The Localization Problem
Localization is one of the hardest problems in robotics. Outdoors, we have GPS (though it has errors). Indoors, GPS fails, so robots must use UWB anchors, Visual Odometry (tracking camera movement), or Lidar SLAM to figure out their coordinates.
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GNSS / GPS Receivers
Global Navigation Satellite Systems (GPS, GLONASS, Galileo, BeiDou) providing absolute position anywhere on Earth.
Cat: Outdoor PositioningSpecs: accuracy:2m - 5m (Standard),updateRate:1Hz - 10Hz
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RTK-GPS (Real-Time Kinematic)
Advanced GPS that uses a stationary base station to correct errors, achieving centimeter-level accuracy.
Cat: High PrecisionSpecs: accuracy:1cm - 2cm,cost:High ($$$)
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Ultra-Wideband (UWB)
Radio technology for precise indoor localization where GPS fails. Uses "anchors" placed in the room.
Cat: Indoor PositioningSpecs: accuracy:10cm,range:50m - 100m
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Visual Odometry
Estimating position change by analyzing movement of features in camera images (SLAM).
Cat: Relative PositioningSpecs: drift:Low (with loop closure),hardware:Camera + CPU
Arduino - Parsing NMEA GPS Data (TinyGPS++)
#include <TinyGPS++.h>
#include <SoftwareSerial.h>
TinyGPSPlus gps;
SoftwareSerial ss(4, 3); // GPS TX -> Pin 4, GPS RX -> Pin 3
void setup() {
Serial.begin(115200);
ss.begin(9600);
}
void loop() {
// Feed GPS data to the library
while (ss.available() > 0) {
if (gps.encode(ss.read())) {
displayInfo();
}
}
}
void displayInfo() {
Serial.print("Location: ");
if (gps.location.isValid()) {
Serial.print(gps.location.lat(), 6);
Serial.print(",");
Serial.print(gps.location.lng(), 6);
} else {
Serial.print("INVALID");
}
Serial.print(" Date/Time: ");
if (gps.date.isValid()) {
Serial.print(gps.date.year());
Serial.print("/");
Serial.print(gps.date.month());
Serial.print("/");
Serial.print(gps.date.day());
}
Serial.println();
}