GPS Navigation and Mapping
GPS stands for Global Positioning System. It's a network of satellites orbiting Earth that can tell you exactly where you are anywhere on the planet! Your smartphone uses GPS to show your location on maps and give you directions.
Think of GPS like a giant game of "Marco Polo" in space. The satellites are constantly saying "Marco!" (sending signals), and your GPS receiver says "Polo!" (receives the signals). By measuring how long it takes for the signals to travel, your device can figure out exactly where you are.
It's like being at the center of overlapping circles - where all the circles meet is exactly where you are!
GPS coordinates use two numbers to describe any location on Earth:
Example: The Statue of Liberty is at 40.6892° North, 74.0445° West
GPS coordinates can be written in different formats:
// Different ways to write the same location:
// Decimal Degrees (most common for programming)
float latitude = 40.6892;
float longitude = -74.0445;
// Degrees, Minutes, Seconds (traditional)
// 40° 41' 21.12" N, 74° 2' 40.2" W
void setup() {
Serial.begin(9600);
Serial.print("Location: ");
Serial.print(latitude, 6); // Print 6 decimal places
Serial.print(", ");
Serial.println(longitude, 6);
} The number of decimal places in coordinates affects accuracy:
To find the distance between two GPS points, we can use a simplified version of the "straight line" distance formula. For short distances (like within a city), this works well:
// Simple distance calculation between two GPS points
float calculateDistance(float lat1, float lon1, float lat2, float lon2) {
// Convert degrees to approximate meters
float latDiff = (lat2 - lat1) * 111000; // 1 degree ≈ 111km
float lonDiff = (lon2 - lon1) * 111000 * cos(lat1 * PI / 180);
// Use Pythagorean theorem: distance = sqrt(a² + b²)
float distance = sqrt(latDiff * latDiff + lonDiff * lonDiff);
return distance; // Returns distance in meters
} To navigate, your robot needs to know which direction to go. We can calculate the bearing (compass direction) from one point to another:
// Calculate direction (bearing) from point A to point B
float calculateBearing(float lat1, float lon1, float lat2, float lon2) {
float latDiff = lat2 - lat1;
float lonDiff = lon2 - lon1;
// Use atan2 to get angle in radians, then convert to degrees
float bearing = atan2(lonDiff, latDiff) * 180 / PI;
// Make sure bearing is 0-360 degrees
if (bearing < 0) {
bearing += 360;
}
return bearing;
}