提出新型混合信念模型,高效解决机器人环境感知中的语义几何耦合难题。
Online Hybrid-Belief POMDP with Coupled Semantic-Geometric Models
- 构建语义-几何耦合的混合信念模型,融合深度学习先验与观测
- 设计可高效采样的新信念形式,使安全概率计算复杂度从指数降至多项式
- 适用于复杂未知环境中需兼顾语义理解与几何精度的机器人规划任务
在复杂未知环境中,机器人需依赖环境的语义-几何表示以安全执行任务。由于物体类别为离散变量,而机器人自身位姿及物体位姿为连续变量,环境可用混合式离散-连续信念表示,并随模型和观测数据更新。通过深度学习算法可从数据中学习先验概率与观测模型,这些模型常耦合语义与几何属性,导致语义状态空间维度呈指数增长。本文研究基于部分可观测马尔可夫决策过程(POMDP)的不确定性规划,采用考虑语义-几何耦合的混合信念模型。引入语义感知安全概念。获取理论混合信念的代表性样本以估计价值函数极为困难。作为关键贡献,我们提出一种新型混合信念形式,并用于生成代表性样本。在特定条件下,可显式计算价值函数与安全概率。仿真显示,我们的估计器在准确率上与穷举整个语义状态空间的采样方法相当,但计算复杂度为多项式而非指数级。
原文摘要 · Abstract (English)
Robots operating in complex and unknown environments frequently require geometric-semantic representations of the environment to safely perform their tasks. While inferring the environment, they must account for many possible scenarios when planning future actions. Since objects' class types are discrete and the robot's self-pose and the objects' poses are continuous, the environment can be represented by a hybrid discrete-continuous belief which is updated according to models and incoming data. Prior probabilities and observation models representing the environment can be learned from data using deep learning algorithms. Such models often couple environmental semantic and geometric properties. As a result, semantic variables are interconnected, causing semantic state space dimensionality to increase exponentially. In this paper, we consider planning under uncertainty using partially observable Markov decision processes (POMDPs) with hybrid semantic-geometric beliefs. The models and priors consider the coupling between semantic and geometric variables. Within POMDP, we introduce the concept of semantically aware safety. Obtaining representative samples of the theoretical hybrid belief, required for estimating the value function, is very challenging. As a key contribution, we develop a novel form of the hybrid belief and leverage it to sample representative samples. We show that under certain conditions, the value function and probability of safety can be calculated efficiently with an explicit expectation over all possible semantic mappings. Our simulations show that our estimates of the objective function and probability of safety achieve similar levels of accuracy compared to estimators that run exhaustively on the entire semantic state-space using samples from the theoretical hybrid belief. Nevertheless, the complexity of our estimators is polynomial rather than exponential.
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