Design Of Stabilization And Robust Controller For Underactuated TORA System

Translational oscillations with a rotational actuator system(TORA)is a mechanical system that is designed to study the self-oscillation problem of a dual-spin aerial vehicle.This system has two degrees of freedom and one control input.It is a typical underactuated nonlinear mechanical system.This mechanical system has strong coupling between the state variables.The system itself has a non-holonomic constraint.This makes the motion control problem be difficult to solve.In this paper,the stabilization control and robust control problems for the underactuated TORA system are studied.And several effective motion control algorithms are developed.The motion control objectives of TORA are better achieved by the presented control methods.Two stabilization control methods called the backstepping method and the cascade linearization method are designed.First,the backstepping method constructs a state transformation,which transforms the original system into a nonlinear system with a simple structure.Then a virtual control input is designed for the first subsystem of the transformed system and the first Lyapunov function is designed.Then the second and third Lyapunov functions are designed for the system using the backstepping idea.The stabilization controller of the system is obtained by applying Lyapunov stabilization theory.On the basis of the backstepping method,the cascade linearization method utilizes the virtual control input of the subsystem to construct a state transformation for the TORA system.The state transformation further transforms the original system into a cascade system.Afterthat,a simple PD stabilization controller is designed for the cascade system.It ensures the stabilization control objective of the cascade system to be achieved.To further enhance the practicality of the control algorithm and eliminate the influence of external disturbances on the stabilization control performance of the TORA system,a robust sliding mode control method is presented based on a disturbance observer.First,a disturbance observer is designed by using the dynamic characteristics of the system.It can quickly estimate both matched and mismatched external unknown disturbances.Then,a robust controller is designed using the estimated disturbances and a fixed-time sliding mode control method.The robust stabilization control objective of the TORA is achieved by the developed robust controller.