Mathematical Model of the APC Guarani equipped with 30 mm Turret and Magnetorheological Dampers 2021-36-0096

The combat cars design seeks to balance mobility and fire power, in order to enable the vehicle to shot with accuracy, although running on rough roads. The gun follows the chassis movement, as well as the cannon shots produce forces that change the car dynamics. Because of that, the suspension system of military vehicles has not only to reduce the oscillations caused by the terrain but also has to damper the gun recoil after each shot, preventing misalignment between the tube and the target. Therefore, the present study goal is to evaluate how semiactive dampers could reduce the chassis pitch motion of the Armored Personnel Carrier 6x6 Guarani, from the Brazilian Army, equipped with magnetorheological dampers, while running on a rough road and shooting with the 30 mm cannon at the same time. The proposed model uses the power flow concept to establish the kinematics relationships of the vehicle subsystems, and thus determinate the causality relationships among the components. It is considered the MacPherson setup and the hypothesis that the suspension springs are non-linear. Besides that, the magnetorheological damper is controlled by a system that uses fuzzy logic. The computational implementation was developed in MATLAB software Simulink in order to reproduce the three-axle vehicle model using block diagram. Finally, the results shows that the semi-active suspension helps to reduce the chassis response against obstacles and forces due the cannon shots, besides to improve the ride comfort.