Improved output-feedback second order sliding mode control design with implementation for underactuated slosh-container system having confined track length

In this study, a new second order sliding mode controller is designed through a novel non-linear sliding surface proposal for a slosh-container system. A linear sliding surface based controller using second order sliding mode is also derived for the comparison purpose. Both the controllers need only output measurements. The super-twisting algorithm is employed to ensure the finite time convergence of system trajectories to a second order sliding set. In sliding phase, the asymptotic stability of the system states to a desired origin is proved by proposing a new Lyapunov function for the system. A slosh-container system representing underactuated interconnected non-linear dynamics is considered. It is shown that how the consideration of limited track length of container affects the stability conditions. To generate a position trajectory for container from the control input signal, a new approach is employed for the implementation purpose. It is demonstrated through simulations and experimental results that the proposed controller based on the novel non-linear sliding surface outperforms the other controller based on the linear surface and it is more suitable on various practical aspects. This also validates the theoretical findings of the study.