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sensors
20262 articles
How a Drone Stays Level: Gyros, Motors and PID Loops
A quadcopter is naturally unstable. See how four motors, motion sensors and a fast feedback loop called PID let it hover and hold its angle.
How a Smartwatch Measures Your Heart Rate With Light
Smartwatches shine green light into your wrist and read how much blood absorbs. Here is how the method, called photoplethysmography, works and where it struggles.