A Novel Disturbance Estimation and Compensation Approach Applied to Three-Axis Inertially Stabilized Platform

Three-axis inertially stabilized platform (ISP) is a key technology in airborne remote sensing system, which is used to support an optical imaging sensor and hold the line of sight (LOS) of the sensor vertical to the earth, whose accuracy has a great effect on the remote sensing image quality. Presently the control method for ISP is mostly focused on conventional PID control, which has disadvantages of low accuracy, bad disturbance rejection capacity. A novel disturbance observer(DOB) is devised in this paper aiming to attenuate the influence of the disturbing torque and enhance the accuracy for the ISP, in which the disturbing torque is calculated according to the gimbal angular acceleration estimated from the angular rate information and the motor current, then the equivalent compensation current is calculated and added into the input of the current loop to compensate disturbances. The proposed approach has the advantage of high accuracy, strong disturbance rejection capacity and strong practicality in engineering. Simulations and vehicle experiments prove that, compared to conventional PID and DOB based on PID, the proposed approach can enhance the accuracy of the ISP significantly.