Control Moment Gyroscopes & Falling Cats: Attitude Control

Space Vehicle Dynamics 🐈‍⬛ Lecture 27: part 1. When a body is made up of multiple rigid bodies, you can rotate one part of the body to make the rest counter-rotate. Useful for spacecraft attitude control and also for cats to land on their feet 🙀 We demonstrate with a bicycle wheel gyroscope and other experimental set ups. The control moment gyroscope in the International Space Station (ISS) 🛰 Coupled rigid bodies and conservation of angular momentum.

► Next and final lecture of series
Physics Analysis of Interstellar Docking Scene

► Previous
Gravity Gradient, Part 4, Space Shuttle, Asteroids, and the Moon

Gravity Gradient, Part 3, Stability Conditions, Attitude Oscillation Frequencies

Gravity Gradient, Part 2, Equilibrium Orientations

Gravity Gradients, Part 1, Deriving the Gravity Gradient Torque on a Body in Orbit

► More lectures posted regularly

► Dr. Shane Ross 🙋🏽‍♀️ aerospace engineering professor, Virginia Tech
Background: Caltech PhD | worked at NASA/JPL & Boeing
Research website for @ProfessorRoss

► Follow me on Twitter 🦩

► Space Vehicle Dynamics course videos (playlist)

► Lecture notes (PDF)

► References
Schaub & Junkins📘Analytical Mechanics of Space Systems, 4th edition, 2018

Video of falling cat from @smartereveryday
Slow Motion Flipping Cat Physics | Smarter Every Day 58

Video of spinning wheel in spinning chair:

Video animation of control moment gyroscope:

Video of reaction wheel experimental platform:

Video animation of twisting somersault
Dullin & Tong (2016)

► Chapters
0:00 Space station attitude stability continued
0:19 Control moment gyroscope
0:43 Falling cat physics
1:44 Spinning bicycle wheel demonstration
4:13 Same principle behind control moment gyroscopes on spacecraft
6:08 Human attitude control in space

- Typical reference frames in spacecraft dynamics
- Kinematics of a single particle: rotating reference frames, transport theorem
- Multiparticle systems: kinematics and dynamics, definition of center of mass (c.o.m.)
- Multiparticle systems: motion decomposed into translational motion of c.o.m. and motion relative to the c.o.m.
- Multiparticle systems: imposing rigidity implies only motion relative to c.o.m. is rotation
- Rigid body: continuous mass systems and mass moments (total mass, c.o.m., moment of inertia tensor/matrix)
- Rigid body kinematics in 3D (rotation matrix and Euler angles)
- Rigid body dynamics; Newton's law for the translational motion and Euler’s rigid-body equations for the rotational motion
- Solving the Euler rotational differential equations of motion analytically in special cases
- Constants of motion: quantities conserved during motion, e.g., energy, momentum

► Other Series by Dr. Ross

📚Nonlinear Dynamics and Chaos

📚Lagrangian and 3D Rigid Body Dynamics

📚Hamiltonian Dynamics

📚Center Manifolds, Normal Forms, and Bifurcations

📚Space Vehicle Dynamics

📚3-Body Problem Orbital Dynamics Course

📚Space Manifolds

CMG Variable Speed Control Moment Gyroscopes VSCMG Momentum Exchange Device

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[man_dills]

I've just finished the Space Vehicle Dynamics course. An awesome collection of videos that I'm sure I'll refer back to as I've just started a new role as an ADCS Engineer. Cheers Dr. Ross!

[Karlemilstorm]

0:25 "people are walking around"? Eh? 😁

[GiovaniCrepaldi]

Professor, in the video of the wheel, before the student rotates the wheel downwards, the angular momentum vector is pointing in the, let's say, x hat direction. I understand that the chair rotates in the way to keep the total angular momentum in the y hat direction equals to zero, but what about the conservation in x hat direction?

[ButilkaRomm]

Hi. People always tell me that rockets work because they are throwing something (burned fuel at high velocity) and that is why they propel forward. They say it is the second law of Newton. You need to throw something (backward) to move forward. So I do not understand how CMG can provide torque. Can CMG be used for propulsion?

[mattman]

Have you done any presentation of yourfluid dynamics concepts in a large glass aquarium with an additive of the substances found in yellow highlighters under blacklight or other light to attempt a visual effect of the situation?