让机器人实时调整轨迹,应对传感器误差和模型偏差。
Kinodynamic Trajectory Following with STELA: Simultaneous Trajectory Estimation & Local Adaptation
- 用因子图统一估计轨迹与调整控制,支持任意动力学模型。
- 在线更新控制频率达10Hz,实现在动态环境中稳定跟踪。
- 适合需要高精度轨迹跟随的无人车、无人机等复杂系统。
状态估计与控制通常分开处理,导致因感知噪声、执行误差以及规划模型与现实差异而出现安全隐患。已有方法虽提出通过概率图模型统一求解,但依赖合适的高斯先验,且仅适用于具有线性时变模型的全向机器人。本文提出适用于任意动力学系统的同步轨迹估计与局部自适应(STELA)方法。首先使用基于采样的运动规划器生成可行轨迹;随后在因子图框架下,同时:(i) 基于噪声观测估计历史轨迹,(ii) 调整待执行控制以最小化与规划轨迹的偏差并避免碰撞。该方法将轨迹离散中两状态间的时间间隔设为优化变量,可应用于任意具备一阶或二阶状态更新方程的动力系统。为提升计算效率,采用iSAM进行增量式更新,并引入时间窗口机制,使因子图仅维护有限历史与前向视野内的信息,实现每秒至少10次的在线控制更新。实验表明,对于理想线性动力学车辆,STELA性能不低于现有框架。
原文摘要 · Abstract (English)
State estimation and control are often addressed separately, leading to unsafe execution due to sensing noise, execution errors, and discrepancies between the planning model and reality. Simultaneous control and trajectory estimation using probabilistic graphical models has been proposed as a unified solution to these challenges. Previous work, however, relies heavily on appropriate Gaussian priors and is limited to holonomic robots with linear time-varying models. The current research extends graphical optimization methods to vehicles with arbitrary dynamical models via Simultaneous Trajectory Estimation and Local Adaptation (STELA). The overall approach initializes feasible trajectories using a kinodynamic, sampling-based motion planner. Then, it simultaneously: (i) estimates the past trajectory based on noisy observations, and (ii) adapts the controls to be executed to minimize deviations from the planned, feasible trajectory, while avoiding collisions. The proposed factor graph representation of trajectories in STELA can be applied for any dynamical system given access to first or second-order state update equations, and introduces the duration of execution between two states in the trajectory discretization as an optimization variable. These features provide both generalization and flexibility in trajectory following. In addition to targeting computational efficiency, the proposed strategy performs incremental updates of the factor graph using the iSAM algorithm and introduces a time-window mechanism. This mechanism allows the factor graph to be dynamically updated to operate over a limited history and forward horizon of the planned trajectory. This enables online updates of controls at a minimum of 10Hz. Experiments demonstrate that STELA achieves at least comparable performance to previous frameworks on idealized vehicles with linear dynamics.[...]
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