RaccoonBot: An Autonomous Wire-Traversing Solar-Tracking Robot for Persistent Environmental Monitoring

TL;DR

The paper addresses persistent forest environmental monitoring using a novel wire-traversing robot, RaccoonBot, that integrates a fail-safe non-reversible worm-gear mechanism to lock the robot on a wire during power loss and a mobile Solar Tracking System to locate sunlit positions along the wire for continuous energy harvesting. The approach combines a hardware design with end pulleys and a 28:1 worm-gear drive, robust mechanical features, and efficient power electronics (boost to $12$ V and buck-boost to $5$ V, ~90% efficiency) with a dynamic STS algorithm that updates position via $x_i = x_{i-1} + (\Delta x \cdot I)$ and $I = I \cdot \zeta$, subject to boundary constraints and MPPT delay $T_p \ge 50$ ms. Key contributions include the non-reversible, safe mechanical design, the integrated energy-harvesting and regulation hardware, and the mobile STS algorithm validated through mobility, disturbance, and climbing experiments, demonstrating energy autonomy and robust operation in real forest conditions. The work advances persistent environmental monitoring by enabling long-term, autonomous operation with limited human intervention in challenging canopy environments.

Abstract

Environmental monitoring is used to characterize the health and relationship between organisms and their environments. In forest ecosystems, robots can serve as platforms to acquire such data, even in hard-to-reach places where wire-traversing platforms are particularly promising due to their efficient displacement. This paper presents the RaccoonBot, which is a novel autonomous wire-traversing robot for persistent environmental monitoring, featuring a fail-safe mechanical design with a self-locking mechanism in case of electrical shortage. The robot also features energy-aware mobility through a novel Solar tracking algorithm, that allows the robot to find a position on the wire to have direct contact with solar power to increase the energy harvested. Experimental results validate the electro-mechanical features of the RaccoonBot, showing that it is able to handle wire perturbations, different inclinations, and achieving energy autonomy.

Figures (14)

• Figure 1: RaccoonBot traveling along a wire between two trees.
• Figure 2: a) Typical frame of Robots for live line inspections. b) Mechanical representation of the LineRanger design, live4_ino. c) Robot schematic of a single line inspection robot with two pairs of mechanized wheels, bahrami2016novel. d) Mechanical representation of a single line inspection robot, singleLineModel. e) Mechanical features sketch of the proposed robot's wire-traversing mechanism.
• Figure 3: Mechanical features of the RaccoonBot.
• Figure 4: Electrical structure embedded inside the RaccoonBot.
• Figure 5: Simple MPPT structure to regulate the voltage ($V_{PV}$) and current ($i_{PV}$) provided by the solar panel.