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

GF82.61-P-3006SK Basic Position Finding, Function
- with CODE (525) MB Audio 50 APS radio
- with CODE (527) COMAND APS with single DVD drive (with navigation)







On vehicles with radio and navigation unit (A2/56) with code (525) Audio 50 APS MB radio the navigation processor is integrated into the control unit.On the COMAND operating, display and control module (A40/3) with code (527a) COMAND APS (with navigation) the external navigation module is called navigation processor (N41/1).

Basic position finding is the basic function of continuous position finding. It is carried out continuously by the navigation processor (N41/1) with "Circuit 15R ON" and is independent of the DVD-ROM 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 rotation signal is determined by the left front speed sensor (L6/1), right front speed sensor (L6/2), rear left speed sensor (L6/3) right rear speed sensor (L6/4) and is read by the ESP and BAS control module (N47-5) in discrete manner. This message is transmitted to the controller area network bus class C (engine compartment) (CAN-C) and is transmitted by the central gateway control module (N93) to the controller area network bus class B (interior) (CAN-B). As a result, the navigation processor (N41/1) detects the direction of travel (forward or reverse).

Direction of travel
Through the wheel rotation direction signal which is also transmitted by the ESP and BAS control module (N47-5) and by the central gateway control module (N93) to the interior CAN-B, the navigation processor detects the direction of travel (forwards or backwards).

Vehicle orientation
From the data of the yaw rate sensor and the sequence of the locations calculated with the global positioning system (GPS), the navigation processor (N41/1) calculates the orientation (compass direction) of the vehicle.

The difference between the calculated and actual distance traveled between two turns is used for the automatic recalibration of the tire circumference.

Errors with basic position finding
Rolling with the ignition switched off or transport of the vehicle also make the position finding result erroneous. In both cases, this deviation is automatically corrected by the navigation processor (N41/1) on receipt of GPS data.