GF82.61-P-3006SKJ Basic Position Finding, Function

GF82.61-P-3006SKJ Basic Position Finding, Function
- with CODE (498) Japan version






Basic position finding, function
Basic map matching (dead reckoning) is the basic function of constant map matching. This is performed continuously by the navigation processor of the COMAND operating, display and control unit (A40/3) with "Circuit 15R ON" and is independent of the Digital Versatile Disk (DVD) map. After "Circuit 15R OFF" the current position is stored. The following information is calculated with the aid of basic position finding
^ Distance traveled
^ Direction of travel (forward or reverse)
^ Vehicle orientation

The basic position finding is performed approx. every 1 s.

Distance traveled
The wheel direction signal is determined by the left front rpm sensor (L6/1), the right front rpm sensor (L6/2), the left rear rpm sensor (L6/3) and the right rear rpm sensor (L6/4) and discretely read in by the ESP and BAS control unit (N47-5).

This message is transmitted on the Controller Area Network bus class C (engine compartment) (CAN-C) and transmitted by the central gateway control unit (N93) to the audio gateway control unit (N93/1) via the Controller Area Network Bus class B (interior) (CAN-B). This acts as an interface between the CAN-B and the Media Oriented System Transport (MOST).

Direction of travel
The navigation processor of the COMAND operating, display and control unit (A40/3) detects the direction of travel (forward or reverse) from the wheel direction signal, which is also transmitted by the ESP and BAS control unit (N47-5) and transferred by the central gateway control unit (N93) on the CAN-B.

Vehicle orientation
The navigation processor of the COMAND operating, display and control unit (A40/3) calculates the orientation (compass point) of the vehicle from the data from the yaw rate sensor (gyrosensor) and the sequence of the locations calculated by the Global Positioning System (GPS).

The difference between the calculated mileage and actual mileage covered between 2 turning-off points can be used to recalibrate the tire circumference automatically.

Errors with basic position finding
Coasting with the ignition switched off or transporting the vehicle can also distort the position finding. The difference is automatically corrected by the navigation processor of the COMAND operating, display and control unit (A40/3) in both cases when the GPS data are received.