Hydraulic Transmission of Agricultural Machine Appropriate for Treating Extreme Steep Farmland Terrains

The paper presents the conception and design of the hydraulic transmission for agricultural machine appropriate for the treatment of extreme steep farmland. The small IC diesel engine powers a hydraulic pump that feeds the drive system as well as all working accessories. Hydraulic transmission systems perfectly satisfy the basic condition about the lowest weight but initially, they require totally new management. This paper outlines a simple but effective management system consisting of basic valves, electric sensors, and switches, which fits perfectly this specialized machine. The management enables the use of the potential energy for powering the accessories. When climbing up and downhill, the power is automatically distributed to the driving wheels or a winch, depending on the situation on the terrain. Significant working situations of the machine are predicted and analyzed. The appropriate function diagrams, hydraulic schemas and analytical calculations are presented. To raise the efficiency of the machine the close and the open hydraulic circuits are treated and analyzed. The machine is prototyped and partially tested. The results confirmed a big fuel saving of about 30 percent as predicted

Development of Electrohydraulic Steering Control System for Tractor Automatic Navigation

The most of tractors employed in agriculture are equipped with an electrohydraulic actuator to implement steering control to realize automatic navigation. Electrohydraulic steering system plays an important role in realizing accurate steering control for an automatic navigation tractor because of its complicated characteristics. The objective of this paper is to develop an electrohydraulic steering control system used for automatically guided agricultural tractors. As for the identified electrohydraulic steering system model, a modified Smith control structure was discussed. Based on the structure, an improved design method for voltage servo controller and disturbance rejection controller was proposed to enhance the performance of the steering control subsystem. The effectiveness and the superiority of the proposed method were verified by simulation under Matlab. Simulation results demonstrated the efficiency of the proposed method by showing fast response, control accuracy, and robust performance for the steering control system