Parameter Estimation of Dynamic Equations and Sliding Mode Control of a Two-axis Gimbal

A major problem in design of a controller is that some of the parameters of the governing dynamic equation might be unknown. The purpose of the present study is to provide a method for identification of the unknown parameters of the dynamic equations of the two-axis gimbal system and then applying a suitable controller to it. Among the uncertain parameters which may exist in the dynamic equations of a two-axis gimbal, the components of the inertia matrix, the coriolis matrix, and the friction matrix can be named. In this research, in order to estimate the unknown parameters of the system, the Gauss-Newton method which is a gradient-based inverse technique is used. Regarding the severe sensitivity of inverse problems to measurement errors, by using a proper smoothing technique, this undesirable effect is reduced. In the present work, for the first time, an accurate technique for computation of sensitivity coefficients of the dynamic equations of the gimbal is presented. After identification of the unknown parameters, the control of the two-axis gimbal is also performed by sliding mode control. The applied moments are designed by sliding mode control to stabilize the line of sight. Also, proof of stability is presented for the sliding mode control. Simulation of the laboratory tests in the identification section and also control results are obtained by modeling of the system in MATLAB.