Development of Electro-Hydraulic Hitch Control System through Lower Link Draft Sensing of a Tractor

Abstract

Three-point linkage plays an important role in controlling tillage implements with the hydraulic system of the tractor which includes draft control too. With increase in the usage of electronics and instrumentation in agriculture, the need was to upgrade the present mechanical hydraulic system of the tractor with electrohydraulic hitch control system (EHH) for better performance. The selection of draft sensing media was at the lower links for better sensitivity. The EHH control system through lower link draft sensing was developed using draft sensors, a control panel for user input and a controller with usage of MATLAB Simulink as an application software. Developed system was tested infield using duck foot cultivator and instrumentation like angle sensor, data acquisition and data logger were used for data capturing. The test results showed that for a change in set draft of 1500N, the system response time and change in depth of operation were 1.3s and 5 cm respectively. Whereas, for change in set draft of 500N the system response time was 0.9 s and change in depth of operation was 4 cm. For the conducted test, the variation in depth of operation was limiting to ±3.1 cm. The results concluded a direct relationship of change in set draft with system response time and change in operating depth. This study provides an overview of developing an EHH system through lower link draft sensing, as well as details of system architecture, control algorithm, MATLAB Simulink code, components used and the methodology and instrumentation technique for testing the same.