建立中间坐标系{R},{Q},{P},把在坐标系{i}中定义的矢量变换为在坐标系{i-1}中的描述,对应的变换可以写成
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(2-1)
^{i - 1}{\bf{P}} = _R^{i - 1}{\bf{T}}_Q^R{\bf{T}}_P^Q{\bf{T}}_i^P{\bf{T}}{}^i{\bf{P}} \tag{2-1}
i−1P=Ri−1TQRTPQTiPTiP(2-1) 变换矩阵为
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(2-2)
^{i - 1} _i{\bf{T}} = {}_R^i{\bf{T}}{}_Q^R{\bf{T}}{}_P^Q{\bf{T}}{}_i^P{\bf{T}} \tag{2-2}
ii−1T=RiTQRTPQTiPT(2-2) 即
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(2-3)
{}^{i - 1}_i{\bf{T}} = {{\bf{R}}_X}({\alpha _{i - 1}}){{\bf{D}}_X}({a_{i - 1}}){{\bf{R}}_Z}({\theta _i}){{\bf{D}}_Z}({d_i}) \tag{2-3}
ii−1T=RX(αi−1)DX(ai−1)RZ(θi)DZ(di)(2-3) 计算得到
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^{i-1}_{i}\mathbf{T}
ii−1T的一般表达式为
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(2-4)
^{i - 1}_i{\bf{T}} = \left[ {\begin{matrix} {c{\theta _i}}&{ - s{\theta _i}}&0&{{a_{i - 1}}}\\ {s{\theta _i}c{\alpha _{i - 1}}}&{c{\theta _i}c{\alpha _{i - 1}}}&{ - s{\alpha _{i - 1}}}&{ - s{\alpha _{i - 1}}{d_i}}\\ {s{\theta _i}s{\alpha _{i - 1}}}&{c{\theta _i}s{\alpha _{i - 1}}}&{c{\alpha _{i - 1}}}&{c{\alpha _{i - 1}}{d_i}}\\ 0&0&0&1 \end{matrix}} \right] \tag{2-4}
ii−1T=⎣⎢⎢⎡cθisθicαi−1sθisαi−10−sθicθicαi−1cθisαi−100−sαi−1cαi−10ai−1−sαi−1dicαi−1di1⎦⎥⎥⎤(2-4)