Volcanic gas emissions are key precursors of eruptive activity. Yet, obtaining accurate near-surface measurements remains hazardous and logistically challenging, motivating the need for autonomous solutions. Limited mobility in rough volcanic terrain has prevented wheeled systems from performing reliable in situ gas measurements, reducing their usefulness as sensing platforms. We present a legged robotic system for autonomous volcanic gas analysis, utilizing the quadruped ANYmal, equipped with a quadrupole mass spectrometer system. Our modular autonomy stack integrates a mission planning interface, global planner, localization framework, and terrain-aware local navigation. We evaluated the system on Mount Etna across three autonomous missions in varied terrain, achieving successful gas-source detections with autonomy rates of 93-100%. In addition, we conducted a teleoperated mission in which the robot measured natural fumaroles, detecting sulfur dioxide and carbon dioxide. We discuss lessons learned from the gas-analysis and autonomy perspectives, emphasizing the need for adaptive sensing strategies, tighter integration of global and local planning, and improved hardware design.

翻译：火山气体排放是喷发活动的关键前兆。然而，获取准确的近地表测量数据仍然危险且后勤保障困难，这推动了对自主解决方案的需求。崎岖火山地形中的有限机动性阻碍了轮式系统进行可靠的原位气体测量，降低了其作为传感平台的有效性。我们提出了一种用于自主火山气体分析的腿式机器人系统，该系统采用四足机器人ANYmal，并配备了四极杆质谱仪系统。我们的模块化自主堆栈集成了任务规划界面、全局规划器、定位框架和地形感知局部导航。我们在埃特纳火山上跨越三种不同地形进行了三次自主任务评估，成功实现了气体源检测，自主率达到93-100%。此外，我们执行了一次遥操作任务，机器人测量了天然喷气孔，检测到二氧化硫和二氧化碳。我们从气体分析和自主性的角度讨论了经验教训，强调了自适应传感策略的必要性、全局与局部规划的更紧密集成以及硬件设计的改进。