Solution to GPS failure

[zboss]

University of Michigan invents small, affordable, and highly accurate gyroscope.


https://news.umich.edu/small-precise...g-without-gps/

[SeanPatrick]

Very interesting, indeed! Not only would this lower the cost of inertial navigation systems, it could be used in a smartphone, sextant or standalone unit to provide an artificial horizon and thus, accurate measurements of altitudes of celestial bodies without the need for a natural horizon. In combination with an app that could identify star patterns, this could mean the possibility of an automatic Sun/star tracker in everyone's hands.

[karle]

Are there systems that can switch over to Glonass or Galileo or BDS or Navic when GPS fails?

[Paul L]

Way innovative, thanks for posting. It'll be interesting to see how long it takes to commercialize.

[Freedom45]

Why didn’t I think of that........oh, I know.

[dougweibel]

@Karle - yes there are multi-constellation receivers that use GPS, Glonass, Galileo and BDS. The problem, if for example GPS fails, is "what is the failure mode?" and would the receiver know not to use GPS. That is to say if the GPS satellites are still transmitting, just with bad info, then the combined solution will be bad.

@SeanPatrick - I think the existing MEMS gyroscopes are more than adequate for your suggestion of an artificial horizon. The problem with the current small, low cost gyros is their long term drift. In an inertial nav unit you combine accelerometer data inferring the direction of gravity and gyro data to account for the near term motion to determine the direction of "up", and this can be done very will with current cheap small devices. The reason you need a better gyroscope for a full inertial navigation solution is because you cannot use the direction of gravity to determine the direction of "North" and so need a gyro that you can count on for a long time period without drift. You can use a magnetometer for this but of the three sensor types, gyros, accelerometers, and magnetometers, mags are the most problematic. One reason is there is much more variation in the magnetic field from place to place than in the gravitational field so the produce an accurate solution you need a very accurate magnetic map/model, or a very good gyroscope.

[jack4566]

@karle - Any GNSS device you buy will use GPS, Glonass, and Galileo (in newer units) simultaneously. its not a "use one or the other". The more satellites you can see, the better your fix. Plus it would never fail in a way you could only see GPS and not Glonass. Most likely random failure for GPS module is the RF front end gets overloaded and fries it. Or some other electrical failure (lightening strike, cables degrading, etc)

I know they are promising some CRAZY low drift but honestly, having done IMU assisted drone stuff, i don't trust it. You can buy battery powered handheld GPS for under $100, buy a few, put them in separate Pelican cases and never worry.

[Josh.]

Yep, modern GPS chips found in most modern plotters and smartphones will happily work with most systems to varying levels of accuracy without even alerting you.

The problem with inertial navigation is they need an accurate starting point and reliable power source. Something large enough to take out all the GPS birds (ie very large solar storm with the sky lighting up) is something you want to be powering down and putting your eletronics into pots over.

If anything, such a failure reinforces tracking your position on an old-fashioned chart and being able to at-least dead-reckon back to a coast line in an emergancy.

Certainly intresting technology for small cubesats and high-end aviation avionics which require eye-watering expensive ring laser gyros.

[flightlead404]

Originally Posted by Josh.

Something large enough to take out all the GPS birds (ie very large solar storm with the sky lighting up) is something you want to be powering down and putting your eletronics into pots over.

If (when?) we get another Carrington Event, you're going to be worrying about a lot more about than just your cell phone.

Think COVID disturbed the global economy and supply lines?