Pesticides Research, 97 – Autonomous Weeder for Christmas Trees – Basic Development and Tests

Autonomous Weeder for Christmas Trees – Basic Development and Tests

9 Conclusion

The conducted work on development of an autonomous Christmas tree weeder consisting of a modified self-propelled lawn mower equipped with a special weed cutter devise and a suitable control system has shown that:

It is technically feasible to build a small autonomous machine for weeding of Christmas trees and other similar row cultures,
The principle of using a tree location map as basis for defining an appropriate vehicle route plan and for dynamic positioning of a weeding tool close to the trees is technically feasible. The manual way of establishing the tree location map is rather time consuming, but alternative automated methods were suggested,
On even ground the developed control system enabled the vehicle to track the defined route plans with a precision of a few cm on basis of the RTK-GPS signal only, but on undulated and uneven ground it was necessary to correct the GPS signal with data from a tilt-meter,
The rotor cutter principle developed was found to be well suited for cutting of weed plants close to trees without observable damages so far, when operated in the passive mode (spring loaded positioning). But the active control, which uses the position of the trees relative to the vehicle, needs improvements,
Additional work is needed to improve the reliability of the vehicle route tracking, particularly integration of a supplementary sensor for navigation and a Kalman filter,
Additional work is also needed to improve safety, especially a sensor for detection of larger obstructions and a bumper sensor that can stop the machine in case of collision,
The Matlab/Simulink software used for development of the algorithms for the control system was found to be an efficient tool that supports simulations, tests, and fault diagnosis as well as extensions of the control system relatively easy.
The system has possibilities of becoming economic competitive to mechanical weeding with manned machines when the reliability and safety issues have been developed. Competitiveness with present costs of spraying may occur in 5 - 10 years.