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cs:localization:rotation:start [2017/01/22 02:41]
Brian Moore
cs:localization:rotation:start [2017/01/22 03:07]
Brian Moore [Inverse Rotation]
Line 163: Line 163:
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-It is worth stating explicitly that $R^{-1} \neq R(-\psi,​-\phi,​-\theta)$. If you yaw, then pitch, then roll into an orientation,​ you //cannot// anti-yaw, then anti-pitch, then anti-roll from that orientation to get back to the origin. ​ You'd have to anti-roll, then anti-pitch, then anti-yaw. ​ It must be multiplied by its //​transpose//​ $R^{\mathrm {T}}$.+It is worth stating explicitly that $R^{-1} \neq R(-\psi,​-\phi,​-\theta)$. If you yaw, then pitch, then roll into an orientation,​ you //cannot// anti-yaw, then anti-pitch, then anti-roll from that orientation to get back to the origin. ​ You'd have to anti-roll, then anti-pitch, then anti-yaw.  It must be rotated completely in reverse.  It must be multiplied by its //​transpose//​ $R^{\mathrm {T}}$.
  
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-U \neg (R_{-\theta} R_{-\phi} R_{-\psi})(R_\theta R_\phi R_\psi) U \\+U \neq (R_{-\theta} R_{-\phi} R_{-\psi})(R_\theta R_\phi R_\psi) U \\ 
 +U = (R_{-\psi} R_{-\phi} R_{-\theta}) (R_\theta R_\phi R_\psi) U \\
 U = (R_{-\psi} (R_{-\phi} (R_{-\theta} R_\theta) R_\phi) R_\psi) U \\ U = (R_{-\psi} (R_{-\phi} (R_{-\theta} R_\theta) R_\phi) R_\psi) U \\
 U = (R_{-\psi} (R_{-\phi} (I) R_\phi) R_\psi) U \\ U = (R_{-\psi} (R_{-\phi} (I) R_\phi) R_\psi) U \\