Reliable control using equivalent transfer function for position servo system in current loop failure

A reliable control method is proposed for multiple loop control systems. If a feedback loop fails (e.g., as a result of a sensor breakdown), the control system develops an unstable fluctuation. To cope with this problem, the proposed method uses an equivalent transfer function (ETF) for active redundancy compensation after the loop failure. The ETF does not change the transfer function of the entire system before and after the loop failure. In this study, the characteristics of a reliable control system that uses an ETF are examined using an experimental method. A position servo system with a DC servo motor is used in the experiment. The ETF is used for motor control after current feedback loop failure.