Agricultural Robotic Platform with Four Wheel Steering for Weed Detection

A robotic platform for mapping of weed populations in fields was used to demonstrate intelligent concepts for autonomous vehicles in agriculture which may eventually result in a new sustainable model for developed agriculture. The vehicle presented here is adapted to operate in 0·25 and 0·5 m row crops and equipped with cameras for row guidance and weed detection. A modular approach is taken with four identical wheel modules, allowing four wheel steering and propulsion of the platform. The result is improved mobility which allows parallel displacement of the vehicle during turns by decoupling adjustments in position from adjustments in orientation. Control of the platform is provided through a vehicle electronics and control system based on embedded controllers and standard communication protocols. The software implements a hybrid deliberate software architecture that allows a hierarchical decomposition of the operation. The lowest level implements a reactive feedback control mechanism based on an extension of simple control for car-like vehicles to the four wheel case. The controller design forces the front and rear of the vehicle to follow a pre-determined path and allows the vehicle to maintain a fixed orientation relative to the path. The controller rationale is outlined and results from experiments in the field are presented.