9

The Apollo attitude control system starts from a known orientation established by taking star sightings, then uses gyroscopes to track the change in orientation over time. The problem with gimbal lock is that the system can no longer distinguish the axes of rotation properly, so can't tell how the orientation is changing. The remedy for gimbal lock is just ...


6

Per Elon via twitter, magnetic torquers. Magnetic torque rods for desaturation of momentum wheels.


5

A hemispherical resonator is an example of a mechanical gyroscope that has no bearing parts and for practical purposes no moving parts either. See the Wiki page here. I actually find the description of the principal of operation there a little hard to follow so I've just taken the black box principle, that the vibration patterns in the surface respond to ...


5

In this figure, ζ is the input axis, η is the output axis, and the spin axis is obvious. If the vehicle is rotated around the axis ζ (the input axis) with an angular velocity ωζ, the frame will rotate around the axis η (the output axis) to an angle β. The dependence of this angle on ωζ is given by the equation β = ωζH/c, where H is the moment of momentum of ...


3

Gyroscopes used as sensors can be mechanical, ie with spinning parts, or electrical in which case lasers are often used. Movement is measured and the output is some sort of data which goes to a guidance system. Gyroscopes used to provide physical force to stabilize or orient a craft have to be mechanical as the electric signals or lasers used in electronic ...


3

Some of the confusion may arise in that the gyros under discussion are not used to actually change the attitude of the HST...that is done by Reaction Wheel Assemblies, (separate spinning devices) and magnetic torquers. The gyros in question are sensors only. Knowing that, it makes sense that. Both the FHST and the FGS measure two degrees-of-freedom of ...


2

A gyrocompass mounts a gyroscope in a particular way so that its axis (eventually) self-aligns with the axis of the planet, e.g. Earth’s, rotation. In this way you get a self-contained indication of true North. It doesn’t depend on a magnetic field, which might be handy on e.g. Mars. It works because the planet rotates and carries the mount along. If ...


2

Planets rotate. Place an accurate gyroscope on a table and you can readily observe earth's rotation. A 3-axis gyroscope measures the axis of rotation and angular velocity around it. Angular velocity is rather unimportant as it is a known quantity anyway (earth: 360°/24h), but knowledge of the axis of rotation proves to be valuable: The horizontal component ...


2

Gyrocompass is type of non magnetic compass. It is similar in principle of gyroscope but not same. The principle namely is gyroscopic precession. One can definitely use the gyroscope/gyroscopic compass to get a coarse attitude. If you are in a particular latitude and longitude one can calculate the direction of rotation vector one would measure in the ...


2

Not a real answer, but some thoughts that are too long for a comment I doubt there was a concern about optimizing the directions for easier calculations. Positions are fixed and known, so all equations can be "hand-crafted" to allow for rather quick but still precise calculations in the on-board computers. The orientation of the 4 reaction wheels seems ...


1

This needs to be assessed on a case-by-case basis, with simulations, and with all hardware and algorithms properly modeled. But to give an ideia of what is concerned and what is usual: Image blur on star trackers is a thing indeed, you may expect a star tracker to stop providing measurements while thrusting occurs. Some satellites such as geostationary ...


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