The Vehicle Stability Assist (VSA) system is another technology introduced by Honda together with two other technologies on the 2nd of July 1997. The VSA system is an active safety system that consists of three technologies. Two of them are existing safety systems – Anti-lock Braking System (ABS) and Traction Control System (TCS) – previously offered in Honda vehicles. The third technology in a VSA system is a Side Slip Control feature.
An example of when side slip may occur is when a driver engages a corner too quickly on a wet road. When the cornering forces of a vehicle are greater than the available tire grip levels, side slip occurs. If the front wheels are slipping sideways, the car is understeering. On the other hand, if the rear wheels are slipping sideways, the car is oversteering.
Sensors are placed around the vehicle to help detect when a side slip is occurring. These sensors include wheel speed sensors, steering angle sensor, yaw rate sensor and lateral acceleration sensor. The intelligent unit that detects and controls the VSA system to correct a side slip is the VSA-ECU component. This component detects understeers or oversteers by comparing the target yaw rate by the driver with the actual yaw rate of the vehicle.
The yaw rate used to detect understeers is calculated using the steering angle and vehicle speed variables collected from the respective sensors. When this happens, the VSA system reduces the engine torque and may even apply the brakes to the inner front wheel to correct the understeer. On the other hand, the yaw rate used to detect oversteers is calculated using the lateral acceleration, steering angle and vehicle speed variables. The VSA system applies the brakes to the outer front wheel to correct such oversteers.
In short, the VSA system helps to prevent accidents by preventing vehicles from sliding sideways caused by sudden changes in vehicle behavior or wet road. Such safety features is definitely worth the money that one has to fork out when buying a Honda.