Modelling of main battle tank as hull and weapon system  APG road profile is used as disturbance effect for the main battle tank  Designing LQR controller for active suspension system and decrease vertical oscillations in weapon system a) b) Figure A. APG road profile a) bump dimensions b) distance between bumps Purpose: The aim of the study is modelling of main battle tank and to decrease vertical oscillations of the weapon system arising from APG (Aberdeen Proven Ground) road profile by controlling active suspension system via LQR controller Theory and Methods: The hull of main battle tank is modelled as the body consisting of sprung mass and unsprung masses. Also weapon system is included to the model by considering azimuth dynamics and elevation dynamics. The main battle tank is excited by APG road profile which is used for elevation dynamics analyses and the active suspension system is controlled by LQR controller. Results: It is concluded that obtained controller forces are applicable and pitch motion, roll motion and bounce motion od sprung mass and deviation of the barrel (breech section and muzzle section) arising from disturbance affect are avoided. It is succeeded to provide the lock on of barrel independent from main battle tank motion Conclusion: In this study, it is succeeded that the vertical oscillations of the weapon system has been controlled by LQR controller. Also, it is possible to examine the horizontal oscillations of weapon system by designing different controller for the future studies.