Overview
This document contains information on:
General
Function requirements
Function
General
The rear axle steering changes the toe angle on the rear wheels. The toe angle on the rear wheels is adjusted by a tie rod on each rear axle steering control unit. The toe angle change at the rear wheel is a maximum of 1.5 °.
The active rear axle steering assists the driver in unexpected driving situations such as, e.g. in the event of any evasive maneuvers thereby providing a major contribution to active safety.
Function requirements
Ignition ON (circuit 15)
Function
The right rear axle steering control unit evaluates the status and sends corresponding data to the ESP® control unit.
Turn rear wheels to opposite direction of front wheels
Turn rear wheels parallel to front wheels
System and warning messages
Turn rear wheels to opposite direction of front wheels
At a vehicle speed up to 100 km/h the rear wheels are turned in the opposite direction to the front wheels. This virtual shortening of the wheelbase enables the vehicle to be even more agile when steering into corners and requires less force of the hand on the steering wheel, particularly on routes involving lots of changes in direction or ones that have a slalom character. The advantage in daily driving situations such as, e.g. when turning off a road or when parking lies in the reduced turning circle.
The rear axle steering control units evaluate information from the ESP® control unit and change the toe angle at the rear wheels accordingly. At the same time, the right rear axle steering control unit sends the toe angle change request to the left rear axle steering control unit.
The right rear axle steering control unit sends the status and steering position of the rear axle steering to the ESP® control unit.
Turn rear wheels parallel to front wheels
If the vehicle is moving at a speed faster than 100 km/h, the rear wheels are turned parallel to the front wheels. This is equivalent to a virtual extension of the wheelbase and thereby significantly improves driving stability. The faster build-up of lateral force on the rear wheels when changing direction results in a quicker response to steering commands.
The rear axle steering control units evaluate information from the ESP® control unit and change the toe angle at the rear wheels accordingly. At the same time, the right rear axle steering control unit sends the toe angle change request to the left rear axle steering control unit.
The right rear axle steering control unit sends the status and steering position of the rear axle steering to the ESP® control unit.
System and warning messages
The right rear axle steering control unit sends requests to output system or warning messages to the instrument cluster. The corresponding system or warning messages are shown on the multifunction display.