Collision Avoidance and Parking Assist Systems: Description and Operation
Parking Aid
COMPONENT LOCATION - PARKING AID
OVERVIEW
The parking aid system provides an audible warning to the driver when any obstacles are in the path of the vehicle during forward and reverse parking maneuvers. The system consists of 4 ultrasonic parking aid sensors in each bumper, a control module, a sounder and a switch. The system also uses the sounder driven by the instrument cluster.
At low speed, the parking aid module uses the sensors to monitor the area around the bumpers, then outputs a warning on the parking aid sounder or the instrument cluster sounder if an object is detected within a monitored area. As well as detecting solid objects such as posts, walls and other vehicles, the system can also detect less solid objects such as a wire mesh fence. Objects close to the ground may escape detection but, because of their low height, will not foul the vehicle.
Some vehicles may also be fitted with a rear view camera. The rear view camera provides the driver with a rear view image displayed on the touch screen display to assist when reversing the vehicle.
The rear view camera is located under the rear spoiler on the upper tail door, adjacent to the center high mounted stop lamp. The rear view camera is connected directly to the touch screen display via a co-axial cable. The rear view camera transmits a wide angle, color image of the area at the rear of the vehicle which is displayed on the touch screen display when reverse gear is selected.
PARKING AID SENSORS
The ultrasonic parking aid sensors are transceivers which are installed in inserts in the bumpers. All 8 sensors are identical and keyed to the inserts to ensure correct orientation.
When the system is active, the sensors transmit ultrasonic pulses. Any reflections from the pulses received by the transmitting and adjacent sensors are then converted to digital format and output to the parking aid module.
PARKING AID MODULE
The parking aid module is located next to the AJB (auxiliary junction box), behind the trim in the RH (right-hand) side of the luggage compartment.
Inputs and Outputs
Three connectors provide the interface between the parking aid module and the vehicle wiring. The parking aid module is powered by the AJB (auxiliary junction box). In addition to hardwired connections with the parking aid sensors, parking aid sounder and power supply, the parking aid module communicates with the instrument cluster on the medium speed CAN (controller area network).
PARKING AID SOUNDER
The parking aid sounder produces the audible warnings with which the parking aid module informs the driver of system status and objects detected at the rear of the vehicle. The parking aid sounder is installed behind the trim in the RH (right-hand) side of the luggage compartment, on the underside of the shelf.
The chime produced by the parking aid sounder has a lower tone than that produced by the instrument cluster sounder (which is used to warn of objects detected at the front of the vehicle), to enable the driver to differentiate between the two.
PARKING AID SWITCH
The parking aid switch is a non latching push switch installed on the center console for selecting the system on and off. When pressed, the switch connects a ground to the parking aid module. An orange LED (light emitting diode) above the switch indicates when the parking aid system is active. The LED (light emitting diode) is activated by a power feed from the parking aid module.
CONTROL DIAGRAM - PARKING AID
NOTE:
A = Hardwired; N = Medium speed CAN (controller area network) bus
PRINCIPLES OF OPERATION
When the vehicle is in power mode 6 and either reverse gear is selected or the parking switch is pressed, both sets of acoustic sensors are activated. The parking aid module only activates the system if reverse is selected for more than 1 second, to avoid nuisance audible warnings when the gear selector lever is being moved between Drive and Park. The rear sensors are disabled when a trailer is connected to the vehicle.
Park Distance Control Detection Areas
When it activates the system, the parking aid module illuminates the indicator LED (light emitting diode) in the parking aid switch, switches on the parking aid sensors and generates a single chime on the parking aid sounder and the instrument cluster sounder to indicate the system is active. The parking aid module then processes the distance readings from the sensors to determine if there are any objects within the detection areas.
If there are no objects in the detection areas, there are no further audible warnings. If an object is detected, repeated audible warnings are produced on the parking aid sounder or the instrument cluster sounder as appropriate. The time delay between the audible warning tones decreases as the distance between the detected object and the vehicle decreases until, at approximately 250 mm (10 in), the audible warning tone is continuous.
After the initial detection of an object, if there is no decrease in the distance between the object and the vehicle:
- If the object is detected by one of the central acoustic sensors the time delay between audible warning tones remains constant
- If the object is detected by a corner transducer the audible warning tones stop after approximately 3 seconds.
The audible warning tones are discontinued when the gearbox selector lever is moved out of reverse, but will restart if the parking aid module detects a decrease in the distance between the vehicle and an object.
System operation is cancelled when the vehicle is in power mode 0. System operation is also cancelled if the vehicle travels more than 50 m (164 ft) or forward speed exceeds 19 mph (30 km/h).
The parking aid module software incorporates routines that compensate for the effect of ice, frost and rain on the parking aid sensors. Ice compensation occurs if the ambient temperature is less than 6°C (43°F).
Diagnostics
The parking aid module performs self check routines and checks the system wiring for short and open circuits. While the system is active the parking aid module also monitors the data from the parking aid sensors.
If a fault is detected, a related DTC (diagnostic trouble code) is stored in the non volatile memory of the parking aid module and either the front sensors, the rear sensors or the complete system is disabled, as appropriate. To advise the driver of the failure, the parking aid module flashes the indicator LED (light emitting diode) at 2 Hz and sounds a continuous warning tone for 3 seconds, in place of the normal short tone, when the system is activated.
DTC (diagnostic trouble code)'s can be accessed using the Land Rover approved diagnostic system, which communicates with the parking aid module via the instrument cluster and the medium speed CAN (controller area network) bus.
Rear View Camera
When reverse gear is selected, the TCM (transmission control module) provides a reverse gear signal to the integrated head unit over the high speed CAN (controller area network) bus. On receipt of the reverse gear signal, the integrated head unit will instruct the touch screen display to display the image from the rear view camera.
The rear view camera image is not displayed under the following circumstances:
- The transmission is in 'D' drive and the vehicle speed is more than 16 km/h (10 mph)
- 'D' drive has been selected on the transmission for more than the 15 seconds time-out period and the vehicle speed is less than 16 km/h (10 mph).
The rear view camera is selected by moving the transmission selector lever to 'R' reverse. The touch screen display changes automatically to rear view camera display. The rear view camera image can be cancelled at any time by pressing the 'return' icon in the top right hand corner of the touch screen display.
When the rear view camera is active, a disclaimer is displayed across the top of the touch screen display to warn the driver to take care when performing reverse maneuvers.
TOW ASSIST
Tow Assist aids the driver with the reversing of a trailer by displaying information on the TSD (touch screen display).
The system uses a tracking target sticker attached to the trailer to monitor and predict the direction of the trailer. Calculations are made by the proximity camera control module, based on the relationship of angles between the vehicle and trailer and the current steering wheel position.
Tow Assist becomes active when a trailer is attached to the vehicle and the trailer electrical plug is attached to the vehicle socket. The CJB (central junction box) detects the connection has been made and sends a message via the medium speed CAN (controller area network) to the proximity camera control module.
NOTE:
If the connection is not detected, setup can be manually prompted by touching the 'Tow Assist' icon on the 'Camera' menu.
Tow Assist - New Trailer
When the CJB detects the trailer electrical plug has been connected, the trailer setup screen is displayed automatically on the TSD with the question: 'Has a trailer been connected?'
Selecting 'Yes' will bring up the first of a number of trailer setup screens. On first use the setup screens take the user through a series of configuration options for the connected trailer. To configure a new trailer select 'Add New' and then 'OK'.
Trailer Setup - Step 1 of 6
- Choose from the list of generic trailer descriptive names for the trailer attached, then select 'Next'.
Trailer Setup - Step 2 of 6
- Position the trailer straight behind the vehicle, to allow more accurate positioning of the target. Stick the self adhesive tracking target to the front of the trailer within the orange highlighted zone as displayed, then select 'Next'.
- The highlighted zone will turn green when the target sticker is correctly positioned.
Tracking target sticker
Trailer Setup - Step 3 of 6
- Select the correct number of axles for the chosen trailer, then select 'Next'.
Trailer Setup - Step 4 of 6
- Select the preferred camera view for use with this trailer, then select 'Next'.
NOTE:
The Side Cameras view is more suited to tall and/or long trailers for example caravans. The Reverse Camera view is more suited to small and/or short trailers.
Trailer Setup - Step 5 of 6
- Using the numeric pad, enter the Hitch Length of the trailer, then select 'Next'.
NOTE:
Hitch Length is the distance from the hitch point to the pivot point of the trailer. The pivot point will vary depending on the number of axles, and will be:
- the center-line of the axle on a single axle trailer,
- the mid-point between the axles on a twin axle trailer,
- the center line of the center axle on a triple axle trailer.
Trailer Setup - Step 6 of 6
- Using the distance adjustment buttons, set the orange overlay graphics at the width of the trailer wheels, or trailer edges when a tall trailer is to be used, then select 'Finish'.
NOTE:
The orange overlay graphics determine the position of the trailer reverse guidance lines.
A confirmation message will appear to show that the trailer information has been retained.
Finally, highlight the trailer that has been memorized, and select 'OK'.
NOTE:
In order to learn the central position of the trailer, the vehicle must be driven forwards at less than 15mph with the steering wheel in the straight-ahead position. There is currently no confirmation for when this process has completed, however the status can be derived by selecting Reverse gear and noting the presence of message 'Trailer tracking in progress'. Whilst tracking feature is learning the central position, the trailer trajectory lines will appear in a light blue color, when process is complete they will change to a dark purple color.
The Tow Assist feature is now ready to use.
Tow Assist - Previously Saved Trailer
When the CJB detects the trailer electrical plug has been connected, the trailer setup screen is displayed automatically on the TSD with the question: 'Has a trailer been connected?'
Selecting 'Yes' from the previous screen brings a list of pre-set, or previously saved, trailers. Highlight the required trailer, and select 'OK'.
NOTE:
In order to learn the central position of the trailer, the vehicle must be driven forwards at less than 15mph with the steering wheel in the straight-ahead position. There is currently no confirmation for when this process has completed, however the status can be derived by selecting Reverse gear and noting the presence of message 'Trailer tracking in progress'. Whilst tracking feature is learning the central position, the trailer trajectory lines will appear in a light blue color, when process is complete they will change to a dark purple color.
The Tow Assist feature is now ready to use.