Modelling and controller design for a blade operation of a motor grader

The subject of this study is the creation of a system that will provide automatic height control of the motor grader blade mechanism. It is aimed to increase both working precision and working efficiency with automatic height control. The height of the blade from the ground was determined by reference to the right and left cutting edges. Two hydraulic cylinders, right and left, provide the up and down movement of the blade. The relationship between the position of the hydraulic cylinders and the cutting edges of the blade was determined using polynomial surface fitting method. The behavior of the hydraulic system was examined with the test records taken on the real machine and the transfer functions were obtained by using the system identification method. The effect of the flow generated by the hydraulic pump (at a certain RPM value) through the electro-hydraulic valve and the elapsed time were investigated. Forward and feedback control methods were used in Matlab/Simulink model created for cylinder movements. Simulation outputs and real test records were examined. Using the functions obtained by the polynomial surface fitting method, the positions of the right and left edges in three axes were calculated against a height input. The terrain was designed in the simulation environment and the behavior of the model was observed at diffirent altitudes. Cylinder speed coefficients were obtained for different RPM values to be examined in the future studies, and the dynamic model of the vehicle was examined for possible disturbances from the road and the effect on the blade edges of the blade was observed.