Development of a novel mechatronic system for mechanical weed ...
Development of a novel mechatronic system for mechanical weed ...
Development of a novel mechatronic system for mechanical weed ...
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Results and discussion<br />
Conventional method <strong>for</strong> measurement <strong>of</strong> a rotary torque is use <strong>of</strong> a strain<br />
gauge based sensors. In these types <strong>of</strong> sensors strain gauges are coupled with<br />
brushes and slip rings to trans<strong>for</strong>m the torque signal into output voltage. The<br />
output voltage depends on a resistance change due to de<strong>for</strong>mation in strain<br />
gauges that are bonded to the torque sensor structure. The magnitude <strong>of</strong> the<br />
resistance change is proportional to the de<strong>for</strong>mation <strong>of</strong> the torque sensor and<br />
there<strong>for</strong>e the applied torque. A rotary torque sensor manufactured by<br />
Walterscheid with detection range 0 and 250 daNm was attached between the<br />
cardan shaft and the gear <strong>for</strong> measuring the torque.<br />
All sensors were connected to the DAQPad-6015 through the signal<br />
conditioning unit. A simple VI generating a report file was written <strong>for</strong> data<br />
acquisition. The report file contains basic in<strong>for</strong>mation about the measurement<br />
such as: date and time <strong>of</strong> the experiment, arm lengths, hoeing depth and a data<br />
array with <strong>for</strong>ward speed <strong>of</strong> the tractor, rotational speed <strong>of</strong> the hoe and torque<br />
on the axis. The results <strong>of</strong> one experimental hoeing are illustrated in the Figure<br />
5.18.<br />
Rot speed [RPM]<br />
Fwd speed [km/h]<br />
Torque [Nm]<br />
88<br />
100<br />
60<br />
20<br />
20<br />
10<br />
0<br />
500<br />
400<br />
300<br />
200<br />
100<br />
0<br />
0 5 10 15 20 25 30<br />
0 5 10 15 20 25 30<br />
0 5 10 15 20 25<br />
Time [s]<br />
Figure 5.18 Results <strong>of</strong> the field experiment providing insight into the<br />
size <strong>of</strong> the torque required <strong>for</strong> undisturbed hoeing with<br />
hoeing tool with three arms in extreme conditions<br />
30