GPS Reader

Interface

Instructions

1. Communication - select the appropriate COM port that your GPS is connection to. Note that 4800 baud is set as a default communication rate which most GPS devices will use.

2. Load Simulation File - if you do not currently have a GPS device available (or are located indoors) then you can instead specify a file that contains recorded NMEA statements. Once specified this file will be read in and acted on just as if the information was being passed from a GPS device.

3. Map - the white area will display the points specified by the GPS device in black. The current robot location is specified in blue with the waypoints in orange and the planned route in green. If you uncheck the "Center on Robot" checkbox you can move the map around using the mouse to investigate the route. You can also use the zoom dropdown to move towards and away from the map. If you want to clear the map and start from a blank page press the Reset button. If you want to use the map for your own purposes you can use the Marker module to pull in the GPS_MAP image that is produced by this module and kept in memory.

4. Information - The number of satellites and date received by the GPS is displayed in the information section. Use this interface to determine how well your connection is to any satellites. Remember, if you go indoors you will lose all connections.

5. Waypoints - The main purpose of using GPS is to be able to steer the robot along some known path. Using the waypoints interface you can enter in a new Latitude and Longitude coordinate such as 5408.0079 and 01345.6965 and add that as a waypoint. Note that the first 2 and 3 digits are the location degrees with the remainder being seconds. This is the format produced by most NMEA GPS devices. Once this waypoint is added into the list you will see it displayed in the map and additional variables will become active. The two most important variables are the GPS_ROBOT_HEADING which gives you your current heading and GPS_WAYPOINT_HEADING which is the heading you should be on in order to meet with the waypoint. Using these two variables you can decide on how to move the robot to get to the waypoint. Once the waypoint is reached the module will automatically switch to the next.

You can also specify a variable that will contain the list of waypoints. Please note that this variable needs to be created from VB or Python using the SetArrayVariable function in order for the waypoints to be accessed correctly.

Note that the Waypoint Removal Distance is in minutes.

Resetting the waypoints resets the waypoints that have been visited back to zero and repeats the process. You can chose to loop again and again through waypoints (auto reset) or specify a variable that when non-zero will activate all the waypoints again.

6. Robot Color - the color marker used to identify the robot (circle with an arrow)

7. Route Color - the route between waypoints

8. Waypoints color - the color of the square that identifies the targeted waypoints

9. Visited color - the color of the waypoints that have already been visited

Variables

GPS_LATITUDE - the current GPS latitude value in degrees
GPS_LONGITUDE - the current GPS longitude value in degrees
GPS_DISTANCE - the total distance in meters that the robot has traveled
GPS_ALTITUDE - the current height of the robot (note this
  is typically very inaccurate)
GPS_ROBOT_HEADING - the current orientation of the robot, i.e. direction
  it is moving
GPS_WAYPOINT_HEADING - the orientation of the waypoint relative to the robot
GPS_WAYPOINT_DISTANCE - the distance in meters till the next waypoint
GPS_NUMBER_SATELLITES - the number of satellites currently being used by
  the GPS device
GPS_DATE_TIME - the date time stamp as reported by the GPS satellites

If you need a sample GPS NMEA file to run via the simulation you can download this file, save it to a known location and then specify that location in the File Simulation in the GUI dialog. This file is the raw NMEA recorded from a GPS device while walking around the block from Club Workshop in Denver, Colorado.

See Also

For more information