Robust control design for an electrohydraulic wheel loader system with a human-in-the-loop assessment in a virtual environment

Abstract

<p>This dissertation is about control and real time virtual reality simulation of a type of off highway machine known as a wheel loader. Wheel loaders are hydraulically operated machines which are used for material handling and excavation for construction, industrial, and agricultural purposes. The wheel loader has a linkage attached to the front of the machine used for manipulating a bucket or other work tool. In this dissertation, work is aimed at designing PI, LQG, Hinfinity, and nonlinear controllers for an electro-hydraulic front loader and comparing these designs for possible implementation on a real-life machine. The controller designs are shown to have various degrees of stability robustness and nominal performance. A nonlinear control design technique know as feedback linearization is used in conjunction with a linear Hinfinity control design to yield a control system with superior robustness properties. A virtual reality simulation is developed and used to implement a human-in-the loop test for evaluating the automatic control system.</p>