# In-Field Load Acquisitions on a Variable Chamber Round
## 3 Load Acquisition Results and Discussion  
### Load Identification  
Figure 10 reports a satellite image of the two fields where the maneuvers were carried out and the routes followed by the baler, while Figure 11 shows the baler used for the in-field load acquisitions towed by a Claas Arion 660 tractor during a _product collection maneuver_. The corresponding vertical loads F\({}_{\text{v}}\)(t) on the left and right hub carriers are presented in Figure 12a. Figure 12d displays the path followed by the round baler according to the acquired GPS signal. Figure 12b,e report the vertical forces while the baler was towed to collect product along the sowing lines with the pick-up (Figure 11) deployed. In Figure 12c, the baler was towed while crossing the sowing lines with the pick-up raised (Figure 16), and no product was collected during such maneuver. It is seen that the acquired vertical forces \begin{table}
\begin{tabular}{c c c} \hline \hline  & **Raised Pick-Up [kN]** & **Deployed Pick-Up [kN]** \\ \hline R hub carrier & 13.79 & 13.36 \\ L hub carrier & 14.32 & 13.45 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Weight distribution of the baler. Figure 9: Sketch of the off-line procedure adopted for zeroing the signals of the dynamometric towing pin (the 4 mm clearance is highlighted). in Figure 12c differ significantly from those in Figure 12b,e, showing oscillations at higher amplitude and frequency. Therefore, when reporting the maximum and minimum loads acquired for each maneuver in the next Table 4, which will be commented later, the two portions of the _product collection_ maneuvers reported in Figure 12c and Figure 12b and 12e, respectively, were kept distinct. In more detail, the portion where the baler moved from one swath to another (as in Figure 12c) is referred to as a _headland turning_. It is worth mentioning that the _headland turning_ is present only in four out of the seven _product collection_ maneuvers carried out; in the remaining three cases, the bale was collected, tied, and unloaded within the same swath. Figure 12 highlights also that the R hub carrier channel consistently exhibited higher vertical loads compared to the L hub carrier, with the exceptions during the intervals 120 s < t < 130 s (Figure 12b), 160 s < t < 170 s (Figure 12b), and 180 s < t < 240 s (Figure 12c). In the latter interval (180 s < t < 240 s, Figure 12c), the baler was towed while running perpendicular to the swing lines. To the Authors, the consistently higher F,v,R-hub carrier loads compared to the F,v,L-hub carrier when running parallel to the swing lines during the product collection maneuver (Figure 12b,d) could be attributed to the influence of the sowing lines, which caused the baler to stay inclined to its right side. Figure 12f reports the effect of the baler's rear door opening (at t = 351.3 s) on the R and L hub carriers. The baler's rear door is reported in Figure 11. Once the baler's rear door reached the fully opened position, the load on the hub carriers temporarily decreased, triggering a damped oscillation. Figure 12g reports the effect of starting the PTO (at t = 55 s) on the R hub carrier signal. The rotating parts of the baler caused small-amplitude and high-frequency loads on the hub carriers. Figure 10: Satellite image of the fields where the load acquisitions took place; the routes followed by the baler during the different acquisitions are reported. Using the dedicated fast Fourier transform (FFT) routine available in the commercial software IMC FAMOS(r) Enterprise 2023, the signals reported in Figure 12f, g are presented in the frequency domain in Figures 13a and 13b, respectively. Figure 13b highlights a peak at around 7.3 Hz, corresponding to the PTO rotation frequency. Another peak at around 5.5 Hz is present and is also present in Figure 13a, suggesting that it might correspond to the baler's natural frequency. A peak at the same frequency was observed also during the _road transportation_ acquisitions while running on asphalt at constant speed.