Dive into the fourth class of the Introduction to FPV Drones series, taught by Ayan Pahwa. Explore crucial concepts in drone technology, including degrees of freedom, flight controller mechanics, and Inertial Measurement Units (IMUs). Gain insights into digital signal processing, filtering techniques, and sensor fusion. Delve into control systems and understand the importance of PID (Proportional-Integral-Derivative) controllers. Conclude with an overview of flight controller firmware, equipping you with comprehensive knowledge to advance your understanding of FPV drone operations and mechanics.