<p><pre><code>  &gt;&gt; inertial, ...
</code></pre>
A nice discussion of inertial navigation capability (<a href="https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=10752294" rel="nofollow">https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=10752294</a>):<p><pre><code>    Consumer grade MEMS ...are not sufficient for intertial navigation, ... 

    At around the $2K-30K you get systems that can 
    provide accurate navigation for up to 2 minutes or so. 

    Aviation grade IMUs ... maximum horizontal position drift of 1.5km 
    in the first hour of operation. These will run 100K and up.</code></pre>