Adaptive Cruise Control With Stop And Go
DESCRIPTION
The following components are part of the Adaptive Cruise Control (ACC) with Stop and Go system:
| 1. | Refer to ANTI-LOCK BRAKE SYSTEM (ABS) MODULE . |
| 2. | Refer to POWERTRAIN CONTROL MODULE (PCM) . |
| 3. | Refer to BODY CONTROL MODULE (BCM) . |
| 4. | Refer to DRIVERS ASSISTANCE SYSTEM MODULE (DASM) . |
| 5. | Refer to RADIO . |
| 6. | Refer to INSTRUMENT PANEL CLUSTER (IPC) . |
| 7. | Refer to CRUISE CONTROL SWITCH MODULE (CSWC) . |
| 8. | Refer to STEERING COLUMN CONTROL MODULE (SCCM) . |
Adaptive Cruise Control (ACC) with Stop and Go is a Driver Assistance System with functionality beyond that of the conventional Cruise Control system.
When the ACC with Stop and Go equipped vehicle is brought to a stop due to the presence of a slower moving target vehicle, the ACC with Stop and Go system can keep the host vehicle at a stand-still by initially applying the brakes, and once the brake system times out, by applying the Electronic Park Brake (EPB). However, if the target vehicle starts moving before the brake system times out, the ACC with Stop and Go system allows the vehicle to automatically resume motion with little or no driver intervention.
Vehicles that are equipped with the ACC with Stop and Go system incorporate the DASM to control the ACC with Stop and Go system and conventional Cruise Control system.
OPERATION
The ACC On/Off button in the CSWC can be used to enable or disable the ACC with Stop and Go system. The CSWC sends the status of the ACC button to the SCCM over the Local Interface Network (LIN) network. The SCCM gates this signal to the DASM.
Once the system in enabled, the ACC with Stop and Go or the conventional Cruise Control system can be engaged by pressing the Set+ or Set- buttons in the CSWC. The CSWC transmits the Set button state to the SCCM. The SCCM gates the signal to the DASM. If driver override occurs and either Set button is pressed, the current speed becomes the new set speed. The DASM determines the set speeds based on the vehicle speed value received from the ABS module.
For ACC with Stop and Go, the driver can configure the set target distance by using either of the two distance buttons in the CSWC. These button are:
- Distance Decrease - This button is used to select a shorter following distance than the current selected following distance.
- Distance Increase - This button is used to select a longer following distance than the current selected following distance.
The CSWC sends the status of the Distance buttons to the SCCM which gates the request to the DASM.
The Distance value is interpreted as a time gap by the DASM. This value is modified by the presence of a Trailer Tow Module (TTM) that is actively operating during ACC with Stop and Go operation.
When the Resume or Cancel button is used, the CSWC sends the request to the SCCM which gates the request to the DASM.
For the North American Free Trade Agreement (NAFTA) vehicle, the range of operation for the ACC with Stop and Go system is a minimum of 32 Kilometers Per hour (km/h) (20 Miles Per Hour/mph) and a maximum of 160 km/h (100 mph).
The DASM transmits the ACC with Stop and Go or the conventional Cruise Control system states over the Controller Area Network (CAN) bus. When the ACC with Stop and Go is in use, the DASM also transmits the adjusted vehicle speed on the CAN bus. The adjusted speed is determined when the DASM detects a target vehicle in the path of the host vehicle and the system is in the Engaged/Set state. The system automatically configures the speed of the host vehicle to the speed of the target vehicle and trails the target vehicle at a set following distance. In this case the desired speed of the vehicle will be less than the set speed.
The DASM uses its own internal logic to convert the vehicle speed that is sent to it by the ABS module to the vehicle speed that is to be displayed to the driver on the IPC.
The DASM uses an integral radar and camera, by means of data fusion, to detect vehicles in the forward path of the vehicle that are moving, stopped or stationary. The DASM considers an object moving if it has a velocity greater than zero while being tracked. The DASM considers an object stopped if it has a velocity greater than zero and then comes to a stop. The DASM will consider an object stationary if it has zero velocity the entire time that it is being tracked.
When the DASM detects that an object with velocity is slowing to a stop, the DASM sends a request to the ABS module for braking. The ABS module then sends a signal back to the DASM confirming that the host vehicle is at a complete stop. The ABS module then begins an internal timer countdown and holds the brake. If the target object begins to accelerate, the DASM sends the request to the ABS module to release the brakes. If the countdown timer expires before the target vehicle starts to accelerate, the DASM sends a request to the ABS module to apply the EPB until the target object begins to move. At this point, the DASM sends a request to the ABS module to release the EPB. If the host vehicle is on an incline and the ABS modules internal timer expires, movement of the host vehicle will require driver override by depressing the accelerator pedal or by pressing the Resume button. The driver override condition is detected by the PCM and sent to the DASM while the Resume button actuation is detected by the SCCM and bussed to the DASM.
When the host vehicle is brought to a stop due to DASM object detection, the driver seatbelt status and the driver door ajar signal are monitored. If the seatbelt buckle is unbuckled or the door becomes ajar, the system will become disabled once the EPB is applied.
The DASM also requests a brake prefill command to the ABS module. Under normal circumstances, there is space between the brake pads and the brake rotors to prevent the brake pads from wearing out prematurely. This space between the brake pads and the brake rotors increases the response time during any situation which may require emergency braking. The brake prefill prepares the system for braking by moving the brake pads closer to the brake rotor to improve braking response time. The DASM controls the activation and deactivation of the brake prefill operation.
If the ACC system is unable to maintain the following distance, a take over request is issued. This is a request for the vehicle driver to take control of the vehicle for safety reasons. This request is initiated by the system simultaneously sending an audible and visual warning to the IPC, along with an audio warning to the audio system. A take over request can also be initiated by the DASM when there is a close cut-in of a vehicle from an adjacent lane to the lane that the host vehicle is currently occupying.
The ACC system is also capable of providing proximity warning. A proximity warning occurs when an object or a vehicle in close proximity is detected. This warning will alert the driver if the ACC system predicts that its maximum braking level is not sufficient to maintain the set distance. Like the take over request warning, the proximity warning system request is initiated by the system simultaneously sending an audible and visual warning to the IPC, along with an audio warning to the audio system.
The DASM is able to determine its acceleration, deceleration and gear requests by utilizing sensor data along with specific data received from the PCM, ABS module and the TCM (MTX not supported for this function). This allows for when the slower moving object or vehicle is no longer detected, the ACC with Stop and Go system will accelerate the host vehicle back to the original set speed with no customer interaction. Using those same inputs, the DASM also allows for an overtake event to occur. When the host vehicle is trailing a slower moving object and the host driver activates the turn indicator, the DASM applies additional amounts of acceleration while still trailing the object vehicle to aid in a lane shift maneuver. In locations with left hand drive traffic, overtake aid will only be provided on the left hand side. The same applies for the right hand side. The DASM is able to determine the direction of traffic flow by observing oncoming traffic. The DASM will disable overtake aid if the DASM detects an object in the lane the vehicle is attempting to move into in order to pass the slower moving object vehicle. The overtake aid also disables or will not assist if the host vehicle is equipped with a Blind Spot Monitor (BSM) system that is currently detecting a vehicle in the blind spot of the host vehicle.
For transmission shift requests, the DASM sends the gear requests to the ABS module which in turn sends the request to the TCM as well as the ACC with Stop and Go system status. The DASM transmits the current set speed as well as the DASM requested desired speed to the TCM. The TCM uses this information to enable a internal logic cruise shift strategy.
Deactivation Conditions:
The ACC with Stop and Go system has several cancel and switch-off conditions that will deactivate the system. The conditions are as follows:
- DASM internal fault
- DASM Electronic Control Unit (ECU) over temperature
- DASM external fault
- ACC system status faulted
- Brakes applied by vehicle operator
- EPB applied or being applied
- Driver door opened while vehicle is travelling below 5 MPH and vehicle is not at a standstill
- Seatbelt is unfastened while vehicle is travelling below 5 MPH
- Vehicle is above the maximum ACC operating speed
- Vehicle is below the minimum ACC operating speed
- Transfer case engaged in 4LO
- Transmission is in (P) park, (N) neutral or (R) reverse
- Electronic Stability Control (ESC) event occurs
- ESC is in full OFF mode
- Brake are overheated
- Hill Descent Control (HDC) is active or being activated
- Stationary object below minimum distance threshold in front of the vehicle
- Object detected in close proximity is below minimum distance threshold in front of the vehicle
- Vehicle is rolling backward
- Vehicle is on a steep grade while below calibrated speeds when travelling downhill or uphill
- Forward Collision Warning + intervention occurs
- CSWC CANCEL button pressed
- DASM radar blinded, misaligned or requiring service
- Cancel requests from the ESC system
- ACC On/Off button pressed when the ACC is in an engaged state
- Conventional Cruise Control On/Off button pressed while the ACC is in an engaged state
- Conventional Cruise Control On/Off button pressed while the conventional Cruise Control system is in an engaged state
- Engine stops or falls below a calibrated minimum RPM value
- Engine overspeed detected
- DASM detects the brake switch is ON while the ITBM indicates a trailer is present
| Refer to COMPONENT INDEX . |
The ABS module is an integral controller of the ACC with Stop and Go system. Most performance functions for this system route through or start from the ABS module.
The ABS module incorporates the EPB module, the ESC module and the Electronic Stability Protection (ESP) system and uses all of these modules and systems to help facilitate ACC with Stop and Go operation.
Inputs
- Door ajar status from the BCM
- Transmission PRNDL status from the TCM
- Occupant Restraint Controller (ORC) seatbelt unbuckled signal to the ABS module
- Accelerator Pedal Position Sensor (APPS) signal from the PCM
- Brake prefill requests from the DASM
- Vehicle configuration data from the BCM
- ACC system type and DASM equipped signal from the BCM
- Cruise Control override signal from the PCM
- DASM ACC operating state signals
- DASM engine transmission torque value signal
- DASM fuel shut off disable signal
- DASM engine torque request signal
- DASM requested maximum gear value
- SCCM CSWC button outputs pertinent to ACC with Stop and Go requirements
Outputs
- Braking status to the DASM
- Yaw rates to the DASM
- Vehicle acceleration to the DASM
- Brake torque to the DASM
- Brake intervention active to the DASM
- Wheel speed data to the DASM
- Vehicle speed data to the DASM
- Brake pedal status to the DASM
- EPB status to the DASM
- Active brake event to the DASM
- ACC engaged status to the PCM
- Fuel shut off, fuel economy measure, disable signal to the PCM
- Requested torque management requests to the PCM
- Acceleration and deceleration request to the PCM
- Gear maximum request from to the TCM
- ACC with Stop and Go active message to the TCM
| Refer to COMPONENT INDEX . |
When the ACC with Stop and Go system is in the Set state, the ABS module transmits an ACC engaged signal to the BCM. The BCM gates and then broadcasts this signal to the relevant modules and systems on the bus that are involved in the ACC operation.
Inputs
- ACC engaged signal from the ABS module
Outputs
- Ignition OFF time to DASM
- Wiper system status to DASM for ambient temperature determination
- Vehicle configuration data to multiple bus nodes
- Outside air temperature value to the DASM
- Battery system voltage to the DASM
- Commanded ignition status to multiple network nodes
- Driver door ajar signal to the DASM and ABS module
- DASM configuration and ACC system type for several network nodes
- ACC engaged signal to multiple network nodes
| Refer to COMPONENT INDEX . |
The CSWC contains the ACC with Stop and GO Distance buttons as well as the conventional Cruise Control buttons. When these buttons are pressed, the CSWC sends a LIN bus message to the SCCM with the pushed button value.
| Refer to COMPONENT INDEX . |
The DASM detects the following signals that are general requirements for system functionality:
- Ignition ON, time since last ON value determined from the BCM
- 12v battery from the BCM
- Wheel speed sensor values from the ABS module to determine if the vehicle is in standstill or in motion
- Steering wheel angle values from the SCCM
- Engine configuration information from the PCM
- Accelerator Pedal Position Sensor (APPS) actual value
- If equipped, vehicle ride height information from the Active Stabilizer Control Module (ASCM) for vertical radar alignment determination
- ESC active signal from the ABS module indicating that ESC is able to provide braking during ACC with Stop and GO operation
Inputs
- BSM warning system and configuration inputs
- Integrated Trailer Brake Module (ITBM) trailer status and brake switch input
- Internal DASM signal for camera or radar blocked
- ABS module input for braking status
- ABS module input for yaw rates
- ABS module input vehicle acceleration
- ABS module input brake torque
- ABS module input brake intervention active
- ABS module wheel speed data
- ABS module vehicle speed data
- ABS module brake pedal status
- ABS module EPB status
- ABS module active brake event
- PCM Cruise Control override
- PCM engine torque status and management requests
- PCM accelerator pedal position status
- PCM RPM status
- PCM transmission torque status
- PCM engine configuration information
- PCM Engine Stop Start (ESS) status, if equipped
- SCCM turn signal active
- Internal radar and camera communications
- BCM battery voltage
- BCM commanded ignition state
- BCM ignition off timing
- BCM vehicle configuration information
- BCM ambient air temperature
- BCM wiper system status
- BCM driver door ajar signal
- TCM transmission limp mode status
- TCM PRND status
- TCM target and current gear
- IPC speedometer unit; miles
- ASCM suspension ride height information
- Drivetrain Control Module (DTCM) transfer case status
- SCCM steering wheel angle
- ORC driver seat belt buckle status
- CSWC Cruise Control switch status and requests
Outputs
- ACC system state to multiple BUS nodes
- ACC message requests to the IPC
- ACC set speed status to the IPC
- ACC visual and audio warning enable requests to the IPC and Radio
- Vehicle speed actual, desired and set values to the TCM
- Transmission max gear range to the ABS module
- ACC system configuration requests to the ABS module and PCM
- Engine management requests to support ACC operation
- Brake prefill request to the ABS module
| Refer to COMPONENT INDEX . |
The IPC is used in the ACC system for displaying visual, auditory, and textual messages to the driver of the vehicle for the ACC system.
Inputs
- ACC warning display telltale requests from the DASM
- ACC system operation display information telltale requests from the DASM
- Vehicle configuration parameters from the BCM
- Cruise Control Set speed display from the DASM
Outputs
- Visual, auditory, and textual messages to the vehicle operator
| Refer to COMPONENT INDEX . |
The PCM interfaces with several nodes on the BUS network to support ACC with Stop and Go operation as well as the conventional Cruise Control operation.
Inputs
- ACC engaged status from the ABS module
- Fuel shut off, fuel economy measure, disable signal from ABS module
- Vehicle configuration information from the BCM
- DASM requested torque management requests from the ABS module
- DASM acceleration and deceleration request from the ABS module
- APPS indicating driver interaction with the pedal
Outputs
- Cruise Control override signal to the DASM
- Engine torque status and management requests to the DASM
- Accelerator pedal position status to the DASM
- RPM status to the DASM
- Transmission torque status to the DASM
- Engine configuration information to the DASM
- ESS status, if equipped, to the DASM
- Engine in limp home mode status to the DASM
| Refer to COMPONENT INDEX . |
In certain circumstances, the radio receives an input from the DASM to provide an auditory warning chime strategy to the vehicle operator
Inputs
- Audible warning requests from the DASM
Outputs
- Auditory warning to the vehicle operator
| Refer to COMPONENT INDEX . |
The SCCM is the interface between the CSWC and the DASM. The CSWC evaluates the status of the Cruise Control buttons (pressed or not pressed) and then outputs this information to the SCCM. The SCCM receives this LIN input from the CSWM and forward the request over the CAN-C network to the DASM.
If the SCCM detected invalid signals or no signal from the CSWC, it will set a LIN based DTC on the CAN-C network.
Inputs
- Receives vehicle configuration indicating Cruise Control, ACC Stop and Go and Active Speed Limiter options are available on the vehicle
- CSWC switch LIN inputs from CSWC
Outputs
- Transmits the LIN CSWC inputs over the CAN-C network to the DASM.
- Power and ground to the CSWC
- Illumination to the CSWC
- Steering wheel angle sensor output to the DASM
- Turn signal lever state to the DASM
- Certain ACC with Stop and Go and conventional Cruise Control button outputs to the ABS module