Forward Collision Warning Plus: Notes

DESCRIPTION 

Courtesy of CHRYSLER GROUP, LLC

The Forward Collision Warning Plus (FCW+) system uses the following components:

1.	Integrated Center Stack (ICS)  not used in the Forward Collision Warning Plus system
2.	Refer to RADIO RECEIVER MODULE (RRM) .
3.	Refer to FORWARD FACING CAMERA MODULE (FFCM) .
4.	Refer to STEERING COLUMN CONTROL MODULE (SCCM) .
5.	Refer to INSTRUMENT PANEL CLUSTER (IPC) .
6.	Refer to BODY CONTROL MODULE (BCM) .
7.	Refer to ANTILOCK BRAKE SYSTEM (ABS) MODULE  - Electronic Stability Module.
8.	Refer to POWERTRAIN CONTROL MODULE (PCM) .
9.	Refer to ADAPTIVE CRUISE CONTROL (ACC) MODULE .
10.	Refer to TRANSMISSION CONTROL MODULE (TCM) .
-	Refer to STEERING WHEEL SWITCHES  on the steering wheel spokes.

Forward Collision Warming Plus (FCW+) is a driver assistance system designed to assist the driver in detecting, avoiding and mitigating collisions with vehicles in its forward path.

The FCW+ system is an enhancement to the current vehicles equipped with ACC and a FFCM. This system uses the FFCM for enhanced sensitivity to objects in front of the vehicle. The system utilizes radar and video input to detect whether the vehicle is approaching another vehicle in its path too rapidly and warn/assist the driver in avoiding the incident. The system communicates with other components on the vehicle to apply the brakes and/or to alert the driver through visual and audible warnings. The FCW+ function operates regardless of whether ACC with stop and go is active or not. The system operates down to 0 km/h (0 mph) and provides audible closing/proximity warnings.

Courtesy of CHRYSLER GROUP, LLC

If the driver does not react, the vehicle's braking system is activated to prevent or mitigate the potential impact. Detail below:

• The FCW+ system uses a radar sensor and the FFCM to detect if the vehicle is approaching another vehicle or a big obstacle too fast and warns/helps the driver to avoid/mitigate any collision.
• Using the dedicated menu, the driver can adjust the sensitivity (close, medium, far) and activate or deactivate the warning.
• The Prefill function  prepares the braking system for an emergency braking event.
• FCW+ provides audible, visual and torque alerts. 
• The brake jerk produced by the use of the braking system alerts the driver of the possible impact with a haptic signal.
• Advanced Brake Assist (ABA)  : if the driver reacts, but does not brake enough, the ABA will increase the braking force to prevent/reduce the collision.
• Collision Mitigation System (CMS)  : if the driver does not react, the system activates the braking system to prevent/reduce the collision.

IMPORTANT: 

Both on versions equipped with manual gearbox and on those with automatic transmission, after the vehicle is stopped the brake calipers may be stuck for about two seconds for safety reasons. Make sure you press the brake pedal if the vehicle moves slightly forwards. The system has been designed for road use only. If the vehicle is driven off-road, the system must be deactivated, to avoid unnecessary warnings. By selecting the 4WD LOW mode, the system is automatically deactivated.

FCW+ settings can be changed. When the vehicle is equipped with a newer Uconnect® system screen, the Safety and Driving Assistance soft key needs to be selected to access the options menu. When the vehicle is equipped with the Uconnect® 5.0 system, pressing the "+ MORE" hard-key located on the lower right side of the Uconnect® system will bring you to the "Settings" soft key.

OPERATION 

The following is a list of FCW+ functions and operations:

• The FCW+ system is disabled and enabled via a soft key in the radio.
• The FCW+ system uses the ACC module to determine the range and speed of the vehicle(s) and objects in the forward path of the host vehicle.
• The FCW+ system uses the FFCM to perform object classification and to determine lane markings.
• The FCW+ system uses a sensor fusion algorithm to combine the information from the ACC module and the FFCM.
• The FCW+ system uses this sensor fusion information to determine probable collisions with vehicles and objects in the forward path of the host vehicle.
• The sensor fusion algorithm and logic is contained within the ACC module.
• Based on the sensor fusion algorithm and vehicle dynamic data the FCW+ System determines a Time To Collision (TTC) between the host vehicle and any target vehicles or objects in its forward path.
• When the TTC becomes too small the FCW system issues visual, audible and torque warning(s) to alert the driver of a probable collision.
• The Full Speed Range Forward Collision Warning Plus system will only be active at speeds above 0.5 m/s.
• The system will react on moving objects. A target is considered to be a moving object if it has a velocity greater than zero while the system is tracking it.
• The system will react on stopped objects. A target is considered to be a stopped object if it has a velocity greater than zero, then comes to a stop while the system is tracking it.
• The system will react on stationary objects. A target is considered to be a stationary object if it has zero velocity the entire time the system is tracking it.
• The FCW+ system prepares the brakes for emergency braking by pre filling.
• The FCW+ system provides a short deceleration brake jerk.

FCW+ FUNCTION: 

• Upon the detection of a probable frontal collision, meaning the calculated TTC is too small for the situation, the system shall provide up to two warnings.
• The first warning provided by the system is a combined audible/visual warning to the driver.
• The audible/visual warning can be activated at the same time the brake prefill is performed.
• After the first warning, if the driver has not responded and the collision is still probable, the system provides a second warning. The second warning is a torque warning in the form of a brake jerk.
• The ACC module requests a brake jerk by transmitting a signal to the ABS module.
• The ABS module responds to the execution of the brake jerk request.
• The audible/visual warnings will be active during the brake jerk warning.
• After the brake jerk, if the driver still has not responded and the collision is still probable the system will activate autonomous braking.
• The autonomous braking will be activated for a maximum duration of 2.5 seconds with a maximum deceleration of 0.4 g.
• The ACC module makes the deceleration requests for autonomous braking by transmitting bus signals to the ABS module. That signal is used to determine the type of request being made by the ACC module.
• Audible and visual warnings are now active during this event.
• If an ABS or ESP event is active, the ACC module continuously sends an autonomous brake request while the ABS/ESP event is active. Under this condition, the ESC honors the autonomous brake request.
  NOTE:

  Autonomous braking may be requested after, at the same time as, or without a brake jerk request, and the request will be honored by the ABS module in this condition.

FCW+ WARNINGS: 

• The FCW+ System uses three levels of warnings: visual, audible, and haptic.
• The visual warning used by the system is displayed in the IPC and will display a "BRAKE!" visual.
• The ACC module controls the activation and deactivation of the visual warning.
• The audible warning used by the FCW system is generated by the cluster or IPC.
• The torque warning used by the FCW system is a brake jerk. A brake jerk is a brake pulse or a momentary application of the brakes (usually 150 to 750 milliseconds).
• The brake jerk warning profile, the duration and magnitude, is contained and implemented by the ABS module.
• The ACC module controls the activation and deactivation of the brake jerk warning with a bussed signal to the ABS module.
• The ESC responds over the bus to the ACC module that the brake jerk was executed.
• The brake lights activate during the brake jerk.
• The brake jerk is suppressed when the ACC system requests braking, the driver applies the brake or the driver applies the throttle.
  NOTE:

  Autonomous braking may be requested without any prior brake jerk request, and the request must be honored by the ABS module in this condition.

FCW+ SETTINGS AND REQUIREMENTS: 

• The FCW+ System has customer configurability for six settings, FCW+ Far, FCW+ Near, FCW Far and FCW Near.
• FCW+ Far - Autobraking Enabled: In this setting, the following features will be enabled:
  • Brake prefill
  • FCW audible and visual pre-warning
  • FCW audible, visual and brake-jerk acute warnings
  • ABA
  • CMS
  • LSCM
• FCW+ Medium - Autobraking Enabled: In this setting the following features will be enabled:
  • Brake Prefill
  • FCW pre-warning - audible and visual
  • FCW acute waning-audible, visual, and brake-jerk
  • Active Braking Assist - ABA
  • CMS
  • LSCM
• FCW+ Near - Autobraking Enabled: This setting is "less sensitive" than the Far setting. In this setting, the following features will be enabled:
  • Brake prefill
  • FCW acute warnings providing audible, visual and brake-jerk responses
  • ABA
  • CMS
  • LSCM
• FCW Far - Autobraking Disabled: This setting is National Highway Traffic and Safety Administration (NHTSA) compliant. In this setting, the following features will be enabled:
  • Brake prefill
  • FCW pre-warnings both audible and visual
  • FCW acute warnings both audible and visual
• FCW Medium - Autobraking Disabled: In this setting the following features will be enabled:
  • Brake Prefill
  • FCW pre-warning - audible and visual
  • FCW acute waning-audible, visual, and brake-jerk
• FCW Near - Autobraking Disabled: This setting is "less sensitive" than the Far setting. In this setting, the following features will be enabled:
  • Brake prefill
  • FCW acute warnings both audible and visual

DISABLING AND ENABLING THE FCW+ SYSTEM: 

• The FCW+ system is disabled and enabled via a soft switch since in the radio.
• The ACC module retains its last known configuration settings for the FCW configuration through ignition cycles when the PROXI parameter Country_Code = "USA" OR "CND" OR "MEX".
• The radio indicates the status of the FCW+ system.
  • When the system is disabled by the user the LED in the IPC will be illuminated.
  • When the system is enabled the LED in the IPC will be off.
  • When the system is disabled due to a fault, the LED will be illuminated.
• The ICS will not change the state of the LED based on a "press" of the Defeat Switch. The ICS changes the state of the LED based on the state of the FCW signal transmitted by the ACC module to the ICS.
• The FCW+ system is disabled when the BCM is in shipping mode. ACC module will continuously activate the FCW OFF telltale and shall ignore the request to enable the FCW system.

FCW+ SYSTEM FAULT STATUS: 

• The FCW+ system has three possible operating states. These are:
  1. No error
  2. FCW error
  3. Limited FCW
• The ACC module transmits the error signal to indicate the status of the FCW system.
• The system will have degraded or limited performance if the FFCM is unavailable. This can be due to faults in the FFCM or camera blindness.
• The system will be totally deactivated when the ACC module radar is unavailable. This can be due to faults in the radar, or radar blindness.
• The FCW+ will be disabled/unavailable when there are faults in the ESC system or located in the TCM or PCM.

ADVANCED BRAKE ASSIST 

• The ABA feature of FCW+ provides additional braking during an emergency braking event if the driver provides insufficient braking for the situation.
• The ABA feature allows the vehicle to achieve a maximum deceleration of 1.0g.
• The ACC module makes deceleration requests for the ABA feature by transmitting the bus signals to the ESC.
• The ACC module sends the deceleration value that the vehicle must be adjusted to.
• The ESC responds to the deceleration request for ABA.
• ABA is aborted when the driver completely releases the brake pedal.
• If an ABS or ESP event is active, the ACC module continuously sends an ABA request while the ABS/ESP event is active. Under this condition, the ESC honors the ABA request based on the arbitration strategy defined for multiple requests to the ESC system.

PREFILL 

• Under normal circumstances, there is space between the pads and rotors to prevent the pads from wearing out prematurely. This space between the pads and rotors increases the response time during any situation which may require emergency braking.
• The brake prefill prepares the system for braking by moving the pads closer to the rotor to improve braking response time.
• The brake prefill is performed by the ESC.
• The ACC module controls the activation and deactivation of the brake prefill.
• The brake prefill causes no audible brake noise.
• The brake prefill causes no vehicle deceleration.
• The ESC sends the ACC module the status of the brake prefill.

COLLISION MITIGATION SYSTEM LIMITATIONS AND BRAKE JERK 

• During an ignition cycle, the total number of brake jerks and collision mitigation events (autonomous braking events including low speed and ABA events) is limited to a maximum of four each (as in four brake jerk events and four collision mitigation events per ignition cycle).
• If the brake jerk and collision mitigation event counter has reached 4, 1 second after the completion of the fourth CMS event, the ACC module sends out a bus signal that changes the radio touchscreen to show that FCW active braking is off and also provides FCW AUTOBRAKE DISABLED indication.
• For USA, Mexico, and Canada country codes. At the next ignition cycle, the FCW+ system will return to the last known active braking setting. All other country codes default to "ON".