Disturbance Rejection of the Galvano Scanner System using Sensorless Acceleration Control and Disturbance Torque Compensation

This paper presents a controller design of a 2-DOF inertial stabilization system. The line of sight (LOS) stabilization and sliding mode control are used for compensation of the nonlinearities and disturbances from the environment. And it proposes an acceleration feedforward for solving the unbalance torque. The disturbance torque from unbalance mass of gimbal structure is unavoidable under the effect of the vibration of the aerial vehicle. Since the acceleration of the aerial carrier can be measured, a feedforward disturbance rejection can be generated to compensate the disturbance torque. The experimental results demonstrate the performance of the controller, the disturbance is in the form of shaking the base's gimbal. The controller can track the reference input in the elevation axis and reject the base rate disturbance while maintaining its LOS direction. The error of pitch angle less than 0.02 rad, so the camera can track a specified point on an object.

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Combined Feedback and Feedforward Control for an Inertial Stabilization System

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.415.101 ◽

2013 ◽

Vol 415 ◽

pp. 101-108

Author(s):

Kritsanun Malithong ◽

Viboon Sangveraphunsiri

Keyword(s):

Disturbance Rejection ◽

Sliding Mode ◽

Feedforward Control ◽

Design Procedure ◽

Stabilization System ◽

Model Uncertainties ◽

Configuration Change ◽

Aerial Vehicle ◽

The Impact ◽

Disturbance Torque

This paper presents environmental disturbance rejection in a 2-DOF inertial stabilization system by a combination of feedback and feedforward control. For feedback control, sliding mode control and the line of sight (LOS) stabilization are used for compensation of the nonlinearities, model uncertainties, friction and disturbances from outside environment. Although our mechanisms are carefully designed with statically balance, the center of the gravity will changed due to the configuration change during moving of the gimbal relative to an aerial vehicle. The disturbance torque from unbalance mass and gimbal geometry is unavoidable under the effect of the vibration of the aerial vehicle, which will lead to degrade the systems accuracy. Since the acceleration of the aerial carrier, due to the disturbance torque, can be measured, a feedforward disturbance rejection can be generated to compensate the disturbance torque. The experimental results confirm the validity of the control design procedure for the two-axis gimbaled stabilization system. The proposed controller is capable enough to overcome the disturbances and the impact of LOS disturbances on the tracking performance.

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The disturbance rejection of magnetically suspended inertially stabilized platform

Transactions of the Institute of Measurement and Control ◽

10.1177/0142331216661623 ◽

2016 ◽

Vol 40 (2) ◽

pp. 565-577 ◽

Cited By ~ 2

Author(s):

Qingyuan Guo ◽

Gang Liu ◽

Biao Xiang ◽

Hu Liu ◽

Tong Wen

Keyword(s):

Disturbance Rejection ◽

Disturbance Observer ◽

Angular Displacement ◽

External Disturbance ◽

Magnetic Bearing ◽

Feedback Compensation ◽

The Cross ◽

Stabilized Platform ◽

Inertially Stabilized Platform ◽

Disturbance Torque

In a magnetically suspended inertially stabilized platform, the yaw gimbal is suspended by the magnetic bearing, which can effectively isolate the external vibrations and disturbances. However, coupling torques and disturbance torques among gimbals still exist. Therefore, based on the cross feedback compensation, the output angles of gimbals are introduced as feedback variables, and the inverse coordinate transformation matrix is designed to compensate for the coupling torques. Furthermore, a disturbance observer is applied to inhibit the disturbance torque and simulations indicate that the disturbance observer can accurately estimate the disturbance torque. Consequently, the experimental results demonstrate that the cross feedback compensation can inhabit the coupling torques, and the disturbance observer greatly suppresses the external disturbance torques and improves the angular displacement precision of gimbals.

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