Active Steering Assist, Basic Function - GF54.71-P-9903A

Model All (4xWD) 

Model All (CAR) 

Courtesy of MERCEDES-BENZ USA

Example illustration of Active Steering Assist intervention 

Overview 

This document contains information on:

• General 
• Function requirements 
• Function 
  • Lane change 
  • Steer and touch recognition 
  • Active Emergency Stop Assist 
  • Functional restrictions 

General 

The "Steering torque specification" function assists the driver in keeping the vehicle in the center of the lane on a straight stretch of road and in slight curves. Up to a speed of 210km/h the system is orientated on the lane markings and up to 130km/h on vehicles driving in front.

This means that active track guidance is also still available when lane markings are not visible or not clearly visible or when a structured traffic situation is given (clustering characteristic).

To evaluate the lane markings, the system uses a multifunction camera behind the windshield close to the inside rearview mirror.

If the driver indicates that he wishes to change lane by turn signaling and the system does not detect another vehicle in the adjacent lane, the system assist the lane change with the aid of steering torques.

An emergency stop assistant is activated if the driver ignores prompts from the intelligent hands-off warning to place the hands onto the steering wheel. It brakes the vehicle in the lane until it comes to a standstill, if the driver is obviously distracted or if the driver has lost control of the vehicle.

The vehicle is routed off-center in the lane (as of market launch of model 167) in stop-and-go traffic (traffic jam) on freeways. This enables a rescue lane/corridor to be formed when required.

The system relieves the driver through active track guidance on freeways and highways thereby improving safety and comfort.

The system is active in a vehicle speed range of 0to 210km/h. It is switched on and off together with Active Distance Assist and can be deactivated in the media system using the Assistance menu.

The system decides whether the vehicle driving in front is to be pursued or if it should follow the lane markings instead.

Torque-assisted traffic jam driving is still possible even where lane markings are not visible or not clearly visible or where structured traffic situations are given (cluster characteristic).

Function requirements 

• Engine in operation or drivetrain operational
• ESP® functional
• Distance control switched on
• Active track guidance switched on
• No trailer operation (vehicles with trailer hitch)
• Tire pressure of all wheels within the tolerance range (no run-flat mode active)
• Standstill comparison successfully completed

Function 

The system evaluates the traffic area monitoring data to calculate any necessary reactions. To do so, the front and rear radar sensors as well as the multifunction camera provide the corresponding information. The system also evaluates the following function-relevant parameters:

• Vehicle speed, direction of travel, acceleration
• Electric power steering, status
• Multifunction camera lane data
• Location information (position finding) for traffic assessment (map data)
• Intention to change lane (flashing)
• Steering torque from driver and wheel angle ("Hands Off Detection" status)
• Steering wheel angle
• Driving stage engaged

The system evaluates all relevant influencing parameters and calculates the required steering torque, which is then implemented by the electric power steering.

For longitudinal control, the system controls engine output, the transmission and the brakes as needed. For lateral control, the system controls the electric power steering as needed.

The driver receives noticeable feedback through the steering wheel. The system status is indicated to the driver by means of a steering wheel symbol in the central display.

The system is intended to assist the driver only. The driver must always be aware that at any given time the system may make a track-aligning intervention. The responsibility for maintaining a safe distance, for speed, timely braking and for staying within the lane remains with the driver.

Lane change 

Valid with code K32 (Active Lane Change Assist)

The Active Lane Change Assist is available in different ways depending on the model and model year! Code K32 (Active Lane Change Assist) must be entered in the vehicle data card or in the Vehicle Documentation (VeDoc).

The system supports the driver when changing lane through appropriate steering wheel torque. Lane changing is assisted between 80and180km/h.

The following conditions must be fulfilled for this:

• The function is activated/switched on.
• The journey is on a freeway or a road with several lanes (roads with multiple lanes are referenced from the map data of the navigation system).
• The driver starts to change lane by switching on the turn signal.
• The turn signal indicator is switched on.
• The adjacent lane is marked with a broken limiting line.
• No other vehicle is detected in the relevant lane into which the change is to be made. The traffic area is monitored by the front and rear radar sensors as well as by the multifunction camera.

The lane changing maneuver is interrupted under the following conditions:

• The driver steers too much in the direction of the lane change.
• The driver switches on the turn signal indicator in the opposite direction.
• The driver steers in the opposite direction.
• Distance control or active track guidance is canceled by depressing the brake.
• The traffic area monitoring detects objects on the lane into which the change is to be made.
• Traffic area monitoring detects a critical situation such as, for example the tail-end of a traffic jam.
• The system is unable to carry out lane changes due to environmental influences such as, e.g.sagging roadway.

Example illustration of steering wheel symbol 

If a lane change is not immediately possible, then the green steering wheel symbol is shown with a green arrow for several seconds.

Courtesy of MERCEDES-BENZ USA

Example illustration of steering wheel symbol 

With the activation conditions are met, the status display changes to green.

Courtesy of MERCEDES-BENZ USA

If the system detects within a brief period that the lane is free, the turn signal indicator is automatically activated and the lane change is then initiated. The driver can cancel the lane changing maneuver at any given time.

The actual lane changing maneuver is shown to the driver. If the maneuver is aborted, a corresponding message is shown.

Steer and touch recognition 

Steering and touch detection monitors the torque at the steering wheel or if the driver's hand touches the steering wheel in vehicles with capacitive steering wheel.

If it does not detect any torque on the steering wheel or torque that is too low or if it determines that the steering wheel is not being touched, it issues a message to the driver. The steering wheel symbol flashes. A warning message also appears. If the driver fails to respond to these messages, warning tones are then issued as a take-over prompt (hands-off warning).

The system regards active steering or system operations using the buttons on the multifunction steering wheel (as of Driving Assistance Package Generation 5) as reactions to these messages.

If the driver fails to respond to the warnings, the distance control reduces speed first. The vehicle is then braked to a standstill using the Active Emergency Stop Assist if no response is forthcoming.

The volume of active audio sources is reduced during the warnings. Warnings are also only issued when tangible hazardous situations are detected.

Example illustration of steering wheel symbol 

When a green steering wheel is shown, the system is switched on and the lateral control is active.

Courtesy of MERCEDES-BENZ USA

Example illustration of steering wheel symbol 

When a gray steering wheel is displayed, the system is switched on, but the lateral control function is in passive mode.

Courtesy of MERCEDES-BENZ USA

Example illustration of steering wheel symbol 

A white steering wheel with red hands indicates when the driver is to take over lateral guidance.

A display is issued in the following situations:

• Lateral control is reaching the system limit (only up to YoM 20/2 (code 051)).
• The maximum duration without driver activity has been exceeded.

Courtesy of MERCEDES-BENZ USA

Example illustration of steering wheel symbol 

The red steering wheel with red hands is displayed if the system was deactivated, e.g. after rapid cornering with high lateral acceleration. The driver must take over lateral guidance.

Courtesy of MERCEDES-BENZ USA

Active Emergency Stop Assist 

The Active Emergency Stop Assist enhances level of road traffic safety. It intervenes when the driver is no longer capable of steering and braking the vehicle. The vehicle is braked to a standstill in its own lane and secured using the parking brake.

As soon as the vehicle is at a standstill for more than 10s, an automatic emergency call is issued. After another 10s, the vehicle is automatically unlocked.

The system recognizes a permanently distracted driver or a driver who is no longer capable of intervening in driving events, e.g. in event of unconsciousness. It evaluates steering and contact detection information for this.

The hands-off warning is issued during an emergency stop. Distance control remains active. The distances to vehicles in front and the track guidance are still supported.

If the system changes because of system impairments (e.g. glare from solar radiation) from an active status to a passive one, the Active Emergency Stop Assist still brakes down to a standstill. Track guidance is not supported here.

Sequence and display:

• After several acoustic hands-off warnings (take-over prompts) the system starts the Active Emergency Stop Assist.
• The driver is prompted to react by brake pulses and seat belt tensioning retractions (as of market launch of model 223).
• After further acoustic hands-off warnings, the deceleration procedure is started.
• If the driver fails to respond, an "Emergency stop initiated" message is shown.
• The speed of the vehicle is reduced in stages until it reaches a standstill.

  Additional sudden brake pulses and seat belt tensioning retractions are also produced as of market launch of model 223.

• The hazard warning lights are switched on at speeds below 60km/h.
• Depending on the country involved, a lane change to the adjacent right lane is performed (as of market launch of model 223).
• Once at vehicle standstill, the vehicle is secured with the electric parking brake.
• After 10s, an emergency call is sent to the Mercedes-Benz Emergency Call Center.
• After another 10s, the vehicle is unlocked so that external assistance can render aid.

The Active Emergency Stop Assist activities are ceased when driver reactions are detected.

Functional restrictions 

The steering torque function specification may be impaired by backlighting, darkness, rain or snow. The system permits a limited degree of steering torque only for lateral guidance. Under certain circumstances, the steering torque may no longer be sufficient to keep the vehicle in the lane.

If traffic area monitoring is impaired, the system changes to a passive mode and no longer offers any assistance.

	Function schematics
	Specify steering torque, function schematic	Model 118, 167, 177, 243, 247, 293 with code 233 (Adaptive cruise control Plus (DISTRONIC PLUS)) Model 213, 238, 257, 290 as of model year 2021 with code 233 (Adaptive cruise control Plus (DISTRONIC PLUS))	PE54.71-P-2504-97A
		Model 223, 297	PE54.71-P-2504-97B
		Model 192, 206, 214, 232, 236, 254, 294, 295, 296	PE54.71-P-2504-97C
	Additional basic functions
	Distance control, basic function	Model all (4xWD) with code 233 (Adaptive cruise control Plus (DISTRONIC PLUS)) with code 239 (Adaptive cruise control Pro (Distronic Pro)) Model all (CAR) with code 233 (Adaptive cruise control Plus (DISTRONIC PLUS)) with code 239 (Adaptive cruise control Pro (DISTRONIC Pro)) with code 23P (Drive package) with code 266 (Active Steering Assist) with code P20 (Driving assistant package Plus)	GF30.30-P-9903A
	Brakes, basic function		GF42.00-P-9900A
	Driver activity detection, basic function	Model all (CAR)	GF54.30-P-1000A
	Traffic area monitoring, basic function		GF54.71-P-1000A
	Track guidance, basic function		GF54.71-P-9900A
	Hand detection, basic function	with steering wheel generation 5 (Capacitive steering wheel) and code 266 (Active Steering Assist)	GF82.90-P-9904A