Pioneer HD3 Betriebshandbuch PDF herunterladen (Seite 169)

The accuracy of the GPS information depends

on how good the reception is. When the sig-

nals are strong and reception is good, GPS

can determine latitude, longitude and altitude

for accurate positioning in three dimensions.

But if signal quality is poor, only two dimen-

sions, latitude and longitude, can be obtained

and positioning errors are somewhat greater.

Positioning by dead reckoning

The 3D Hybrid Sensor in the navigation system

also calculates your position. The current loca-

tion is measured by detecting driving distance

with the speed pulse, the turning direction

with the Gyrosensor and inclination of the

road with the G sensor.

The 3D Hybrid Sensor can even calculate

changes of altitude, and corrects for discre-

pancies in the distance travelled caused by

driving along winding roads or up slopes.

Also, the navigation system learns the driving

conditions and stores information in the mem-

or y; thus, as you drive more, the precision of

the positioning becomes more accurate.

The method of positioning changes as follows

depending on whether the speed pulse of your

vehicle is detected or not:

3D hybrid mode

This is active when the speed pulse is de-

tected. Inclination of a street can be detected.

Simple hybrid mode

When the speed pulse is not detected, posi-

tioning is performed in this mode. Only hori-

zontal movement is detected, so it becomes

less accurate. Also, when the positioning by

GPS is not available, such as when your vehi-

cle enters a long tunnel, the discrepancy be-

tween your actual and calculated position may

become bigger.

How do GPS and dead

reckoning work together?

For maximum accuracy, your navigation sys-

tem continually compares GPS data with your

estimated position as calculated from the data

of 3D Hybrid Sensor. However, if only the data

from the 3D Hybrid Sensor is available for a

long period, positioning errors are gradually

compounded until the estimated position be-

comes unreliable. For this reason, whenever

GPS signals are available, they are matched

with the data of the 3D Hybrid Sensor and

used to correct it for improved accuracy.

To ensure maximum accuracy, the dead reck-

oning system learns with experience. By com-

paring the position it estimates with your

actual position as obtained using GPS, it can

correct for various types of error, such as tyre

wear and the rolling motion of your vehicle. As

you drive, the dead reckoning system gradu-

ally gathers more data, learns more, and the

accuracy of its estimates gradually increases.

So, after you have driven some distance, you

can expect your position as shown on the map

to show fewer errors.

p If you use chains on your wheels for winter

driving or put on the spare wheel, errors

may suddenly increase because of differ-

ence in wheel diameter. The system detects

the fact that the tyre diameter has chan-

ged, and automatically replaces the value

for calculating distance.

p If ND-PG1 is used or if your vehicle is oper-

ating in Simple hybrid mode, the distance

calculation value cannot be replaced auto-

matically.

Appendix

Engb

169

Appendix

Appendix

1 2 ... 164 165 166 167 168 169 170 171 172 173 174 ... 188 189

Kommentare zu diesen Handbüchern

Keine Kommentare