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

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Results and discussion Conventional method for measurement of a rotary torque is use of a strain gauge based sensors. In these types of sensors strain gauges are coupled with brushes and slip rings to transform the torque signal into output voltage. The output voltage depends on a resistance change due to deformation in strain gauges that are bonded to the torque sensor structure. The magnitude of the resistance change is proportional to the deformation of the torque sensor and therefore the applied torque. A rotary torque sensor manufactured by Walterscheid with detection range 0 and 250 daNm was attached between the cardan shaft and the gear for measuring the torque. All sensors were connected to the DAQPad-6015 through the signal conditioning unit. A simple VI generating a report file was written for data acquisition. The report file contains basic information about the measurement such as: date and time of the experiment, arm lengths, hoeing depth and a data array with forward speed of the tractor, rotational speed of the hoe and torque on the axis. The results of one experimental hoeing are illustrated in the Figure 5.18. Rot speed [RPM] Fwd speed [km/h] Torque [Nm] 88 100 60 20 20 10 0 500 400 300 200 100 0 0 5 10 15 20 25 30 0 5 10 15 20 25 30 0 5 10 15 20 25 Time [s] Figure 5.18 Results of the field experiment providing insight into the size of the torque required for undisturbed hoeing with hoeing tool with three arms in extreme conditions 30
Results and discussion During the experiments it was observed that the soil type, previous tillage, roughness of the soil surface, soil humidity, forward speed of the carrier, rotational speed of the hoeing tool, number of arms, as also the hoeing depth have significant influence on the torque. There was no possibility to draw general conclusion because of a high number of varying parameters. Hence, a case with worst condition was chosen to ensure that the resulting prototype will be able to work in all conditions. For rotational speed of uhmax=100 rpm, forward speed around 2m/s, arm lengths of 550 mm and average hoeing depth 5 cm the torque value does not exceeded the value of Mhmaxexp= 600 Nm. According to this worst case experiment for the selection of the motor 350 Nm as a nominal value was taken. The impact of the rotational speed to the level of damage caused to the weeds was observed, as an additional important fact, during the field experiments. It was observed that for arm lengths of 550 mm with implemented duckfoot knives, a rotational speed of 30 rpm provides enough energy to cut the weeds. Higher rotational speed over 80 rpm can originate throwing of the soil particles from the row towards the neighbouring row. For another type of direct weeding implement different from the duckfoot knives, higher speed could be applied because of the reduced contact between the tool and the soil surface. Taking into consideration all the above mentioned facts for a nominal value of the rotational speed uhn=60 rpm were used in calculations. 5.3.2 Calculation and selection of the motor and transmission combination To make an appropriate selection of the motor/transmission combination it is necessary to know the required power, speed range and the operating point of the torque for the system in typical working conditions. Usually the smallest, lightest and most inexpensive motor that meets the requirements will be chosen. As the motor is intended to be implemented on a first prototype of the weeding tool applicable in laboratory condition, the type of the power supply required by motor was not a limiting factor. 89
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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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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
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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 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
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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 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
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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
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Plant position 9 Appendix Table 9.1
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Plant position Table 9.3 Detection
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Personal data Education About the a
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