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优化问题可以等效为如下形式:
三种约束分别通过以下方式获得:
问题:位姿每次优化后会发生变化,其后的IMU惯性积分就要重新进行,运算量过大。
解决思路:直接计算两帧之间的相对位姿,而不依赖初始值影响,即所谓的预积分。
由于此处讨论的优化方案包含组合导航系统,且认为外参已标定,因此会和常见的lio/vio中的方案有所不同,它不包含以下内容:
在第6讲中,已知导航的微分方程如下
p˙wbt=vtwv˙tw=atwq˙wbt=qwbt⊗[012ωbt]\begin{aligned} & \dot{\mathbf{p}}_{w b_t}=\mathbf{v}_t^w \\ & \dot{\mathbf{v}}_t^w=\mathbf{a}_t^w \\ & \dot{\mathbf{q}}_{w b_t}=\mathbf{q}_{w b_t} \otimes\left[\begin{array}{c} 0 \\ \frac{1}{2} \boldsymbol{\omega}^{b_t} \end{array}\right] \end{aligned} p˙wbt=vtwv˙tw=atwq˙wbt=qwbt⊗[021ωbt]根据该微分方程,可知从 iii 时刻到 jjj 时刻 IMU的积分结果为
pwbj=pwbi+viwΔt+∬t∈[i,j](qwbtabt−gw)δt2vjw=viw+∫t∈[i,j](qwbtabt−gw)δtqwbj=∫t∈[i,j]qwbt⊗[012ωbt]δt\begin{gathered} \mathbf{p}_{w b_j}=\mathbf{p}_{w b_i}+\mathbf{v}_i^w \Delta t+\iint_{t \in[i, j]}\left(\mathbf{q}_{w b_t} \mathbf{a}^{b_t}-\mathbf{g}^w\right) \delta t^2 \\ \mathbf{v}_j^w=\mathbf{v}_i^w+\int_{t \in[i, j]}\left(\mathbf{q}_{w b_t} \mathbf{a}^{b_t}-\mathbf{g}^w\right) \delta t \\ \mathbf{q}_{w b_j}=\int_{t \in[i, j]} \mathbf{q}_{w b_t} \otimes\left[\begin{array}{c} 0 \\ \frac{1}{2} \boldsymbol{\omega}^{b_t} \end{array}\right] \delta t \end{gathered} pwbj=pwbi+viwΔt+∬t∈[i,j](qwbtabt−gw)δt2vjw=viw+∫t∈[i,j](qwbtabt−gw)δtqwbj=∫t∈[i,j]qwbt⊗[021ωbt]δt根据预积分的要求,需要求相对结果,而且不依赖于上一时刻位姿,因此需要对上式做转换。
由于 qwbt=qwbi⊗qbibt\mathbf{q}_{w b_t}=\mathbf{q}_{w b_i} \otimes \mathbf{q}_{b_i b_t}qwbt=qwbi⊗qbibt ,把它带入(4)-(6)式可得
pwbj=pwbi+viwΔt−12gwΔt2+qwbi[∬t∈[i,j](qbibtabt)δt2vjw=viw−gwΔt+qwbi∫t∈[i,j](qbibtabt)δt]qwbj=qwbi∫t∈[i,j]qbibt⊗[012ωbt]δt\begin{gathered} \mathbf{p}_{w b_j}=\mathbf{p}_{w b_i}+\mathbf{v}_i^w \Delta t-\frac{1}{2} \mathbf{g}^w \Delta t^2+\mathbf{q}_{w b_i}\left[\iint_{t \in[i, j]}\left(\mathbf{q}_{b_i b_t} \mathbf{a}^{b_t}\right) \delta t^2\right. \\ \left.\mathbf{v}_j^w=\mathbf{v}_i^w-\mathbf{g}^w \Delta t+\mathbf{q}_{w b_i} \int_{t \in[i, j]}\left(\mathbf{q}_{b_i b_t} \mathbf{a}^{b_t}\right) \delta t\right] \\ \mathbf{q}_{w b_j}=\mathbf{q}_{w b_i} \int_{t \in[i, j]} \mathbf{q}_{b_i b_t} \otimes\left[\begin{array}{c} 0 \\ \frac{1}{2} \boldsymbol{\omega}^{b_t} \end{array}\right] \delta t \end{gathered} pwbj=pwbi+viwΔt−21gwΔt2+qwbi[∬t∈[i,j](qbibtabt)δt2vjw=viw−gwΔt+qwbi∫t∈[i,j](qbibtabt)δt]qwbj=qwbi∫t∈[i,j]qbibt⊗[021ωbt]δt可见,此时需要积分的项,就完全和 iii 时刻的状态无关了。
为了整理公式,把积分相关的项用下面的式子 代替
αbibj=∬t∈[i,j](qbibtabt)δt2βbibj=∫t∈[i,j](qbibtabt)δtqbibj=∫t∈[i,j]qbibt⊗[012ωbt]δt\begin{aligned} & \boldsymbol{\alpha}_{b_i b_j}=\iint_{t \in[i, j]}\left(\mathbf{q}_{b_i b_t} \mathbf{a}^{b_t}\right) \delta t^2 \\ & \boldsymbol{\beta}_{b_i b_j}=\int_{t \in[i, j]}\left(\mathbf{q}_{b_i b_t} \mathbf{a}^{b_t}\right) \delta t \\ & \mathbf{q}_{b_i b_j}=\int_{t \in[i, j]} \mathbf{q}_{b_i b_t} \otimes\left[\begin{array}{c} 0 \\ \frac{1}{2} \boldsymbol{\omega}^{b_t} \end{array}\right] \delta t \end{aligned} αbibj=∬t∈[i,j](qbibtabt)δt2βbibj=∫t∈[i,j](qbibtabt)δtqbibj=∫t∈[i,j]qbibt⊗[021ωbt]δt实际使用中使用离散形式,而非连续形式,由于 在解算中,一般采用中值积分方法,即
ω=12[(ωbk−bkg)+(ωbk+1−bkg)]a=12[qbibk(abk−bka)+qbibk+1(abk+1−bka)]\begin{aligned} & \boldsymbol{\omega}=\frac{1}{2}\left[\left(\boldsymbol{\omega}^{b_k}-\mathbf{b}_k^g\right)+\left(\boldsymbol{\omega}^{b_{k+1}}-\mathbf{b}_k^g\right)\right] \\ & \mathbf{a}=\frac{1}{2}\left[\mathbf{q}_{b_i b_k}\left(\mathbf{a}^{b_k}-\mathbf{b}_k^a\right)+\mathbf{q}_{b_i b_{k+1}}\left(\mathbf{a}^{b_{k+1}}-\mathbf{b}_k^a\right)\right] \end{aligned} ω=21[(ωbk−bkg)+(ωbk+1−bkg)]a=21[qbibk(abk−bka)+qbibk+1(abk+1−bka)]那么预积分的离散形式可以表示为
αbibk+1=αbibk+βbibkδt+12aδt2βbibk+1=βbibk+aδtqbibk+1=qbibk⊗[112ωδt]\begin{aligned} & \boldsymbol{\alpha}_{b_i b_{k+1}}=\boldsymbol{\alpha}_{b_i b_k}+\boldsymbol{\beta}_{b_i b_k} \delta t+\frac{1}{2} \mathbf{a} \delta t^2 \\ & \boldsymbol{\beta}_{b_i b_{k+1}}=\boldsymbol{\beta}_{b_i b_k}+\mathbf{a} \delta t \\ & \mathbf{q}_{b_i b_{k+1}}=\mathbf{q}_{b_i b_k} \otimes\left[\begin{array}{c} 1 \\ \frac{1}{2} \boldsymbol{\omega} \delta t \end{array}\right] \end{aligned} αbibk+1=αbibk+βbibkδt+21aδt2βbibk+1=βbibk+aδtqbibk+1=qbibk⊗[121ωδt]经过以上的推导,此时状态更新的公式可以整理为
[pwbjvjwqwbjbjabjg]=[pwbi+viwΔt−12gwΔt2+qwbiαbibjviw−gwΔt+qwbiβbibjqwbiqbibjbiabig]\left[\begin{array}{c} \mathbf{p}_{w b_j} \\ \mathbf{v}_j^w \\ \mathbf{q}_{w b_j} \\ \mathbf{b}_j^a \\ \mathbf{b}_j^g \end{array}\right]=\left[\begin{array}{c} \mathbf{p}_{w b_i}+\mathbf{v}_i^w \Delta t-\frac{1}{2} \mathbf{g}^w \Delta t^2+\mathbf{q}_{w b_i} \boldsymbol{\alpha}_{b_i b_j} \\ \mathbf{v}_i^w-\mathbf{g}^w \Delta t+\mathbf{q}_{w b_i} \boldsymbol{\beta}_{b_i b_j} \\ \mathbf{q}_{w b_i} \mathbf{q}_{b_i b_j} \\ \mathbf{b}_i^a \\ \mathbf{b}_i^g \end{array}\right] pwbjvjwqwbjbjabjg=pwbi+viwΔt−21gwΔt2+qwbiαbibjviw−gwΔt+qwbiβbibjqwbiqbibjbiabig需要注意的是,陀螺仪和加速度计的模型为
bk+1a=bka+nbkaδtbk+1g=bkg+nbkgδt\begin{array}{r} \mathbf{b}_{k+1}^a=\mathbf{b}_k^a+\mathbf{n}_{\mathbf{b}_k^a} \delta t \\ \mathbf{b}_{k+1}^g=\mathbf{b}_k^g+\mathbf{n}_{\mathbf{b}_k^g} \delta t \end{array} bk+1a=bka+nbkaδtbk+1g=bkg+nbkgδt即认为bias是在变化的,这样便于估计不同时刻的bias值,而不是整个系统运行时间内都当做常值对待。这更符合低精度mems的实际情况。但在预积分时,由于两个关键帧之间的时间较短,因此认为 iii 和 jjj 时刻的bias相等。
需要注意的一点是,预积分的结果中包含了bias,在优化过程中,bias作为状态量也会发生变化,从而引起预积分结果变化。
为了避免bias变化后,重新做预积分,可以把预积分结果在bias处泰勒展开,表达成下面的形式, 这样就可以根据bias的变化量直接算出新的预积 分结果。
αbibj=α‾bibj+Jbiaαδbia+Jbigαδbigβbibj=β‾bibj+Jbiaβδbia+Jbigβδbigqbibj=q‾bibj⊗[112Jbiqqδbig]\begin{aligned} & \boldsymbol{\alpha}_{b_i b_j}=\overline{\boldsymbol{\alpha}}_{b_i b_j}+\mathbf{J}_{b_i^a}^\alpha \delta \mathbf{b}_i^a+\mathbf{J}_{b_i^g}^\alpha \delta \mathbf{b}_i^g \\ & \boldsymbol{\beta}_{b_i b_j}=\overline{\boldsymbol{\beta}}_{b_i b_j}+\mathbf{J}_{b_i^a}^\beta \delta \mathbf{b}_i^a+\mathbf{J}_{b_i^g}^\beta \delta \mathbf{b}_i^g \\ & \mathbf{q}_{b_i b_j}=\overline{\mathbf{q}}_{b_i b_j} \otimes\left[\begin{array}{c} 1 \\ \frac{1}{2} \mathbf{J}_{b_i^q}^q \delta \mathbf{b}_i^g \end{array}\right] \end{aligned} αbibj=αbibj+Jbiaαδbia+Jbigαδbigβbibj=βbibj+Jbiaβδbia+Jbigβδbigqbibj=qbibj⊗[121Jbiqqδbig]其中
Jbiaα=∂αbibj∂δbiaJbigα=∂αbibj∂δbijJbiaβ=∂βbibj∂δbiaJbigβ=∂βbibj∂δbiaJbigq=qbibj∂biq\begin{aligned} \mathbf{J}_{b_i^a}^\alpha & =\frac{\partial \alpha_{b_i b_j}}{\partial \delta \mathbf{b}_i^a} \\ \mathbf{J}_{b_i^g}^\alpha & =\frac{\partial \boldsymbol{\alpha}_{b_i b_j}}{\partial \delta \mathbf{b}_i^j} \\ \mathbf{J}_{b_i^a}^\beta & =\frac{\partial \beta_{b_i b_j}}{\partial \delta \mathbf{b}_i^a} \\ \mathbf{J}_{b_i^g}^\beta & =\frac{\partial \beta_{b_i b_j}}{\partial \delta \mathbf{b}_i^a} \\ \mathbf{J}_{b_i^g}^q & =\frac{\mathbf{q}_{b_i b_j}}{\partial \mathbf{b}_i^q} \end{aligned} JbiaαJbigαJbiaβJbigβJbigq=∂δbia∂αbibj=∂δbij∂αbibj=∂δbia∂βbibj=∂δbia∂βbibj=∂biqqbibj注: 此处暂时不直接给出以上各雅可比的结果,它的推导放在后面进行。
在优化时,需要知道残差关于状态量的雅可比。由于已知姿态位姿更新的方法如下:
[pwbjqwbjvjwbjabjg]=[pwbi+viwΔt−12gwΔt2+qwbiαbibjqwbiqbibjviw−gwΔt+qwbiβbibjbiabig]\left[\begin{array}{c} \mathbf{p}_{w b_j} \\ \mathbf{q}_{w b_j} \\ \mathbf{v}_j^w \\ \mathbf{b}_j^a \\ \mathbf{b}_j^g \end{array}\right]=\left[\begin{array}{c} \mathbf{p}_{w b_i}+\mathbf{v}_i^w \Delta t-\frac{1}{2} \mathbf{g}^w \Delta t^2+\mathbf{q}_{w b_i} \boldsymbol{\alpha}_{b_i b_j} \\ \mathbf{q}_{w b_i} \mathbf{q}_{b_i b_j} \\ \mathbf{v}_i^w-\mathbf{g}^w \Delta t+\mathbf{q}_{w b_i} \boldsymbol{\beta}_{b_i b_j} \\ \mathbf{b}_i^a \\ \mathbf{b}_i^g \end{array}\right] pwbjqwbjvjwbjabjg=pwbi+viwΔt−21gwΔt2+qwbiαbibjqwbiqbibjviw−gwΔt+qwbiβbibjbiabig因此,可以很容易写出一种残差形式如下:
[rprqrvrbarbg]=[pwbj−pwbi−viwΔt+12gwΔt2−qwbiαbibj2[qbibj∗⊗(qwbi∗⊗qwbj)]xyzvjw−viw+gwΔt−qwbiβbibjbja−biabjg−big]\left[\begin{array}{c} \mathbf{r}_p \\ \mathbf{r}_q \\ \mathbf{r}_v \\ \mathbf{r}_{b a} \\ \mathbf{r}_{b g} \end{array}\right]=\left[\begin{array}{c} \mathbf{p}_{w b_j}-\mathbf{p}_{w b_i}-\mathbf{v}_i^w \Delta t+\frac{1}{2} \mathbf{g}^w \Delta t^2-\mathbf{q}_{w b_i} \boldsymbol{\alpha}_{b_i b_j} \\ 2\left[\mathbf{q}_{b_i b_j}^* \otimes\left(\mathbf{q}_{w b_i}^* \otimes \mathbf{q}_{w b_j}\right)\right]_{x y z} \\ \mathbf{v}_j^w-\mathbf{v}_i^w+\mathbf{g}^w \Delta t-\mathbf{q}_{w b_i} \boldsymbol{\beta}_{b_i b_j} \\ \mathbf{b}_j^a-\mathbf{b}_i^a \\ \mathbf{b}_j^g-\mathbf{b}_i^g \end{array}\right] rprqrvrbarbg=pwbj−pwbi−viwΔt+21gwΔt2−qwbiαbibj2[qbibj∗⊗(qwbi∗⊗qwbj)]xyzvjw−viw+gwΔt−qwbiβbibjbja−biabjg−big但是和预积分相关的量,仍然与上一时刻的姿态有关,无法直接加减,因此,把残差修正为以下形式
[rprqrvrbarbg]=[qwbi∗(pwbj−pwbi−viwΔt+12gwΔt2)−αbibj2[qqbj∗⊗(qwi∗⊗qwbj)]xyzqwbi∗(vjw−viw+gwΔt)−βbibjbja−biabjg−big]\left[\begin{array}{c} \mathbf{r}_p \\ \mathbf{r}_q \\ \mathbf{r}_v \\ \mathbf{r}_{b a} \\ \mathbf{r}_{b g} \end{array}\right]=\left[\begin{array}{c} \mathbf{q}_{w b_i}^*\left(\mathbf{p}_{w b_j}-\mathbf{p}_{w b_i}-\mathbf{v}_i^w \Delta t+\frac{1}{2} \mathbf{g}^w \Delta t^2\right)-\boldsymbol{\alpha}_{b_i b_j} \\ 2\left[\mathbf{q}_{\mathbf{q}_{b_j}^*} \otimes\left(\mathbf{q}_{w_i}^* \otimes \mathbf{q}_{w b_j}\right)\right]_{x y z} \\ \mathbf{q}_{w b_i}^*\left(\mathbf{v}_j^w-\mathbf{v}_i^w+\mathbf{g}^w \Delta t\right)-\boldsymbol{\beta}_{b_i b_j} \\ \mathbf{b}_j^a-\mathbf{b}_i^a \\ \mathbf{b}_j^g-\mathbf{b}_i^g \end{array}\right] rprqrvrbarbg=qwbi∗(pwbj−pwbi−viwΔt+21gwΔt2)−αbibj2[qqbj∗⊗(qwi∗⊗qwbj)]xyzqwbi∗(vjw−viw+gwΔt)−βbibjbja−biabjg−big待优化的变量是 [pwbiqwbiviwbiabig][pwbjqwbjvjwbjabjg]\left[\begin{array}{lllll}\mathbf{p}_{w b_i} & \mathbf{q}_{w b_i} & \mathbf{v}_i^w & \mathbf{b}_i^a & \mathbf{b}_i^g\end{array}\right]\left[\begin{array}{lllll}\mathbf{p}_{w b_j} & \mathbf{q}_{w b_j} & \mathbf{v}_j^w & \mathbf{b}_j^a & \mathbf{b}_j^g\end{array}\right][pwbiqwbiviwbiabig][pwbjqwbjvjwbjabjg]
但在实际使用中,往往都是使用扰动量,因此实际是对以下变量求雅可比
[δpwbiδθwbiδviwδbiaδbig][δpwbjδθwbjδvjwδbjaδbjg]\begin{aligned} & {\left[\begin{array}{lllll} \delta \mathbf{p}_{w b_i} & \delta \theta_{w b_i} & \delta \mathbf{v}_i^w & \delta \mathbf{b}_i^a & \delta \mathbf{b}_i^g \end{array}\right]} \\ & {\left[\begin{array}{lllll} \delta \mathbf{p}_{w b_j} & \delta \theta_{w b_j} & \delta \mathbf{v}_j^w & \delta \mathbf{b}_j^a & \delta \mathbf{b}_j^g \end{array}\right]} \end{aligned} [δpwbiδθwbiδviwδbiaδbig][δpwbjδθwbjδvjwδbjaδbjg]此处只对几个比较复杂的雅可比进行推导,其余比较简单,感兴趣的可自行完成。
对 iii 时刻姿态误差的雅可比
∂rq∂δθbibi′=∂2[qbjbi⊗(qbiw⊗qwbj)]xyz∂δθbibi′=∂2[qbi,bj∗⊗(qwbi⊗[112δθbibi′])∗⊗qwbj]xyz∂δθbibi′=∂−2[(qbibj∗⊗(qwbi⊗[112δθbibi′])∗⊗qwbj)∗]xyz∂δθbibi=∂−2[qwbj∗⊗(qwbi⊗[112δθbibi′])⊗qbibj]xyz∂δθbibi′\begin{aligned} \frac{\partial \mathbf{r}_q}{\partial \delta \boldsymbol{\theta}_{b_i b_i^{\prime}}} & =\frac{\partial 2\left[\mathbf{q}_{b_j b_i} \otimes\left(\mathbf{q}_{b_i w} \otimes \mathbf{q}_{w b_j}\right)\right]_{x y z}}{\partial \delta \boldsymbol{\theta}_{b_i b_i^{\prime}}} \\ & =\frac{\partial 2\left[\mathbf{q}_{b_i, b_j}^* \otimes\left(\mathbf{q}_{w b_i} \otimes\left[\begin{array}{c} 1 \\ \frac{1}{2} \delta \boldsymbol{\theta}_{b_i b_i^{\prime}} \end{array}\right]\right)^* \otimes \mathbf{q}_{w b_j}\right]_{x y z}}{\partial \delta \boldsymbol{\theta}_{b_i b_i^{\prime}}} \\ & =\frac{\partial-2\left[\left(\mathbf{q}_{b_i b_j}^* \otimes\left(\mathbf{q}_{w b_i} \otimes\left[\begin{array}{c} 1 \\ \frac{1}{2} \delta \boldsymbol{\theta}_{b_i} b_i^{\prime} \end{array}\right]\right)^* \otimes \mathbf{q}_{w b_j}\right)^*\right]_{x y z}}{\partial \delta \boldsymbol{\theta}_{b_i b_i}} \\ & =\frac{\partial-2\left[\mathbf{q}_{w b_j}^* \otimes\left(\mathbf{q}_{w b_i} \otimes\left[\begin{array}{c} 1 \\ \frac{1}{2} \delta \boldsymbol{\theta}_{b_i b_i^{\prime}} \end{array}\right]\right) \otimes \mathbf{q}_{b_i b_j}\right]_{x y z}}{\partial \delta \boldsymbol{\theta}_{b_i b_i^{\prime}}} \end{aligned} ∂δθbibi′∂rq=∂δθbibi′∂2[qbjbi⊗(qbiw⊗qwbj)]xyz=∂δθbibi′∂2[qbi,bj∗⊗(qwbi⊗[121δθbibi′])∗⊗qwbj]xyz=∂δθbibi∂−2[(qbibj∗⊗(qwbi⊗[121δθbibi′])∗⊗qwbj)∗]xyz=∂δθbibi′∂−2[qwbj∗⊗(qwbi⊗[121δθbibi′])⊗qbibj]xyz上式可以化简为
∂rq∂δθbibi′=−2[0I]∂qwbj∗⊗(qwbi⊗[112δθbibi′])⊗qbibj∂δθbibi′=−2[0I]∂[qwbj∗⊗qwbi]L[qbibj]R[112δθbibi′]∂δθbibi′=−2[0I][qwbj∗⊗qwbi]L[qbibj]R[012I]\begin{aligned} \frac{\partial \mathbf{r}_q}{\partial \delta \boldsymbol{\theta}_{b_i b_i^{\prime}}} & =-2\left[\begin{array}{ll} \mathbf{0} & \mathbf{I} \end{array}\right] \frac{\partial \mathbf{q}_{w b_j}^* \otimes\left(\mathbf{q}_{w b_i} \otimes\left[\begin{array}{c} 1 \\ \frac{1}{2} \delta \boldsymbol{\theta}_{b_i b_i^{\prime}} \end{array}\right]\right) \otimes \mathbf{q}_{b_i b_j}}{\partial \delta \boldsymbol{\theta}_{b_i b_i^{\prime}}} \\ & =-2\left[\begin{array}{ll} \mathbf{0} & \mathbf{I} \end{array}\right] \frac{\partial\left[\mathbf{q}_{w b_j}^* \otimes \mathbf{q}_{w b_i}\right]_L\left[\mathbf{q}_{b_i b_j}\right]_R\left[\begin{array}{c} 1 \\ \frac{1}{2} \delta \boldsymbol{\theta}_{b_i b_i^{\prime}} \end{array}\right]}{\partial \delta \boldsymbol{\theta}_{b_i b_i^{\prime}}} \\ & =-2\left[\begin{array}{ll} \mathbf{0} & \mathbf{I} \end{array}\right]\left[\mathbf{q}_{w b_j}^* \otimes \mathbf{q}_{w b_i}\right]_L\left[\mathbf{q}_{b_i b_j}\right]_R\left[\begin{array}{c} \mathbf{0} \\ \frac{1}{2} \mathbf{I} \end{array}\right] \end{aligned} ∂δθbibi′∂rq=−2[0I]∂δθbibi′∂qwbj∗⊗(qwbi⊗[121δθbibi′])⊗qbibj=−2[0I]∂δθbibi′∂[qwbj∗⊗qwbi]L[qbibj]R[121δθbibi′]=−2[0I][qwbj∗⊗qwbi]L[qbibj]R[021I]
对 jjj 时刻姿态误差的雅可比
∂rq∂δθbjbj′=∂2[qbibj∗⊗qwbi∗⊗qwbj⊗[112δθbjbj′]]xyz∂δθbjbj′=∂2[[qbibj∗⊗qwbi∗⊗qwbj]L[112δθbjbj′]]xyz∂δθbjbj′=2[0I][qbibj∗⊗qwbi∗⊗qwbj]L[012I]\begin{aligned} \frac{\partial \mathbf{r}_q}{\partial \delta \boldsymbol{\theta}_{b_j b_j^{\prime}}} & =\frac{\partial 2\left[\mathbf{q}_{b_i b_j}^* \otimes \mathbf{q}_{w b_i}^* \otimes \mathbf{q}_{w b_j} \otimes\left[\begin{array}{c} 1 \\ \frac{1}{2} \delta \boldsymbol{\theta}_{b_j b_j^{\prime}} \end{array}\right]\right]_{x y z}}{\partial \delta \boldsymbol{\theta}_{b_j b_j^{\prime}}} \\ & =\frac{\partial 2\left[\left[\mathbf{q}_{b_i b_j}^* \otimes \mathbf{q}_{w b_i}^* \otimes \mathbf{q}_{w b_j}\right]_L\left[\begin{array}{c} 1 \\ \frac{1}{2} \delta \boldsymbol{\theta}_{b_j b_j^{\prime}} \end{array}\right]\right]_{x y z}}{\partial \delta \boldsymbol{\theta}_{b_j b_j^{\prime}}} \\ & =2\left[\begin{array}{ll} \mathbf{0} & \mathbf{I} \end{array}\right]\left[\mathbf{q}_{b_i b_j}^* \otimes \mathbf{q}_{w b_i}^* \otimes \mathbf{q}_{w b_j}\right]_L\left[\begin{array}{c} \mathbf{0} \\ \frac{1}{2} \mathbf{I} \end{array}\right] \end{aligned} ∂δθbjbj′∂rq=∂δθbjbj′∂2[qbibj∗⊗qwbi∗⊗qwbj⊗[121δθbjbj′]]xyz=∂δθbjbj′∂2[[qbibj∗⊗qwbi∗⊗qwbj]L[121δθbjbj′]]xyz=2[0I][qbibj∗⊗qwbi∗⊗qwbj]L[021I]
对 iii 时刻陀螺仪bias误差的雅可比
∂rq∂δbig=∂2[(qbibj⊗[112Jbiqδbigq])∗⊗qwbi∗⊗qwbj]xyz∂δbig=∂−2[((qbibj⊗[112Jbiqqδbig])∗⊗qwbi∗⊗qwbj)∗]xyz∂δbig=∂−2[qwbj∗⊗qwbi⊗(qbibj⊗[112Jbioδbig])]xyz∂δbig=−2[0I][qwbj∗⊗qwbi⊗qbibj]L[012Jbiqq]\begin{aligned} & \frac{\partial \mathbf{r}_q}{\partial \delta \mathbf{b}_i^g}=\frac{\partial 2\left[\left(\mathbf{q}_{b_i b_j} \otimes\left[\begin{array}{c} 1 \\ \frac{1}{2} \mathbf{J}_{b_i^q \delta \mathbf{b}_i^g}^q \end{array}\right]\right)^* \otimes \mathbf{q}_{w b_i}^* \otimes \mathbf{q}_{w b_j}\right]_{x y z}}{\partial \delta \mathbf{b}_i^g} \\ & =\frac{\partial-2\left[\left(\left(\mathbf{q}_{b_i b_j} \otimes\left[\begin{array}{c} 1 \\ \frac{1}{2} \mathbf{J}_{b_i^q}^q \delta \mathbf{b}_i^g \end{array}\right]\right)^* \otimes \mathbf{q}_{w b_i}^* \otimes \mathbf{q}_{w b_j}\right)^*\right]_{x y z}}{\partial \delta \mathbf{b}_i^g} \\ & =\frac{\partial-2\left[\mathbf{q}_{w b_j}^* \otimes \mathbf{q}_{w b_i} \otimes\left(\mathbf{q}_{b_i b_j} \otimes\left[\begin{array}{c} 1 \\ \frac{1}{2} \mathbf{J}_{b_i^o} \delta \mathbf{b}_i^g \end{array}\right]\right)\right]_{x y z}}{\partial \delta \mathbf{b}_i^g} \\ & =-2\left[\begin{array}{ll} \mathbf{0} & \mathbf{I} \end{array}\right]\left[\mathbf{q}_{w b_j}^* \otimes \mathbf{q}_{w b_i} \otimes \mathbf{q}_{b_i b_j}\right]_L\left[\begin{array}{c} 0 \\ \frac{1}{2} \mathbf{J}_{b_i^q}^q \end{array}\right] \\ & \end{aligned} ∂δbig∂rq=∂δbig∂2[(qbibj⊗[121Jbiqδbigq])∗⊗qwbi∗⊗qwbj]xyz=∂δbig∂−2[((qbibj⊗[121Jbiqqδbig])∗⊗qwbi∗⊗qwbj)∗]xyz=∂δbig∂−2[qwbj∗⊗qwbi⊗(qbibj⊗[121Jbioδbig])]xyz=−2[0I][qwbj∗⊗qwbi⊗qbibj]L[021Jbiqq]
由于位置残差的形式与速度残差极其相似,因此不再重复推导。
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