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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"> <html> <head> <title>page_288</title> <link rel="stylesheet" href="reset.css" type="text/css" media="all"> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> </head> <body> <table summary="top nav" border="0" width="100%"> <tr> <td align="left" width="30%" style="background: #EEF3E2"><a style="color: blue; font-size: 120%; font-weight: bold; text-decoration: none; font-family: verdana;" href="page_287.html">< previous page</a></td> <td id="ebook_previous" align="center" width="40%" style="background: #EEF3E2"><strong style="color: #2F4F4F; font-size: 120%;">page_288</strong></td> <td align="right" width="30%" style="background: #EEF3E2"><a style="color: blue; font-size: 120%; font-weight: bold; text-decoration: none; font-family: verdana;" href="page_289.html">next page ></a></td> </tr> <tr> <td id="ebook_page" align="left" colspan="3" style="background: #ffffff; padding: 20px;"> <table border="0" width="100%" cellpadding="0"><tr><td align="center"> <table border="0" cellpadding="2" cellspacing="0" width="100%"><tr><td align="left"></td> <td align="right"></td> </tr></table></td></tr><tr><td align="left"><p></p><table border="0" cellspacing="0" cellpadding="0" width="100%"><tr><td align="right"><font face="Times New Roman, Times, Serif" size="2" color="#FF0000">Page 288</font></td></tr></table><table border="0" cellspacing="0" cellpadding="0" width="100%"><tr><td rowspan="5"></td> <td colspan="3" height="12"></td> <td rowspan="5"></td></tr><tr><td colspan="3"></td></tr><tr><td></td> <td align="center"><font face="Times New Roman, Times, Serif" size="3"><img src="12cb2377f305ee7b4866fa379df7748e.gif" border="0" alt="0288-01.GIF" width="432" height="159" /></font></td><td></td></tr><tr><td colspan="3"></td></tr><tr><td colspan="3" height="1"></td></tr></table><table border="0" cellspacing="0" cellpadding="0" width="100%"><tr><td rowspan="5"></td> <td colspan="3" height="12"></td> <td rowspan="5"></td></tr><tr><td colspan="3"></td></tr><tr><td></td> <td align="center"><font face="Times New Roman, Times, Serif" size="2">Figure聽7.30<br />Two-antenna聽alignment聽error聽standard聽deviation聽versus聽baseline聽length聽with<br /><img src="b9bfd9527e5eb2fa6afe36ff895bc229.gif" border="0" alt="C0288-01.GIF" width="74" height="18" />聽and聽<img src="8c71967c515d693ee4d51d1b9cb6e0b0.gif" border="0" alt="C0288-02.GIF" width="68" height="18" />.</font></td><td></td></tr><tr><td colspan="3"></td></tr><tr><td colspan="3" height="1"></td></tr></table><table border="0" cellspacing="0" cellpadding="0"><tr><td rowspan="5"></td> <td colspan="3" height="12"></td> <td rowspan="5"></td></tr><tr><td colspan="3"></td></tr><tr><td></td> <td><font face="Times New Roman, Times, Serif" size="3">indicated by 脳's and dashed curves, respectively. As the alignment error standard deviations (right plot) show, the tilt and azimuth errors are accurately estimated. The azimuth error standard deviation is indicated by the 脳's. Note that this error-estimation performance is achieved for an essentially stationary system. The system is accurately initialized within the first quarter of the 60-s period of the assumed vehicle rotation. Because of the observability conditions of the two-antenna configuration, vehicle rotation is not necessary to achieve accurate error estimation.</font></td><td></td></tr><tr><td colspan="3"></td></tr><tr><td colspan="3" height="1"></td></tr></table><table border="0" cellspacing="0" cellpadding="0"><tr><td rowspan="5"></td> <td colspan="3" height="12"></td> <td rowspan="5"></td></tr><tr><td colspan="3"></td></tr><tr><td></td> <td><font face="Times New Roman, Times, Serif" size="3">Figure 7.30 displays the resulting azimuth error standard deviation as a function of the length of the offset vector <i>L</i>. The greatest improvement in the observability of the azimuth error occurs as <i>L</i> increases to 1.0 m. The position error standard deviation is not plotted, as it does not change significantly. The additional order-of-magnitude improvement in performance as <i>L</i> increases from 1.0 to 10.0 is of course significant if the vehicle body is long and rigid enough to allow the increased length. Note that the azimuth estimation error is always below the error bound of (0.01/<i>L</i>) for the GPS-only solution for a level system.</font></td><td></td></tr><tr><td colspan="3"></td></tr><tr><td colspan="3" height="1"></td></tr></table><table border="0" cellspacing="0" cellpadding="0"><tr><td rowspan="5"></td> <td colspan="3" height="12"></td> <td rowspan="5"></td></tr><tr><td colspan="3"></td></tr><tr><td></td> <td><font face="Times New Roman, Times, Serif" size="3">The above analysis has assumed two specific directions for the offset vectors. The specific directions are not critical, as long as the angle between the vectors is large (</font><font face="Symbol" size="3">禄</font><font face="Times New Roman, Times, Serif" size="3"> 90掳). The rigidity of the body along the offset vectors is of primary consideration, since uncompensated oscillations of the lever arm can seriously diminish the benefits of such multiantenna approaches.</font></td><td></td></tr><tr><td colspan="3"></td></tr><tr><td colspan="3" height="1"></td></tr></table><table border="0" cellspacing="0" cellpadding="0"><tr><td rowspan="5"></td> <td colspan="3" height="12"></td> <td rowspan="5"></td></tr><tr><td colspan="3"></td></tr><tr><td></td> <td><font face="Times New Roman, Times, Serif" size="3"><i>7.6.3<br />Comparison</i></font></td><td></td></tr><tr><td colspan="3"></td></tr><tr><td colspan="3" height="1"></td></tr></table><table border="0" cellspacing="0" cellpadding="0"><tr><td rowspan="5"></td> <td colspan="3" height="12"></td> <td rowspan="5"></td></tr><tr><td colspan="3"></td></tr><tr><td></td> <td><font face="Times New Roman, Times, Serif" size="3">Since the simulation analysis discussed above did not include detailed truth models for the GPS and INS errors, the performance shown is not meant to indicate the actual performance to be achieved for a given application. The models in the previous subsections are comparable, and therefore the results enable a discussion of the relative tradeoffs of the GPS-only and GPS INS approaches to attitude determination. Such a discussion is the main objective in this subsection. The discussion provides a nice illustration of the complementary features of the GPS and INS techniques.</font><font face="Times New Roman, Times, Serif" size="3" color="#FFFF00"></font></td><td></td></tr><tr><td colspan="3"></td></tr><tr><td colspan="3" height="1"></td></tr></table></td></tr></table><p><font size="0"></font></p>聽 </td> </tr> <tr> <td align="left" width="30%" style="background: #EEF3E2"><a style="color: blue; font-size: 120%; font-weight: bold; text-decoration: none; font-family: verdana;" href="page_287.html">< previous page</a></td> <td id="ebook_next" align="center" width="40%" style="background: #EEF3E2"><strong style="color: #2F4F4F; font-size: 120%;">page_288</strong></td> <td align="right" width="30%" style="background: #EEF3E2"><a style="color: blue; font-size: 120%; font-weight: bold; text-decoration: none; font-family: verdana;" href="page_289.html">next page ></a></td> </tr> </table> </body> </html>⌨️ 快捷键说明
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