Design On Three Dof Helicopter Controller Based On Sliding Mode Variable Structure

As the new industrial equipment is updated by the rapid development ofmodern society, helicopter in modern army and civilian industry has arisenattention among the engineers. The modern helicopter has been put forwardhigher requirements based on the reality, and the application of modern controlmethods to improve the control performance is widely employed due to thedevelopment of modern control theory and intelligent control. This paper isconcerned with the operation of specified helicopter path based on the3dofexperimental platform by combining sliding mode variable structure theory, poleassignment and switch control.The controlled object possesses several kinds of typical control problems,that is, high order, nonlinear and strong coupling. First of all, according to thecharacteristics of higher order and strong coupling of experiment platform, the7order experiment equipment is decoupled into3-order subsystem and4-ordersubsystem. Because of no coupling between the above two subsystems, therespective design is feasible. The control goal of pitch axis is to achieve positiontransformation swiftly in controlled time and stabilize the desired locationsubsystem. The global fast terminal sliding mode theory is adopted due torequirement of control time. This control algorithm solves the problem of controltime effectively. However, the initialization of the next motion is unable tocomplete because of the chattering characteristics caused by sliding modevariable structure control theory. Therefore, combined with pole assignment thatowns the stability of the steady state characteristics, the quickness controllabilityand the steady-state stability is realized effectively. The requirement of the stability in4order system is strict for the tworotation axis and lateral with strong coupling. Therefore, the backstepping slidingmode control algorithm is employed to completely achieve the stability of thecontrolled object by working backward under the stability of each order system.The simulation results verify the proposed methods feasibly and effectively.