8. Attitude Determination, Control, and Sensing
authored by Dr. Zhu
We care about attitude determination and control because it is one of the core disciplines within spacecraft engineering. Attitude is intimately tied to all other spacecraft functions and almost all spacecraft have to address the following questions:
- Where does it need to point?
- How well does it need to hold an attitude?
This chapter:
- Defines the Attitude Determination, Control, Navigation, and Sensing (ADCS) system
- Distinguishes the responsibilities
- Describes the general design process
- Defines common requirements
- Reviews foundational math around attitude dynamics
- Surveys typical sensor and actuator technology
- Conceptually explains determination and control algorithms
Learning Objectives
- Understand the role of the ADCS subsystem in the context of spacecraft as a whole and between other subsystems
- Understand the equations of motion for attitude dynamics and different variations of attitude representation
- Identify the spacecraft parameters that affect attitude dynamics and relate parameter change to the dynamics model
- Classify which sensors measure which physical phenomena with associated precision/accuracy, limitations, and environments
- Gather intuition as to attitude estimation and define various estimation algorithms relative to sensors available
- Recommend different actuators for different desired maneuvers by calculating the magnitude and precision of actuators
- Identify external/environmental torques and calculate the magnitude of effect that actuators must overcome
- Gather intuition as to the different control policies used aboard spacecraft
Attitude Determination, Control, and Sensing Chapter Contents
Learning Objectives
8.1 Definition
8.2 Subsystem Responsibilities
8.3 General Design Process
8.4 Typical Requirements and Design Considerations
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- Mission-Derived Requirements
- Design Drivers
- Design Configuration
- Artemis ADCS Requirements
- Suggested Activity
8.5 Dynamics
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- Attitude Representation
- Euler Angles
- Rotation Matrix
- Euler Axis/Axis-Angle
- Quaternions
- Converting between Attitude Representations
- Kinematics
- Rotation Matrix Kinematics
- Quaternion Kinematics
- Rigid Body Dynamics
- Moment of Inertia
- Angular Momentum
- Kinetic Energy
- Euler’s Equations
- Parameters and Analysis
- Moments of Inertia
- Equilibria
- Stability
- External Torques
- Magnetic Field
- Gravity Gradient
- Aerodynamic Drag
- Solar Radiation
- Internal Torques
- Damping
- Momentum Control
- Thrusters
- Configurations
- Gravity Gradient Stabilization
- Magnetic Damping
- Spin Stabilization
- Dual-Spin
- Momentum Bias
- Three-Axis Control
- Modes
- Detumbling/Momentum Dumping
- Pointing/Slewing
- Safe
- Suggested Activity
- Attitude Representation
8.6 Sensing
-
- Remote Sensing
- Earth/Horizon Sensor
- Sun Sensor
- Star Sensor/Tracker
- Magnetometer
- Gyroscope
- Inertial Measurement Unit
- Global Positioning System (GPS)
- Sensor Design Process and Drivers
- Common Configurations
- Artemis ADCS Sensors
- Remote Sensing
8.7 Determination
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- TRIAD
- Wahba’s Problem/ Batch Estimation
- Convex Optimization Solution
- SVD solution
- q-Method
- Kalman Filter
- Background
- Problem Statement
- Algorithm Solution
- Concluding Remarks
8.8 Control
-
- Actuators
- Magnetic Torquers
- Reaction Wheels
- Control Moment Gyroscopes
- Thrusters
- Actuator Design Process and Drivers
- Control Algorithms
- Detumbling
- Momentum Dumping
- Actuators Jacobians
- Actuators
8.9 Pointing Analysis and Budget
