Steering: Description and Operation

VGRS System Outline

In the VGRS system, the steering gear ratio can be changed at will. Thus, the VGRS ECU operates the VGRS actuator in order to constantly realize an optimal gear ratio in accordance with the driving conditions of the vehicle. Thus, it attains a high level of maneuverability and stability between the low-and the high-speed driving ranges.

This system is controlled by the VGRS ECU, which operates the VGRS actuator that is mounted on the steering intermediate shaft. The operating angle of the actuator is thus added to the steering angle of the intermediate shaft in order to vary the turning angle of the front wheels in accordance with the vehicle speed.

VGRS System Main Function
- In the extremely low-speed range, which is used when the driver is attempting to park the vehicle, this system changes the steering gear into the smallest gear ratio in order to reduce the driver's steering angle.

- In the low- to medium-speed range, which is used when driving on city streets or on a winding road, this system changes the steering gear ratio to an optimal level in accordance with the vehicle speed. As a result, the vehicle responds with more agility and handles more easily.

- In the high-speed range, the steering gear ratio is set to the maximum level to prevent the vehicle from making over-sensitive movements in response to the driver's steering angle. Thus, this system ensures a stable vehicle response.

- If a vehicle that is driven over a road surface with different friction coefficients brakes suddenly and causes the ABS to activate, the vehicle posture becomes disrupted, thus requiring the driver to operate the steering wheel. When this occurs, the steering gear ratio is rendered even smaller than that of the ordinary VGRS system in order to reduce the driver's steering angle.