Integral Design For North Finder Controller Based On Offset Current

North finder is a kind of autonomous azimuth indicator. It employs the inertial theory and can find true north rapidly and accurately under all weather conditions It has been widely used in both military and civil fields. In this paper, we study the magnetic suspended gyrocompass north finder, that is, magnetic bearings are used to suspend the gimbal axis of the single degree of freedom gyrocompass with zero friction in order to get high degree of north-finding accuracy and increase the orientation speed.After introducing the background of magnetic floating bearings as well as the history and current state of magnetic floating technique ,This dissertation introduces the north-finding system constitutes and working principle of the magnetic floating table, and design process of its hardware circuit. Based on the analysis on the working principle and structure of magnetic floating bearing, by linearization at the equilibrium point, we get the one-dimensional electromagnetic transfer function and the state equation of the magnetic floating systems. Consequently establishes its mathematical model.The "integral" design is a method that we use to design the control law of the system and the hardware parameters (such as the length of the swing stem, initial setting of a slide block etc.) of the system model at the same time. The method considers the adjustable hardware parameter as a variable in the controller design. Based on the calculus of variation, we can obtain the optimal control law and the optimal hardware parameter at the same time based on the calculus of variation. An integrated design approach, which is based on the variation calculus theory, is proposed for optimal control, considering the quadratic performance index as the performance index. The method is applied to the north finder system design and its hardware parameter optimization. Simulation and experimental results demonstrate the effect of the proposed design approach.