Computer control of a double inverted pendulum

A double inverted pendulum is successfully stabilized at the upright position by using a computer control. The control system is designed based on the state space approach by using a computer aided design program named CADOS developed for this purpose. CADOS was used not only for the analysis and design, but also for the simulation to evaluate the designed system. The controller designed consists of the state variable feedback and the observer. The state variable feedback is determined based on either pol-locations or as the optimal control for the quadratic criterion function. As the observer, the minimal order state observer or a linear functional observer is employed, and it is theoretically proved that the linear functional observer for a multiple inverted pendulum can always be realized by the first order. The designed controller is implemented in the mini-computer used for CADOS and could work satisfactorily. The controller using a linear functional observer requires less computation time and controls the system in more stable way.