The NG GPS Support

Introduction

The NG supports all sorts of different GPS receivers. Any 3.3V powered GPS receiver supporting the NMEA protocoll, a serial port and 4-5Hz or more update rate should do.

Proven GPS Modules

Venus GPS with SMA Connector

The Sparkfun Venus GPS is used by several NG developers.

The module can be configured to an amazingly powerful 10Hz update rate, with 14 channel tracking! 28mA operating current, and high sensitivity, this receiver seriously opens new doors for tracking. Module outputs the standard NMEA-0183 or SkyTraq Binary sentences at a default rate of 9600bps (adjustable to 115200bps).

Venus GPS Logger with SMA Connector

The Sparkfun Venus GPS Logger is similar to the above Venus GPS but contains als a 2MB storage for GPS Logging capabilities. It's also used by several NG developers.

The module can be configured to an amazingly powerful 10Hz update rate, with 14 channel tracking! 28mA operating current, and high sensitivity, this receiver seriously opens new doors for tracking. Module outputs the standard NMEA-0183 or SkyTraq Binary sentences at a default rate of 9600bps (adjustable to 115200bps).

Cabeling

How to connect your GPS

The GPS gets connected to the serial port of the SB-Controller using the Molex connector on the NG sensor board.

Configuring your GPS for the NG

Configuring a Sparkfun Venus GPS Logger Module

Start the GPS Viewer Software under Windows and connect to the COM port where you Venus GPS is attached.

Go to the Binary-Menu of the GPS Viewer Software. There configure the following:

• Baudrate: 115200
• AGPS: enabled
• WAAS: enabled
• NMEA Messages needed: GGA, GSA, RMC
• Update rate: 10Hz

Make sure that you kicl on the AGPS Download menu point in the AGPS menu which will download the current ephemeris data using FTP and then flash it to your Venus GPS.

Configuring GPS support on the NG

How to configure the baud rate

You can configure the baud rate on the SB-Controller using it's shell.

Note: The SB-Controller is a 3.3V device!

Checking and setting the SB-Controller terminal baud rate:

• UAVP-NG, SB-Controller, Version 0.60, Revision r4827
  
  Use 'help' to show a list of commands
  
  # set HW.uart.baud 115200
  
  Setting integer 'HW.uart.baud' to '115200'
  
  # show globals
  
  Current global configuration:
  
    HW.uart.baud     115200         UART baudrate
    ...

How to configure the global settings

Make sure you activate the hardware data aquisition drivers in the global parameters. To do GPS navigation you will need to activate NGPP, GPS and the Compass as it has been done it the following settings:

• # set HW.use.ngpp yes
  
  Setting boolean 'HW.use.ngpp' to '1'
  
  # set HW.use.gps yes
  
  Setting boolean 'HW.use.gps' to '1'
  
  # set HW.use.compass yes
  
  Setting boolean 'HW.use.compass' to '1'
  
  # show globals
  
  Current global configuration:
  
    Name                      DCM-TR3530          Configuration name
  
    ...
    HW.use.sound              inverted            HW do use sound device
    HW.use.acc                yes                 HW do use accelerometer
    HW.use.baro               yes                 HW do use barometer
    HW.use.ngpp               yes                 HW do use NG peripherial protocol (NGPP)
    HW.use.gps                yes                 HW do use Global Positioning System (needs NGPP)
    HW.use.compass            yes                 HW do use compass (needs NGPP)
    ...

The above will make sure, your NG will fetch the necessary data from the attached peripherial CPUs and provide them to the NG controllers.

How to configure the controller settings

To get a controller to use the compass and GPS data in it's closed-loop, you also have to activate their usage in the controller dependent parameters:

• # set CTRL.use.compass yes
  
  Setting boolean 'CTRL.use.compass' to '1'
  
  # set CTRL.use.gps yes
  
  Setting boolean 'CTRL.use.gps' to '1'
  
  # show conf
  
  Current system configuration:
  
    Controller               amir-ng             Closed-loop controller
  
    ...
    CTRL.use.acc             yes                 CTRL do use accelerometer
    CTRL.use.baro            yes                 CTRL do use baro
    CTRL.use.compass         yes                 CTRL do use compass (needs NGPP)
    CTRL.use.gps             yes                 CTRL do use GPS (needs NGPP)
    ...

How to check the GPS gets recognized

When the GPS gets recognized by your NG it will create a device table entry for it. You can check if the GPS got recognized like this:

• # show devices
  
  Detected devices: 
  
    Addr  Bus     Description
  
    0x16  I2C0    Atmel 644P RC/Comm Controller
    0x18  I2C0    Atmel 328P SB Controller
    0x02  ADC12   ADXR/MLX MEMS Gyroscope 12bit (nick)
    0x01  ADC12   ADXR/MLX MEMS Gyroscope 12bit (roll)
    0x00  ADC12   ADXR/MLX MEMS Gyroscope 12bit (yaw)
    0x00  SPI0    LIS3LV02DQ 3-Axis Accelerometer
    0x02  SPI0    ADS1255 24bit Analog Digital Converter
    0x03  SPI0    AD7924 12bit Analog Digital Converter
    0x00  SBCTRL  MicroMag 3 Magnetic Compass (calibrated)
    0x02  SBCTRL  NMEA Global Positioning System

How to configure behaviors rules GPS

There are several behavior actions related to GPS navigation:

• nav.position.hold(on/off)
• nav.coming.home(on/off)
• nav.store.target()
• nav.set.target(lat,lon)

Elementary behavior configuration for position hold (PH) consists of two simple behavior rules to activate and deactivate position hold when (for example) pot2 gets triggered:

• # list behaviors
  
  List of currently defined behaviors:
  
      No  Condition                       Action
  
      ...
      14  when.rc.pot.binary(2,0)               =>      nav.position.hold(off)
      15  when.rc.pot.binary(2,1)               =>      nav.position.hold(on)
      ...

Checking GPS data

How to check your NG's current position

You can check your NG's current position with the print position command:

• # print position
  
  GPS Status: valid
  Satellites: 10
  
  Time: 18:45:00.600
  Date: 17-09-2010
  
  Latitude: 47.3614387 degree
  Longitude: 8.600522 degree
  Altitude:  620.9000244 meters
  
  Speed: 10 cm/s

How to check your NG's current date and time

You can check your NG's date and time, received by GPS with the print time and print date commands:

• # print time
  
  18:45:54.200
  
  # print date
  
  17-09-2010

Checking navigation

How to check the current navigation calculation

You can check the current GPS navigation calculation with the command show nav in a GPS-enabled controller. For this to work, your NG has to be flying (so you need to fly or start a simulation) and you need to activate position hold (PH) using a behavior rule.

• # show nav
  
  Navigation:
  
    Flight state: GPS position hold
  
    Kalman Position lon: -4.09 [m] (fused guess)
    Kalman Position lat: -2.43 [m] (fused guess)
  
    Current target position lon: 0.00 [m]
    Current target position lat: 0.00 [m]
  
    Current target curse lon: 4.09 [m]
    Current target curse lat: 2.43 [m]
  
    Current copter heading Y_mag: 129.9 [deg] (compass)
    Current copter heading Y_n:   130.0 [deg] (compass)
  
    Navigation target deviation angle: 19.6 [deg]
    Navigation target distance:        4.8 [m]
  
    Navigation nick stick override navN: 224 [angle] 2.5 [deg]
    Navigation roll stick override navR: -82 [angle] -0.9 [deg]

Using GPS in-flight

How to use GPS Position Hold (PH)

To use position hold (PH) in-flight you need to configure behavior rules the activate it, as described above.

When you switch on PH using the behavior action nav.position.hold(on) your NG will store it's current position as target position, will start doing navigational calculations and it will begin to influence your sticks. The command show nav will display this calculation and it's results.

How to use GPS Coming Home (CH)

Your NG stores it's home position when it starts. You can use coming home (CH) to make your NG fly back to it's start position.

When you switch on CM using the behavior action nav.coming.home(on) your NG will set the home position as target position, will start doing navigational calculations and it will begin to influence your sticks. The command show nav will display this calculation and it's results.

How to use GPS Waypoint Navigation (WN)

TODO