Position Sensors (GPS)
Sun Angle a Java Script to compute the angle of the sun based on location, date, and time.
About using start light to improve INS or GPS operation, Don Hyde [DonH at AXONN.COM] says:
There are a bunch of simplifying facts...
1) The favorite star is Canopus, as I understand (I'm no astronomer) it's the brightest, it's close to the ecliptic, and there are no other bright stars nearby to be confusing.
2) You know pretty nearly where you are by your inertial system, you're merely trying to improve on it, so you can point your telescope pretty close.
3) The image is a single bright point. Your "retina" only needs 4 cells. You move "up" or "down" until the "up" pair of cells matches the "down" pair of cells, and similarly for the "left" and "right" ones. You confirm that you're pointing to the right star by checking the absolute brightness of what you see. If it's not bright enough, it's the wrong star, you were looking for the brightest one.
To get aligned in 3 dimensions, you need one other star, preferably about 90 degrees away. I think Polaris is the favorite for that, the familiar north star.
4) An inertial navigation system intrinsically gives your location "inertially", that is to say, it doesn't turn with the earth, so it doesn't move around the sky with time of day or seasons, as long as the initial position that was set just before launch was chosen that way.
For a weapon system that could be launched at any time, I guess it must be able to use an alternate star in case the one it wants happens to be on the other side of the earth at the time.
Star tracking should be able to null out the gyro drift, at least during the coast phase, though I can't see how it could help for accelerometer errors.
|file: /Techref/method/navigation.htm, 2KB, , updated: 2001/6/11 12:27, local time: 2017/10/17 15:49,
|©2017 These pages are served without commercial sponsorship. (No popup ads, etc...).Bandwidth abuse increases hosting cost forcing sponsorship or shutdown. This server aggressively defends against automated copying for any reason including offline viewing, duplication, etc... Please respect this requirement and DO NOT RIP THIS SITE. Questions?|
<A HREF="http://www.piclist.com/techref/method/navigation.htm"> Navigation Methods</A>
|Did you find what you needed?|
PICList 2017 contributors:
o List host: MIT, Site host massmind.org, Top posters @20171017 RussellMc, Van Horn, David, James Cameron, Sean Breheny, IVP, alan.b.pearce, Neil, David C Brown, Bob Blick, Denny Esterline,
* Page Editors: James Newton, David Cary, and YOU!
* Roman Black of Black Robotics donates from sales of Linistep stepper controller kits.
* Ashley Roll of Digital Nemesis donates from sales of RCL-1 RS232 to TTL converters.
* Monthly Subscribers: Gregg Rew. on-going support is MOST appreciated!
* Contributors: Richard Seriani, Sr.
Welcome to www.piclist.com!