Development and field evaluation of a UWB-IMU navigated autonomous spraying robot for papaya greenhouses

Abstract

• A fully autonomous pesticide spraying vehicle was developed and field-tested in a papaya greenhouse. • The UWB–IMU navigation system provides accurate localization with a simple setup and robust performance in complex greenhouse environments where GPS is unreliable. • This research demonstrates full-scale field implementation, unlike previous studies limited to simulations or lab-scale tests. • The vehicle can autonomously detect tank depletion, return to a refill station, and resume spraying without human intervention. Autonomous vehicles for greenhouse environments offer solutions to enhance efficiency, reduce costs, and improve farmer safety by minimising pesticide exposure. This paper presents the development and field evaluation of an autonomous vehicle for pesticide spraying in papaya greenhouses, focusing on an ultra-wideband (UWB) navigation system integrated with an inertial measurement unit (IMU). The proposed system uses fixed greenhouse UWB modules and two vehicle-mounted mobile UWB modules, integrating IMU data to achieve precise positioning and orientation. Predefined spraying paths and refill station locations are stored on a map, allowing the vehicle to autonomously navigate and adapt to operational needs such as refilling. The entire system, including vehicle, navigation, and spraying components, was developed and field-tested in a papaya greenhouse in Kaohsiung, Taiwan. Field experiment results demonstrate stable operation at speeds up to 0.40 m/s, lateral deviations under 0.2 m, and effective spray coverage. These results highlight the potential of this autonomous spraying system to enhance precision and automation in greenhouse pesticide application, promoting safer and more sustainable agricultural practices.