Development of a novel mechatronic system for mechanical weed ...

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Summary For broad usage of the system, parameter adjustments need to be replaced by a more systematic method. The second part of the work deals with the development of a virtual prototype of a system for intra-row weeding, emulating the manual hoeing motions under the soil surface. The hoeing tool consists of an arm holder and three or more integrated arms rotating around the horizontal axis above the crop row. The hoeing tool is attached to the motor shaft and the working height of the whole assembly is adjustable in order to provide optimal hoeing depth, which should be between 20 and 30 mm. There is a possibility to change the arms’ length and their angular position in relation to the surface perpendicular to the rotation axis in which the arm holder is placed. Depending on the duckfoot knives’ shape and size the necessary number of cuts between two plants could be set, controlling the rotational speed of the hoe. The virtual prototype of the hoe was designed in Pro/engineer®. Kinematical behaviour of the developed prototype in different hoeing strategies was simulated and tested. The hoeing trajectories of the design variants consisting of 3, 4 or 9 arms were simulated in hoeing strategies with 2 and 3 cuts between every two plants. The optimal length of the arms was estimated and the hoeing depth/width ratio was discussed according to the roughness of the soil surface. The influence of the arms’ angular adjustment to the hoeing trajectories was examined for different arm lengths and selection of the appropriate design variant according to the hoeing strategy was discussed. The aim of the comprehensive analysis of the weeding tool’s kinematical behaviour was to verify that the newly designed hoeing system can be adapted to different intra- row distances and growth stages of the crop plants. Most of the kinematical problems were discovered and worked out in the virtual prototyping process, providing easier development of the physical prototype with very few errors. Finally, one of the major benefits of virtual prototyping was reduction of the costs and time needed for development of the physical prototype. 122
Summary The third part of the work was development and testing of the physical prototype realised using a servo motor in laboratory conditions. The servo motor was sized according to the experimental measurement of the torque in field conditions. The motor was selected in combination with transmission gear to cover the full range of speeds and torques which were expected in laboratory experiments. The experimental research was done in a soil box with different soil types. Forward-backward moving, vertical and horizontal positioning of the hoeing tool above the soil box was realised through a carrier with a separate electro motor. The servo system was operated in a mode with direct software control providing rotational speed adjustment according to the forward speed of the carrier, intra- row distance between successive crop plants and the observed angular position of the arms. The controlling algorithm and software solution were developed in the Labview® environment. The main task of the controlling software was permanent calculation, checking and change of the recent rotational speed of the hoeing tool in real time. The software solution used an expanded version of the software previously developed for detection of the plants’ centre position. For well-timed execution of different subfunctions of the software in the time schedule, the optimal distance between the plant detection unit and the plane in which the hoeing tool is positioned was discussed and a methodology for its calculation was proposed. The speed controlling algorithm was thoroughly explained. Finally, the controlling algorithm, stability and robustness of the prototype were comprehensively evaluated by experimental testing. Tests were done with continuous and changeable forward speed on the crops rows with 200 mm and 400 mm intra-row distances. Tests have proved that depending on the angular adjustment of the duckfoot knives an uncultivated area big enough to avoid damaging of the plants can be left around the plants during the intra-row weeding with the developed system. The system is able to autonomously adapt the rotational speed of the hoeing tool in case of non-intensive forward speed change. After intensive forward speed change, depending on the intensity level, several plants could be 123
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Institut für Landtechnik der Rhein
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Development of a novel mechatronic
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Kurzfassung Entwicklung eines neuar
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Acknowledgements Acknowledgements M
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Table of contents Table of contents
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Glossary of abbreviations and symbo
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Symbol Unit Description Mmmax Nm Ma
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Symbol Unit Description Glossary of
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ωold ωout rad s -2 Latest rotatio
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Introduction The most frequently us
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Introduction application that had p
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Introduction be to go from a system
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Introduction limited and environmen
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Introduction than 40 years before g
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Introduction techniques. It is know
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Introduction Sowing and planting al
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Introduction Inter-row weeding syst
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Introduction 18 Figure 1.3 Inter-ro
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State of the art 20 Figure 2.1 a) F
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State of the art cylinder rotates a
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State of the art 1998). This device
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State of the art 26 2.2 Detection o
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State of the art The fluorescence s
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Definition of the problem and resea
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4 Materials and methods 4.1 Detecti
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Materials and methods Figure 4.1 a)
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Materials and methods Figure 4.3 a)
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4.1.2 Data acquisition 4.1.2.1 Hard
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4.1.4 Test objects Materials and me
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Materials and methods become a poss
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Materials and methods environments
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Materials and methods dimensions ne
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Materials and methods (PFM). As the
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Materials and methods A command sig
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Materials and methods The drive con
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Materials and methods Another tool
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Results and discussion 58 Figure 5.
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Results and discussion objects. Acc
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Results and discussion Plant positi
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Results and discussion Plant positi
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Results and discussion 70 5.1.4 Dis
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Page 92 and 93: Results and discussion Connection b
Page 94 and 95: Results and discussion 76 5.2.1 Opt
Page 96 and 97: Results and discussion xmi1 = ( RLA
Page 98 and 99: Results and discussion With the inv
Page 100 and 101: Results and discussion 82 Horizonta
Page 102 and 103: Results and discussion 84 5.2.4 Sel
Page 104 and 105: Results and discussion 86 5.2.5 Dis
Page 106 and 107: Results and discussion Conventional
Page 108 and 109: Results and discussion Since the fi
Page 110 and 111: Results and discussion To avoid con
Page 112 and 113: Results and discussion As the size
Page 114 and 115: Results and discussion 96 5.3.4 Alg
Page 116 and 117: Results and discussion 98 V = zc( t
Page 118 and 119: Results and discussion corresponds
Page 120 and 121: Results and discussion 102 5.3.6 Me
Page 122 and 123: Results and discussion hoeing accur
Page 124 and 125: Results and discussion between the
Page 126 and 127: Results and discussion distance fro
Page 128 and 129: Results and discussion Distribution
Page 130 and 131: Results and discussion cuts are ran
Page 132 and 133: Results and discussion Forward spee
Page 134 and 135: Results and discussion x [mm] Distr
Page 136 and 137: Results and discussion The experime
Page 139: 6 Summary Summary Neither a mechani
Page 143 and 144: 7 Conclusions Conclusions The prese
Page 145 and 146: 8 References References Agrios, G.
Page 147 and 148: References in California's Sacramen
Page 149 and 150: References Johnson, W C and Mullini
Page 151 and 152: References Schans, D. v. d. et al.
Page 153 and 154: List of figures List of figures Fig
Page 155 and 156: List of figures Figure 5.24 Scheme
Page 157 and 158: Plant position 9 Appendix Table 9.1
Page 159 and 160: Plant position Table 9.3 Detection
Page 169: Personal data Education About the a
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