📄 page_285.html
字号:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"> <html> <head> <title>page_285</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_284.html">< previous page</a></td> <td id="ebook_previous" align="center" width="40%" style="background: #EEF3E2"><strong style="color: #2F4F4F; font-size: 120%;">page_285</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_286.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 285</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="e078a937fe5ec05ba13e026660a604e6.gif" border="0" alt="0285-01.GIF" width="439" height="326" /></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7.27<br />Single-antenna聽position聽and聽alignment聽error聽standard聽deviation聽versus聽time.<br />Top聽plots聽have聽<img src="074cf4b9ca240063ed55e9bfb45ae310.gif" border="0" alt="C0285-01.GIF" width="70" height="17" />,聽bottom聽plots聽have聽<img src="f0e091cde62e337a60d3170e41c7d383.gif" border="0" alt="C0285-02.GIF" width="61" height="17" />.</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">errors are assumed negligible. If b</font><font face="Times New Roman, Times, Serif" size="2"><sup><i>b</i></sup></font><font face="Times New Roman, Times, Serif" size="3"> is assumed to be [L, 0, 0] then</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"><img src="1ef2227ebf2f82e712e48b858733e4dc.gif" border="0" alt="0285-02.GIF" width="151" height="53" /></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">where <i>b</i></font><i><font face="Times New Roman, Times, Serif" size="1"><sub>N</sub></font></i><font face="Times New Roman, Times, Serif" size="1"><sub></sub></font><font face="Times New Roman, Times, Serif" size="3"> = <i>L</i> cos(</font><font face="Symbol" size="3"><i>y</i></font><font face="Times New Roman, Times, Serif" size="3">) cos(</font><font face="Symbol" size="3"><i>q</i></font><font face="Times New Roman, Times, Serif" size="3">) and <i>b</i></font><i><font face="Times New Roman, Times, Serif" size="1"><sub>E</sub></font></i><font face="Times New Roman, Times, Serif" size="1"><sub></sub></font><font face="Times New Roman, Times, Serif" size="3"> = <i>L</i> sin(</font><font face="Symbol" size="3"><i>y</i></font><font face="Times New Roman, Times, Serif" size="3">) cos(</font><font face="Symbol" size="3"><i>q</i></font><font face="Times New Roman, Times, Serif" size="3">). Therefore, for fixed values of the pitch and the heading, lever-arm separation along the vehicle <i>u</i> axis results in loss of the ability to estimate one of the position variables. For example, if pitch and heading are both zero, <i>b</i></font><i><font face="Times New Roman, Times, Serif" size="1"><sub>N</sub></font></i><font face="Times New Roman, Times, Serif" size="1"><sub></sub></font><font face="Times New Roman, Times, Serif" size="3"> = <i>L</i> and error in the east direction cannot be discriminated from azimuth error. Based on the simulation trajectory, this will occur at <i>t</i> = <i>k</i> * 30 for integer values of <i>k</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">The above conclusions are illustrated in Fig. 7.27. The top plots correspond to the body-frame lever-arm vector [0, 0,-1]. As the position error standard deviations (left plot) show, the position variables are accurately estimated. As the alignment error standard deviations (right plot) show, the tilt errors are accurately estimated because of the nonzero vertical component of the gravity vector. The azimuth error, indicated by 脳's, is, however, unobservable. The bottom plots of Fig. 7.27 correspond to the body-frame lever-arm vector [1, 0, 0]. In the plot of the position error standard deviations, the north and the east errors are indicated by 脳's and a dashed curve, respectively. The observability of the north and the east position errors is oscillating at twice the frequency of</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_284.html">< previous page</a></td> <td id="ebook_next" align="center" width="40%" style="background: #EEF3E2"><strong style="color: #2F4F4F; font-size: 120%;">page_285</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_286.html">next page ></a></td> </tr> </table> </body> </html>⌨️ 快捷键说明
复制代码
Ctrl + C
搜索代码
Ctrl + F
全屏模式
F11
切换主题
Ctrl + Shift + D
显示快捷键
?
增大字号
Ctrl + =
减小字号
Ctrl + -