"Spacecraft attitude control is the process of controlling the orientation of a spacecraft (vehicle or satellite) with respect to an inertial frame of reference or another entity."
Methods used to control the orientation of a spacecraft, including reaction wheels, thrusters, and GPS.
Fundamentals of Control Theory: Understanding the basic principles of control theory is necessary when designing and implementing attitude control systems for spacecraft.
Spacecraft Dynamics: Understanding the dynamics of spacecraft is crucial for designing attitude control systems that account for the complex interactions between various subsystems.
Sensors and Actuators: Attitude control systems rely on sensors to collect data about the spacecraft's orientation and actuators to adjust its orientation. Familiarity with different types of sensors and actuators is essential for designing effective attitude control systems.
Requirements and Constraints: Attitude control system design is heavily influenced by the spacecraft's mission objectives, size, weight, power limitations, and environmental factors. Understanding these requirements and constraints is crucial for designing effective attitude control systems.
Control Algorithms: There are various control algorithms, including proportional-integral-derivative (PID), fuzzy logic, and adaptive control, that can be used to control spacecraft attitude. Understanding these algorithms' strengths and weaknesses is necessary when selecting the best approach for a given mission.
Angular Momentums and Torques: Angular momentum is the measure of a spacecraft's ability to maintain its angular orientation. Torques can be applied to the spacecraft in different ways to adjust its attitude. Understanding how these principles work is necessary for designing effective attitude control systems.
Attitude Determination: Attitude determination involves determining the spacecraft's orientation relative to its environment. Attitude determination systems can use sensors, such as star trackers, sun sensors, and magnetometers, to provide a reliable estimate of the spacecraft's orientation.
Calibrating Sensors: Sensors used in attitude control systems may experience inaccuracies due to various factors such as temperature variations, radiation, and aging. Calibration of sensors and periodic corrections are necessary for accurate and reliable attitude control.
Response to Environmental Disturbances: Spacecraft can be subjected to various environmental disturbances, such as solar wind, radiation, and magnetic fields. Designing adaptive attitude control systems that can respond to these disturbances effectively is necessary for reliable spacecraft operation.
Testing and Verification: Attitude control systems must be thoroughly tested and verified before deployment. This includes ground-based testing, as well as in-orbit testing to ensure the system works correctly under actual operating conditions.
Reaction wheel attitude control: Uses the principle of conserving angular momentum to change the spacecraft’s orientation. Reaction wheels can spin in opposite directions to cause a spacecraft to spin, or they can slow down or speed up to adjust the spacecraft’s orientation.
Thruster attitude control: Uses small rocket thrusters to make small adjustments to the spacecraft’s attitude.
Magnetic attitude control: Uses magnetic fields to control the orientation of the spacecraft.
Gravity-gradient attitude control: Uses the differences in gravitational attraction experienced by different parts of a long, thin spacecraft to adjust its orientation.
Control moment gyroscope (CMG) attitude control: Uses a rapidly spinning flywheel to generate torque and adjust the spacecraft’s orientation.
Cold-gas attitude control: Uses compressed gas to provide small adjustments to the spacecraft’s attitude.
Electro-reaction wheels: Similar to traditional reaction wheels, but use electric fields to change the spacecraft’s spin.
Horizon sensor attitude control: Uses optical sensors to determine the spacecraft’s orientation relative to the horizon and make adjustments as necessary.
Earth sensor attitude control: Uses optical sensors to determine the spacecraft’s orientation relative to the Earth and make adjustments as necessary.
Star tracker attitude control: Uses a camera to identify and track stars in the spacecraft’s field of view to determine its orientation.
Solar pressure attitude control: Utilizes the pressure of sunlight on a spacecraft’s solar panels to make small adjustments to its attitude.
Pulsed plasma thruster attitude control: Uses miniature electric thrusters that use pulsed plasma to make small adjustments to a spacecraft’s attitude.
Solar sail attitude control: Uses the pressure of solar radiation on a large reflective sail to adjust a spacecraft’s orientation.
Active mass driver attitude control: Relies on a magnetic driver to adjust a spacecraft’s orientation by manipulating its mass distribution.
Purely passive attitude control: Utilizes aerodynamic means to maintain its orientation in the absence of active systems.
Reaction control system (RCS) attitude control: Uses small rockets to adjust the spacecraft’s position, especially in terms of its orientation or pointing.
Control moment magnetometer actuators: Uses magnetic fields to change the spacecraft’s spin orientation.
Spin and gravity gradient attitude control: Uses the spacecraft’s spin combined with the gravitational gradient to maintain its orientation.
"Controlling vehicle attitude requires sensors to measure vehicle orientation, actuators to apply the torques needed to orient the vehicle to a desired attitude, and algorithms to command the actuators based on sensor measurements of the current attitude and specification of a desired attitude."
"Sensors measure vehicle orientation."
"Actuators apply the torques needed to orient the vehicle to a desired attitude."
"The integrated field that studies the combination of sensors, actuators, and algorithms is called guidance, navigation, and control (GNC)."
"The integrated field (GNC) studies the combination of sensors, actuators, and algorithms."
"Controlling vehicle orientation can be done with respect to an inertial frame of reference or another entity such as the celestial sphere, certain fields, and nearby objects, etc."
"Sensor measurements of the current attitude are required."
"Algorithms command the actuators based on sensor measurements of the current attitude and specification of a desired attitude."
"The integrated field that studies the combination of sensors, actuators, and algorithms is called guidance, navigation, and control (GNC)."
"Controlling the orientation of a spacecraft (vehicle or satellite) with respect to an inertial frame of reference."
"The process of controlling the orientation of a spacecraft requires sensors, actuators, and algorithms."
"The orientation of a vehicle should be controlled to a desired attitude."
"Controlling vehicle orientation can be done with respect to the celestial sphere."
"Algorithms command the actuators based on sensor measurements of the current attitude and specification of a desired attitude."
"Actuators apply the torques needed to orient the vehicle to a desired attitude."
"Algorithms command the actuators based on sensor measurements of the current attitude and specification of a desired attitude."
"The integrated field that studies the combination of sensors, actuators, and algorithms is called guidance, navigation, and control (GNC)."
"The collective term for the combination of sensors, actuators, and algorithms is guidance, navigation, and control (GNC)."
"The integrated field of guidance, navigation, and control (GNC) encompasses the combination of sensors, actuators, and algorithms."