Lyapunov-based settling time estimate and tuning for twisting controller

A novel switched control synthesis is developed and an upper bound on the settling time is obtained for a robust second-order sliding mode controller. The framework is based on step-by-step application of classical linear feedback design and the well-known 'twisting' controller. The underlying philosophy is to utilize globally exponentially stable linear feedback so that the trajectories enter an arbitrarily defined domain of attraction in finite time and then switch to the 'twisting' controller so that the trajectories settle at the origin in finite time. The proposed method is applied to the linear inverted pendulum to obtain an upper bound on the settling time of the closed-loop system in a full-state feedback setting in the presence of disturbances. Tuning rules to achieve the desired settling time are explicitly derived without recourse to the differential inequality of the Lyapunov function.