Compara mètodes

	Propagació TLE SGP4	Controlador B-Dot	Representació d'actitud quaterniònica	TCAS
Camp	Aeroespacial	Aeroespacial	Aeroespacial	Aeroespacial
Família	Process / pipeline	Process / pipeline	Process / pipeline	Process / pipeline
Any d'origen	1970s	1980s	1843	1989
Autor original	NORAD, USAF	Spacecraft attitude control engineers	William Hamilton (quaternions), aerospace engineers	FAA, ICAO
Tipus	Propagation method	Control law	Mathematical framework	Avionics system
Font seminal	Vallado, D. A., Crawford, P., Hujsa, R., & Kelso, T. S. (2006). Revisiting Spacetrack Report Number 3. In AIAA/AAS Astrodynamics Specialist Conference.	Wertz, J. R. (Ed.). (2002). Spacecraft Attitude Determination and Control. Kluwer Academic.	Shuster, M. D. (1993). A survey of attitude representations. Journal of the Astronautical Sciences, 41(4), 439–517.	Federal Aviation Administration (2017). Traffic Collision Avoidance System (TCAS II). Technical Standard Order TSO-C119c.
Àlies	SGP4, TLE propagation, simplified perturbations	B-dot control, magnetic damping, momentum dumping	quaternion representation, attitude kinematics, q-vector	TCAS II, ACAS, traffic avoidance
Relacionats	3	3	3	3
Resum	SGP4 (Simplified General Perturbations 4) is a rapid orbital propagation method that predicts satellite position and velocity from Two-Line Element (TLE) sets published by NORAD. Developed in the 1970s, SGP4 accounts for atmospheric drag, gravitational perturbations, and solar radiation pressure using simplified analytical models. SGP4 is the de facto standard for space surveillance, conjunction assessment, and satellite tracking.	The B-Dot controller (magnetic B-dot control law) is a simple, robust spacecraft attitude control method that uses the rate of change of Earth's magnetic field measured onboard to generate a magnetic dipole moment. Developed in the 1980s, the B-Dot law damps spacecraft angular momentum without requiring a complex attitude estimate or external reference, making it ideal for initial momentum dumping after launch or in contingency scenarios. B-Dot is passive, simple to implement, and effective.	Quaternion attitude representation is a mathematical framework for describing three-dimensional rotations using four-dimensional vectors (quaternions). Superior to Euler angles due to the absence of singularities (gimbal lock), quaternions are the standard representation in modern attitude estimation, spacecraft control, and 3D computer graphics. Quaternion kinematics elegantly expresses how attitude evolves under angular velocity measurements from gyroscopes.	TCAS (Traffic Collision Avoidance System) is an airborne safety system that detects nearby aircraft using radar and mode C altitude reports, then provides traffic advisories (TAs) and recommended collision avoidance maneuvers (RAs) to flight crews. Mandated globally on commercial aircraft since 2000, TCAS is considered a last line of defense against mid-air collisions. TCAS II is the most common variant; TCAS I is a simplified advisory-only version for general aviation.