To be allowed to sell Z-suspended vehicles with dipped beam Xenon or LED lighting, Scania have to develop automatic headlight level control. This master’s thesis aims to be the foundation to that development. The thesis consists of several parts; a market analysis of how competitors to Scania and the general vehicle industry solve this problem; several available principles for detecting the amount of control needed; the construction of a test station for sensors, a control unit and components connected controlled by the control unit; a further theoretical and practical development of one principle – one rotational sensor connected between the chassis and the back drive axis; a state flow model programmed in Simulink that produces the control signal for the headlight leveling from the sensor input. Lastly the thesis gives some recommendations to the further development and implementation of automatic headlight level control on Scania vehicles.

Flotation is one part of LKAB's refining process where minerals are separated from iron ore in cascade connected tanks. A good level control in the flotation tanks is vital to get a high recovery of the iron. Nominal and robust performance of different level controllers are compared in the study. Robust performance is analyzed for uncertainties in valve contants and for hysteresis in the valves. The results show that LQG control give better nominal performance than PI control. The robust performance is worse for the LQG controller than the PI controller for modelled uncertainties in valve contants. The robustness analysis shows also that LQG control is less sensitive to hysteresis in the valves compared to PI control. Thus, type of uncertainty affects different control strategies differently. / Flotation är en del av LKAB:s förädlingsprocess där mineraler separeras från järnmalmen i seriekopplade tankar. En god nivåhållning i flotationstankarna är viktigt för att erhålla ett högt järnutbyte. Olika reglerstrategiers nominella och robusta prestanda jämförs i studien. Robust prestanda undersöks vid osäkerhet i ventilkonstanter och hysteres i ventiler. Resultaten visar att LQG-reglering ger bättre nominell prestanda än PI-reglering. Den robusta prestandan vid osäkerhet i ventilkonstanter är sämre för LQG-reglering jämfört med PI-reglering. Robusthetsanalysen visar även att LQG-regulatorn är mindre känslig för hysteres i ventiler än PI-regulatorn. Typen av osäkerhet inverkar sålunda olika på olika reglerstrategier.