ALPINE: a climbing robot for operations in mountain environments

TL;DR

ALPINE addresses the challenge of autonomous maintenance on steep mountain walls by presenting a dual-rope tethered climbing robot with a retractable leg and an auxiliary propeller. The authors develop a tractable reduced-order model for planning and a static wrench feasibility analysis to ensure safe wall contact and operation under friction and unilateral constraints. A two-tier control framework (offline nonlinear planning plus online MPC) enables multi-jump trajectories, disturbance rejection, obstacle avoidance, and precise landing, validated through extensive Gazebo simulations. The platform demonstrates strong potential for rapid deployment, payload handling, and autonomous maintenance tasks in harsh mountain environments, with comparative energy advantages over aerial and walking robots.

Abstract

Mountain slopes are perfect examples of harsh environments in which humans are required to perform difficult and dangerous operations such as removing unstable boulders, dangerous vegetation or deploying safety nets. A good replacement for human intervention can be offered by climbing robots. The different solutions existing in the literature are not up to the task for the difficulty of the requirements (navigation, heavy payloads, flexibility in the execution of the tasks). In this paper, we propose a robotic platform that can fill this gap. Our solution is based on a robot that hangs on ropes, and uses a retractable leg to jump away from the mountain walls. Our package of mechanical solutions, along with the algorithms developed for motion planning and control, delivers swift navigation on irregular and steep slopes, the possibility to overcome or travel around significant natural barriers, and the ability to carry heavy payloads and execute complex tasks. In the paper, we give a full account of our main design and algorithmic choices and show the feasibility of the solution through a large number of physically simulated scenarios.

Figures (18)

• Figure 1: Examples of maintenance operations: rock inspection with rebound hammering (left), debris removal (middle), injection of demolition resin (right).
• Figure 2: Use cases and challenges for tethered climbing robots and main capabilities of the ALPINE platform.
• Figure 3: Topology of the joints for the full detail model. Links are red boxes and joints blue circles (revolute) or blue boxes (prismatic). Shaded joints are the passive ones, not shaded ones are the active ones.
• Figure 4: Kinematic model of the ALPINE robot with two ropes (standard definitions). A propeller is mounted on the rear of the robot. In pink are depicted all the actuation forces. The inertial ($\mathcal{W}$) frame is attached to the left anchor frame.
• Figure 5: Overview of the landing mechanism, with joint and variable definitions. $d_w$ and $d_b$ are the wall clearance and distance between landing wheels. Passive wheels are attached to the extremes of the landing legs.