System Description

RAS SYSTEM


System Description


DESCRIPTION
- RAS control unit controls the rear active steer.
- RAS system consists of RAS control unit and RAS actuator components.
- RAS control unit controls the RAS actuator assembly according to the steering angle and vehicle speed.
- Self-diagnosis can be performed with CONSULT-III at each control unit to another RAS control unit.
- It transmits/receives each signal from the following control unit via CAN communication line.






Model Following Control
- Situation :





The rear wheels turn to the opposite phase of front wheels for a moment so as to improve the start-up of yaw rate (steering angle speed).
- Situation :
The rear wheels turn to the same phase of front wheels after securing the necessary yaw rate (steering angle speed) to cornering.

OPERATION DESCRIPTION
The rear wheel angle changes as per the following:

During high-speed driving
- The rear wheels turn to the same phase of front wheels regardless of the operation speed of steering wheel.






During middle- low-speed driving
- When turning the steering wheel rapidly, the rear wheels turn to the opposite phase of front wheels for a moment just after starting the steering wheel operation. And then, they turn to the same phase.
- The rear wheels turn to the same phase of front wheels when turning the steering wheel slowly.






During extremely slow-speed driving and at straight-ahead driving
- The rear wheels do not turn during extremely slow-speed driving regardless of the operation speed of steering wheel.
- The rear wheels do not turn at straight-ahead driving regardless of the vehicle speed.






OPERATION FEATURE

RAS ACTUATOR
- It is driven by RAS motor.
- The irreversible efficiency performance hypoid gear secures the toe-stiffness of rear wheels against the road external force and keep the steering angle when system is malfunction.
- The power from the pinion gear (motor side) is transmitted, but the pinion gear does not rotate as caused by the gear mechanical characteristics (teeth angle) even though the ring gear (tire side) starts to rotate.