GF82.61-P-2010RI Position Finding and Destination-Oriented Navigation, Function

GF82.61-P-2010RI Position Finding And Destination-oriented Navigation, Function
- with CODE (512) COMAND APS with DVD changer

Function requirements for position finding and navigation
^ "Circuit 30 ON" status.
^ The Cockpit Management and Data System (COMAND) is authorized and operating free of faults.

General
The position finding and navigation function is divided into the following subareas:
^ General Global Positioning System (GPS) position finding
^ Function sequence for GPS position finding
^ General information on basic position finding
^ Basic position finding function sequence
^ Recalibration
^ General information on route calculation
^ Function sequence for destination-oriented navigation through voice output
^ General information on dynamic route guidance, for vehicles except code (494) USA version
^ Function sequence for dynamic route guidance, for vehicles except code (494) USA version
^ Destination-oriented navigation through driving lane recommendations
^ Map function

General information on GPS position finding
The GPS is a satellite-based positioning system. It is available worldwide. The GPS satellites permanently transmit time and position data (longitude and latitude).
GPS position finding is irretrievable after vehicle transport (e.g. by train or ferry or after towing). A new GPS position (after interruption of the satellite reception) can take several minutes (up to 20 minutes when the equipment is commissioned).

The accuracy of the position finding and the actual calculation is essentially based on the measurement of the runtimes of the signals transmitted synchronously by the various satellites. A vital precondition is the synchronicity of the clocks in the satellites and in the receiver. To this end the receiver is equipped with an automatic time correction, which in turn is made possible with the aid of the satellite signals.

Possible problems in GPS signal reception
Since GPS operates in the giga hertz (GHz) range (microwaves) and the signals are weak, reception interference can occur as a result of the following events:
- Atmospheric interference, e.g. inclement weather, water vapor, fog
- Multi-path reception due to signal reflections, e.g. from building walls
- Signal blocking, e.g. in built-over areas and in tunnels, through high-rise buildings, trees

GPS position finding function requirements
^ No error in GPS antenna system

Function sequence for GPS position finding
GPS signals are received by the GPS receiver integrated into the COMAND operating, display and controller unit (A40/3) directly by the GPS antenna (A2/23).
The GPS signals are used by the COMAND operating, display and controller unit to calculate the current position of the vehicle (receiver). In addition, the vehicle's direction of travel is determined with the aid of the sequence of the locations calculated with GPS.

For vehicles with code (359) TELE AID emergency call system, the GPS signals are sent via direct lines from the GPS antenna to the COMAND operating, display and controller unit via the antenna splitter (A2/5).

General information on basic position finding
Basic position finding runs parallel to GPS position finding. The COMAND operating, display and controller unit requires the following information for basic position finding:
- Wheel speed signals
- Distance traveled data
- Vehicle alignment (cardinal points)
- Data for direction of travel (forward or reverse)

Basic position finding function requirements
^ Communication with ESP, SPS [PML] and BAS control unit (N47-5) is operating free of faults

Basic position finding function sequence
For basic position finding the COMAND operating, display and controller unit requires signals from the following components:
- ESP, SPS [PML] and BAS control unit
- Left front rpm sensor (L6/1), right front rpm sensor (L6/2), left rear rpm sensor (L6/3), right rear rpm sensor (L6/4), for recording wheel speed and direction of travel signals
- Turn rate sensor (gyro sensor), integrated into the COMAND operating, display and controller unit, for determining vehicle alignment (cardinal points)
- Central gateway control unit (N93)
- Steering angle sensor (N49), for recording steering angle

The COMAND operating, display and controller unit receives the wheel speed and direction of travel signals from the listed rpm sensors as follows:
- Direct line
- ESP, SPS [PML] and BAS control unit
- Engine compartment CAN
- Central gateway control unit
- Interior CAN

The data in the turn rate sensor (gyro sensor) integrated into the COMAND operating, display and controller unit is forwarded within the COMAND operating, display and controller unit.
Finally, the COMAND operating, display and controller unit uses the travel distance covered to calculate the current vehicle position (longitude and latitude), taking the vehicle alignment into consideration as well as the direction of travel.
The steering angle signal of the steering angle sensor is read in by the steering column tube module (N80) and forwarded to the COMAND operating, display and controller unit via the interior CAN.

Calculation of the basic position finding takes approx. 1/s.

Error during position finding
Basic position finding is falsified when a vehicle rolls backwards with "circuit 15 OFF" (ignition switched off) or if it is transported somewhere. The deviation is automatically corrected in both instances by the navigation processor integrated into the COMAND operating, display and controller unit.

Recalibration
Because of the tire abrasion, a constant recalibration of the tire circumference is required. It is carried out automatically and uses the difference between the calculated and actually traveled distance between 2 turning points calculated with the aid of map-based position finding.

General information on route calculation
The following stretches can be removed from the route calculation under "Navi":
- Freeway, except code (494) USA version
- Freeways, with code (494) USA version
- Ferries
- Tunnels

For vehicles except code (494) USA version, additional stretches can be excluded from the route calculation:
- Toll road
- Roads requiring toll stickers
- Car trains

Route calculation is accomplished using the options set to the best possible extent. If observance of the options is not possible, then the options set are ignored for the sections in question and a message is displayed and signaled audibly.

The set criteria and options can be displayed and changed at any time. After a successful calculation, the route is displayed on the map and this information is then relayed acoustically -"Route calculated".

Function sequence for destination-oriented navigation through voice output
The integrated navigation processor continuously compares the route calculation data with the position finding data and uses the data to deduce measures for further destination-oriented navigation.
The voice output for navigation on vehicles with code (810) Sound system is sent to the Media Oriented System Transport (MOST), where it is then amplified in the amplifier for sound system (N40/3) and output via direct lines at the following speakers:
- Left door speaker group (H4/1)
- Right door speaker group (H4/2)
- Center cockpit speaker (centerfill) (H4/27)

On vehicles except code (810) Sound system, the voice output takes place by means of the COMAND operating, display and controller unit via direct lines at the following speakers:
- Left door speaker group
- Right door speaker group

The signals for visual display of the navigation (map navigation) are generated by the COMAND operating, display and controller unit and shown on the display of the COMAND operating, display and controller unit as well as in the instrument cluster (A1) in the form of arrow symbols.

General information on dynamic route guidance, for vehicles except code (494) USA version
The current traffic situation is taken into consideration in the dynamic route guidance. The incoming information on the traffic situation can be received by the radio data system/Traffic Message Channel (RDS/TMC) function via FM radio. The information on the current traffic situation is sent out by a specially equipped broadcasting corporation on an area-related basis via FM. A suitable FM/RDS transmitter must be tuned in. The traffic data recorder decodes the traffic information and forwards it internally to the navigation processor upon request. The navigation processor makes the decision whether the route should be changed. If necessary, a message that the route should be changed is output via the vehicle speaker.

Function sequence for dynamic route guidance, for vehicles except code (494) USA version
The FM receiver in the COMAND operating, display and controller unit receives the traffic reports from the left antenna amplifier module (A2/64) and right antenna amplifier module (A2/65) and forwards them to the traffic data recorder in the COMAND operating, display and controller unit. The traffic reports are stored in the traffic data recorder of the COMAND operating, display and controller unit and made available to the integrated navigation processor. The voice output for dynamic route guidance on vehicles with code (810) Sound system is sent to the Media Oriented System Transport (MOST), where it is then amplified in the amplifier for sound system (N40/3) and output via direct lines at the following speakers:
- Left door speaker group
- Right door speaker group
- Center cockpit speaker (centerfill)

On vehicles except code (810) Sound system, the voice output takes place by means of the COMAND operating, display and controller unit via direct lines at the following speakers:
- Left door speaker group
- Right door speaker group

Destination-oriented navigation through driving lane recommendations
For certain turnoff situations on multiple-land exit points (e.g. freeway intersection) driving lane recommendations are shown in the bottom line. Along with a turnoff recommendation, the distance to the actual turnoff point is also displayed by means of a bar graph. The lanes have arrows assigned to them, which indicate on which lane the destination can be reached or the best way t reach it.
The following colors apply for representation on the display of the COMAND operating, display and controller unit:
Midnight blue: The best or recommended lane.
Light blue: The lane is correct, but a lane change will soon be required.
Gray: This lane will not take you to the destination.

The instrument cluster only displays the midnight blue arrows.

Map function
The map display is always controlled by the COMAND operating, display and controller unit. The following display functions are supported:
- Destination-oriented navigation map
- Position map
- Route map
- Scrollable map
- Destination entry map