Fuzzy logic control of active suspension for maintaining a minimum transverse and longitudinal slope of a field working machine

This master thesis deals with the problem of maintaining the minimum transverse and longitudinal slope of a field working machine by the usage of fuzzy logic active suspension. The primary aim of the thesis is to determine whether the active suspension is efficient in maintaining the minimum slopes while moving around very uneven terrain and to what extent. For this purpose we used the Simulink programming environment to build a model of the whole vehicle with passive suspension. This was then expanded with fuzzy controllers for maintaining transverse and longitudinal slopes. In this way we obtained a model of the entire vehicle with active suspension. The fuzzy control algorithm has three main objectives: maintenance of transverse and longitudinal slopes in the desired range, maintenance of actuator reaches within the working area and maintenance of the best possible working range of all actuators or in other words the reduction of absolute cylinder reaches. The correct functioning of the control algorithm was first tested on an ideal terrain, where the first section causes only the lateral slope of the vehicle, while the next section causes only the longitudinal slope. Since such individual anomalies do not reflect the actual situation of the terrain on which the actual machine will be used, we came up with an algorithm for generating a variety of very uneven terrains that are suitable for testing the robustness of the control algorithm. A comparison of the proposed active and passive suspension was made on three different terrains and with two different vehicle speeds (1 m/s and 4 m/s)