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

More documents

Recommendations

Info

Introduction Inter-row weeding systems, their operating speeds and limitations were reviewed by Marfield and Bond (Marfield 2002; Bond et al. 2003). Weeding quality is highly dependant on equipment adjustment and on the row steering accuracy. Steering can be done manually, where experience and skills are expected from operator, or with sophisticated equipment e.g. computer vision guidance system or DGPS. Typical systems for inter-row weed control are toolbars pulled or pushed by a tractor. A tractor can simply be driven along the crop row carrying a toolbar with the weeding implement mounted at a constant horizontal spacing. The weeding tool as a part of the system can usually be adjusted to different inter-row distances and plant sizes. To achieve optimum weed reduction, the goal is to work as close to the plant as possible to minimise the non-hoed intra-row area. For most inter-row systems, the operator is just as important as the machinery. Without precise steering and appropriate adjustment, the equipment will damage the plant row and result in a crop loss. Generally, inter-row weeding system can be divided into non-powered and powered systems. The simplest non-powered systems are duckfoot-hoes with hoeing blades either rigidly mounted to the crossbar or mounted on a spring, forming a so called vibrating hoe. With an optimal hoeing depth of 1-2 cm, multiple hoeing tools can be placed side by side to accommodate larger row widths. Vibrating hoes usually cultivate the soil surface more deeply, uprooting a larger portion of the weeds. On that way they disturb the soil more and bring weed seeds to the surface, increasing the number of seeds which could germinate. The rigidly mounted type effectively cuts the weeds with less disturbance of the soil. Both types can be mounted on a parallelogram carriers providing accommodation of the hoeing blades to different soil contours. When a hoe is not sufficient in weed removal, powered equipment is an often- used option. A brush weeder consists of stiff bristles mounted to a rotating disk, which rotates with a high speed to uproot shallow weeds. The main advantage is very minimum disturbance of the soil since the brushes do not penetrate the ground. However, it is hard to adjust the brush width and the tractor’s speed needs to be kept below 4 km/h. Also, they are ineffective in hard soil and can 16
Introduction cause dust contamination on the plants. For harder soils, a rotary strip cultivator is an option. It works on the concept of rotating cutting blades which can cultivate very hard soils. Working depth can be 2-3 cm or more if the weeds are very thick or large, but depths over 4 cm can cause damage on the plant’s root system. Disadvantages are that the working width is very hard to change and the soil must not be too wet. One other powered cultivator option is a weed-fix. Unlike most powered cultivators that rotate on an axis parallel to the ground, a weed-fix’s rotating axis is perpendicular to the ground surface. A set of two or three rotating tines works the ground and uproots the weeds. It works especially well with hard soils because of the powerful fixed tines and allows a tractor speed of up to 8 km/h. There are other alternatives such as pneumatic systems but they are not used on a large scale because of very high operating costs. One of the main problems with inter-row weeding systems is steering. Weeding increases and decreases in effectiveness with every centimetre closer to, or further from the row. Because most weeding systems are rigidly mounted to a crossbar on the front of a tractor, driver skill is crucial. Even the slightest deviation in direction can cause a movement of 3-4 cm in the toolbar position, which added to the usual buffer space from the plant can result in a 6-8 cm width that is not weeded. Mounted on the front of the tractor, the toolbar can be easily seen by the driver, but is very sensitive to steering. If the toolbar is mounted directly below or behind the driver it is much less sensitive to small, immediate changes in steering but does not allow the driver to see the hoeing machinery, increasing error to sometimes 8 cm per side of the crop row. The displacement of the hoeing machinery’s centre of rotation can help to reduce this error, as can having the centre of rotation of each individual hoe directly behind the blade. This approach has been successfully applied on the Mutsaers QI steering system (see Figure 1.3). 17
Page 1 and 2: Institut für Landtechnik der Rhein
Page 3 and 4: Development of a novel mechatronic
Page 5 and 6: Kurzfassung Entwicklung eines neuar
Page 7 and 8: Acknowledgements Acknowledgements M
Page 9 and 10: Table of contents Table of contents
Page 11 and 12: Glossary of abbreviations and symbo
Page 13 and 14: Symbol Unit Description Mmmax Nm Ma
Page 15 and 16: Symbol Unit Description Glossary of
Page 17: ωold ωout rad s -2 Latest rotatio
Page 20 and 21: Introduction The most frequently us
Page 22 and 23: Introduction application that had p
Page 24 and 25: Introduction be to go from a system
Page 26 and 27: Introduction limited and environmen
Page 28 and 29: Introduction than 40 years before g
Page 30 and 31: Introduction techniques. It is know
Page 32 and 33: Introduction Sowing and planting al
Page 36 and 37: Introduction 18 Figure 1.3 Inter-ro
Page 38 and 39: State of the art 20 Figure 2.1 a) F
Page 40 and 41: State of the art cylinder rotates a
Page 42 and 43: State of the art 1998). This device
Page 44 and 45: State of the art 26 2.2 Detection o
Page 46 and 47: State of the art The fluorescence s
Page 48 and 49: Definition of the problem and resea
Page 51 and 52: 4 Materials and methods 4.1 Detecti
Page 53 and 54: Materials and methods Figure 4.1 a)
Page 55 and 56: Materials and methods Figure 4.3 a)
Page 57 and 58: 4.1.2 Data acquisition 4.1.2.1 Hard
Page 59 and 60: 4.1.4 Test objects Materials and me
Page 61 and 62: Materials and methods become a poss
Page 63 and 64: Materials and methods environments
Page 65 and 66: Materials and methods dimensions ne
Page 67 and 68: Materials and methods (PFM). As the
Page 69 and 70: Materials and methods A command sig
Page 71 and 72: Materials and methods The drive con
Page 73: Materials and methods Another tool
Page 76 and 77: Results and discussion 58 Figure 5.
Page 82 and 83: Results and discussion objects. Acc
Page 84 and 85:
Results and discussion Plant positi
Page 86 and 87:
Results and discussion Plant positi
Page 88 and 89:
Results and discussion 70 5.1.4 Dis
Page 90 and 91:
Results and discussion 72 Figure 5.
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 and 140:
6 Summary Summary Neither a mechani
Page 141 and 142:
Summary The third part of the work
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 161 and 162:
Page 163 and 164:
Page 165 and 166:
Page 167 and 168:
Page 169:
Personal data Education About the a
show all

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

Create successful ePaper yourself

Delete template?

Save as template?