Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Coverage trajectory planning for a bush trimming robot arm
Kaljaca, Dejan ; Vroegindeweij, Bastiaan ; Henten, Eldert van - \ 2019
Journal of Field Robotics (2019). - ISSN 1556-4959
agriculture - manipulators - planning

A novel motion planning algorithm for robotic bush trimming is presented. The algorithm is based on an optimal route search over a graph. Differently from other works in robotic surface coverage, it entails both accuracy in the surface sweeping task and smoothness in the motion of the robot arm. The proposed method requires the selection of a custom objective function in the joint space for optimal node traversal scheduling, as well as a kinematically constrained time interpolation. The algorithm was tested in simulation using a model of the Jaco arm and three target bush shapes. Analysis of the simulated motions showed how, differently from classical coverage techniques, the proposed algorithm is able to ensure high tool positioning accuracy while avoiding excessive arm motion jerkiness. It was reported that forbidding manipulation posture changes during the cutting phase of the motion is a key element for task accuracy, leading to a decrease of the tool positioning error up to 90%. Furthermore, the algorithm was validated in a real-world trimming scenario with boxwood bushes. A target of 20 mm accuracy was proposed for a trimming result to be considered successful. Results showed that on average 82% of the bush surface was affected by trimming, and 51% of the trimmed surface was cut within the desired level of accuracy. Despite the fact that the trimming accuracy turned out to be lower than the stated requirements, it was found out this was mainly a consequence of the inaccurate, early stage vision system employed to compute the target trimming surface. By contrast, the trimming motion planning algorithm generated trajectories that smoothly followed their input target and allowed effective branch cutting.

Trimbot cutting tools and manipulator
Hemming, Jochen ; Tuijl, Bart Van; Tielen, Toon ; Kaljaca, Dejan ; IJsselmuiden, Joris ; Henten, Eldert Van; Mencarelli, Angelo ; Visser, Pieter De - \ 2018
In: Applications of Intelligent Systems - Proceedings of the 1st International APPIS Conference 2018, APPIS 2018. - IOS Press (Frontiers in Artificial Intelligence and Applications ) - ISBN 9781614999287 - p. 89 - 93.
Agriculture - End-effector - Path planning - Pruning - Robot - Trimming

This article describes the tasks and first results of the work package "Manipulator and Control" of the EU project Trimbot2020. This project develops a mobile robot for outdoor hedge, rose and bush trimming. The Kinova Jaco 2 robotic arm was selected as manipulator. Two different types of robotic end-effectors have been developed. The tool for trimming topiaries uses two custom designed circular contra-rotating blades. The tool for single stem cutting is based on a commercial electrical pruner. The arm and the tools can all be controlled by using the Robot Operating System (ROS). The motion planning algorithm of the arm for the bush trimming action is divided into the planning setup module, the coverage planning module and the trajectory planning module. The path planning is modelled as a traveling salesman problem. In the first phase of the project the trimming control is performed open loop. A positioning genetic algorithm was developed that minimizes the needed number of vehicle poses for one target object. In the next phase of the project a vision feedback mechanism will be implemented.

Trimbot Cutting Tools and Manipulator
Hemming, J. ; Tuijl, B.A.J. van; Tielen, A.P.M. ; Kaljaca, D. ; Ijsselmuiden, J.M.M. ; Henten, E.J. van; Mencarelli, A. ; Visser, P.H.B. de - \ 2018
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