3 ms·
That's not entirely true. Early navigation was done with gyroscopes, see http://en.wikipedia.org/wiki/Inertial_navigation_system http://en.wikipedia.org/wiki/In
by tlow 13y ago
That's not entirely true. Early navigation was done with gyroscopes, see http://en.wikipedia.org/wiki/Inertial_navigation_system http://en.wikipedia.org/wiki/Inertial_navigation_system specifically:
"The INS is initially provided with its position and velocity from another source (a human operator, a GPS satellite receiver, etc.), and thereafter computes its own updated position and velocity by integrating information received from the motion sensors. The advantage of an INS is that it requires no external references in order to determine its position, orientation, or velocity once it has been initialized."
- falcolas 13y agoOne good earthquake will cause some real problems... I find it interesting that the GPS is even receiving signals inside of a machine shop. One would think that the interference from the machine itself, not to mention the typically metal building, would attenuate the already weak signals pretty badly.
- avn2109 13y agoWhile it is true that INS's exist, the cost of a reliable and accurate one is on the same order of magnitude as the CNC Machine itself. Also, errors accumulate [0] over time in an INS (aka "Integration Drift"), such that it becomes wildly inaccurate after a certain critical threshold. Also, almost all INS's require regular calibration and tuning, [1] and are sensitive to vibrational stresses (which is abundantly present in a machine shop). Therefore it seems unlikely that these machines include INS's. [0] http://en.wikipedia.org/wiki/Inertial_navigation_system#Error http://en.wikipedia.org/wiki/Inertial_navigation_system#Erro... [1] http://www.aerostudents.com/files/avionics/navigationBasicsAndInertialNavigation.pdf http://www.aerostudents.com/files/avionics/navigationBasicsA... (scroll down to bottom for tuning discussion)
- tlow 13y agoAgain, it is true that drift exists, but you're mischaracterizing, from [0]: "these errors accumulate roughly proportionally to the time since the initial position was input. Therefore the position must be periodically corrected by input from some other type of navigation system." [0]http://en.wikipedia.org/wiki/Inertial_navigation_system#Error http://en.wikipedia.org/wiki/Inertial_navigation_system#Erro...