## Methods
### Design of Unmanned Agricultural Machine Operation under Improved Fuzzy Adaptive Algorithm
#### 3.1.2 Design of Automatic Driving Operation Control System of Agricultural Machine
Considering the fact that the environment faced by farming machines during operation is mostly open farmland, this study collects the vehicle's coordinates, speed, and other information with differential global positioning. In order to ensure the smoothness of signal reception, the antenna is mounted on the roof of the vehicle and then the differential positioning coordinates output from the mobile station can be obtained with the help of antenna point coordinates [30; 31]. When the operating environment of the agricultural machine is not flat, the positioning coordinates output by the system will have a large error with the actual coordinate position, so the vehicle position coordinates need to be corrected, and its calculation formula is shown in Equation (9). \[\left\{ \begin{array}{l}x_{m}=x_{m}t+H\sin\varphi\cos\theta-H\sin\psi\sin \theta\\ y_{m}=y_{m}t+H\sin\varphi\cos\theta-H\sin\psi\sin\theta\end{array} \right. \tag{9}\]  
In Equation (9), \((x_{m},y_{m})\) is the coordinates of the corrected point, \((x_{m}t,y_{m}t)\) is the coordinate result of the differential positioning measurement, \(H\) is the antenna mounting height, \(\varphi\) is the lateral inclination angle, \(\psi\) is the pitch angle, and \(\psi\) is the vehicle heading angle. The output positioning results can be processed with the help of the equation to reduce the tilt error when different tilt angles are considered. The main controller drives the steering wheel to rotate when calculating the desired turning angle of the farming machine, and in the kinematic modelling, the conversion of the turning angle is mostly carried out with a two-wheeled vehicle. Equation (10) is the equivalent converted expression for the turning angle of the front wheels. \[\delta=\frac{\delta_{L}+\delta_{R}}{2} \tag{10}\]  
In Equation (10), \(\delta\) is the virtual front wheel angle of the model, \(\delta_{L}\) is the left front wheel, and \(\delta_{R}\) is the right front wheel. The angle of rotation of the differential lever position can be measured with the help of the angle sensor so as to effectively obtain the feedback information of the front wheel steering of the vehicle. In order to facilitate the realisation of automatic steering of the vehicle, this study provides a motor power source for the steering wheel and the wheel turning angle joint main controller in the controller cycle by changing the message situation to achieve speed control. The throttle pedal in the electric actuator contracts and extends during the movement, so this study focuses on the controller's conversion module to achieve, based on the feedback actuator information, the formation of closed-loop control of the throttle. The speed of agricultural machinery is adjusted by the throttle position, and the more the throttle pedal is pressed, the faster the vehicle's speed. To achieve automatic driving of agricultural machinery, a speed regulation and control system has been researched and designed. In this system, the electric push rod controls the depression of the accelerator pedal through a steel cable connected to the accelerator pedal. When the electric push rod contracts, the accelerator pedal is pressed down; when extended, the accelerator pedal returns upward due to the action of the spring. The push rod is equipped with a sliding rheostat inside, and the slider changes with the movement of the push rod. Therefore, the voltage of the sliding rheostat can be measured through the AD conversion module of the controller to obtain the position information of the push rod, which is used for closed-loop control of the throttle position. The speed controller receives throttle position instructions from the main controller, uses the push rod position feedback read by the AD module, and adjusts the push rod to the desired position through PID control algorithm to achieve automatic speed adjustment. The actual position of the throttle will also be transmitted back to the main controller through the CAN bus.