Basic position finding, function with code 530 - GF82.61-P-3006SKU

MODEL 171.4 with CODE (530) COMAND APS USA (with navigation system)

Fig 1: Basic Position Finding Function Chart

Courtesy of MERCEDES-BENZ USA

Basic location finding (dead reckoning) is the basic function of continuous location finding. It is performed continuously by the navigation processor (N41/1) with the ignition switched on (circuit 15 ON) and is independent of the Digital Versatile Disk (DVD) card. When the ignition is switched off (circuit 15 OFF), the current position is stored.

The following information is calculated with the aid of basic position finding (composite positioning):

Distance traveled
Direction of travel (forward or reverse)
Vehicle orientation

Basic position finding (dead reckoning) is performed every 1 s.

Distance traveled

The navigation processor (N41/4) receives the wheel speed signals from the ESP and BAS control unit (N47-5) via the class C (engine compartment) controller area network bus (CAN-C). These wheel speed signals are evaluated to determine the distance traveled.

Direction of travel

The navigation processor (N41/4) detects the direction of travel (forward or reverse) from the reversing signal, which is transmitted from the EIS control unit (N73) via the class B (interior) Controller Area Network Bus (CAN-B).

Vehicle orientation

The navigation processor (N41/1) calculates the orientation (compass direction) of the vehicle from the data of the yaw rate sensor (gyro sensor) and the sequence of positions calculated by the global positioning system (GPS).

Position finding errors during basic position finding (composite positioning)

Rolling backwards without the transmission being shifted into reverse gear is evaluated as moving forwards and can lead to temporary errors in location finding. Rolling with the ignition switched off (circuit 15 OFF) or transporting the vehicle can also distort the position finding. In both cases the deviation is automatically corrected by the navigation processor (N41/1) upon receipt of GPS data.

Calibration

Wheel calibration is necessary following a tire change. To do this, the input of tire size and the coding, whether new tires (depth of tread approx. 5 to 10 mm) or worn tires (depth of tread approx. 3 to 5 mm) have been fitted, is necessary. The entry is accomplished with Star Diagnosis or directly at the COMAND operating, display and control unit (A40/3). A special calibration drive is not required.

Recalibration

The tire circumference must be recalibrated because of tire wear. This takes place automatically, and uses the difference between the distance between 2 turn-off points that is calculated by the map-based position finding and the distance that has actually been traveled.

Operating, display and control unit, location/ task/design/function

GF82.85-P-3114SKU