Guidance, navigation and control (GNC) deals with controlling the movement of space vehicles. GNC includes guidance to establish the desired path, navigation to determine the current and future position, and control actions to match the current position to the desired path. The key elements of GNC are guidance, navigation, control systems, and attitude control. GNC is essential for space missions to navigate from point to point, control the vehicle's orientation, and guide trajectories between planets and spacecraft pointing.

1. Guidance, Navigation and control
By
Periyanayaga kristy. A
M.Tech-Nanotechnology
SRM University

2. Guidance, navigation and control
• “...Guidance, navigation and control (abbreviated GNC) is a branch
of engineering dealing with the design of systems to control the
movement of space vehicles...”
• GUIDANCE: establishment of the desired path to follow (current,
i.e. in real-time and future).
• NAVIGATION: establishment of the current and future state.
• CONTROL: actions to match the current state (navigation) with the
foreseen path (guidance)
Definition

3. Guidance, navigation and control

4. Problem description: Position
Want to “move” a space vehicle from point “A” to point “B”
Guidance, navigation and control

5. Problem description: Attitude
Want to “slew” the axis of a space vehicle from axis “A” to axis “B”
Guidance, navigation and control

6. Simplified GNC block diagram
Guidance, navigation and control

7. GNC elements
Guidance, navigation and control

8. Definition Navigation
• NAVIGATION is the process to find the present and future position
and orbit of a spacecraft using a series of measurements.
• Step 1: MEASURING Obtaining state vectors (x, y, z, Vx, Vy, Vz,...)
at timely intervals.
• Step 2: DETERMINING Reconstructing the orbit based on a set of
state vectors.
• Step 3: PREDICTING Forecasting the imminent future state vector
Guidance, navigation and control

9. Spacecraft Control
• Minimize the spacecraft propellant mass or overall mass,
hence reducing mission cost.
• Increase the accuracy of the control when tracking or
regulating the plant.
• Increase the agility of the spacecraft maneuvers.
• Facilitate the overall design process of the GNC subsystem,
hence reducing mission cost.
Guidance, navigation and control

10. Attitude control
Guidance, navigation and control

11. Spacecraft Pointing Control
Guidance, navigation and control

12. Broad Control System Categories
Guidance, navigation and control

13. Interplanetary Vehicles and GNC:
• Fly-by between planets
• Mid-course correction maneuvers
• Optimal pointing of antennae to ground
stations Station.
• keeping in Lagrangian points
Guidance, navigation and control

14. Missions Examples
• High pointing accuracy on attitude stabilization agility on attitude
slew.
Guidance, navigation and control

15. GNC for launchers
• Trajectory optimization of nominal ascent trajectories
• Performance maps of rockets
• Optimization of non-nominal trajectories: missionization
• Nominal Splash down of stages
• Stages fragmentation analysis and splash down locations
Guidance, navigation and control

16. GNC of a Small Rocket
Guidance, navigation and control