Development of an ISOBUS-compliant communication node for multiple machine vision systems on wide boom sprayers for nozzle control in spot application schemes

Abstract

This study focuses on developing a node named machine vision node (MVN) for hybrid communication between Ethernet and Controller Area Network (CAN) on the implement bus of boom sprayers. This enabled the integration of multiple machine vision systems and simultaneous control of as many as 60 nozzles based on pest detection results by machine vision. The MVN consists of an electronic control unit (ECU) built around a single-board computer, equipped with a 2-channel CAN hat and an Ethernet router. The ECU utilizes AgIsoStack++ library to maintain ISOBUS compliance, enabling data exchange between the MVN and other electronic components on the sprayer. A threaded client-server firmware incorporates a checksum verification subroutine to ensure reliable protocol message handling, followed by message queuing for uninterrupted real-time processing. The MVN demonstrated robust communication and processing capabilities while receiving protocol messages via Ethernet, reading speed-related CAN frames, and converting CAN data for individual nozzle control simultaneously. The MVN parses and synchronizes over 30 predefined protocol messages every 40 ms. The CAN bus load on the implement bus increased by only 5.86 %, which remained well within the accepTable 45 % limit. ISOBUS compatibility tests across three different virtual terminals confirmed interoperability and standardized control within 51.5 to 70 s. In-field tests confirmed that the MVN dynamically adjusted nozzle opening times based on vehicle speed, maintaining consistent spray lengths of 71.52 cm across different speeds of 3.22 kph, 6.44 kph, and 9.66 kph with nozzle opening times ranging from 270 ms to 800 ms.

Keywords

• Precision agriculture
• Ethernet protocol
• Spray
• CAN bus
• ISOBUS/ISO11783