用并行变分推断加速不确定环境下的机器人路径规划。
Efficient Iterative Proximal Variational Inference Motion Planning
- 在高斯分布空间优化路径,通过近端算法迭代求解。
- 线性系统下计算速度提升10倍以上,非线性系统也成功求解。
- 适合需要快速响应的自主机器人系统,如自动驾驶、无人机。
我们将不确定性下的运动规划建模为随机最优控制问题,其最优后验分布具有显式形式。为近似该后验,本文在路径分布空间中构建变分推断(VI)优化问题,将求解限定于高斯分布空间。针对线性-高斯随机动力学,提出一种近端算法,可迭代求解最优高斯提议分布。计算瓶颈在于对密集轨迹的提议分布梯度评估,为此引入稀疏规划因子图与高斯信念传播(GBP),实现基于图形处理器(GPU)的并行梯度计算。该新范式称为并行高斯变分推断运动规划(P-GVIMP)。在此高效算法基础上,进一步提出基于统计线性回归(SLR)的迭代框架,用于求解非线性随机系统,其中每步对线性化时变系统调用P-GVIMP作为子程序。所提框架在多种机器人系统上验证,显著加速计算并成功获得不确定条件下的规划解。开源代码已发布于https://github.com/hzyu17/VIMP。
原文摘要 · Abstract (English)
We cast motion planning under uncertainty as a stochastic optimal control problem, where the optimal posterior distribution has an explicit form. To approximate this posterior, this work frames an optimization problem in the space of Gaussian distributions by solving a Variational Inference (VI) in the path distribution space. For linear-Gaussian stochastic dynamics, a proximal algorithm is proposed to solve for an optimal Gaussian proposal iteratively. The computational bottleneck is evaluating the gradients with respect to the proposal over a dense trajectory. To tackle this issue, the sparse planning factor graph and Gaussian Belief Propagation (GBP) are exploited, allowing for parallel computation of these gradients on Graphics Processing Units (GPUs). We term the novel paradigm the \textit{Parallel Gaussian Variational Inference Motion Planning (P-GVIMP)}. Building on the efficient algorithm for linear Gaussian systems, we then propose an iterative paradigm based on Statistical Linear Regression (SLR) techniques to solve planning problems for nonlinear stochastic systems, where the P-GVIMP serves as a sub-routine for the linearized time-varying system at each iteration. The proposed framework is validated on various robotic systems, demonstrating significant speed acceleration achieved by leveraging parallel computation and successful planning solutions for nonlinear systems under uncertainty. An open-sourced implementation is presented at \href{https://github.com/hzyu17/VIMP}{https://github.com/hzyu17/VIMP}.
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