Robust tracking control of MBT autoloaders with oscillatory chassis and compliant actuators

Ammunition autoloaders are widely utilized on main battle tanks to accomplish the tasks of transferring ammunitions from magazines to the gun breech. In practice, movements of autoloaders are significantly influenced by disturbances caused by chassis oscillations. This leads to autoloader–breech interaction and consequent poor control accuracy and low reliability. Compliant actuators, which possess the attractive feature of shock tolerance, are used in new autoloaders. However, this in turn leads to vibrations of structural flexibility, bringing more challenges for the control of autoloaders. To deal with these issues, this paper proposes a novel hybrid control based on singularly perturbed theory. The entire controlled system is decomposed into two subsystems of different timescales. Rigid autoloaders dynamics with oscillatory chassis disturbances is in the slow timescale, whereas compliant actuators dynamics is in the fast timescale. A novel trajectory tracking controller for the slow timescale dynamical subsystem is proposed based on assimilation of both the computed torque method and a feedback control law based on implicit Lyapunov function (implicit Lyapunov control). The tracking controller is theoretically proved to be robust and globally convergent. On the other hand, suppression of the flexible vibrations in the fast timescale dynamics is realized via a proposed derivative-type control law, which is shown to globally stabilize the compliant actuators. As far as we know, this is the first study providing a control strategy to asymptotically regulate the autoloader subject to chassis-induced perturbations and flexible joint vibrations. Finally, numerical simulation results are presented to show efficacy as well as robustness of the proposed control scheme.