Research On Motion Control Of The Underacturated TORA System

In our life, most of the control systems are nonlinear, so the control problemsof the nonlinear system have become hot spots in recent years. Due to the lack ofinput, the control of underactuated systems is very challenging. TORA system is afourth order nonlinear underactuated benchmark system, which was originallyproposed as simplified model of a dual-spin spacecraft to investigate the resonancecapture phenomenon. TORA is an ideal platform to study control theory and theresearch on the control of TORA has deep theoretical value.TORA (Translational oscillators with rotating actuator) is a typicalunderactuated mechanical system with two degrees of freedom. Firstly, based onLagrange equations, this paper establishes the dynamic model of TORA with theball rotating in the horizontal plane. Simulation results demonstrate the feasibilityof the dynamic model. In order to facilitate the design of the controller, a closed-loop global change of coordinates system is used to transform the dynamic model ofTORA into a strict feedback cascade nonlinear system after partial feedbacklinearization. Then the balance points, the controllability, the observability of thesystem are analyzed, which deepen the understanding of this system and lay thefoundations for the design of the controller.This paper presents a new stability control strategy based on backsteppingsliding mode. Each converted state variable is regarded as a subsystem. Then theLyapunov functions and the virtual control inputs are designed for each subsystem.The sliding mode control is employed to compensate the uncertain part of the finalactual amount of control. When the system is in the disturbance or the parametersare changed, the controller can make the TORA system back to to the equilibriumpoint from the initial state quickly. Simulation results demonstrate the feasibility ofthe presented controller. and present the system has better robustness.By adopting the mechanical software Solidworks, a TORA mechanicalnoumenon is designed. And the electrical platform and the mechanical platform areset up. This paper introduces the selection of the motor and its driver, encoder,linear guide and the circuit of the controller.Finally, experimental results show the effectiveness of the control method.