VSA System Description - VSA Control
Overview
The VSA modulator-control unit calculates the target yaw rate from the wheel speed signal, lateral acceleration signal and steering angle signal and compares the calculated target yaw rate against the actual yaw rate to make a judgment on the slip condition of the vehicle. The VSA modulator-control unit calculates the target fluid pressure based on this condition, determines one of three fluid pressure control modes (increase, decrease or hold), and adjusts the fluid pressure of the applicable wheel accordingly.
Oversteer Suppression Control
The oversteer suppression control outputs a brake pressure signal that is optimally distributed between the outside front and rear wheels through the VSA modulator-control unit when the vehicle goes into oversteer. This generates a moment that suppresses oversteer and stabilizes the vehicle.
Understeer Suppression Control
The understeer suppression control outputs a brake pressure signal that is optimally distributed between the inside front and rear wheels. This generates a moment that suppresses understeer through the VSA modulator-control unit when the vehicle goes into understeer. During acceleration, a drive torque down signal is also output to the management ECU, which increases the cornering force of the driving wheels in order to maintain steerability and improve line traceability.