本文仅供学习使用,总结很多本现有讲述运动学或动力学书籍后的总结,从矢量的角度进行分析,方法比较传统,但更易理解,并且现有的看似抽象方法,两者本质上并无不同。
2024年底本人学位论文发表后方可摘抄
若有帮助请引用
本文参考:
黎 旭,陈 强 洪,甄 文 强 等.惯 性 张 量 平 移 和 旋 转 复 合 变 换 的 一 般 形 式 及 其 应 用[J].工 程 数 学 学 报,2022,39(06):1005-1011.
食用方法
质量点的动量与角动量
刚体的动量与角动量——力与力矩的关系
惯性矩阵的表达与推导——在刚体运动过程中的作用
惯性矩阵在不同坐标系下的表达
务必自己推导全部公式,并理解每个符号的含义
对式 H ⃗ Σ M / O F \vec{H}_{\Sigma _{\mathrm{M}}/\mathrm{O}}^{F} HΣM/OF进一步分析,有:
H ⃗ Σ M / O F = ∫ R ⃗ O P i F × ( d m i ⋅ d R ⃗ P i F d t ) = ∫ ( ( R ⃗ P i F − R ⃗ O F ) × V ⃗ P i F ) d m i = ∫ ( R ⃗ P i F × V ⃗ P i F ) d m i − ∫ ( R ⃗ O F × V ⃗ P i F ) d m i = H ⃗ Σ M F − R ⃗ O F × P ⃗ G F \begin{split} \vec{H}_{\Sigma _{\mathrm{M}}/\mathrm{O}}^{F}&=\int{\vec{R}_{\mathrm{OP}_{\mathrm{i}}}^{F}\times \left( \mathrm{d}m_i\cdot \frac{\mathrm{d}\vec{R}_{\mathrm{P}_{\mathrm{i}}}^{F}}{\mathrm{d}t} \right)}=\int{\left( \left( \vec{R}_{\mathrm{P}_{\mathrm{i}}}^{F}-\vec{R}_{\mathrm{O}}^{F} \right) \times \vec{V}_{\mathrm{P}_{\mathrm{i}}}^{F} \right) \mathrm{d}m_i} \\ &=\int{\left( \vec{R}_{\mathrm{P}_{\mathrm{i}}}^{F}\times \vec{V}_{\mathrm{P}_{\mathrm{i}}}^{F} \right) \mathrm{d}m_i}-\int{\left( \vec{R}_{\mathrm{O}}^{F}\times \vec{V}_{\mathrm{P}_{\mathrm{i}}}^{F} \right) \mathrm{d}m_i} \\ &=\vec{H}_{\Sigma _{\mathrm{M}}}^{F}-\vec{R}_{\mathrm{O}}^{F}\times \vec{P}_{\mathrm{G}}^{F} \end{split} HΣM/OF=∫ROPiF×(dmi⋅dtdRPiF)=∫((RPiF−ROF)×VPiF)dmi=∫(RPiF×VPiF)dmi−∫(ROF×VPiF)dmi=HΣMF−ROF×PGF
对上式进一步求导,则有:
d H ⃗ Σ M / O F d t = d H ⃗ Σ M F d t − d ( R ⃗ O F × P ⃗ G F ) d t = d H ⃗ Σ M F d t − V ⃗ O F × P ⃗ G F − m t o t a l ⋅ R ⃗ O F × a ⃗ G F \frac{\mathrm{d}\vec{H}_{\Sigma _{\mathrm{M}}/\mathrm{O}}^{F}}{\mathrm{d}t}=\frac{\mathrm{d}\vec{H}_{\Sigma _{\mathrm{M}}}^{F}}{\mathrm{d}t}-\frac{\mathrm{d}\left( \vec{R}_{\mathrm{O}}^{F}\times \vec{P}_{\mathrm{G}}^{F} \right)}{\mathrm{d}t}=\frac{\mathrm{d}\vec{H}_{\Sigma _{\mathrm{M}}}^{F}}{\mathrm{d}t}-\vec{V}_{\mathrm{O}}^{F}\times \vec{P}_{\mathrm{G}}^{F}-m_{\mathrm{total}}\cdot \vec{R}_{\mathrm{O}}^{F}\times \vec{a}_{\mathrm{G}}^{F} dtdHΣM/OF=dtdHΣMF−dtd(ROF×PGF)=dtdHΣMF−VOF×PGF−mtotal⋅ROF×aGF
其中:
H ⃗ Σ M F = ∫ R ⃗ P i F × p ⃗ P i F = ∫ ( R ⃗ G F + R ⃗ G P i F ) × ( d m i ⋅ ( V ⃗ G F + V ⃗ G P i F ) ) = ∫ R ⃗ G F × V ⃗ G F d m i ⏟ m t o t a l ⋅ R ⃗ G F × V ⃗ G F + ∫ R ⃗ G F × V ⃗ G P i F d m i ⏟ 0 + ∫ R ⃗ G P i F × V ⃗ G F d m i ⏟ 0 + ∫ R ⃗ G P i F × V ⃗ G P i F d m i ⏟ ∫ R ⃗ G P i F × ( ω ⃗ M F × R ⃗ G P i F ) d m i = m t o t a l ⋅ R ⃗ G F × V ⃗ G F + ∫ R ⃗ G P i F × ( ω ⃗ M F × R ⃗ G P i F ) d m i = m t o t a l ⋅ R ⃗ G F × V ⃗ G F + ∫ ( R ⃗ G P i F ⋅ R ⃗ G P i F ) ω ⃗ M F d m i − ∫ ( R ⃗ G P i F ⋅ ω ⃗ M F ) R ⃗ G P i F d m i \begin{split} \vec{H}_{\Sigma _{\mathrm{M}}}^{F}&=\int{\vec{R}_{\mathrm{P}_{\mathrm{i}}}^{F}\times \vec{p}_{\mathrm{P}_{\mathrm{i}}}^{F}}=\int{\left( \vec{R}_{\mathrm{G}}^{F}+\vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F} \right) \times \left( \mathrm{d}m_i\cdot \left( \vec{V}_{\mathrm{G}}^{F}+\vec{V}_{\mathrm{GP}_{\mathrm{i}}}^{F} \right) \right)} \\ &=\begin{array}{c} \underbrace{\int{\vec{R}_{\mathrm{G}}^{F}\times \vec{V}_{\mathrm{G}}^{F}}\mathrm{d}m_i}\\ m_{\mathrm{total}}\cdot \vec{R}_{\mathrm{G}}^{F}\times \vec{V}_{\mathrm{G}}^{F}\\ \end{array}+\begin{array}{c} \underbrace{\int{\vec{R}_{\mathrm{G}}^{F}\times \vec{V}_{\mathrm{GP}_{\mathrm{i}}}^{F}}\mathrm{d}m_i}\\ 0\\ \end{array}+\begin{array}{c} \underbrace{\int{\vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F}\times \vec{V}_{\mathrm{G}}^{F}}\mathrm{d}m_i}\\ 0\\ \end{array}+\begin{array}{c} \underbrace{\int{\vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F}\times \vec{V}_{\mathrm{GP}_{\mathrm{i}}}^{F}}\mathrm{d}m_i}\\ \int{\vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F}\times \left( \vec{\omega}_{\mathrm{M}}^{F}\times \vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F} \right)}\mathrm{d}m_i\\ \end{array} \\ &=m_{\mathrm{total}}\cdot \vec{R}_{\mathrm{G}}^{F}\times \vec{V}_{\mathrm{G}}^{F}+\int{\vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F}\times \left( \vec{\omega}_{\mathrm{M}}^{F}\times \vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F} \right)}\mathrm{d}m_i \\ &=m_{\mathrm{total}}\cdot \vec{R}_{\mathrm{G}}^{F}\times \vec{V}_{\mathrm{G}}^{F}+\int{\left( \vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F}\cdot \vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F} \right) \vec{\omega}_{\mathrm{M}}^{F}}\mathrm{d}m_i-\int{\left( \vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F}\cdot \vec{\omega}_{\mathrm{M}}^{F} \right) \vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F}}\mathrm{d}m_i \end{split} HΣMF=∫RPiF×pPiF=∫(RGF+RGPiF)×(dmi⋅(VGF+VGPiF))= ∫RGF×VGFdmimtotal⋅RGF×VGF+ ∫RGF×VGPiFdmi0+ ∫RGPiF×VGFdmi0+ ∫RGPiF×VGPiFdmi∫RGPiF×(ωMF×RGPiF)dmi=mtotal⋅RGF×VGF+∫RGPiF×(ωMF×RGPiF)dmi=mtotal⋅RGF×VGF+∫(RGPiF⋅RGPiF)ωMFdmi−∫(RGPiF⋅ωMF)RGPiFdmi
将 H ⃗ Σ M F \vec{H}_{\Sigma _{\mathrm{M}}}^{F} HΣMF进一步求导,则有:
d H ⃗ Σ M F d t = { R ⃗ G F × m t o t a l ⋅ a ⃗ G F + 2 ∫ ( V ⃗ P i F ⋅ R ⃗ G P i F ) ω ⃗ M F d m i + ∫ ( R ⃗ G P i F ⋅ R ⃗ G P i F ) α ⃗ M F d m i − ∫ ( V ⃗ G P i F ⋅ ω ⃗ M F ) R ⃗ G P i F d m i − ∫ ( R ⃗ G P i F ⋅ α ⃗ M F ) R ⃗ G P i F d m i − ∫ ( R ⃗ G P i F ⋅ ω ⃗ M F ) V ⃗ G P i F d m i = { R ⃗ G F × m t o t a l ⋅ a ⃗ G F + ( ∫ ( R ⃗ G P i F ⋅ R ⃗ G P i F ) α ⃗ M F d m i − ∫ ( R ⃗ G P i F ⋅ α ⃗ M F ) R ⃗ G P i F d m i ) − ∫ ( R ⃗ G P i F ⋅ ω ⃗ M F ) ( ω ⃗ M F × R ⃗ G P i F ) d m i = { R ⃗ G F × m t o t a l ⋅ a ⃗ G F + ( ∫ ( R ⃗ G P i F T R ⃗ G P i F ) ⋅ E 3 × 3 α ⃗ M F d m i − ∫ ( R ⃗ G P i F T α ⃗ M F ) R ⃗ G P i F d m i ) − ∫ ( R ⃗ G P i F T ω ⃗ M F ) ( ω ⃗ M F × R ⃗ G P i F ) d m i = { R ⃗ G F × m t o t a l ⋅ a ⃗ G F + α ⃗ M F ∫ ( R ⃗ G P i F T R ⃗ G P i F ⋅ E 3 × 3 − R ⃗ G P i F R ⃗ G P i F T ) d m i − ω ⃗ M F × ( ∫ ( R ⃗ G P i F R ⃗ G P i F T ) d m i ⋅ ω ⃗ M F ) \begin{split} \frac{\mathrm{d}\vec{H}_{\Sigma _{\mathrm{M}}}^{F}}{\mathrm{d}t}&=\begin{cases} \vec{R}_{\mathrm{G}}^{F}\times m_{\mathrm{total}}\cdot \vec{a}_{\mathrm{G}}^{F}+2\int{\left( \vec{V}_{\mathrm{P}_{\mathrm{i}}}^{F}\cdot \vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F} \right) \vec{\omega}_{\mathrm{M}}^{F}}\mathrm{d}m_{\mathrm{i}}+\int{\left( \vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F}\cdot \vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F} \right) \vec{\alpha}_{\mathrm{M}}^{F}}\mathrm{d}m_{\mathrm{i}}\\ -\int{\left( \vec{V}_{\mathrm{GP}_{\mathrm{i}}}^{F}\cdot \vec{\omega}_{\mathrm{M}}^{F} \right) \vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F}}\mathrm{d}m_{\mathrm{i}}-\int{\left( \vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F}\cdot \vec{\alpha}_{\mathrm{M}}^{F} \right) \vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F}}\mathrm{d}m_{\mathrm{i}}-\int{\left( \vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F}\cdot \vec{\omega}_{\mathrm{M}}^{F} \right) \vec{V}_{\mathrm{GP}_{\mathrm{i}}}^{F}}\mathrm{d}m_{\mathrm{i}}\\ \end{cases} \\ &=\begin{cases} \vec{R}_{\mathrm{G}}^{F}\times m_{\mathrm{total}}\cdot \vec{a}_{\mathrm{G}}^{F}+\left( \int{\left( \vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F}\cdot \vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F} \right) \vec{\alpha}_{\mathrm{M}}^{F}}\mathrm{d}m_{\mathrm{i}}-\int{\left( \vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F}\cdot \vec{\alpha}_{\mathrm{M}}^{F} \right) \vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F}}\mathrm{d}m_{\mathrm{i}} \right)\\ -\int{\left( \vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F}\cdot \vec{\omega}_{\mathrm{M}}^{F} \right) \left( \vec{\omega}_{\mathrm{M}}^{F}\times \vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F} \right) \mathrm{d}m_{\mathrm{i}}}\\ \end{cases} \\ &=\begin{cases} \vec{R}_{\mathrm{G}}^{F}\times m_{\mathrm{total}}\cdot \vec{a}_{\mathrm{G}}^{F}+\left( \int{\left( {\vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F}}^{\mathrm{T}}\vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F} \right) \cdot E^{3\times 3}\vec{\alpha}_{\mathrm{M}}^{F}}\mathrm{d}m_{\mathrm{i}}-\int{\left( {\vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F}}^{\mathrm{T}}\vec{\alpha}_{\mathrm{M}}^{F} \right) \vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F}}\mathrm{d}m_{\mathrm{i}} \right)\\ -\int{\left( {\vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F}}^{\mathrm{T}}\vec{\omega}_{\mathrm{M}}^{F} \right) \left( \vec{\omega}_{\mathrm{M}}^{F}\times \vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F} \right) \mathrm{d}m_{\mathrm{i}}}\\ \end{cases} \\ &=\begin{cases} \vec{R}_{\mathrm{G}}^{F}\times m_{\mathrm{total}}\cdot \vec{a}_{\mathrm{G}}^{F}+\vec{\alpha}_{\mathrm{M}}^{F}\int{\left( {\vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F}}^{\mathrm{T}}\vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F}\cdot E^{3\times 3}-\vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F}{\vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F}}^{\mathrm{T}} \right)}\mathrm{d}m_{\mathrm{i}}\\ -\vec{\omega}_{\mathrm{M}}^{F}\times \left( \int{\left( \vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F}{\vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F}}^{\mathrm{T}} \right)}\mathrm{d}m_{\mathrm{i}}\cdot \vec{\omega}_{\mathrm{M}}^{F} \right)\\ \end{cases} \end{split} dtdHΣMF=⎩ ⎨ ⎧RGF×mtotal⋅aGF+2∫(VPiF⋅RGPiF)ωMFdmi+∫(RGPiF⋅RGPiF)αMFdmi−∫(VGPiF⋅ωMF)RGPiFdmi−∫(RGPiF⋅αMF)RGPiFdmi−∫(RGPiF⋅ωMF)VGPiFdmi=⎩ ⎨ ⎧RGF×mtotal⋅aGF+(∫(RGPiF⋅RGPiF)αMFdmi−∫(RGPiF⋅αMF)RGPiFdmi)−∫(RGPiF⋅ωMF)(ωMF×RGPiF)dmi=⎩ ⎨ ⎧RGF×mtotal⋅aGF+(∫(RGPiFTRGPiF)⋅E3×3αMFdmi−∫(RGPiFTαMF)RGPiFdmi)−∫(RGPiFTωMF)(ωMF×RGPiF)dmi=⎩ ⎨ ⎧RGF×mtotal⋅aGF+αMF∫(RGPiFTRGPiF⋅E3×3−RGPiFRGPiFT)dmi−ωMF×(∫(RGPiFRGPiFT)dmi⋅ωMF)
其中:
⇒ − ω ⃗ M F × ∫ ( R ⃗ G P i F R ⃗ G P i F T ) d m i ⋅ ω ⃗ M F = ω ⃗ M F × ( ∫ ( R ⃗ G P i F T R ⃗ G P i F ⋅ E 3 × 3 − R ⃗ G P i F R ⃗ G P i F T − R ⃗ G P i F T R ⃗ G P i F ⋅ E 3 × 3 ) d m i ⋅ ω ⃗ M F ) = ω ⃗ M F × ( ∫ ( R ⃗ G P i F T R ⃗ G P i F ⋅ E 3 × 3 − R ⃗ G P i F R ⃗ G P i F T ) d m i ⋅ ω ⃗ M F ) − ω ⃗ M F × ( ∫ ( R ⃗ G P i F T R ⃗ G P i F ⋅ E 3 × 3 ) d m i ⋅ ω ⃗ M F ) ⏟ 0 \begin{split} \Rightarrow &-\vec{\omega}_{\mathrm{M}}^{F}\times \int{\left( \vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F}{\vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F}}^{\mathrm{T}} \right)}\mathrm{d}m_{\mathrm{i}}\cdot \vec{\omega}_{\mathrm{M}}^{F} \\ &=\vec{\omega}_{\mathrm{M}}^{F}\times \left( \int{\left( {\vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F}}^{\mathrm{T}}\vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F}\cdot E^{3\times 3}-\vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F}{\vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F}}^{\mathrm{T}}-{\vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F}}^{\mathrm{T}}\vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F}\cdot E^{3\times 3} \right)}\mathrm{d}m_{\mathrm{i}}\cdot \vec{\omega}_{\mathrm{M}}^{F} \right) \\ &=\vec{\omega}_{\mathrm{M}}^{F}\times \left( \int{\left( {\vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F}}^{\mathrm{T}}\vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F}\cdot E^{3\times 3}-\vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F}{\vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F}}^{\mathrm{T}} \right)}\mathrm{d}m_{\mathrm{i}}\cdot \vec{\omega}_{\mathrm{M}}^{F} \right) -\begin{array}{c} \underbrace{\vec{\omega}_{\mathrm{M}}^{F}\times \left( \int{\left( {\vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F}}^{\mathrm{T}}\vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F}\cdot E^{3\times 3} \right)}\mathrm{d}m_{\mathrm{i}}\cdot \vec{\omega}_{\mathrm{M}}^{F} \right) }\\ 0\\ \end{array} \end{split} ⇒−ωMF×∫(RGPiFRGPiFT)dmi⋅ωMF=ωMF×(∫(RGPiFTRGPiF⋅E3×3−RGPiFRGPiFT−RGPiFTRGPiF⋅E3×3)dmi⋅ωMF)=ωMF×(∫(RGPiFTRGPiF⋅E3×3−RGPiFRGPiFT)dmi⋅ωMF)− ωMF×(∫(RGPiFTRGPiF⋅E3×3)dmi⋅ωMF)0
将上两式进行汇总,可得:
⇒ d H ⃗ Σ M F d t = { R ⃗ G F × m t o t a l ⋅ a ⃗ G F + ∫ ( R ⃗ G P i F T R ⃗ G P i F ⋅ E 3 × 3 − R ⃗ G P i F R ⃗ G P i F T ) d m i α ⃗ M F + ω ⃗ M F × ( ∫ ( R ⃗ G P i F T R ⃗ G P i F ⋅ E 3 × 3 − R ⃗ G P i F R ⃗ G P i F T ) d m i ⋅ ω ⃗ M F ) = R ⃗ G F × m t o t a l ⋅ a ⃗ G F + [ I ] Σ M / G F α ⃗ M F + ω ⃗ M F × ( [ I ] Σ M / G F ⋅ ω ⃗ M F ) \begin{split} \Rightarrow \frac{\mathrm{d}\vec{H}_{\Sigma _{\mathrm{M}}}^{F}}{\mathrm{d}t}&=\begin{cases} \vec{R}_{\mathrm{G}}^{F}\times m_{\mathrm{total}}\cdot \vec{a}_{\mathrm{G}}^{F}+\int{\left( {\vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F}}^{\mathrm{T}}\vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F}\cdot E^{3\times 3}-\vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F}{\vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F}}^{\mathrm{T}} \right)}\mathrm{d}m_{\mathrm{i}}\vec{\alpha}_{\mathrm{M}}^{F}\\ +\vec{\omega}_{\mathrm{M}}^{F}\times \left( \int{\left( {\vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F}}^{\mathrm{T}}\vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F}\cdot E^{3\times 3}-\vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F}{\vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F}}^{\mathrm{T}} \right)}\mathrm{d}m_{\mathrm{i}}\cdot \vec{\omega}_{\mathrm{M}}^{F} \right)\\ \end{cases} \\ &=\vec{R}_{\mathrm{G}}^{F}\times m_{\mathrm{total}}\cdot \vec{a}_{\mathrm{G}}^{F}+\left[ I \right] _{\Sigma _{\mathrm{M}}/\mathrm{G}}^{F}\vec{\alpha}_{\mathrm{M}}^{F}+\vec{\omega}_{\mathrm{M}}^{F}\times \left( \left[ I \right] _{\Sigma _{\mathrm{M}}/\mathrm{G}}^{F}\cdot \vec{\omega}_{\mathrm{M}}^{F} \right) \end{split} ⇒dtdHΣMF=⎩ ⎨ ⎧RGF×mtotal⋅aGF+∫(RGPiFTRGPiF⋅E3×3−RGPiFRGPiFT)dmiαMF+ωMF×(∫(RGPiFTRGPiF⋅E3×3−RGPiFRGPiFT)dmi⋅ωMF)=RGF×mtotal⋅aGF+[I]ΣM/GFαMF+ωMF×([I]ΣM/GF⋅ωMF)
其中:
[ I ] Σ M / G F = ∫ ( R ⃗ G P i F T R ⃗ G P i F ⋅ E 3 × 3 − R ⃗ G P i F R ⃗ G P i F T ) d m i \left[ I \right] _{\Sigma _{\mathrm{M}}/\mathrm{G}}^{F}=\int{\left( {\vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F}}^{\mathrm{T}}\vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F}\cdot E^{3\times 3}-\vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F}{\vec{R}_{\mathrm{GP}_{\mathrm{i}}}^{F}}^{\mathrm{T}} \right)}\mathrm{d}m_i [I]ΣM/GF=∫(RGPiFTRGPiF⋅E3×3−RGPiFRGPiFT)dmi
[ I ] Σ M / G F \left[ I \right] _{\Sigma _{\mathrm{M}}/\mathrm{G}}^{F} [I]ΣM/GF被称为惯性矩阵inertia matrix
(或称为惯量矩阵),为该物体在固定坐标系下相对于质心点 G G G的惯性张量。
进而可知:
d H ⃗ Σ M F d t = M ⃗ Σ M F = ∫ R ⃗ P i F × d F ⃗ P i F = R ⃗ G F × m t o t a l ⋅ a ⃗ G F + [ I ] Σ M / G F α ⃗ M F + ω ⃗ M F × ( [ I ] Σ M / G F ⋅ ω ⃗ M F ) \frac{\mathrm{d}\vec{H}_{\Sigma _{\mathrm{M}}}^{F}}{\mathrm{d}t}=\vec{M}_{\Sigma _{\mathrm{M}}}^{F}=\int{\vec{R}_{\mathrm{P}_{\mathrm{i}}}^{F}\times \mathrm{d}\vec{F}_{\mathrm{P}_{\mathrm{i}}}^{F}}=\vec{R}_{\mathrm{G}}^{F}\times m_{\mathrm{total}}\cdot \vec{a}_{\mathrm{G}}^{F}+\left[ I \right] _{\Sigma _{\mathrm{M}}/\mathrm{G}}^{F}\vec{\alpha}_{\mathrm{M}}^{F}+\vec{\omega}_{\mathrm{M}}^{F}\times \left( \left[ I \right] _{\Sigma _{\mathrm{M}}/\mathrm{G}}^{F}\cdot \vec{\omega}_{\mathrm{M}}^{F} \right) dtdHΣMF=MΣMF=∫RPiF×dFPiF=RGF×mtotal⋅aGF+[I]ΣM/GFαMF+ωMF×([I]ΣM/GF⋅ωMF)
上式被称为:欧拉方程在惯性坐标系下相对固定点的表达式;当固定点与质心点重合时(此时G点为固定点),则有:
M ⃗ Σ M / G F = M ⃗ Σ M F − R ⃗ G F × ( m t o t a l ⋅ a ⃗ G F ) = R ⃗ G F × ( m t o t a l ⋅ a ⃗ G F ) + [ I ] Σ M / G F α ⃗ M F + ω ⃗ M F × ( [ I ] Σ M / G F ⋅ ω ⃗ M F ) − R ⃗ G F × ( m t o t a l ⋅ a ⃗ G F ) = [ I ] Σ M / G F α ⃗ M F + ω ⃗ M F × ( [ I ] Σ M / G F ⋅ ω ⃗ M F ) \begin{split} \vec{M}_{\Sigma _{\mathrm{M}}/\mathrm{G}}^{F}&=\vec{M}_{\Sigma _{\mathrm{M}}}^{F}-\vec{R}_{\mathrm{G}}^{F}\times \left( m_{\mathrm{total}}\cdot \vec{a}_{\mathrm{G}}^{F} \right) \\ &=\vec{R}_{\mathrm{G}}^{F}\times \left( m_{\mathrm{total}}\cdot \vec{a}_{\mathrm{G}}^{F} \right) +\left[ I \right] _{\Sigma _{\mathrm{M}}/\mathrm{G}}^{F}\vec{\alpha}_{\mathrm{M}}^{F}+\vec{\omega}_{\mathrm{M}}^{F}\times \left( \left[ I \right] _{\Sigma _{\mathrm{M}}/\mathrm{G}}^{F}\cdot \vec{\omega}_{\mathrm{M}}^{F} \right) -\vec{R}_{\mathrm{G}}^{F}\times \left( m_{\mathrm{total}}\cdot \vec{a}_{\mathrm{G}}^{F} \right) \\ &=\left[ I \right] _{\Sigma _{\mathrm{M}}/\mathrm{G}}^{F}\vec{\alpha}_{\mathrm{M}}^{F}+\vec{\omega}_{\mathrm{M}}^{F}\times \left( \left[ I \right] _{\Sigma _{\mathrm{M}}/\mathrm{G}}^{F}\cdot \vec{\omega}_{\mathrm{M}}^{F} \right) \end{split} MΣM/GF=MΣMF−RGF×(mtotal⋅aGF)=RGF×(mtotal⋅aGF)+[I]ΣM/GFαMF+ωMF×([I]ΣM/GF⋅ωMF)−RGF×(mtotal⋅aGF)=[I]ΣM/GFαMF+ωMF×([I]ΣM/GF⋅ωMF)
此时为固定坐标系下相对固定点质心 G G G求解的欧拉方程。