H_∞ Controller Design For The Ball And Beam System Based On RTW

Ball and Beam System is the important experimental apparatus in control laboratories. For its simple structure, easy operation and intuitive observed effect of control, it is usually used to implement the existing control theories and methods, or verify the new theories and new control laws.Research object of this paper is the ball and beam apparatus of the Amira company, which can only implement several fixed control algorithms, in order to apply other control algorithms, it is reformed from the hardware point of view. Specific reform programmes of hardware are as follows:the signals of position for the ball and angle for the beam can be got from the original equipment, then the processed signals are sent to Matlab, after that, the signals which processed by the computer are sent to the servo driver to drive the servo motor, so as to achieve the purpose of adjusting the position for the ball.RTW(Real-Time Workshop) is the important real time control toolbox in Matlab. Using RTW completes the connection with the hardware, helping to improve the efficiency, reduce the development cycle and cost, combine the off-line simulation and real-time simulation to achieve the purpose of real time control.This paper also analyze the physical properties of the Ball and Beam System, use Newton Euler method to establish mathematical model, demonstrate the real time control system which is set up through state feedback on RTW experimental platform. First design a controller using the pole placement. Secondly, because computer is working at the discrete state, controller should be discretized, then set up real time control diagram in RTW and experiment.For the uncertainties and disturbance problems of the system, PS/T problem of H∞control is used to design the controller. First of all, the system is taken as single input multiple output, as the order of the designed H∞controller is high, which is difficult to achieve in the real system, it is reduced the order and discretized. The design of H∞controller is poor through real time control, further analysis indicate that that the H∞control of such systems is fragile. Secondly, the system is taken as single input multiple output, design results show that the system also lacks robustness.