System Description

1. It is essential that the navigation system correctly tracks the current vehicle position and displays it on the map. There are 2 methods to track the current vehicle position: autonomous (dead reckoning) and GPS* (satellite) navigation. Both navigation methods are used in conjunction with each other.

   HINT: 

   *: GPS (Global Positioning System)

   Fig 1: Vehicle Position Tracking Methods

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   Operation	Description
   Vehicle Position Calculation	The display and navigation module display calculates the current vehicle position (direction and current position) using the direction deviation signal from the gyro sensor and the running distance signal from the vehicle speed sensor and creates the driving route.
   Map Display Processing	The display and navigation module display processes the vehicle position data, vehicle running track, and map data from the hard disc.
   Map Matching	The map data from the hard disc is compared to the vehicle position and running track data. Then, the vehicle position is matched with the nearest road.
   GPS Correction	The vehicle position is matched to the position measured by GPS. Then, the GPS measurement position data is compared with the vehicle position and running track data. If the position is widely different, the GPS measurement position is used.
   Distance Correction	The running distance signal from the vehicle speed sensor includes error caused by tire wear and slippage between the tires and road surface. Distance correction is performed to account for this. The display and navigation module display automatically offsets the running distance signal to make up for the difference between it and the distance data of the map. The offset is automatically updated.

   HINT: 

   The combination of autonomous and GPS navigation makes it possible to display the vehicle position even when the vehicle is in places where the GPS radio wave cannot be received. When only autonomous navigation is used, the mapping accuracy may slightly decline.

   Fig 2: Where The GPS Radio Wave Cannot Be Received

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

This method determines the relative vehicle position based on the running track determined by the gyro and vehicle speed sensors.

1. Gyro sensor

   Calculates the direction by detecting angular velocity. It is located in the display and navigation module display.

2. Vehicle speed sensor

   Used to calculate the vehicle running distance.

This method detects the absolute vehicle position using radio waves from a GPS satellite*.

HINT: 

*: GPS satellites were launched by the U.S. Department of Defense for military purposes.

Fig 3: Identifying GPS Navigation (Satellite Navigation) System Description

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

The current driving route is calculated by autonomous navigation (according to the gyro sensor and vehicle speed sensor) and GPS navigation. This information is then compared with possible road shapes from the map data on the hard disc and the vehicle position is set onto the most appropriate road.

Fig 4: Map Matching Flow Chart

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Fig 6: View Of Disc Identification Marks - Usable Discs

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. Precaution for use of discs
   NOTE:

   • PAL or SECAM color television standard discs cannot be played (only NTSC discs can be played).
   • Keep the discs away from dirt. Be careful not to damage the discs or leave fingerprints on them.
   • Hold discs by the outer edge and center hole with the label side up.
   • Leaving the disc exposed halfway out of the slot for a long time after pressing the disc eject button may cause deformation of the disc, making the disc unusable.
   • Do not use odd-shaped CDs because these may cause player malfunctions.
   • Do not use discs whose recording portion is transparent or translucent because they may not be able to be inserted, ejected or played normally.
   • DualDiscs that combine DVD recorded material on one side with CD digital audio material on the other cannot be played.