Pole placement design with open-loop crossover frequency constraint for three-loop autopilot

In three-loop autopilot design, if the dynamics of those hardwares such as actuator, gyro, accelerometer, structural filters and so on is considered, the autopilot open-loop crossover frequency should be constrained in order that the system stability requirement can be satisfied. Based on the pole placement method, a nonlinear equation with open-loop crossover frequency constraint is found. Solving this equation, the non-dominate poles will be obtained. Finally, through an autopilot design example, it is demonstrated that this method is very convinced to be used in the three-loop autopilot engineering design.