Hydraulic closed loop control

Abstract: The purpose of the thesis work is to investigate methods for closed loop control of hydraulic pressure in transmissions to make them be more precise. This is desirable since it decreases the fuel consumption as well as emissions, and improves the driving performance. To be able to study the behaviour of the transmission, a Simulink model is designed with the parts relevant to the problem, and from this a linear model is obtained. Three different controllers are designed and implemented in the Simulink model, to compare and analyze different solutions. The controllers implemented are a PI controller, a PID controller and a LQR controller. The results from the simulation with the different controllers show step responses to be able to evaluate their individual performance. The results show that all of the controllers meet the requirements for a step response under better conditions, but under worse ones the LQR controller performs best of the three. The LQR controller is therefore the most suitable of the three controllers for this particular problem.

Examiner: Cristian Rojas