Multi-degree-of-freedom Internal Model Control for Optoelectronic Stabilized Platform Based on Sliding Mode Friction Compensation

A multi-degree-of-freedom (multi-DOF) control method is proposed in this paper for the optoelectronic platform affected by internal and external disturbances. First, internal model control (IMC) is used to track the desired signal, and combined with radial basis function neural network (RBFNN)-based sliding mode control (SMC) to compensate for friction torque and weaken model uncertainty. Then, linear active disturbance rejection control (LADRC) is introduced to observe and compensate for sensor noise as well as external unknown disturbances, so that the optoelectronic platform can operate under complex working conditions. The input and disturbance sensitivity functions in a pure feedback control system cannot reach their minimum values in the same frequency band, so there is an inherent contradiction between their tracking and disturbance rejection performance. Combining IMC-SMC-RBFNN with LADRC as a multi-DOF controller can guarantee both tracking and disturbance rejection performance. Lyapunov theory and Barbalat lemma prove the asymptotic stability of the control system. Simulations show that the multi-DOF controller has a good control effect under the mixed disturbances such as parameter perturbation, friction torque and sensor noise, which has reference value for the development of practical optoelectronic platform systems.