Design of Fractional-Order PID for Stabilized Sight System via Internal Model Control Approach

This paper aims at the problem of accuracy reduction of stabilized sight system caused by uncertain factors and disturbances under complex working conditions. Here, a fractional-order PID (FOPID) controller design method based on internal model control (IMC) approach is proposed for stabilized sight system. First, the IMC-PID is constructed by IMC approach, and then the fractional order is added to its differential and integral terms to obtain the FOPID. The traditional FOPID requires five parameters for tuned, while the proposed FOPID has only three tuning parameters, which can be obtained through the CRONE control technology. The optimal rational approximation algorithm (ORAA) with a high degree of fit is used to approximate the fractional-order calculus operator. Matlab simulation experiments show that the proposed controller outperforms other controllers and can obtain good robustness, disturbance rejection and tracking performance.