手法を比較

	SGP4 TLE伝播	クォータニオン姿勢	TCAS
分野	航空宇宙工学	航空宇宙工学	航空宇宙工学
系統	Process / pipeline	Process / pipeline	Process / pipeline
提唱年	1970s	1843	1989
提唱者	NORAD, USAF	William Hamilton (quaternions), aerospace engineers	FAA, ICAO
種類	Propagation method	Mathematical framework	Avionics system
原典	Vallado, D. A., Crawford, P., Hujsa, R., & Kelso, T. S. (2006). Revisiting Spacetrack Report Number 3. In AIAA/AAS Astrodynamics Specialist Conference.	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.
別名	SGP4, TLE propagation, simplified perturbations	quaternion representation, attitude kinematics, q-vector	TCAS II, ACAS, traffic avoidance
関連	3	3	3
概要	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.	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.