Search

Agricultural production mode has been required for the intelligence and digitization of agricultural machinery. An automatic control system has gradually been the research interest of agricultural machinery in recent years. Among them, the navigation system with path tracking control can be expected to improve the accuracy of the agricultural machinery and the adaptability to the environment. Specifically, the accuracy and efficiency of agricultural production can be improved to realize more complex tasks, in order to avoid the wide crop coverage due to leakage testing. In this review, the types of agricultural machinery models were evaluated with/without the navigation path tracking control system. Three categories were also divided into the path-tracking control system with the kinematic or dynamic models, as well as the model-independent path-tracking control. Agricultural machinery was assumed as a rigid or single rigid body system for control with the kinematic model. The kinematic model of agricultural machinery included pure tracking, linear quadratic optimal control, and the model predictive control. By contrast, the dynamic model of agricultural machinery considered the influence of the mass and inertia of agricultural machinery on the control, particularly with the sliding mode variable structure control. The path-tracking control method unrelated to the agricultural machinery model was utilized to directly extract the features from the sensor data or visual information. The PID, and fuzzy control were the widely-used path-tracking control systems in the path-tracking control methods unrelated to the agricultural machinery model. The optimal path-tracking control of the agricultural machinery was achieved to correct the control system using the error between the sensor feedback and reference input values. The pros and cons of various control methods were clarified to evaluate the existing solutions. The current research progress was reviewed on the general and specific existing solutions to the navigation path tracking control of agricultural machinery. The applicability of various control methods was also evaluated for the current development status of agricultural machinery navigation products. The development prospects were then proposed for a navigation path tracking control of agricultural machinery. Some recommendations were as follows: (1) The current model was limited to describing the motion process of agricultural machinery. There was a high demand for the high precision model research of agricultural machinery; (2) In order to improve the adaptability and robustness of the control method, the research should be extended from the conventional to extreme and complex conditions; (3) The single control method was confined in the navigation path tracking control method of agricultural machinery. It can be expected to require the development trend of multi-method fusion control. This finding can provide strong references for subsequent research on the path-tracking control methods, particularly for the intelligent development of agricultural machinery in China. [ABSTRACT FROM AUTHOR]

With the vigorous development of China's shipbuilding industry in recent years, the research of underactuated unmanned submarines has gradually come into people's vision. Underactuated Unmanned Submarine is driven by propeller thrust and yaw moment. The input freedom of the control system of under-actuated unmanned submarine is very small. Because of its low altitude, which control is more difficult than general underactuated mechanical systems because it belongs to a special nonholonomic system. At the same time, the working conditions of submarines are very complicated. It will be disturbed by the marine environment such as living things and water flow. These velocities increase the difficulty of motion control and tracking of underactuated unmanned submarines. With the development of society, people's demand for underactuated unmanned submarines is increasing, which is mainly used in military and marine development. So, the study of underactuated unmanned submarines has important practical significance. Firstly, this paper designs the path tracking and control algorithm based on Lyapunov theory by establishing the model. Then, the correctness of the test results is verified by simulation. The final results show that the model and algorithm can effectively realize the tracking control of submarine and improve the tracking accuracy. [ABSTRACT FROM AUTHOR]

• Correcting the agricultural machine body posture using the attitude of implement. • Establishment of kinematics model of agricultural machinery implement. • The Model Predictive Control path tracking control method is designed. The annual rice planting area in China is approximately 30 million ha. With continuous reductions in the rural labour force and increasing production costs, it is urgent to develop unmanned technology for paddy field agricultural machinery to solve the problem of "who will farm the land". In paddy field environments with slippery mud and uneven hard underlying, side slip and slip of paddy farm machinery can easily occur. Due to the relative movement and attitude changes between paddy farm machinery and implements and the inconsistent driving track of the farm machinery and implements, it is difficult to track and control the path of unmanned paddy farm machinery. In view of the above problems, this paper takes the paddy field agricultural machinery body as the control object and the agricultural machinery pose as the observation quantity and establishes an agricultural machinery kinematics model based on agricultural machinery pose correction. Based on the model and model predictive control (MPC), the linear model, objective function and constraint function of paddy field agricultural machinery are designed, an MPC path tracking control method is established based on the pose of the agricultural machinery, and field experiments are conducted. The results show that the average root mean square error of the three-line straight-line path tracking is 0.043 m, the average absolute error is 0.033 m, and the effect is favourable. The MPC path tracking method based on the pose correction of agricultural machinery can effectively suppress abrupt lateral position deviations caused by the relative position and attitude changes of the machine, can improve the control accuracy, and can meet the control accuracy requirements of unmanned paddy field agricultural machinery operations. [ABSTRACT FROM AUTHOR]

Cui, Y.-N.; Dong, C., and Ren, J., 2019. Under actuated unmanned submarine path tracking method in complex environment. In: Gong, D.; Zhu, H., and Liu, R.(eds.), Selected Topics in Coastal Research: Engineering, Industry, Economy, and Sustainable Development. Journal of Coastal Research, Special Issue No. 94, pp. 149–152. Coconut Creek (Florida), ISSN 0749-0208. With the vigorous development of China's shipbuilding industry in recent years, the research of underactuated unmanned submarines has gradually come into people's vision. Underactuated Unmanned Submarine is driven by propeller thrust and yaw moment. The input freedom of the control system of under-actuated unmanned submarine is very small. Because of its low altitude, which control is more difficult than general underactuated mechanical systems because it belongs to a special nonholonomic system. At the same time, the working conditions of submarines are very complicated. It will be disturbed by the marine environment such as living things and water flow. These velocities increase the difficulty of motion control and tracking of underactuated unmanned submarines. With the development of society, people's demand for underactuated unmanned submarines is increasing, which is mainly used in military and marine development. So, the study of underactuated unmanned submarines has important practical significance. Firstly, this paper designs the path tracking and control algorithm based on Lyapunov theory by establishing the model. Then, the correctness of the test results is verified by simulation. The final results show that the model and algorithm can effectively realize the tracking control of submarine and improve the tracking accuracy. [ABSTRACT FROM AUTHOR]