CAFEs: Cable-driven Collaborative Floating End-Effectors for Agriculture Applications
Hung Hon Cheng, Josie Hughes
TL;DR
CAFEs address scalable, precise manipulation in large-scale agriculture by introducing a cable-driven architecture with a shared roller-driven cable and a two-layer clamping mechanism, enabling multiple end-effectors to operate independently or cooperatively along a common network. A spring–mass dynamic model predicts tension distribution and cable sag, which is validated experimentally showing open-loop positioning errors below $25 \text{ mm}$ over $1.25 \text{ m}$ and robust relative synchronization with errors under $3 \text{ mm}$. The work demonstrates practical feasibility for harvesting, monitoring, and object transport in greenhouses and fields, aided by distributed anchoring strategies and active tension monitoring for scalability. These findings suggest CAFEs can reduce localization dependencies while increasing workspace efficiency and multi-robot collaboration in agricultural automation, with future work improving control, hardware efficiency, and damping to further enhance stability.
Abstract
CAFEs (Collaborative Agricultural Floating End-effectors) is a new robot design and control approach to automating large-scale agricultural tasks. Based upon a cable driven robot architecture, by sharing the same roller-driven cable set with modular robotic arms, a fast-switching clamping mechanism allows each CAFE to clamp onto or release from the moving cables, enabling both independent and synchronized movement across the workspace. The methods developed to enable this system include the mechanical design, precise position control and a dynamic model for the spring-mass liked system, ensuring accurate and stable movement of the robotic arms. The system's scalability is further explored by studying the tension and sag in the cables to maintain performance as more robotic arms are deployed. Experimental and simulation results demonstrate the system's effectiveness in tasks including pick-and-place showing its potential to contribute to agricultural automation.