Identifying Location Details Using the GPS Sensor in the VRC Over Under Playground

You can use the GPS Sensor to help you navigate the VRC Over Under Playground in VEXcode VR, with the (X, Y) coordinates of locations.

How the GPS Sensor Works in VRC Over Under in VEXcode VR


The GPS (Game Positioning System) Sensor, uses the VEX Field Code on the interior of the Field to triangulate X, Y position and heading. That checkerboard pattern in the Field Code is used to identify the location for each individual block in that pattern. The VEX GPS is an absolute position system, so it does not drift nor does it require calibration on a per-field basis.

To sense the Field Code, the VEX GPS Sensor, a black and white camera, is mounted on the rear of the robot and faces rearwards.

The GPS Sensor reports the (X, Y) coordinates of the center of rotation of Striker on the Field, in millimeters or inches.

Identifying (X, Y) Coordinates on the VRC Field

The VRC Over Under Field in VEXcode VR ranges from approximately -1800mm to 1800mm for the X and Y positions. The starting location of Striker depends on the starting position selected.

The center location, or the origin (0,0), is located in the center of the Field.


Identifying the (X, Y) Coordinates of the GPS Sensor


The GPS Sensor can be used to identify the X and Y coordinates of Striker on the Field. These coordinates reflect the location of Striker's center of rotation, which is located between the front wheels, as indicated in this image.



Reporter blocks from the Sensing category in the Toolbox can be used to report positional values from the GPS Sensor in your project.


The current X and Y coordinates of Striker's GPS Sensor on the Field can be displayed in the Print Console using blocks from the Looks category in the Toolbox.

Using the GPS Sensor to Help Striker Navigate the Field

You can use the GPS Sensor to help Striker navigate the Field by driving to specific locations using your knowledge of the Cartesian coordinate system. Using the GPS Sensor, Striker can drive along the X or Y-axes until the value of the sensor is greater than or less than a threshold value. This allows Striker to drive using sensor feedback instead of set distances.


In this project, Striker will drive forward from starting position A, until the value of the Y-axis is greater than -1000 millimeters (mm), then stop, placing Striker in position to turn and collect a Triball.

Note: You may have to account for the robot’s inertia or drift when setting your parameters.

GPS Sensor Location and the Center of Rotation on Striker


The GPS Sensor is mounted in the rear of the robot, whereas Striker's center of rotation is located in the front of the robot.

The GPS Sensor is configured in VRC Over Under in VEXcode VR to account for this offset (approximately -150 mm on the X axis, and -295 mm on the Y axis), so that the values that are reported reflect the center of rotation of Striker.

(X, Y) Coordinates of Game Elements in VRC Over Under for VEXcode VR

Knowing the coordinates of game elements, like the Triballs and scoring zones, can help you plan your projects in VRC Over Under in VEXcode VR.

The following reference is provided as a guide, based on the Field setup at the start of each Match, for the approximate center point coordinate locations of the game elements on the VRC Field in the Playground.

Scoring Zone Coordinates


Triball Coordinates


Post Coordinates


Identifying the GPS Heading of Striker


The GPS Sensor can also be used to identify the GPS heading. The heading ranges from 0 degrees to 359.9 degrees, following a compass heading style.

When using the GPS Sensor to detect location, the GPS heading will remain constant in relation to the Field, regardless of the starting position of the robot.

For more information, help, and tips, check out the many resources at VEX Professional Development Plus

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