用概率控制提升多足机器人在复杂地形的行进速度与稳定性
Probabilistic approach to feedback control enhances multi-legged locomotion on rugged landscapes
- 通过生物启发的垂直躯体波动控制,减少对传感器依赖
- 实测速度达0.235倍体长/周期,较开环提升约50%
- 适用于野外复杂环境,如碎石、泥地、落叶等
在复杂地形上实现稳健的多足机器人行走面临高不确定性挑战。尽管近年双足和四足机器人已在崎岖地形展现良好移动性,但其稳定性高度依赖传感器,源于高重心与窄支撑面带来的低静态稳定性。我们假设:多足系统可通过额外腿数带来的形态冗余,降低对传感的需求。已有研究表明,足够多腿的系统可在无感测与控制下可靠穿越噪声地形,但速度仅达0.1体长/周期。由于环境交互复杂,如何在高自由度系统中识别关键控制参数仍不明确。本文提出一种生物启发的垂直躯体波动波,结合实验与概率模型,有效缓解环境干扰对速度的影响。进一步引入控制框架,利用二值足地接触传感器监测粗糙地形上的足地接触模式,估算地形粗糙度,并根据肢体平均实际/理想接触率偏差调整垂直躯体波。该方法使实验室粗糙地形上的速度提升至0.235体长/周期,相较开环控制器速度提升约50%,速度方差减少约40%。控制器亦在真实复杂环境中验证,包括松针、机器人大小的岩石、泥地和落叶。
原文摘要 · Abstract (English)
Achieving robust legged locomotion on complex terrains poses challenges due to the high uncertainty in robot-environment interactions. Recent advances in bipedal and quadrupedal robots demonstrate good mobility on rugged terrains but rely heavily on sensors for stability due to low static stability from a high center of mass and a narrow base of support. We hypothesize that a multi-legged robotic system can leverage morphological redundancy from additional legs to minimize sensing requirements when traversing challenging terrains. Studies suggest that a multi-legged system with sufficient legs can reliably navigate noisy landscapes without sensing and control, albeit at a low speed of up to 0.1 body lengths per cycle (BLC). However, the control framework to enhance speed on challenging terrains remains underexplored due to the complex environmental interactions, making it difficult to identify the key parameters to control in these high-degree-of-freedom systems. Here, we present a bio-inspired vertical body undulation wave as a novel approach to mitigate environmental disturbances affecting robot speed, supported by experiments and probabilistic models. Finally, we introduce a control framework which monitors foot-ground contact patterns on rugose landscapes using binary foot-ground contact sensors to estimate terrain rugosity. The controller adjusts the vertical body wave based on the deviation of the limb's averaged actual-to-ideal foot-ground contact ratio, achieving a significant enhancement of up to 0.235 BLC on rugose laboratory terrain. We observed a $\sim$ 50\% increase in speed and a $\sim$ 40\% reduction in speed variance compared to the open-loop controller. Additionally, the controller operates in complex terrains outside the lab, including pine straw, robot-sized rocks, mud, and leaves.
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