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

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Results and discussion Since the first prototype will be used for intensive experimental testing, the motor was oversized. Both of the two parameters relevant for calculation of the required power were increased with safety factor equal to 6 to avoid overloading or damaging of the system during the testing. P = 6 * M * u = 6 * 600 *1 = 3600W (5.13) 90 required hmaxexp hn The intra-row weeding system requires a closed loop control of the rotational speed because the on-line calculation of the optimal speed takes into account the carrier’s forward speed, observed distance between two successive crop plants and position of the hoeing arms. One of the main advantages of servo motors is the ability to keep a constant torque at both very low and high engine speeds which is in case of the intra-row weeding tool of crucial importance. According to the calculation of the required power of the hoeing system, an AC- servo motor from Yaskawa type SGMGH-44DCA6F with Pmn= 4.4 kW, with maximum rotational speed ummax= 1500 rpm, nominal torque Mmn= 28.4 Nm, maximum torque Mmmax= 71.1 Nm, and appropriate servo drive from Yaskawa type SGDH-50DE were chosen. The servo system includes a 17-bit encoder as feedback device. The motor was combined with a planetary gearing type TP110S-MF2 with gear ratio G= 25 and nominal torque on the gearbox output shaft Mhn= 710 Nm and corresponds to the torque of the hoeing tool. In that way the prototype was able to provide continuous and highly accurate speed change in a range from 0 to 60 rpm with available torque up to Mhn= 710 Nm in the whole range of speeds. 5.3.2.1 External control of the rotational speed The advantages of the servo system implemented into the intra-row hoe’s prototype can be taken with the servo drive in the speed control mode, by an analog signal created in external controlling unit. The combination of DAQPad- 6015 and signal conditioning unit used for plant detection was also used for speed control as an external controller. Controlled inputs to the servo drive were rotation speed, as analog signal, and servo ON as digital signal. Acquired
Results and discussion outputs from the servo drive were data from the incremental encoder and alarm signals. The motor’s rated (maximum) speed is 1,500 rpm and the equivalent rated speed of the hoe is u hmax ummax 1500 = = = 60 rpm = 1 rps (5.14) G 25 To define the adequate voltage/speed ratio the speed reference input gain Pn300 in the servo drive needed to be adjusted. The parameter Pn300 has a setting range between 150 and 3000 and corresponds to the input voltage V- REF with the ratio 100 to 1. E.g. if the Pn300 is adjusted to 600, the rated speed will be achieved with V-REF equal to 6 V. The servo ON signal is required as a main signal for starting the servo motor. In the case where this signal is “low” the servo motor cannot be controlled with external signals. To receive appropriate information about the position of the motor and accordingly the angular position of the hoeing tool, in relation to the “zero” position, the encoder dividing ratio was set to 24 pulses per rotation. Hence the gear ratio is G=25, 600 pulses correspond to one full rotation of the hoeing tool and this represents the resolution of the hoeing tool system RESsys. 5.3.3 Discussion of the distance between the plant detection unit and the plane in which the hoeing tool is positioned The rotational speed of the hoeing tool is directly proportional to the forward speed of the carrier. For travelled distances which are short, speed can be approximated with a constant value as shown in Equation (5.15). ∂s ∆s V = ≅ ∂t ∆ t (5.15) 91
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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)
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 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 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
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Plant position Table 9.3 Detection
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Personal data Education About the a
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