This diploma thesis deals with the control design of mobile valves. The investigations in this work are concerned with an electro-hydraulically actuated spool-type directional control valve. The industry for mobile machinery shows a growing demand for such valves with an improved dynamical performance to meet the high requirements of modern control algorithms. Therefore, this thesis focuses on developing an improved concept to control the spool of a mobile valve. The need for a sensor to capture the spool's position shall be avoided due to cost and constructive considerations. First, a mathematical model of the mobile valve is developed. For this purpose, the basic laws of mechanics and fluid dynamics are applied. The parameters of the derived model are adapted to fit a real valve. The resulting model is then validated by comparing simulation results with dynamic measurements of the mobile valve. In the next step, the model is simplified to reduce its complexity. This reduced model is further used to develop a flatness-based feed-forward control algorithm. For showing that the proposed approach works, several simulation studies are performed. In this work, the limitations of the actuating variables, the time-discrete implementation as well as the usage of PWM concepts and dither signals for controlling the valve-s voltage inputs are analyzed. Moreover, jet forces and variations of parameter values are investigated in more detail. The results show that the flatness-based feed-forward control brings along a significant improvement of the valve's dynamical behavior without the need of a spool position sensor.