor and a lateral accelerometer are used to monitor the vehicle's dynamic state.

The VSC system also helps in potential rollover situations, a concern of the National Highway Transportation Safety Agency (NHTSA) with regard to trucks and sport utility vehicles (SUVs). The system can be taken a step further to more integrated vehicle control systems called full-vehicle dynamic control. For example, the addition of an active roll control (ARC) system on a vehicle equipped with VSC can create significant stability and control improvements, with a 25% saving compared to the cost of a standalone ARC system. Similarly, by adding and integrating other subsystems that can share electronics, sensors, and software—such as electrohydraulic braking, active body control, rear-wheel steering, and adaptive cruise control—TRW can increase functionality and improve performance, while minimizing complexity and cost.

Kevin Jost

AEI September 2000