19 lines
553 B
Matlab
19 lines
553 B
Matlab
function m = rv2m(rv)
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% 等效旋转矢量转换为旋转矩阵
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%
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% Input: rv - 旋转矢量
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% Output: m -旋转矩阵 Cb2n 严龚敏 2.2.23
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% m = I + sin(|rv|)/|rv|*(rvx) + [1-cos(|rv|)]/|rv|^2*(rvx)^2
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% where rvx is the askew matrix or rv.
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nm2 = rv'*rv; % 旋转矢量的模方
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if nm2<1.e-8 % 如果模方很小，则可用泰勒展开前几项求三角函数
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a = 1-nm2*(1/6-nm2/120); b = 0.5-nm2*(1/24-nm2/720); % a->1, b->0.5
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else
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nm = sqrt(nm2);
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a = sin(nm)/nm; b = (1-cos(nm))/nm2;
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end
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VX = askew(rv);
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m = eye(3) + a*VX + b*VX^2;
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