# Research on Global Navigation Operations for Rotary Burying of Stubbles Based on Machine Vision
## 2 Materials and Methods  
To ensure the quality of straw rotary burying and returning to the field operations, the straw rotary burying and returning machine set was used in this study, which is powered by a wheeled tractor (Dongfanghong LX954, China Yituo (Luoyang, China)) and is equipped with a V-shaped dual-purpose rotary filler for stubble burying developed by the project team. Long-term field applications have shown that this machine set is suitable for straw rotary burying operations in diverse rice cultivation areas with flexible and rigid straw in the middle and lower reaches of the Yangtze River, demonstrating strong versatility. The specific technical parameter indicators are shown in Table 1[30]. To achieve precise control over the operation unit, the navigation and operation system designed by our team consists mainly of a GNSS receiving antenna, GNSS mobile station, onboard computer, steering controller, steering angle sensor, electronic proportional hydraulic steering valve, industrial camera, rotary tiller for stubble burying, electronic proportional hydraulic lifting valve, lifting angle sensor, and lifting controller, as depicted in Figure 1.  
The structure of the auxiliary navigation control system for rotary burying and returning to the field operations is shown in Figure 2, which is mainly composed of four parts: Dongfanghong LX954 power equipment, sensor, control system, and steering system. The auxiliary navigation control system obtains the position status information of the operating unit and field environment information through the sensors, and the control system controls the steering system to realize the auxiliary navigation operation according to the incoming information from the sensors. \begin{table}
\begin{tabular}{c c} \hline \hline
**Parameters** & **Values** \\ \hline Working width/mm & 2300 \\ Deep blowing/mm & 120–180 \\ Overall quality/kg & 4820 \\ Calibrated power/kW & 70 \\ Power output shaft speed/r\(\cdot\)min\({}^{-1}\) & 540/720 (adjustable) \\ Power output shaft power/kW & 56.52 \\ Overall dimensions/(mm \(\times\) mm \(\times\) mm) & 5660 \(\times\) 2500 \(\times\) 2900 \\ Front wheelbase/mm & 1760–2000 (adjustable) \\ Rear wheelbase/mm & 1632–2132 (adjustable) \\ Minimum ground clearance/mm & 430 \\ Minimum turning circle radius/m & 5.6 \(\pm\) 0.3 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Main technical parameters of the straw rotary burying and returning unit. Figure 1: Composition of auxiliary navigation and tillage depth control systems for straw rotary burying and returning: 1. GNSS receiving antenna; 2. GNSS mobile station; 3. onboard computer; 4. steering controller; 5. steering angle sensor; 6. electronic proportional hydraulic steering valve; 7. industrial camera; 8. rotary tiller for stubble burying; 9. electronic proportional hydraulic lifting valve; 10. lifting angle sensor; 11. lifting controller. The hardware used for the sensors includes an industrial camera (VCHY300 color industrial camera, Micro Valley Technology, Luoyang, China), a steering angle sensor (ANG1 series non-contact angle sensor, range \(-45^{\circ}\)-\(45^{\circ}\), accuracy 0.05%, resolution 0.025%, Luoyang Mita Electric Control Technology, Wuhan, China), and an RTK-GNSS positioning system (K726-OEM type). Other parameters include a dual-antenna satellite positioning and orientation system, plane accuracy of 1 cm, elevation accuracy of 2 cm, and a heading angle accuracy better than 0.2\({}^{\circ}\)/R (R is the length of dual-antenna baseline, m), (Shanghai Sinan Satellite Navigation Technology Co., Shanghai, China).