## 2 Materials and Methods
### Key Component Design  
#### 2.2.1 Touch to Line Mechanism Design  
The touching alignment mechanism consists of a non-contact angle sensor, a four-rod mechanism, a rotary shaft, a reset torsion spring, bearings, a touching rod, a limit sleeve and a fixed frame, as shown in Figure 3. As shown in Table 1, the actual needs of the touch alignment mechanism are taken into consideration when designing components and performance parameters for the 4 LZ-8 corn harvester.  
Figure 3: Touch to travel mechanism 3D modeling (1) Angle sensor (2) Four-rod mechanism (3) Rotation shaft (4) Reset torsion spring (5) Bearing (6) Adjustable fixed torsion spring fixing bolt (7) Touch rod fixing sleeve (8) Touch rod (9) Limit sleeve (10) Fixing frame.  
Figure 2: Working principle of automatic row alignment system for corn harvesters.  
The four-bar mechanism of the touching alignment mechanism is positioned coaxially with the crossbar of the alignment system when it is operating normally. It is the touching bar that rotates coaxially the four-bar mechanism when a corn stalk touches it; rain harvesters are guided by the deflection of the four-bar mechanism in order to steer the blade in the direction of the angle sensor; depending on the arrangement of the torsion springs, it can be assured that the touching mechanism will be reset in a timely manner following the removal of the touching bar from the stalk.  
Consequently, this study has devised a touch-type alignment mechanism using a high-precision angle sensor, which can accurately estimate the size of the offset by using the change law of the output value of the angle sensor [28,29], and the structure schematic is shown in Figure 4.  
A grain harvester that starts its operation is successful if the corn stalk is placed between two touching bars and no contact is established between the corn stalk and the touching bar. The angle sensor's output does not change in this situation, and the harvester angle does not need to be changed as shown in Figure 5a. If the corn stalk collides with one of the touch bars, i.e., the corn stalk is not in the reference row, the touch bar drives the angle sensor to shift as demonstrated in Figure 5b; the harvester continues to advance until the touch bar and corn stalk are about to separate. As shown in Figure 5c, the angle output of the angle sensor achieves the maximum value at this time, and set the deflection angle of the touching rod as \(\alpha\).  
\begin{table}
\begin{tabular}{c c c c} \hline
**Parts** & **Model** & **Parameters** & **Value** \\ \hline Angle sensors & KALAMOYI/P3022-V-CW180 & Output voltage & (0–5) v / (0–180)\({}^{\circ}\) \\ Touch bar retaining sleeve & Q235 steel & 0.817 & 40 mm \\ Resetting Torsion Springs & Carbon spring steel & Wire diameter & 3 mm/28 mm/6 mm \\ Touch Bar & Aluminum round tube & Length & 150 mm /200 mm/ \\  & & & 180 mm \\ \hline \end{tabular}
\end{table}
Table 1: The main parameters of the touch-to-travel mechanism.  
Figure 4: Sketch of automatic row alignment system for corn harvesters (1) Touch pair of line mechanism (2) Cutting table.  
The working principle of the touch-to-travel mechanism is shown in Figure 6, where the angle between the first and middle sections of the touch-to-travel mechanism is 120\({}^{\circ}\), and the offset can be calculated according to the schematic diagram as,  
\[\Delta L=L_{0}\cos 30^{\circ}-L_{0}\cos(30^{\circ}+\alpha) \tag{1}\]  
where, \(L_{0}\): length of the initial section of the touch bar, mm; \(L_{1}\): length of the middle section of the touch bar, mm; \(\alpha\): offset angle of the touch bar, \(\circ\); \(L_{2}\): length of the last section of the touch bar, mm.  
Figure 5: Schematic diagram of the action of the touch-to-travel mechanism (1) Touch lever (2) Corn stalk (3) Touch sensor holder. (**a**) Automatic row close; (**b**) Automatic row start; (**c**) Auto row ending.  
Figure 6: Automatic alignment system angle sensor offset calculation schematic (1) Corn stalk (2) Touching the middle section of the rod.